The Dumb Science Questions - Pro Science Answers Megathread

[Lallante]

A Repeat of my SHC thread.

And to kick us off:

Is it better to eat before or after strenuous exercise (or neither?) why?

How close is science to fully functional flexible & fully transparant screens?

We have used GM to make glow in the dark mice. Could we do that with humans just as easily? Are there any rogue labs in china or North korea or wherever that do shit like that?

[Hatepeace Lovewar]

Thread lacks Yuto. :cry:

[Amantus]

How close is science to fully functional flexible & fully transparant screens?

They've existed for years. They're hard to mass-produce though, which is why they're not available in the mass market.


We have used GM to make glow in the dark mice. Could we do that with humans just as easily? Are there any rogue labs in china or North korea or wherever that do shit like that?

Mice are a good mammalian model organism and if you can make something like a mouse bioluminescent, it'd be pretty easy to do with humans too. I believe they've already done pigs and some other mammals.
The glow in the dark technology that they're using is GFP (green fluorescent protein), which is used loads in research. It responds with a green colour when put under blue light.
Has it already been done in humans in a rogue lab? Probably not, since humans are fucking terrible test organisms since it takes so long for us to mature and reproduce, as well as the obvious ethical issues. I can't see an obvious point in doing it anyway. It's more likely to have been done in other test primates though.

(I'm p sure someone made this thread already on FHC?)

[Pacefalm]

A Repeat of my SHC thread.

And to kick us off:

Is it better to eat before or after strenuous exercise (or neither?) why?
Its better to eat both before and after. Before should be food with lots of carbohydrates like bread or pasta. If you eat a lot though its better to wait a bit to prevent cramps. Energy bars are also good. Afterwards should be some easily digestible foods like a salad.

If youre excercising to lose weight though its better not to eat anything before training (afterwards is fine).

[SteeleResolve]

What is the best :science: cure for a hangover?

[Wanten]

What is the best :science: cure for a hangover?

My medic mates give each other drips when they are hungover, say it works a treat.

[SteeleResolve]

What is the best :science: cure for a hangover?

My medic mates give each other drips when they are hungover, say it works a treat.

BUT WHAT IF DRIPS IS NOT AVAILABLE AT TIME?

[Wanten]

What is the best :science: cure for a hangover?

My medic mates give each other drips when they are hungover, say it works a treat.

BUT WHAT IF DRIPS IS NOT AVAILABLE AT TIME?

We have all seen shitty commando/fugitive films (Shooter), a bottle of water, knitting needle and a hosepipe will form a suitable replacement.

[eshru]

water
fruit juice/vitamins b&c
eggs
bananas/potassium

http://health.howstuffworks.com/wellnes ... gover6.htm (http://health.howstuffworks.com/wellness/drugs-alcohol/hangover6.htm)

[Fara]

http://www.brianmac.co.uk/drinks.htm

This site might help. Its for sports.. but it still gives couple of infos.
What you need, based on my knowledge, is something Hypotonic to get your fluids back.


1/2 small spoon of salt into every drink. Theory says its shit, but it works wonders for me.

[eshru]

why would salt help? your body is already dehydrated and stuff yeah?

[SteeleResolve]

You are all wrong.

The only way to cure a hangover is more beer.

FACT

:monocledowns:

edit: more beer, then a couple of hours sleep :guinness:

[Calks]

Something to do with Sodium helping the body to regulate/optimize the amount of water absorbed into the body and how much to send to the bladder as waste. Other electrolytes are supposed to be beneficial too.

Stuff like Dioralyte or nuun tablets work along these lines to help maintain hydration if your ill or very active.

From Fara's link above:

Electrolytes, especially sodium and potassium, in a drink will reduce urine output, enable the fluid to empty quickly from the stomach, promote absorption from the intestine and encourage fluid retention. ["The Effect of Different Forms of Fluid Provision on Exercise Performance", International Journal of Sports Medicine, vol. 14, p. 298, 1993]

[Pacefalm]

Brainiac says English Breakfast so that must be true.

[Frug]

1/2 small spoon of salt into every drink. Theory says its shit, but it works wonders for me.
Fuck theory. My mother has prescribed a shot of pickle brine during a hangover for years. It's really refreshing and does the trick for me, but you have to have good pickles. Real pickles. Not the cheap shit where the brine is basically plain vinegar and nothing else. That brine is gross to drink, but good stuff is delicious. It should be cloudy and I like it when it's a little spicy.

I'm sure it's something to do with drinking and peeing and drinking and peeing causing you to flush electrolytes.

[elmicker]

What is the best :science: cure for a hangover?

My medic mates give each other drips when they are hungover, say it works a treat.

this is brilliant, until one of them puts the drip on a bedside table, falls asleep and rolls over, dragging the bag onto the floor. a hangover combined with losing a quarter of a litre of blood is nothing but hilarity.

[KKassandra]

That would be pretty hilarious.

[mazzilliu]

http://external.ak.fbcdn.net/safe_image.php?d=0eb5686020e399ce1103d0e5dc3003a8&url=http%3A%2F%2Fknowyourmeme.com%2Fi%2F000%2F074% 2F256%2Foriginal%2F1285770302993.jpg%3F1285772817

[Pacefalm]

http://www.trollscientist.com/image/102-isaac-newton-troll-physics.jpg

[Evelgrivion]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?

[fffuuu]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?

IANA Physicist, but I would guess because the "vacuum" area in the universe isn't a true vacuum at the quantum level. influence from the gravitational and electromagnetic forces from the rest of the particles of the universe would prevent it?

I believe even observing this vacuum area would fark up the outcome anyway.

my personal pet theory is that black holes are what create new universes, they suck up matter and create such a high gravitational effect, it rips space-time a new arse, and dumps it into a new universe, or multiverse shard or something. I have nothing to support this. just a thought.

[Lusulpher]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
God.



Science concept:
If FUTUREScience was able to prove the non-existence of 'God', would their next goal be to create one? To protect space empires from calamities/aliens/end of Universe?
Wouldn't a device capable of controlling those/defining the matters of the Universe be known as a god, especially if it was tied to a pro-Human AI?
Would other primitive aliens worship us?
Would we correct them?

[Lallante]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
God.



Science concept:
If FUTUREScience was able to prove the non-existence of 'God', would their next goal be to create one? To protect space empires from calamities/aliens/end of Universe?
Wouldn't a device capable of controlling those/defining the matters of the Universe be known as a god, especially if it was tied to a pro-Human AI?
Would other primitive aliens worship us?
Would we correct them?


Read the latest Ian M. Banks book

[Belid Hagen]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?


TL:DR "I don't know or understand any of the terms or fields in science, therefore i assert X".

please shut up and read, at the very least, the wiki pages on those subjects.

[KKassandra]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy

This is a long, long way from being established as 'true'. It's a possibility, that's all. And it's not a possibility in the way you're thinking of.



, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?

1. We're still here, so it can't have
2. We got lucky (even if the Big Bang was a 'vacuum fluctuation', that doesn't mean another such fluctuation has any significant chance of happening in the time since the Big Bang - eternity is a LONG time)
3. Google 'vacuum collapse'

[Pacefalm]

At least it qualifies as a dumb science question.

[Evelgrivion]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?


TL:DR "I don't know or understand any of the terms or fields in science, therefore i assert X".

please shut up and read, at the very least, the wiki pages on those subjects.

1. It wasn't my assertion

2. At least I'm trying to understand this shit. What's wrong with asking questions about it, asshole? Give me some fucking direction, here.

[KKassandra]

1. It wasn't my assertion


Well, whoever made the assertion (either you, or whatever source you read it in), was wrong. It isn't established. See my previous post for some potential answers to your questions given that your assumption is true.

[Belid Hagen]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?


TL:DR "I don't know or understand any of the terms or fields in science, therefore i assert X".

please shut up and read, at the very least, the wiki pages on those subjects.

1. It wasn't my assertion

2. At least I'm trying to understand this shit. What's wrong with asking questions about it, asshole? Give me some fucking direction, here.

1: ok
2: read every wikipedia page on every term you used. Thats a good place to start. (thats where the rest of us started (at least figuratively, for others more literally)).

[L'oiseau]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
The current universe's accelerating expansion prevents any theoretical baby universes from "catching up" to our current one basically.

[Quarantine]

[quote=Evelgrivion]Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?


TL:DR "I don't know or understand any of the terms or fields in science, therefore i assert X".

please shut up and read, at the very least, the wiki pages on those subjects.

1. It wasn't my assertion

2. At least I'm trying to understand this shit. What's wrong with asking questions about it, asshole? Give me some fucking direction, here.

1: ok
2: read every wikipedia page on every term you used. Thats a good place to start. (thats where the rest of us started (at least figuratively, for others more literally)).[/quote:30hotmlw]

"I don't understand it well enough myself to properly explain it to you, but it sounds stupid and therefore you should check wikipedia and see if you can come up with an answer yourself :monocledowns: "

[Phrixus Zephyr]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?


TL:DR "I don't know or understand any of the terms or fields in science, therefore i assert X".

please shut up and read, at the very least, the wiki pages on those subjects.
Did you even read the thread title, asshat?

[Borgh]

yay! full on trolling and yelling by poage 2!

as far as I understood it, the universe didn't jump out of a vacuum. It went bang out of nothing at all.The entire concept of a "vacuum" did not exist yet.

[Nareg Maxence]

- B.sc. for what it's worth..


Since the universe appears to have sprung out from the vacuum as a result of quantum energy,

Now, I learn more towards the experimentalists viewpoint than that of a theorist. It seems to me that how exactly it all started is not that well established. It may have been some kind of tension in some quantum vacuum that caused it all to spring into existence, but we don't really know yet.


why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?

The reason why they are just virtual particles is because the energy of the vacuum is very low. If you believe that the universe was created by some fluctuation in a quantum state, the way to picture it is that the energy of the universe was all curled up into a spring. At some point something snapped and all the energy was released, creating our universe.

[Belid Hagen]

It's funny how people that never bothered answering questions on the 30 page thread we had on SHC come here bad mouthing the people that did. GTFO

my immediate dismissal of the questions that in themselves were completely flawed, was completely legitimate.

[killfalcon]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
The current universe's accelerating expansion prevents any theoretical baby universes from "catching up" to our current one basically.

This.

ISTR one of the 'can the LHC blow up the world' studies* noting that in the incredibly unlikely event we accidentally a whole universe, we'd have an incredibly hard time proving we'd done anything at all.


*Scientists, being both nerds and reasonably cautious with the universe they keep all their stuff in, did a lot of careful theory before we built the thing. Much like the "can an atom bomb ignite the atmosphere' study, we got a very reassuring 'no'.

[kzig]

I thought the people at the LHC got around that one by pre-emptively destroying the Earth (http://qntm.org/board)?

Not really a question, but can anyone here provide informed commentary on this article (http://www.bbc.co.uk/news/magazine-13128701)?

[Donte]

I was under the impression that "how the universe started" theories all have so many holes in them that "god did it" is just as probable.

again, im under the impression that as vast as mankinds collective knowledge about the universe is, we realy dont know shit.

oh and my dumb question... why the hell is the universe accelerating as it expands?

[Chakrai]

I was under the impression that "how the universe started" theories all have so many holes in them that "god did it" is just as probable.

again, im under the impression that as vast as mankinds collective knowledge about the universe is, we realy dont know shit.

oh and my dumb question... why the hell is the universe accelerating as it expands?

Disclaimer - our physics came about in order to describe how stuff in our universe works. It seriously runs into trouble when trying to think about things that occur before/after/outside our universe. More technically, if you try to go past a singularity (either the big bang singularity or a black hole) or try to imagine wtf the universe is expanding into then conventional physics fucks itself up the arse and we have to do complicated stuff.

That out of the way I'll answer your question. One answer is that we have assumed that the universe is both homogenous and isotropic in the vicinity of Earth when in reality it isn't. Essentially we've assumed that the universe in every direction is the same on average, however it is entirely possible that there is a large scale variation that means the universe is locally showing accelerated expansion (maybe because of gravitational effects in galaxy superclusters or whatever) but on a larger scale is actually showing decelerating expansion. I doubt that this will be the case but it does have some serious support and has not been fully discounted as of yet.

Another answer involves quantum fields and dark energy and shit. As the universe expands then it's size increases and there's more room for stuff inside it. This - through some weird stuff that I don't completely understand - causes there to be even more expansion which gives us a nice positive feedback effect. However this accounts for only a tiny fraction of the acceleration that we see.

So yeah, we don't know shit about shit.

[Loire]

It's funny how people that never bothered answering questions on the 30 page thread we had on SHC come here bad mouthing the people that did. GTFO

my immediate dismissal of the questions that in themselves were completely flawed, was completely legitimate.

I'm sure everyone will be jumping at posting in this thread. I know I definitely love having my uneducated misconceptions ripped into by an equally uneducated neckbeard who spends a good portion of his time on Wikipedia.

[Belid Hagen]

Ignorance is truely bliss, I Shall be looking forward to your questions Loire.

[Nareg Maxence]

I was under the impression that "how the universe started" theories all have so many holes in them that "god did it" is just as probable.

again, im under the impression that as vast as mankinds collective knowledge about the universe is, we realy dont know shit.

oh and my dumb question... why the hell is the universe accelerating as it expands?

Because of the cosmological constant. Because of dark energy. Dark energy acts as an internal pressure on the universe causing it to expand faster.

[KKassandra]

I was under the impression that "how the universe started" theories all have so many holes in them that "god did it" is just as probable.

again, im under the impression that as vast as mankinds collective knowledge about the universe is, we realy dont know shit.

oh and my dumb question... why the hell is the universe accelerating as it expands?

Because of the cosmological constant. Because of dark energy. Dark energy acts as an internal pressure on the universe causing it to expand faster.

Which I'm sure you'll notice isn't really an answer :) Some of this is down to our lack of understanding (the accelrating expansion was only discovered in the last 10 years), and some is down to the philosophical issues surrounding what you are prepared to accept as your starting point for discussion and reasoning (for comparison, see discussions passim on magnets, and how they work).

[Don Pellegrino]

Please stop acting like little offended schoolgirls and get back on topic, thanks!

[Phoku5]

oh and my dumb question... why the hell is the universe accelerating as it expands?


On the most basic level:

If you subscribe to the Big Bang theory, expansion results from the conservation of momentum. Lending from the late poet-philosopher Biggie Smalls, the universe "grew up a fuckin screw up, got introduced to the game got an ounce and fuckin blew up". Shit blew up and kept movin' because its outer space man. Big bang or not, objectively the "something happen theory", shits moving and its gonna keep moving in that direction until it interacts with another force.

Now the acceleration part implies an interaction between forces. This is exciting because whatever force interacting with the universe is probably a) fucking everywhere b) near-infinitely massive and c) yet to be described by science. Current theory points to "Dark matter" and the even murkier "Dark energy". These are basically unknowns which arise from calculations based observable gravity interactions within the visible universe (i.e. hmmm I can see shit contantly moving apart). Going from these calculations, and a metric fuckton of incomprehensible math, Dark matter accounts for 80% of the know mass of the universe. Nobody knows what it is and we can't see it but we can observe its effects so it exists as a yet to be described unknown -- basically an infinite amount of invisible darkies in ur base, stealing your bicycles and moving your starz.

Dark energy is a hypothetical force that is responsible for the acceleration of the universe. Again we don't know shit, but there is an observed interaction and we need a name for whats causing it. Dark energy ultimately may or may not have anything to do with Dark matter, but probably does. Again, Dark energy, like it's asshole brother, is everywhere and accounts for the majority (70%) of the mass energy of the universe.

OH SHI- recently (too lazy to find peer-reviewed sauce) there were observations that while the universe is accelerating and expanding, it is also being pulled in one direction. According to the observations there is a net (+) disproportionate amount of acceleration in one direction than the other. If this is true, whatever is pulling the universe in that direction is abso-fucking-lutely unimaginably massive, possibly rivaling our universe in size. I for one am hoping its a giant pair of tits. Queue physics troll, but there is no proof or disproof that our universe is infinite. Our universe could in fact be finite, but this sort of stuff is mostly out of the reach of our comprehension (and according to many permutations of string theory, dimension), so deal with it.

So now we're getting into string theory, and more specifically M-theory. I'm not going to get into that much because i'm a microbiologist, not a quantum theoretical physicist and nobody is reading anymore at this point. I fucked your sister. Also its fucking difficult to describe and understand within the bounds of every day anything. Knock yourself out: http://en.wikipedia.org/wiki/Introduction_to_M-theory -and- http://en.wikipedia.org/wiki/M-theory

SO to tl;dr this bitch:

tl;dr 1

The observable acceleration of the universe occurs because of an interaction with an unknown force, Dark energy, which may or may not arise from interactions between visible matter, and and an invisible unknown matter, Dark matter, which is everywhere and makes up the majority of the mass of the universe.

tl;dr 2

The unknown Dark matter and energy could be, in part or in whole, a mass/energy interaction dynamic between different dimensional membranes proposed in M-theory. Our known visible universe, occupying only a segment of these dimensional membranes, could be simultaneously accelerated outward and towards a finite point of near infinate mass/energy larger than our universe.

Of course, all of this is un-testable.

If you need me i'll be looking at porn.

[smagd]

*mind* *blown*

[KKassandra]

Of course, all of this is un-testable.

If you need me i'll be looking at porn.

Actually untestable, or untestable without building a particle accelerator the size of the solar system or some shit?

Because if it's the first, it's not science.

[Izo Azlion]

When are we going to get an energy source on the common marketplace thats cool? Like, electric cars - sorry, but boring - plus the electricity comes from the factories anyway.

I want something that sounds badass, and seeing as Petrol will run out in the near future (relatively) - we must have something cool coming up, right?

[Quarantine]

When are we going to get an energy source on the common marketplace thats cool? Like, electric cars - sorry, but boring - plus the electricity comes from the factories anyway.

I want something that sounds badass, and seeing as Petrol will run out in the near future (relatively) - we must have something cool coming up, right?

Nothing viable coming up anytime soon. The most promising research currently lies in energy storage, since one of the major problems of power generation is that we have very high peaks of energy consumption (in the morning and evening) and far, far less energy consumption during the rest of the day. To some extent this is already done by for example activating water electricity plants during the peaks and using the surplus energy in the off-hours to pump the released water back up, solutions similar to that will give the next few larger improvements in that sector.

Fossil fuels, however, are not running out anytime soon. Peak oil is a real possibility, but it's based on our current technical level of extraction methods so it might not even happen anytime soon. It's more a question of how much you are willing to pay and/or pollute the environment to generate fuel than our sources running out. Only if you combine the goal of not heating up the planet anymore with the rising energy consumption and dwindling of easily accessible fossil ressources, you get a huge problem - far larger than most people can imagine right now, because it's not possible to hope for a limitless, cheap, pollution free method of energy generation to just pop up and solve it for us.

[Quarantine]

To add at least something cool to my rather bleak post above, this is a somewhat promising new technology: http://en.wikipedia.org/wiki/Concentrated_solar_power

[CastleBravo]

Has there been any news on the potential of liquid fluoride thorium reactors lately?

[Phrixus Zephyr]

my immediate dismissal of the questions that in themselves were completely flawed, was completely legitimate.

The Dumb Science Questions
You are a fucking idiot.

[Quarantine]

Has there been any news on the potential of liquid fluoride thorium reactors lately?

My knowledge of this is second or rather third hand, as it doesn't come from physics or engineering background, but through a mate who does his PhD in energy transition studies. So I can't say much about technological advances in fission technology, only that it's still far more likely that we have to switch over to a decentralized, smart distribution system for our energy, gather it from renewable sources and greatly reduce our energy consumption than any new technology becoming viable soon to solve our energy problem.

[Belid Hagen]

Fossil fuels, however, are not running out anytime soon. Peak oil is a real possibility, but it's based on our current technical level of extraction methods so it might not even happen anytime soon. It's more a question of how much you are willing to pay and/or pollute the environment to generate fuel than our sources running out. Only if you combine the goal of not heating up the planet anymore with the rising energy consumption and dwindling of easily accessible fossil ressources, you get a huge problem - far larger than most people can imagine right now, because it's not possible to hope for a limitless, cheap, pollution free method of energy generation to just pop up and solve it for us.

http://www.youtube.com/watch?v=F-QA2rkpBSY

I'll advertise this series of videos for the 4th time in the history of the science thread, in the hope that people will actually watch it one of these times - or in the case that someone missed it.

While it is true that there are large quantities of oil, gas and coal deposits that our current technology will be unable to extract at both economically as well as energy sustainable methods - fossil fuels are indeed running out, and at an ever increasing pace.

The surveys conducted in the USA in the 70'ties estimated 5-700 years of coal left in the known reserves. but with the exponential increase in consumption, thats now closer to 100, or less. As the good professor explains, the human brain just has a problem working with exponential growth. In the oil industry there's the same problems, even though vast reserves were found a couple of years ago, the largest found in decades (in an industry of diminishing finds - every find is smaller and harder to extract, than the pocket it replaces), if they were exploited would only bed able to cover the global consumption for a decade. going by OPEC's own figures, oil production has indeed peeked, and the not even the saudies can increase output anymore, with every indian and chinese citizen wanting to own a car now aswel, why do you think gas prices has been rising steadily and some times alarmingly the past years.

My country has no coal, and our small supply of oil and gas has already peeked, and will be so little that it wont be worth mentioning in 10-15 years. Thats why we already have 30'ish percent of our electricity needs covered by renewable sources and will have 43'ish percent by 2020.

[Loire]

Fossil fuels, however, are not running out anytime soon. Peak oil is a real possibility, but it's based on our current technical level of extraction methods so it might not even happen anytime soon. It's more a question of how much you are willing to pay and/or pollute the environment to generate fuel than our sources running out. Only if you combine the goal of not heating up the planet anymore with the rising energy consumption and dwindling of easily accessible fossil ressources, you get a huge problem - far larger than most people can imagine right now, because it's not possible to hope for a limitless, cheap, pollution free method of energy generation to just pop up and solve it for us.

http://www.youtube.com/watch?v=F-QA2rkpBSY

I'll advertise this series of videos for the 4th time in the history of the science thread, in the hope that people will actually watch it one of these times - or in the case that someone missed it.

While it is true that there are large quantities of oil, gas and coal deposits that our current technology will be unable to extract at both economically as well as energy sustainable methods - fossil fuels are indeed running out, and at an ever increasing pace.

The surveys conducted in the USA in the 70'ties estimated 5-700 years of coal left in the known reserves. but with the exponential increase in consumption, thats now closer to 100, or less. As the good professor explains, the human brain just has a problem working with exponential growth. In the oil industry there's the same problems, even though vast reserves were found a couple of years ago, the largest found in decades (in an industry of diminishing finds - every find is smaller and harder to extract, than the pocket it replaces), if they were exploited would only bed able to cover the global consumption for a decade. going by OPEC's own figures, oil production has indeed peeked, and the not even the saudies can increase output anymore, with every indian and chinese citizen wanting to own a car now aswel, why do you think gas prices has been rising steadily and some times alarmingly the past years.

My country has no coal, and our small supply of oil and gas has already peeked, and will be so little that it wont be worth mentioning in 10-15 years. Thats why we already have 30'ish percent of our electricity needs covered by renewable sources and will have 43'ish percent by 2020.


It all depends on how you look at it. Current estimations for the Alberta Tar sands alone say there is enough oil to fuel North American consumption for 40 years. However then you have to factor in a growing Chinese middle class, India etc etc.

We also don't truly know how much oil is out there. When an oil company says "lol too expensive" what they actually mean is they can extract the same amount from another source. Deposits that were long considered "too expensive" have been put to use in the past before. It's hard too believe (although within the realm of possibility) that the human race has used over 500 million years worth of organic marine buildup within the span of 150 years. Most of our petroleum reserves come from the Kaskaskia sequence and that lasted only 100 million years. There have been at least 3 other similar geological periods that should have produced similar conditions.

In all likelihood don't expect petroleum deposits to run out within your lifetime, although that doesn't mean we shouldn't be moving away from it.

[Devec]

When are we going to get an energy source on the common marketplace thats cool? Like, electric cars - sorry, but boring - plus the electricity comes from the factories anyway.

I want something that sounds badass, and seeing as Petrol will run out in the near future (relatively) - we must have something cool coming up, right?

Electrical cars have their advantage. Generally a gasoline engine has a effective energy output of ~20% that means 82% goes to heat emission. Compare this to your regular coal or oil factory which has a ~70% effective energy output. Mainly because the heat is used to generate energy there instead of pressure force inside a engine. They will probably become mainstream when better battery technologies hit the market (which is currently the biggest problem)

I personally find Cars with hydrogen engines (http://en.wikipedia.org/wiki/Hydrogen_internal_combustion_engine_vehicle) very interesting (due to the high energy/volume ratio) although they are technically difficult.

Hybrid cars and their owners can suck cock.




Has there been any news on the potential of liquid fluoride thorium reactors lately?

My knowledge of this is second or rather third hand, as it doesn't come from physics or engineering background, but through a mate who does his PhD in energy transition studies. So I can't say much about technological advances in fission technology, only that it's still far more likely that we have to switch over to a decentralized, smart distribution system for our energy, gather it from renewable sources and greatly reduce our energy consumption than any new technology becoming viable soon to solve our energy problem.

Basically the system is a ton more complicated than our plutonium generating brothers we are using now, you can stuff your conspiracy theories in your ass though.

Your friend is quite right the biggest problem is that we can't store electricity properly right now without converting it into a different form of energy, which is very inefficient. Superconductors are something to keep on the lookout. Although local generation would be great (seen from the energy perspective) it would become very expensive compared to a centralized plant. A good comparison would be central heating which is already installed on-site, it is effective because it generates on demand but most of the year it is sitting still and it works. Electricity is however needed 365 days a year and knows lower peaks and highs because of our 24/7 society so on-site generation is less desirable for it.

[fffuuu]

what they mean by "lol too expensive" is "lol not obscenely profitable enough"


Has there been any news on the potential of liquid fluoride thorium reactors lately?

"lol too expensive"

srsly though. we (the USA, and most other nuke countries) built the reactors we have because they made Plutonium, which we needed for bombs, because OMG COMMIES. electric energy was just a bonus.

[Quarantine]

The surveys conducted in the USA in the 70'ties estimated 5-700 years of coal left in the known reserves. but with the exponential increase in consumption, thats now closer to 100, or less. As the good professor explains, the human brain just has a problem working with exponential growth. In the oil industry there's the same problems, even though vast reserves were found a couple of years ago, the largest found in decades (in an industry of diminishing finds - every find is smaller and harder to extract, than the pocket it replaces), if they were exploited would only bed able to cover the global consumption for a decade. going by OPEC's own figures, oil production has indeed peeked, and the not even the saudies can increase output anymore, with every indian and chinese citizen wanting to own a car now aswel, why do you think gas prices has been rising steadily and some times alarmingly the past years.

You are right about all of this, but all I said was that the estimations of peak oil are based around current extraction methods and estimated reserves. Oil sand has already been mentioned as an alternate method that will be economically viable soon, the other one being coal hydrogenation. Technological advances might at some point permit to exploit untapped oil reserves, like the reminder of already exploited oil fields (I forgot the exact figure, but it's a pretty high percentage).
If we stop burning oil for energy we could last another couple of hundred years on fossil fuels, even with exponential growth, mainly by increasing our energy efficiency and caring fuck all about side effects. We would do this at the expense of massively polluting the environment and blowing Co2 into the atmosphere, which is the far larger issue at hand. The fuss about peak-oil is good because it directs attention towards the issue, but it's not the core of the problem.

[elmicker]

srsly though. we (the USA, and most other nuke countries) built the reactors we have because they made Plutonium, which we needed for bombs, because OMG COMMIES. electric energy was just a bonus.

Tony Benn, who once resigned as Shadow Defence Secretary stating that he could never employ nuclear weapons, nor support their development, happily worked as industry/energy secretary from 74-79. He revealed in his latest book "Letters To My Grandchildren" that it was specifically kept from him that the reactors the UK built it built for plutonium production and that all of that plutonium was being shipped to the US as part of the nassau/polaris agreements. He raegd.

[Phoku5]

hijackin for a poast



Actually untestable, or untestable without building a particle accelerator the size of the solar system or some shit?

Because if it's the first, it's not science.

The basics of older string theory and the newer M permutation are generally regarded as the best possible explanations for what we observe on the subatomic level. And yes, a lot of these observations come out of particle accelerator research. Fundamentally we are searching for unknowns so the difficult part is knowing what to look for in the first place and where to find it. For example: every particle accelerator has a limited range of energy it can produce, so with each bigger and better one we build, we are still only able to look into one specific limited bandwidth of energy at a time. The answer to Dark matter, Dark energy or even the elusive Higgs could require energy 10X that of the Large Hadron Collider, or it could be in a lower energy bandwitch and we just missed it because we don't know how to detect it. The challenge is immense but testable.

The un-testable part factors in when you consider: 1) both string and M-theory begin to address multiple dimensions as a solution to unify our current flawed model of quantum physics. 2) things quickly become un-testable when you ask questions dealing in the scale of the Universe. Combining these two yields 3) how the fuck do I test for multi-dimensional parallel universes?

At this point we arrive at another fundamental limitation: 4) wat?

These higher level concepts are intrinsically out of our grasp to begin with and we are only able paint an increasingly fuzzy picture through God-tier mathematics. Simply put, this shit is way the fuck down the rabbit hole of human comprehension. I'm no expert on M-theory by any means and I don't have any LSD but i'll give you an example:

From what I recall, M/Brane-theory predicts that our universe is a giant vibrating dimensional fluid-membrane (analogous to string vibrations). There are a bunch of other dimensional membranes (Branes) around ours all vibrating at the same time and eventually at some point in the vibration cycle, part of our fluid Brane smacks into another Brane, everything as we know it asplodes and bukkakes all over itself in a massive phpBB critical error (okay okay think big-bang type event), and then resets itself as the Branes move apart again to continue their cycles. Of course this takes a bajillian earth years and has happened a bajillian times since infinity etc. etc... At this point its all math. Also its probably not real and the whole thing is orchestrated by barack obama and the lizard people. Fuck you physics.

tl;dr 3

Yes its science and built on the culmination of what we can observe up to this point, but we know we are missing something and don't really know where to look.

[Belid Hagen]

A fact that seems to support M theory, is the slight pull on the entire observable universe in the same direction. A phenomenon called "Dark flow"


"Dark flow" is no fluke, suggests a new study that strengthens the case for unknown, unseen "structures" lurking on the outskirts of creation.

In 2008 scientists reported the discovery of hundreds of galaxy clusters streaming in the same direction at more than 2.2 million miles (3.6 million kilometers) an hour.

This mysterious motion can't be explained by current models for distribution of mass in the universe. So the researchers made the controversial suggestion that the clusters are being tugged on by the gravity of matter outside the known universe.

Now the same team has found that the dark flow extends even deeper into the universe than previously reported: out to at least 2.5 billion light-years from Earth.

After using two additional years' worth of data and tracking twice the number of galaxy clusters, "we clearly see the flow, we clearly see it pointing in the same direction," said study leader Alexander Kashlinsky, an astrophysicist at NASA's Goddard Space Flight Center in Maryland.

"It looks like a very coherent flow."

The find adds to the case that chunks of matter got pushed outside the known universe shortly after the big bang—which in turn hints that our universe is part of something larger: a multiverse.

(Related: "Searching for Other Earths" in National Geographic magazine.)

Dark Flow's Extended Reach

Kashlinsky and colleagues first noticed the dark flow when studying the way gas in galaxy clusters interacts with the cosmic microwave background radiation. This burst of light is thought to have been released just 380,000 years after the big bang and now permeates the universe.

(Related: "Universe 20 Million Years Older Than Thought.")

Data from the Wilkinson Microwave Anisotropy Probe (WMAP) can show the minute temperature changes created as the cosmic microwave background radiation moves through gases in galaxy clusters.

These gases scatter light from the cosmic microwave background radiation as it passes through the clusters, similar to the way Earth's atmosphere can scatter starlight, making some stars twinkle.

But the clusters are also moving relative to the background radiation, so the scattered light gets distorted further by the Doppler effect. This distortion appears in the form of temperature shifts in WMAP data, which can reveal the clusters' direction and speed.

"It is very difficult to isolate [the temperature change] for each individual cluster," Kashlinsky said, so the original study had examined 700 clusters.

The new study is based on the collective motion of about 1,400 galaxy clusters, and seeing dark flow with the greater number of clusters gives the researchers more confidence in their result.

In addition, the team tested their analysis method by comparing the x-ray brightness of certain clusters with the strength of temperature changes seen in the WMAP data. Brighter clusters—those with more hot gases—would be expected to have greater effects on the cosmic microwave background, and that's what the new study confirmed.

Kashlinsky speculates that the dark flow extends "all the way across the visible universe," or about 47 billion light-years, which would fit with the notion that the clusters are being pulled by matter that lies beyond known horizons.

Dark flow, he said, "would be much more difficult to explain theoretically if it extended [2.5 billion light-years] and then just stopped."

source: National Geographic (http://news.nationalgeographic.com/news/2010/03/100322-dark-flow-matter-outside-universe-multiverse/)

and the wiki page: http://en.wikipedia.org/wiki/Dark_flow

[Mrenda]

With spinning things, like the wheels on a car and the blades on a helicopter, what determines what you see of it? With a propellor you generally see a couple of clear lines amidst the blur. What does that?

[Pacefalm]

Eyes can only see a limited amount of images / second.
Same reason why sometimes you look at a driving car's rims and they seem to go in reverse, it's because in every "frame" that you see the wheels haven't made a full circle.

[Mrenda]

There has to be more to it than that. If you look at a propellor the blades will show up in roughly the same place no matter how many times you look away and look back.

It's not simple refresh rate issue.

[lubica]

afaik, it is just that simple. Also, remember that what your eyes see and what your brain interprets these images as, are not always identical or even real (drugs/alchohol not included).

[Miriam Sasko]

Not entirely sure, but iirc it has something to do with angles and reflected light.

[Hels]

I see that phenomenon all the time. If you watch props upspeed or downspeed you'll see that they go from forward, slow to a stop, to reverse and back again as they come down off the RPMs. It's literally refresh rate, and why computers need what, 32 FPS for it to even seem smooth and 60 to be indistinguishable.

Film gets away with it because their images are blurred with movement already, except for CGI films which have to add in the blur to run on the 24fps projectors. The brain likes the blur and uses it to fill in the movements afaik, whereas you get like Eve running at 24fps and it seems jumpy.

Saw a show about this a while back, mostly focusing on the blurring aspect that needed to be done in CGI films (I think it focused on Monsters Inc). Can't say for sure.

[Chakrai]

It's a stroboscopic effect. Your eyes can see a certain FPS and if you are looking at something that is oscillating at a multiple of that FPS then it appears to stand still. If it is oscillating at a multiple +- a few Hertz then it will appear to move slowly.

Similar effect to this:

http://www.youtube.com/watch?v=4XkywLza-9E

[Pacefalm]

It's a stroboscopic effect. Your eyes can see a certain FPS and if you are looking at something that is oscillating at a multiple of that FPS then it appears to stand still. If it is oscillating at a multiple +- a few Hertz then it will appear to move slowly.

Similar effect to this:

[youtube:64gkyq0o]4XkywLza-9E[/youtube:64gkyq0o]

fyp

[balistic void]

It's absolutely related to refresh rates and phase beats. In my werk I deal with this problem a lot. If I want to make a chart scroll across a screen it will flicker like crazy if it's "out of phase" and thus look shit. Solution is to set scrolling speed to a something in-phase with the monitors 60hz.

The first post on this thread asked about flexible screens and stuff, saw this: http://www.bbc.co.uk/news/technology-13308452

[smagd]

Not a Dumb Question, but I figured this would go here:

Technology behind Gravity Probe B that proved a spinning mass will distort space and time nearby.

http://einstein.stanford.edu/TECH/technology1.html

They had to solve quite a few nice brain-teasers, i. e. how exactly do you measure the spinning axis of a perfect globe without slowing it down, or how do you balance any orbit disturbence by solar wind or stray particles?

[Swamp Donkey]

http://www.technologyreview.com/blog/arxiv/26813/?p1=Blogs

What kind of sweet real life applications does that have?

[elmicker]

What I'm more interested in is why it's "Dynamical" and not just "Dynamic".

[Belid Hagen]

http://www.technologyreview.com/blog/arxiv/26813/?p1=Blogs

What kind of sweet real life applications does that have?

the Casimir effect was proven to exist decades ago. As for applications, we'd have to get a guy or gal witha phd in applied physics and one in theoretical physics to give an actual answer.

[Tellenta]

There has to be more to it than that. If you look at a propellor the blades will show up in roughly the same place no matter how many times you look away and look back.

It's not simple refresh rate issue.

It really is that simple, next time you stare at a helicopters rotors blink rapidly for a more still image result instead of the spinning rotor thing.

[Keorythe]

There has to be more to it than that. If you look at a propellor the blades will show up in roughly the same place no matter how many times you look away and look back.

It's not simple refresh rate issue.

It really is that simple, next time you stare at a helicopters rotors blink rapidly for a more still image result instead of the spinning rotor thing.

In this video they used a special camera which sort of eliminated a frame per section. They did this to observe the bend and stress on these rotor blades. The effect is the blades look like they aren't moving.

[youtube:340euzo4]Rdo3PsBHEPo[/youtube:340euzo4]

[Hellkyte]

How close is science to fully functional flexible & fully transparant screens?

They've existed for years. They're hard to mass-produce though, which is why they're not available in the mass market.

As an add-on to this response, they are nowhere near commercial. In my old job I worked w/ CNTs (= carbon nanotubes) and we were working on this kind of stuff. The first challenge for flexible electronics is high conductivity w/ high transparency. As of the last time I was really involved in it the only option for that at the conductivities needed were CNTs. There may have been some inprovements in conductive polymers but I highly doubt it has gone far enough for flexible electronics

One problem with CNTs is that they are black, not just dark but literally the blackest substance known to man. So you have to massively thin them out in some junk and spray them on something. The nature of CNTs is that they don't dissolve in....well anything easily so this is a massively difficult frabrication process.

The hardest part with the CNTs though is mass producing the nanotubes themselves consistently. There are numerous low volume methods for producing high quality CNTs, but they are irrelevant for commercial products (we're talking 2-20k per gram). The mass production methods out there are batch only, difficult to scale up, and hard to control. A lot of this has to do with them having reaction conditions requiring temperatures of ~800 C.

Anyways, the "idea" of how to do a flexible screen has been around for a long time. The reality of doing it though is years off if not more. There is little interest in the commercial sector for pushing it beyond e-ink readers (which are already viable) as long as ITO (indium tin oxide, primary material in LCDs) remains as obscenely cheap as it is.

Another bumber tied to this story is the fact that these materials that are too expensive to build small little screens, are the same materials that would be required to build a space elevator. So space elevators are basically science fiction as building one would cost more than the annual GDP of every major country in the world combined.

The good side of the story is that CNTs provide a feasible route towards a lot of other important tech problems. They can be used to build better solar cells. They can be used to build beter fuel cells. They can be used to fight cancer (no shit). So they're here to stay and we'll see them push forward in a lot of different realms and eventually get those flexible touch screens.

--------------

Now, a question. Simple particle in a box wavefunction is a sin curve(idealized I know). When you square it you get the particle density (where it spends its time). Since the particle inhabits either side of teh wave function (the grand tetons) how does the particle get from the left side to the right side without passing through the node in the center?

And for anyone who says "that's an idealized system" look at the x,y,and z p-orbitals of a molecule. There is a node there in the center, the particle passes through that node, yet according to the particle density function it never spends any time there. d-orbitals show this even more clearly.

So how does this occur? The electrons aren't jumping to different orbitals (like the s orbital) to pass the node (from what I understand). They can't just teleport across the node. So where is your precious SCIENCE NOW! Jk. Seriously though this always tripped me out.

[pratell]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
anyone who hypothesizes about the existence of the universe before the big bang is a philosopher, not a scientist.

[super7]

ignore me, I'm too dumb to read the previous replies. :facepalm:

[cpl_fisher]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?


TL:DR "I don't know or understand any of the terms or fields in science, therefore i assert X".

please shut up and read, at the very least, the wiki pages on those subjects.Reading wiki pages about how the universe sprung into existence is about as dumb as reading the bible for the same answers.

[Tellenta]

]Reading wiki pages about how the universe sprung into existence is about as dumb as reading the bible for the same answers.

You take that back! Wikki has all the answers!

[kzig]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
anyone who hypothesizes about the existence of the universe before the big bang is a philosopher, not a scientist.
Does that still apply if they can make (and test) predictions about how the hypothetical other universe(s) could affect our own?

[Tarminic]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
anyone who hypothesizes about the existence of the universe before the big bang is a philosopher, not a scientist.
Does that still apply if they can make (and test) predictions about how the hypothetical other universe(s) could affect our own?
Then you're no longer hypothesizing, you're testing and predicting in addition to hypothesizing.

[hippoking]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
anyone who hypothesizes about the existence of the universe before the big bang is a philosopher, not a scientist.
Does that still apply if they can make (and test) predictions about how the hypothetical other universe(s) could affect our own?
Yes, but I've never seen any thought along those lines. It's rather in the definition of 'universe' that it's everything. Unless it has a direct consequence to our universe, discussing it is completely useless scientifically.

Like the 'maybe our universe is just inside an electron in another universe' idea - if it has no effect on us, and no possible way of verifying its truth or falsehood then it's literally the most pointless discussion ever.

[pratell]

Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?
anyone who hypothesizes about the existence of the universe before the big bang is a philosopher, not a scientist.
Does that still apply if they can make (and test) predictions about how the hypothetical other universe(s) could affect our own?
Yes, but I've never seen any thought along those lines. It's rather in the definition of 'universe' that it's everything. Unless it has a direct consequence to our universe, discussing it is completely useless scientifically.

Like the 'maybe our universe is just inside an electron in another universe' idea - if it has no effect on us, and no possible way of verifying its truth or falsehood then it's literally the most pointless discussion ever.
obv we need mallory quinn to help us out here.

[Lusulpher]

Not a Dumb Question, but I figured this would go here:

Technology behind Gravity Probe B that proved a spinning mass will distort space and time nearby.

http://einstein.stanford.edu/TECH/technology1.html

They had to solve quite a few nice brain-teasers, i. e. how exactly do you measure the spinning axis of a perfect globe without slowing it down, or how do you balance any orbit disturbence by solar wind or stray particles?

-Create perfect vacuum. In space. Vacuum is protected with some superdense material. No neutrinos here bro.
-Spin liquid composed of very tiny particles. Let settle into perfect sphere.
-Map with laser grid?
-Coat using laser-aimed robotics. A soft eggshell that can be punctured to suck out the fluid inside.
-Repeat?
-Near-flawless ball bearings for maglev trains, green energy tech.
-profit?

Space is awesome for technology. But I just found out they can't build Sir Branson's space elevators without bankrupting the universe. :cry:

http://boards.straightdope.com/sdmb/archive/index.php/t-505115.html
Good questions.
http://www.dailygalaxy.com/my_weblog/2008/11/will-a-nano-fib.html
http://en.wikipedia.org/wiki/Carbon_nanotube
My question is, who is working on scaling up production? What is the projected cost?

[Belid Hagen]

[quote=Evelgrivion]Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?


TL:DR "I don't know or understand any of the terms or fields in science, therefore i assert X".

please shut up and read, at the very least, the wiki pages on those subjects.Reading wiki pages about how the universe sprung into existence is about as dumb as reading the bible for the same answers.[/quote:eopmm764]

I get my answers on astrophysics from the writings of Stephen Hawking, Lawrence Krauss, Neil DeGrasse Tyson and others. But if people can't even go so far as to read the "cliffs notes" provided on wikipedia for just about every subject, giving an actual answer is usually a waste of time - much like this post to respond to your inane drivel is.

[cpl_fisher]

[quote="Belid Hagen":1p1a2ekk][quote=Evelgrivion]Since the universe appears to have sprung out from the vacuum as a result of quantum energy, why hasn't another universe sprung out of the huge bulk of vacuum that permeates the universe? "Virtual particles" are popping in and out all the time, but why aren't "real" ones?


TL:DR "I don't know or understand any of the terms or fields in science, therefore i assert X".

please shut up and read, at the very least, the wiki pages on those subjects.Reading wiki pages about how the universe sprung into existence is about as dumb as reading the bible for the same answers.[/quote:1p1a2ekk]

I get my answers on astrophysics from the writings of Stephen Hawking, Lawrence Krauss, Neil DeGrasse Tyson and others. But if people can't even go so far as to read the "cliffs notes" provided on wikipedia for just about every subject, giving an actual answer is usually a waste of time - much like this post to respond to your inane drivel is.[/quote:1p1a2ekk]
lulsulpher is allowed to edit wiki post. If he edits an article that isn't visited very often, it could be months or years before his rantings could be discovered and changed. Think about that before you defend the reliability of Wikipedia.

[mitthrawn]

Question: If one could build a spaceship which is as fast as 99% of the speed of light. And if this very spaceship launches (forward of course -.-) a rocket with a speed of 2% the speed of light. Would the universe as we know it end?

[Chakrai]

Question: If one could build a spaceship which is as fast as 99% of the speed of light. And if this very spaceship launches (forward of course -.-) a rocket with a speed of 2% the speed of light. Would the universe as we know it end?

Couldn't happen. You can never accelerate up to the speed of light, as you get closer it becomes harder and harder to accelerate any more.

Oh as to the wiki vs. this thread - You're all talking bollocks. Although the wiki will have 90% of the information you want, not everyone can understand things from just reading out of a wiki. If that was a reliable way of understanding new and weird concepts then my jobs would just be making sure that 20 hormonal teenagers stayed on wikipedia for several hours a day and bollocking the ones that look for porn or flash games instead.

[mitthrawn]

Question: If one could build a spaceship which is as fast as 99% of the speed of light. And if this very spaceship launches (forward of course -.-) a rocket with a speed of 2% the speed of light. Would the universe as we know it end?

Couldn't happen. You can never accelerate up to the speed of light, as you get closer it becomes harder and harder to accelerate any more.
Why?

[Chakrai]

Question: If one could build a spaceship which is as fast as 99% of the speed of light. And if this very spaceship launches (forward of course -.-) a rocket with a speed of 2% the speed of light. Would the universe as we know it end?

Couldn't happen. You can never accelerate up to the speed of light, as you get closer it becomes harder and harder to accelerate any more.
Why?

Albert Einstein's theory of special relativity. Essentially if you live in a universe where the speed of light is a constant and the same for every observer (like ours) then the universe twists everything to ensure that this remins the case. This means that your simple equations for stuff like kinetic energy, momentum and acceleration get an extra term that depends on how close the speed of light you are. Oh it causes weird stuff to happen to time as well but we'll save the Emmett Brown shit for another post.

(Kinetic energy is the energy a body has by virtue of its motion. Essentially you can think of it as a measure of how hard it is to get a body up to a certain speed.)

The upshot of this is that at the speed of light you will have infinite kinetic energy. As you get closer, the amount of energy required to go just that tiny bit faster increases exponentially. Going from 99% lightspeed to 99.9% requires similar amounts of kinetic energy as going from stationary to 99% in the first place*. Going from 99.9% to 99.99% requires an even stupider amount of energy input. The closer you get, the more energy required. Actually hitting lightspeed will require an infinite amount of energy to be put in.

*These numbers are semi-made up - I really can't be arsed to do the maths tonight but they show the principle.

[mitthrawn]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?

[Pacefalm]

What do you mean with "has the capability of traveling with 2% of the speed of light"?
In essence the reason you can;t get to or past the speed of light, is because you need progressively more energy to accellerate further. So when firing the missile from "standstill", it has enough thrust to accellerate to 2% of lightspeed. But once you fire it from a spaceship moving at 99% of the speed of light, it can maybe only reach 99.5% of lightspeed with the same thrust. And it goes on and on like that, eventually you need an infinite amount of energy to get from 99.99999999...% to 100% of the speed of light.

[elmicker]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

Accelerations are only additive at low velocities. Once you get up to so-called relativistic speeds, speeds where you're describing things in terms of significant fractions of the speed of light, accelerations become multiplicative; instead of adding 2% of the speed of light, as you would from a standstill, it's going to add 2% of what's left between the current speed and the speed of light*. Each unit of energy added results in less and less speed, tending towards a requirement of infinite energy, or zero mass, to reach the speed of light.

*Not 2%, but it serves as a good example of how it works. Things only appear to be linear and additive in classical physics because the bit of the curve we exist on is so minor and so flat that the inaccuracies that result from the linear/additive assumptions are close to nil.

[Chakrai]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?
Remember what I said about the universe twisting things? Well this applies here as well. What you see depends on where you are observing from.

If you are observing from the ship then you see the rocket moving away from you at 2% the speed of light. If you are observing at something "stationary" compared to the ship then you see the ship going at 99% the speed of light and the rocket going a little faster - but still slower than the speed of light.

This is because of the weird stuff that happens with time when you are in high speed situations.

[Frug]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?
Remember what I said about the universe twisting things? Well this applies here as well. What you see depends on where you are observing from.

If you are observing from the ship then you see the rocket moving away from you at 2% the speed of light. If you are observing at something "stationary" compared to the ship then you see the ship going at 99% the speed of light and the rocket going a little faster - but still slower than the speed of light.

This is because of the weird stuff that happens with time when you are in high speed situations.
So I already thought I knew this but now I'm unsure.

Is it because space/time is bent (well, relatively skewed) and prevents objects from moving that fast relative to eachother, or is it because of the amount of energy required to propel something that fast?

Or is it both?

I had previously heard it explained as a problem of energy required reaching infinity.

edit: also your pacman signature looks like your question which is weird.

[cpl_fisher]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?
Remember what I said about the universe twisting things? Well this applies here as well. What you see depends on where you are observing from.

If you are observing from the ship then you see the rocket moving away from you at 2% the speed of light. If you are observing at something "stationary" compared to the ship then you see the ship going at 99% the speed of light and the rocket going a little faster - but still slower than the speed of light.

This is because of the weird stuff that happens with time when you are in high speed situations.
My question is what do you measure the speed of light against? Speed is always relative. There are two coins sitting on my desk, relative to each other, they have no speed. Relative to the sun, they are going at a pretty fast clip.
So my thought experiment is this: what happens if I have two bodies, going in exactly opposite directions from each other. From an observer sitting right in the middle of them, they are traveling at 51% of c. relative to each other, they are going 102% of c.
I just don't see how in an entire universe, where things are flying everywhere, you don't get some fucked up readings.

[Chakrai]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?
Remember what I said about the universe twisting things? Well this applies here as well. What you see depends on where you are observing from.

If you are observing from the ship then you see the rocket moving away from you at 2% the speed of light. If you are observing at something "stationary" compared to the ship then you see the ship going at 99% the speed of light and the rocket going a little faster - but still slower than the speed of light.

This is because of the weird stuff that happens with time when you are in high speed situations.
My question is what do you measure the speed of light against? Speed is always relative. There are two coins sitting on my desk, relative to each other, they have no speed. Relative to the sun, they are going at a pretty fast clip.
So my thought experiment is this: what happens if I have two bodies, going in exactly opposite directions from each other. From an observer sitting right in the middle of them, they are traveling at 51% of c. relative to each other, they are going 102% of c.
I just don't see how in an entire universe, where things are flying everywhere, you don't get some fucked up readings.
It took Albert Einstein to crack that one. Lightspeed is always the same. Whatever speed you are travelling at. That's the Special bit of Special Relativity.

Oh and it gives a metric fuckton of crazy stuff.




I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?
Remember what I said about the universe twisting things? Well this applies here as well. What you see depends on where you are observing from.

If you are observing from the ship then you see the rocket moving away from you at 2% the speed of light. If you are observing at something "stationary" compared to the ship then you see the ship going at 99% the speed of light and the rocket going a little faster - but still slower than the speed of light.

This is because of the weird stuff that happens with time when you are in high speed situations.
So I already thought I knew this but now I'm unsure.

Is it because space/time is bent (well, relatively skewed) and prevents objects from moving that fast relative to eachother, or is it because of the amount of energy required to propel something that fast?

Or is it both?

I had previously heard it explained as a problem of energy required reaching infinity.

edit: also your pacman signature looks like your question which is weird.

Yeah it is due to energy reaching infinity. You need infinite energy to go at lightspeed but you can (obviously) never get infinite energy. And ya, this is because of spacetime acting in a very weird way when you go really fast (essentially you have to redefine momentum which leads to a redefinition of kinetic energy that then tends towards infinity at the speed of light).

EDIT - mitthrawn I am in sexual love with the woman in your avatar. Who is this fine siren?

[TurielD]

Hm, I have no actual knowledge but the way it worked in my head was that time slows down as you get closer to the speed of light. As acceleration is distance/time/time when time is at a crawl you can't really 'speed up' by expending more energy, because the rate of expenditure goes down over relative time. As time would effectively stop at the speed of light it's not possible to accelerate up to there, because time is so closed to stopped as for acceleration to no longer be possible.

[Pacefalm]

My question is what do you measure the speed of light against? Speed is always relative. There are two coins sitting on my desk, relative to each other, they have no speed. Relative to the sun, they are going at a pretty fast clip.
So my thought experiment is this: what happens if I have two bodies, going in exactly opposite directions from each other. From an observer sitting right in the middle of them, they are traveling at 51% of c. relative to each other, they are going 102% of c.
I just don't see how in an entire universe, where things are flying everywhere, you don't get some fucked up readings.
The thing is, while moving at low velocities (for example 10mph), 2 objects moving from eachother can be seen as having a total velocity of 10+10=20mph between them. However if you get close to c, this does no longer hold.

In actuality according to special relativity, there is a factor (called the lorentz factor) which is used to "unify" two different observations into a the other's frame of reference. This factor is equal to 1/sqr(1-(v^2/c^2)) where v = speed. You can immediately see that at very low velocities, v^2/c^2 ~0. 1/sqrt(1-0)=1, so there is no effect. But at v=0.5c, the calculation is 1/sqrt(1-0.25) is not the same as 1. I won't go into too much detail but basically once you get past a few % of c, it's no longer possible to simply add speeds together to get the relative speed between objects, you have tot take into account that space and time stretch which can affect the observations.

[Frug]

Hm, I have no actual knowledge but the way it worked in my head was that time slows down as you get closer to the speed of light. As acceleration is distance/time/time when time is at a crawl you can't really 'speed up' by expending more energy, because the rate of expenditure goes down over relative time. As time would effectively stop at the speed of light it's not possible to accelerate up to there, because time is so closed to stopped as for acceleration to no longer be possible.
This and chakkrai's post make it pretty simple to understand, thx.

[CastleBravo]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?

Time dilation. A space ship capable of accelerating .99 the speed of light is launched from a mothership already traveling at .99 the speed of light relative to an outside observer. Because time is moving slower for the people on the ships compared to the stationary observer, the people on the launched ship will see themselves moving away from the mothership at 99% the speed of light, while the stationary outside observer will see the mothership moving at 99% and the ship it launched moving at 99.99%.

[CastleBravo]

My question is what do you measure the speed of light against? Speed is always relative. There are two coins sitting on my desk, relative to each other, they have no speed. Relative to the sun, they are going at a pretty fast clip.
So my thought experiment is this: what happens if I have two bodies, going in exactly opposite directions from each other. From an observer sitting right in the middle of them, they are traveling at 51% of c. relative to each other, they are going 102% of c.
I just don't see how in an entire universe, where things are flying everywhere, you don't get some fucked up readings.

To the observer in the middle, for whom time is moving "normally", the distance between the two moving bodies is expanding at 102% of c, but for observers in the bodies moving away, time is moving slower relative to the stationary observer, so they perceive the other moving body to be moving away at less than c.

[Frug]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?

Time dilation. A space ship capable of accelerating .99 the speed of light is launched from a mothership already traveling at .99 the speed of light relative to an outside observer. Because time is moving slower for the people on the ships compared to the stationary observer, the people on the launched ship will see themselves moving away from the mothership at 99% the speed of light, while the stationary outside observer will see the mothership moving at 99% and the ship it launched moving at 99.99%.
AGH WHICH ONE IS IT

or is it both. I'm quickly thinking it must be a combination of factors conspiring to prevent us from going back in time to kill hitler.

[CastleBravo]

I understand the principle here but why wouldn't it be possible to launch a rocket (with the capability to go as fast as at least 2% the speed of light) from a ship that already travels with 99% the speed of light?

I mean if I would launch a rocket would it actually fly backwards or what? What happens in such situation? Doesn't the rocket already travels with 99% the speed of light, has already the kinetic energy of the spaceship, so the extra speed of the rocket should push it over the edge?

Time dilation. A space ship capable of accelerating .99 the speed of light is launched from a mothership already traveling at .99 the speed of light relative to an outside observer. Because time is moving slower for the people on the ships compared to the stationary observer, the people on the launched ship will see themselves moving away from the mothership at 99% the speed of light, while the stationary outside observer will see the mothership moving at 99% and the ship it launched moving at 99.99%.
AGH WHICH ONE IS IT

or is it both. I'm quickly thinking it must be a combination of factors conspiring to prevent us from going back in time to kill Hast.

There is no real speed, there is only relative speed measured from a particular frame of reference. There is no superior frame of reference from which to measure speed.

[Belid Hagen]

My question is what do you measure the speed of light against? Speed is always relative. There are two coins sitting on my desk, relative to each other, they have no speed. Relative to the sun, they are going at a pretty fast clip.
So my thought experiment is this: what happens if I have two bodies, going in exactly opposite directions from each other. From an observer sitting right in the middle of them, they are traveling at 51% of c. relative to each other, they are going 102% of c.
I just don't see how in an entire universe, where things are flying everywhere, you don't get some fucked up readings.
The thing is, while moving at low velocities (for example 10mph), 2 objects moving from eachother can be seen as having a total velocity of 10+10=20mph between them. However if you get close to c, this does no longer hold.

In actuality according to special relativity, there is a factor (called the lorentz factor) which is used to "unify" two different observations into a the other's frame of reference. This factor is equal to 1/sqr(1-(v^2/c^2)) where v = speed. You can immediately see that at very low velocities, v^2/c^2 ~0. 1/sqrt(1-0)=1, so there is no effect. But at v=0.5c, the calculation is 1/sqrt(1-0.25) is not the same as 1. I won't go into too much detail but basically once you get past a few % of c, it's no longer possible to simply add speeds together to get the relative speed between objects, you have tot take into account that space and time stretch which can affect the observations.

but in the example he chose the two bodies would be going faster than the speed of light (relative to each other), and that is just fine and dandy. the observer standing still would still see them both as they are both going half the speed of light (assuming we had the instruments to see those stellar bodies in the depth of space without a star near them).

[Pacefalm]

The observer would see them both moving away at 0,51c, but from the frame reference of either of the bodies, it would not look like the other is moving away at 1,02c, but slower.

[Belid Hagen]

The observer would see them both moving away at 0,51c, but from the frame reference of either of the bodies, it would not look like the other is moving away at 1,02c, but slower.

no. by the virtue of going faster than the speed of light relative to each other, they would be unable to ever see each other.

[Pacefalm]

Oh you are correct my bad, i thought for one second special relativity was an accepted theory in the scientific community, boy was i wrong

[Frug]

There is no real speed, there is only relative speed measured from a particular frame of reference. There is no superior frame of reference from which to measure speed.
I know, but that statement alone doesn't preclude them moving faster than c relative to eachother. Time dilation can affect how they perceive it relative to eachother. I do know a few of the thought experiments explaining why, for example, you can't take a ridiculously long pole and swing it around fast enough so that the end of the pole moves faster than light, or the train with the bouncing light.

But the energy requirement argument also sounds legit and I keep hearing it backed up by people, so I can't help but think that both reasons are true.

[MortyM]

There is no real speed, there is only relative speed measured from a particular frame of reference. There is no superior frame of reference from which to measure speed.
I know, but that statement alone doesn't preclude them moving faster than c relative to eachother. Time dilation can affect how they perceive it relative to eachother. I do know a few of the thought experiments explaining why, for example, you can't take a ridiculously long pole and swing it around fast enough so that the end of the pole moves faster than light, or the train with the bouncing light.

But the energy requirement argument also sounds legit and I keep hearing it backed up by people, so I can't help but think that both reasons are true.
Reason for what? That you can't go faster than the speed of light?
There is no real reason for that, it just how things work. The closest you'll ever come to a reason is that if you apply Einstein's formulas to calculate the amount of energy needed to accelarate to the speed of light, you end of with infinity.

[EchoEpsilon23]

What are some good books on the astronomy of Earth and Moon lagrange points, the moon geology in depth and realistic travel between planets in the solar system. Just looking to seperate myself from what Science fiction likes to say is true, so I'm better informed with space mumble jumble.

[Tyrus Tenebros]

There is no real speed, there is only relative speed measured from a particular frame of reference. There is no superior frame of reference from which to measure speed.
I know, but that statement alone doesn't preclude them moving faster than c relative to eachother. Time dilation can affect how they perceive it relative to eachother. I do know a few of the thought experiments explaining why, for example, you can't take a ridiculously long pole and swing it around fast enough so that the end of the pole moves faster than light, or the train with the bouncing light.

But the energy requirement argument also sounds legit and I keep hearing it backed up by people, so I can't help but think that both reasons are true.

The reason a single body cannot go faster than c is that to accelerate to that speed requires an infinite amount of energy.

The reason 2 different observers will not observe things going over c despite the frame of reference is due to time dilation. Time dilation is wierd. As mentioned before: if you're on a craft going .99 c, and you launch a rocket capable of going .1c, you see the rocket moving away from you as if everything is normal and dandy: your frame of reference, which is time-dilated, sees a rocket moving away from you at .1c. An outside observer, however, sees your time-dilated craziness and a rocket moving away from you at some percentage faster than you, but not at 1.09c

if two objects at .51c move away from each other, the time dilation effect still takes hold and you see the other guy moving away at some percentage of c

[MortyM]

There is no real speed, there is only relative speed measured from a particular frame of reference. There is no superior frame of reference from which to measure speed.
I know, but that statement alone doesn't preclude them moving faster than c relative to eachother. Time dilation can affect how they perceive it relative to eachother. I do know a few of the thought experiments explaining why, for example, you can't take a ridiculously long pole and swing it around fast enough so that the end of the pole moves faster than light, or the train with the bouncing light.

But the energy requirement argument also sounds legit and I keep hearing it backed up by people, so I can't help but think that both reasons are true.

The reason a single body cannot go faster than c is that to accelerate to that speed requires an infinite amount of energy.

The reason 2 different observers will not observe things going over c despite the frame of reference is due to time dilation. Time dilation is wierd. As mentioned before: if you're on a craft going .99 c, and you launch a rocket capable of going .1c, you see the rocket moving away from you as if everything is normal and dandy: your frame of reference, which is time-dilated, sees a rocket moving away from you at .1c. An outside observer, however, sees your time-dilated craziness and a rocket moving away from you at some percentage faster than you, but not at 1.09c

if two objects at .51c move away from each other, the time dilation effect still takes hold and you see the other guy moving away at some percentage of c
Every reference frame is time-dilated. There are no right or wrong reference frames, or superior or inferior ones, each and everyone is just valid as every other. You can't say the rocket has antmore time-dilated craziness than the observer, both have just as much.

[Tyrus Tenebros]

I was saying the outside observer would see something different due to the overall effects of the time dilation. Both frames are indeed time-dilated, but nobody really cares that much what the rocket thinks (unless somebody is inside it, or its an advanced AI suicide rocket)

[Sallah Hernandes]

I was saying the outside observer would see something different due to the overall effects of the time dilation. Both frames are indeed time-dilated, but nobody really cares that much what the rocket thinks (unless somebody is inside it, or its an advanced AI suicide rocket)

Suicide AI, best AI.

[youtube:2paxnkwn]g_47mmt5SZY[/youtube:2paxnkwn]

[MortyM]

Anyway, more relativity craziness.

Objects also contract in size as they go faster.
So for instance a train with a 'rest-length' of 100 meters will be only 60 meters at a certain percentage of the light speed. Now this train enters a tunnel that is 80 meters long. So the train fits inside the tunnel entirely.
Now if you close the tunnel doors once its inside, so the train crashes into the door and comes to a halt instantaneously. Since its 'rest-length' is 100 meters it suddenly won't fit anymore, how can this be ?!

[Sallah Hernandes]

Because all compressible space between materials has been used to push passenger's asses through their eyeballs?

[Cydo]

Why are cold's so common ?

[Aramendel]

Thats not that crazy. I mean, objects change volume based on temperature too. Due to easily undertsandable phyiscal laws, sure, but size change to due speed isn't really different there. Exept that the laws aren't as easy to understand that is ^^

[SteeleResolve]

holy shit this thread

sofail thread <-----------------------(gazillion light years) -------------------------> this thread

GG FHC. It's like the chavtastic Asda ultrastore of awesomeness and failureness rolled into one. o7

[Jags]

Great thread, mind is indeed fucked.

One quick question about tidal/wave power , are we realistically only 3 or 4 generations from this being economically viable as a replacement for some of the coal burning power stations ? Watching the developments with interest due to the west/north coasts of Scotland reportedly being one of the more ideal locations for these types of renewable energy creation , plus having oil it would be the Saudi of the North here :D

[MortyM]

Thats not that crazy. I mean, objects change volume based on temperature too. Due to easily undertsandable phyiscal laws, sure, but size change to due speed isn't really different there. Exept that the laws aren't as easy to understand that is ^^
But it doesn't 'really' change in size, its size is just different in different reference frames. So in one reference frame it can be inside the tunnel entirely, while in the other it can't. So in the one reference frame you can close both doors instantaneously at the exact same time, trapping the train inside, while in the other that can not acctually happen.
So which one is the 'correct' reference frame, well both are, since there is never any preference in reference frames. It is just that the sequence of events also differs between the reference frames, what happens at the same time in one, does not necessarily happen at the same time in another.

[elmicker]

Why are cold's so common ?

There are over 200 different viruses that cause "the common cold", and they can mutate and change at a surprising rate. Between the sheer number of viruses and that rate of change, there's more than enough common cold to keep you supplied for your entire lifetime.

[Tyrus Tenebros]

Thats not that crazy. I mean, objects change volume based on temperature too. Due to easily undertsandable phyiscal laws, sure, but size change to due speed isn't really different there. Exept that the laws aren't as easy to understand that is ^^
But it doesn't 'really' change in size, its size is just different in different reference frames. So in one reference frame it can be inside the tunnel entirely, while in the other it can't. So in the one reference frame you can close both doors instantaneously at the exact same time, trapping the train inside, while in the other that can not acctually happen.
So which one is the 'correct' reference frame, well both are, since there is never any preference in reference frames. It is just that the sequence of events also differs between the reference frames, what happens at the same time in one, does not necessarily happen at the same time in another.
not trying to troll if this is a stupid Q but how long does the tunnel appear to the people on the train?

[MortyM]

Thats not that crazy. I mean, objects change volume based on temperature too. Due to easily undertsandable phyiscal laws, sure, but size change to due speed isn't really different there. Exept that the laws aren't as easy to understand that is ^^
But it doesn't 'really' change in size, its size is just different in different reference frames. So in one reference frame it can be inside the tunnel entirely, while in the other it can't. So in the one reference frame you can close both doors instantaneously at the exact same time, trapping the train inside, while in the other that can not acctually happen.
So which one is the 'correct' reference frame, well both are, since there is never any preference in reference frames. It is just that the sequence of events also differs between the reference frames, what happens at the same time in one, does not necessarily happen at the same time in another.
not trying to troll if this is a stupid Q but how long does the tunnel appear to the people on the train?
To the people in the train, the train is stationary and the tunnel is moving at something close to the speed of light. So the tunnel will actually be smaller than it's 80m 'rest-length' for them (while the train is at it's 100m 'rest-length').

[Frug]

Thats not that crazy. I mean, objects change volume based on temperature too. Due to easily undertsandable phyiscal laws, sure, but size change to due speed isn't really different there. Exept that the laws aren't as easy to understand that is ^^
But it doesn't 'really' change in size, its size is just different in different reference frames. So in one reference frame it can be inside the tunnel entirely, while in the other it can't. So in the one reference frame you can close both doors instantaneously at the exact same time, trapping the train inside, while in the other that can not acctually happen.
So which one is the 'correct' reference frame, well both are, since there is never any preference in reference frames. It is just that the sequence of events also differs between the reference frames, what happens at the same time in one, does not necessarily happen at the same time in another.
not trying to troll if this is a stupid Q but how long does the tunnel appear to the people on the train?
To the people in the train, the train is stationary and the tunnel is moving at something close to the speed of light. So the tunnel will actually be smaller than it's 80m 'rest-length' for them (while the train is at it's 100m 'rest-length').
All of this.

it's not like things changing volume because of temperature. They measure smaller due to frames of reference, there's no actual change in volume happening.

So my question is: If this train and tunnel are both made out of super adamantium material that cannot be physically compressed or altered, and you do this, what would happen to the train and tunnel? You get a train larger than the tunnel it can be in? That can't be right. It seems to me like they should reconcile their lengths somehow before allowing fuckups to happen in my computer simulation of the invincible train... rather than having the doors explode off the tunnel...

[untilted]

Anyway, more relativity craziness.

Objects also contract in size as they go faster.
So for instance a train with a 'rest-length' of 100 meters will be only 60 meters at a certain percentage of the light speed. Now this train enters a tunnel that is 80 meters long. So the train fits inside the tunnel entirely.
Now if you close the tunnel doors once its inside, so the train crashes into the door and comes to a halt instantaneously. Since its 'rest-length' is 100 meters it suddenly won't fit anymore, how can this be ?!

according to this lecture (http://galileoandeinstein.physics.virginia.edu/lectures/sreltwins.html) the train won't be trappd on both sides.


The Tunnel Doors are Closed Simultaneously

The key to understanding what is happening here is that we said the bandits closed the two doors at the ends of the tunnel at the same time. How could they arrange to do that, since the doors are far apart? They could use walkie-talkies, which transmit radio waves, or just flash a light down the tunnel, since it’s long and straight. Remember, though, that the train is itself going at a speed close to that of light, so they have to be quite precise about this timing! The simplest way to imagine them synchronizing the closings of the two doors is to assume they know the train’s timetable, and at a prearranged appropriate time, a light is flashed halfway down the tunnel, and the end doors are closed when the flash of light reaches the ends of the tunnel. Assuming the light was positioned correctly in the middle of the tunnel, that should ensure that the two doors close simultaneously.

Or are They?

Now consider this door-closing operation from the point of view of someone on the train. Assume he’s in an observation car and has incredible eyesight, and there’s a little mist, so he actually sees the light flash, and the two flashes traveling down the tunnels towards the two end doors. Of course, the train is a perfectly good inertial frame, so he sees these two flashes to be traveling in opposite directions, but both at c, relative to the train. Meanwhile, he sees the tunnel itself to be moving rapidly relative to the train. Let us say the train enters the mountain through the “front” door. The observer will see the door at the other end of the tunnel, the “back” door, to be rushing towards him, and rushing to meet the flash of light. Meanwhile, once he’s in the tunnel, the front door is receding rapidly behind him, so the flash of light making its way to that door has to travel further to catch it. So the two flashes of light going down the tunnel in opposite directions do not reach the two doors simultaneously as seen from the train.

The concept of simultaneity, events happening at the same time, is not invariant as we move from one inertial frame to another. The man on the train sees the back door close first, and, if it is not quickly reopened, the front of the train will pile into it before the front door is closed behind the train.

but then again, i just found this when googling and can't actually comment on it's validity.

[TurielD]

Now this has all got me thinking of time being relative...

Speed is distance/time, and C is an absolute speed, but time is not an absolute :psyduck:

Also, how much is time 'slowed' for us, just due to the Earth's absolute velocity (and what is this velocity atm) given earth spinning around sun spinning around centre of galaxy moving outwards from centre of universe?

[Tyrus Tenebros]

Anyway, more relativity craziness.

Objects also contract in size as they go faster.
So for instance a train with a 'rest-length' of 100 meters will be only 60 meters at a certain percentage of the light speed. Now this train enters a tunnel that is 80 meters long. So the train fits inside the tunnel entirely.
Now if you close the tunnel doors once its inside, so the train crashes into the door and comes to a halt instantaneously. Since its 'rest-length' is 100 meters it suddenly won't fit anymore, how can this be ?!

according to this lecture (http://galileoandeinstein.physics.virginia.edu/lectures/sreltwins.html) the train won't be trappd on both sides.


The Tunnel Doors are Closed Simultaneously

The key to understanding what is happening here is that we said the bandits closed the two doors at the ends of the tunnel at the same time. How could they arrange to do that, since the doors are far apart? They could use walkie-talkies, which transmit radio waves, or just flash a light down the tunnel, since it’s long and straight. Remember, though, that the train is itself going at a speed close to that of light, so they have to be quite precise about this timing! The simplest way to imagine them synchronizing the closings of the two doors is to assume they know the train’s timetable, and at a prearranged appropriate time, a light is flashed halfway down the tunnel, and the end doors are closed when the flash of light reaches the ends of the tunnel. Assuming the light was positioned correctly in the middle of the tunnel, that should ensure that the two doors close simultaneously.

Or are They?

Now consider this door-closing operation from the point of view of someone on the train. Assume he’s in an observation car and has incredible eyesight, and there’s a little mist, so he actually sees the light flash, and the two flashes traveling down the tunnels towards the two end doors. Of course, the train is a perfectly good inertial frame, so he sees these two flashes to be traveling in opposite directions, but both at c, relative to the train. Meanwhile, he sees the tunnel itself to be moving rapidly relative to the train. Let us say the train enters the mountain through the “front” door. The observer will see the door at the other end of the tunnel, the “back” door, to be rushing towards him, and rushing to meet the flash of light. Meanwhile, once he’s in the tunnel, the front door is receding rapidly behind him, so the flash of light making its way to that door has to travel further to catch it. So the two flashes of light going down the tunnel in opposite directions do not reach the two doors simultaneously as seen from the train.

The concept of simultaneity, events happening at the same time, is not invariant as we move from one inertial frame to another. The man on the train sees the back door close first, and, if it is not quickly reopened, the front of the train will pile into it before the front door is closed behind the train.

but then again, i just found this when googling and can't actually comment on it's validity.

I'm not sure about the way the guy discusses the signaling. He's using a light flash, which the train sees hitting the doors at different times.

But for the purpose of a thought experiment why not have the doors close due to two synchronized but otherwise independent signals? E.G. a perfectly synchronized set of two timers which both trigger the door closing event. That eliminates the reference frame of the light signal reaching both ends of the tunnel (still an interesting part of the thought experiment, but it seems to complicate the issue...?)

[Pacefalm]

Now this has all got me thinking of time being relative...

Speed is distance/time, and C is an absolute speed, but time is not an absolute :psyduck:

Also, how much is time 'slowed' for us, just due to the Earth's absolute velocity (and what is this velocity atm) given earth spinning around sun spinning around centre of galaxy moving outwards from centre of universe?

Time is not slowed on an absolute scale, only relative to another object. For example, an astronaut flying around in space at high speeds. Once he gets back on earth, he will be a few seconds younger compared to the people who stayed on earth.

[Evelgrivion]

Time is not slowed on an absolute scale, only relative to another object. For example, an astronaut flying around in space at high speeds. Once he gets back on earth, he will be a few seconds younger compared to the people who stayed on earth.

Of course, the faster you go, the greater this difference in time becomes. Physicists are looking to exploit this phenomenon to create a Muon collider. Normally, a Muon decays in microseconds, but if you keep it in an accelerator ring at 99.9999999999% the speed of light, relative to the physicists, they'll persist, functionally, indefinitely.

:psyduck:

[TurielD]

Now this has all got me thinking of time being relative...

Speed is distance/time, and C is an absolute speed, but time is not an absolute :psyduck:

Also, how much is time 'slowed' for us, just due to the Earth's absolute velocity (and what is this velocity atm) given earth spinning around sun spinning around centre of galaxy moving outwards from centre of universe?

Time is not slowed on an absolute scale, only relative to another object. For example, an astronaut flying around in space at high speeds. Once he gets back on earth, he will be a few seconds younger compared to the people who stayed on earth.

Surely there is a scale between absolute 0 movement and C?

[elmicker]

There's no such thing as absolute zero movement. There's no absolute anything. That's what makes special and general relativity so powerful and so accurate. Everything is determined in terms of everything else.

[pratell]

Now this has all got me thinking of time being relative...

Speed is distance/time, and C is an absolute speed, but time is not an absolute :psyduck:

Also, how much is time 'slowed' for us, just due to the Earth's absolute velocity (and what is this velocity atm) given earth spinning around sun spinning around centre of galaxy moving outwards from centre of universe?

Time is not slowed on an absolute scale, only relative to another object. For example, an astronaut flying around in space at high speeds. Once he gets back on earth, he will be a few seconds younger compared to the people who stayed on earth.

Surely there is a scale between absolute 0 movement and C?
there's a reason the saying "everything's relative" exists, as elmicker points out.

[Pacefalm]

Time is not slowed on an absolute scale, only relative to another object. For example, an astronaut flying around in space at high speeds. Once he gets back on earth, he will be a few seconds younger compared to the people who stayed on earth.

Of course, the faster you go, the greater this difference in time becomes. Physicists are looking to exploit this phenomenon to create a Muon collider. Normally, a Muon decays in microseconds, but if you keep it in an accelerator ring at 99.9999999999% the speed of light, relative to the physicists, they'll persist, functionally, indefinitely.

:psyduck:
Which is also the basis of an interesting experiment. Muons created in the top layers of the atmosphere should not be measurable on the ground because their lifetime is so short: in the 'old pre-relativity model' they would have to travel at >c to be able to get to the ground before falling apart. Since we can observe them on the ground, that must mean that for the muon time dilates, so the lifetime of the muon compared to its surroundings is increased to the point where it can reach the ground, even while traveling at speeds below c. This became known as the Rossi–Hall experiment :) Good stuff

[omeg]

I'm not sure about the way the guy discusses the signaling. He's using a light flash, which the train sees hitting the doors at different times.

But for the purpose of a thought experiment why not have the doors close due to two synchronized but otherwise independent signals? E.G. a perfectly synchronized set of two timers which both trigger the door closing event. That eliminates the reference frame of the light signal reaching both ends of the tunnel (still an interesting part of the thought experiment, but it seems to complicate the issue...?)
How would one of them know, that the other started counting? :derper:

[smagd]

Grab two atomic clocks, carry them to the front door, synch them, agree on the best time to close the doors, carry one to the back door (very, very slowly or you'll mess its timer :) - oh wait, from the point of view of the approaching train they're already moving at relativistic speeds :ohnoes: ) then close the doors when the correct time shows on each clock.

Funny. The universe is nano stacking nerfed.

[balistic void]

Moving the clocks apart breaks the sync.

[TurielD]

Now this has all got me thinking of time being relative...

Speed is distance/time, and C is an absolute speed, but time is not an absolute :psyduck:

Also, how much is time 'slowed' for us, just due to the Earth's absolute velocity (and what is this velocity atm) given earth spinning around sun spinning around centre of galaxy moving outwards from centre of universe?

Time is not slowed on an absolute scale, only relative to another object. For example, an astronaut flying around in space at high speeds. Once he gets back on earth, he will be a few seconds younger compared to the people who stayed on earth.

Surely there is a scale between absolute 0 movement and C?
there's a reason the saying "everything's relative" exists, as elmicker points out.

I can't reconcile that with C being an absolute, surely that's light's speed as judged by a stationary observation point? If you take light, and slow it down by C is it then not 'stopped' at 0 motion?

And I still don't know how fast we're going here on this little blue ball.

[Chakrai]

There is no special point at which you can measure absolute velocities from. In all physics you have to pick a reference point and measure from that.

Say you were a drunk driver bombing it down the motorway at 100mph. The copper with a speed camera parked ath the side of the motorway measures your speed at 100mph. Because you are plastered, you instead think that you are standing still and fuzz are coming towards you at 100mph. Both are mathmatically consistent.

[Lallante]

There is no special point at which you can measure absolute velocities from. In all physics you have to pick a reference point and measure from that.

Say you were a drunk driver bombing it down the motorway at 100mph. The copper with a speed camera parked ath the side of the motorway measures your speed at 100mph. Because you are plastered, you instead think that you are standing still and fuzz are coming towards you at 100mph. Both are mathmatically consistent.
nuh uh

[balistic void]

He's right, but the judge won't have any of it :D

[Hellkyte]

Great thread, mind is indeed fucked.

One quick question about tidal/wave power , are we realistically only 3 or 4 generations from this being economically viable as a replacement for some of the coal burning power stations ? Watching the developments with interest due to the west/north coasts of Scotland reportedly being one of the more ideal locations for these types of renewable energy creation , plus having oil it would be the Saudi of the North here :D

So you have a couple of issues:

1) Massive investment

2) Non-optimized technology (it's pretty new)

3) Still no way to store energy created from this.

----

Thing is though those three points apply to pretty much any alternative energy solution. Tidal generators are more expensive than others due to their scale. However they are also pretty interesting in that they are the only renewable energy source that comes from gravity, which is IMHO the "magical" energy as there is instantanious action at a distance and as of now no-one has yet to see a graviton.

Anyways, in a more direct answer to your question, I guess I would say "maybe". Tidal energy is not cheap, and the amount of time it takes to pay off something like that is significant enough that I doubt legitimate (read: big enough to actually matter) private industry gives a crap about it.

[Pacefalm]

I can't reconcile that with C being an absolute, surely that's light's speed as judged by a stationary observation point? If you take light, and slow it down by C is it then not 'stopped' at 0 motion?

And I still don't know how fast we're going here on this little blue ball.

The thing about c is, that you are approaching 0 relative speed compared to light. You don't need a fixed reference point to measure that you are moving at c.
Edit: and remember, the speed of light is the same for each observer no matter what their velocity is.

Also, the earth moves at around 107 279 km/h (~30 km/second) around the sun.

[KKassandra]

gravity, which is IMHO the "magical" energy as there is instantanious action at a distance and as of now no-one has yet to see a graviton.



As an aside, this is not correct (instantaneous action at a distance). In General Relativity, gravitational effects propagate at c. You are correct that no-one has yet directly observed a graviton/gravitational wave (like photon/EM wave but for gravity), but the non-instantaneous propagation has other consequences that have been experimentally observed.

Edit: As an example (:lolwiki, but I didn't spot any immediate howlers in this):


The speed of gravity can be calculated from observations of the orbital decay rate of binary pulsars PSR 1913+16 (the Hulse-Taylor binary system noted above) and PSR B1534+12. The orbits of these binary pulsars are decaying due to loss of energy in the form of gravitational radiation. The rate of this energy loss ("gravitational damping") can be measured, and since it depends on the speed of gravity, comparing the measured values to theory shows that the speed of gravity is equal to the speed of light to within 1%.[17] However, measuring the speed of gravity by comparing theoretical results with experimental results will depend on the theory; use of a theory other than that of general relativity could in principle show a different speed, although the existence of gravitational damping at all implies that the speed cannot be infinite.

Edit2: Just to avoid completely derailing, I agree with your points about tidal power. There are some interesting possibilities to get around the 'massive investment' problem - typically they involve things like putting giant fans on the seabed in areas with strong tidal currents, basically a wind turbine powered by water. Avoids the unreliablility of wind without having to build a fuckoff barrage, but still has major engineering challenges (corrosion etc).

[Tarminic]

So, I was reading about the Double Split experiment, the one where electrons are demonstrated to have both particle-like and wavelike qualities due to quantum superposition.

So, I know that as some point they fired single electrons through the slits and then set up a device to detect each electron as it passed through a slit. Assuming I'm interpreting the results correctly, this detection caused the quantum superposition to collapse, and the electrons created a particle-like interference pattern as a result.

My question is this. How do you "observe" a single electron passing through a space? You have to interact with it somehow, right? So it's not that "observing" the electron collapsed the quantum superposition but the fact that in order to measure the presence of the particle you have to interact with it somehow. And this interaction is what causes the superposition to collapse.

[KKassandra]

My question is this. How do you "observe" a single electron passing through a space? You have to interact with it somehow, right? So it's not that "observing" the electron collapsed the quantum superposition but the fact that in order to measure the presence of the particle you have to interact with it somehow. And this interaction is what causes the superposition to collapse.

You're drawing a distinction where there isn't one - if you find a way of observing WITHOUT interacting, let me know :)


Edit: unless you're referring to a setup where you have the 'observing apparatus' in place, but no-one looks at it? So does the superposition collapse even if no-one looks at the result? In that case, you're basically describing a famous cat, the resolution of which starts to get into more complicated territory (I'd suggest googling 'decoherence'. My knowledge of how this works is basically that the answer ot this problem is called decoherence, but I have NFI how it actually does that. Fuck quantum)

[Tarminic]

That's why "observe" is in quotes. I know that detecting a single electron as it passes through a space requires interacting with it, I just want to know how we do that. Are we just firing a beam of other particles perpendicular to the electron's path?

[KKassandra]

That's why "observe" is in quotes. I know that detecting a single electron as it passes through a space requires interacting with it, I just want to know how we do that. Are we just firing a beam of other particles perpendicular to the electron's path?

That's one (crude) way of doing it (light), or you can use magnets if you understand how they work (since a moving charge generates a magnetic field). Are you after a handwave answer, or a detailed technical description?

[Tarminic]

That's why "observe" is in quotes. I know that detecting a single electron as it passes through a space requires interacting with it, I just want to know how we do that. Are we just firing a beam of other particles perpendicular to the electron's path?
That's one (crude) way of doing it (light), or you can use magnets if you understand how they work (since a moving charge generates a magnetic field). Are you after a handwave answer, or a detailed technical description?
I have no problem with a technical description. :D

[KKassandra]

That's why "observe" is in quotes. I know that detecting a single electron as it passes through a space requires interacting with it, I just want to know how we do that. Are we just firing a beam of other particles perpendicular to the electron's path?
That's one (crude) way of doing it (light), or you can use magnets if you understand how they work (since a moving charge generates a magnetic field). Are you after a handwave answer, or a detailed technical description?
I have no problem with a technical description. :D

I do, that's why I asked :(

Basically it all boils down to shining photons on the electron, either directly using a light (or x-ray beam etc etc), or indirectly by having it take part in some elctromagnetic interaction. The most visual way is using a cloud chanber - you have a vacuum chanber, then add in a very, very small amount of gaseous alcohol. As the electron flies along, it will bump into the alcohol molecules and ionise them (electromagnetic interaction), causing the alcohol vapour to condense. Thus, the path the elctron takes in the chamber will be marked by a trail of tiny droplets.

http://www.ph.utexas.edu/~gositz/gal3_eplus11_thumb.gif

The lines are paths of charged particles - they are curved because in this picture there is a magnetic field across the chamber perpendicular to the page, so a moving charge has a perpendicular force applied to it. The tracks gradually spiral in because the particles are gradually losing energy as they ionise the gas.

If you are after a method that will just go 'Slit A' 'Slit B' 'Slit B', you could just put a loop of wire around each slit - there will be a pulse of current in the wire each time an electron goes through the slit.

Edit: Both of the above methods are pretty ghetto and are almost certainly not what would actually be used if you were to ask a competent person to do the experiment nowadays- bubble/cloud chambers haven't really been used since the 60s, for example. I don't actually know how they would do it nowadays. The principles will be the same though.

[vackris]

I can't reconcile that with C being an absolute, surely that's light's speed as judged by a stationary observation point? If you take light, and slow it down by C is it then not 'stopped' at 0 motion?


Einstein's key idea was that light, which had already been measured to move at a certain speed, in fact appeared to move at that speed to all observers. Before, there was this thing called the aether, which occupied all of space and light moved at a certain speed relative to. This idea was disproved by some very smart experiments in the late 1800's.

The key to relativity is that everyone everywhere always measures light to be moving at c. Everything else falls out of that assumption. Since all experiments match the results given by relativity, it would appear that the assumption is true.

[SRS Tali]

how do magnets work?

[TurielD]

how do magnets work?

Can we get a Feynman smiley?

[Jurskjeld]

What I find most uckedu p about the double slit experiment is the scale to which it applies. As this article explains (http://www.sciencedaily.com/releases/2007/11/071109090639.htm) about collapsing the experiment by giving one of two entangled electrons a different energy, "[after] the interference pattern has disappeared, we can see that coherence is still there, hidden in the entanglement between the two electrons." To see how it applies for c60, find reference no. 41 and Google the title. Should result in some PDFs, of which Zeilinger's caught my interest.

[elmicker]

What always fucked with my mind about the double slit experiment was how there's any difference between "a detector" and "the environment". To detect an electron you're likely going to fire photons off it, or measure the change in electromagnetic fields, right? Well how is that any different from just passing through what's already everywhere? The earth has a pretty significant magnetic field, and magnetic fields extend infinitely, and there are bound to be photons from something in the way.

Or is it that the uncertainty in the posititoning of the electron isn't as binary as I've been led to believe, but is rather proportional to the amount of interaction that takes place..?

[Hellkyte]

how do magnets work?

Can we get a Feynman smiley?

That question definitely deserves one but I'll come in with a runner up to the smilley: a string of Feynman quotes since he is awesome.


To those who do not know mathematics it is difficult to get across a real feeling as to the beauty, the deepest beauty, of nature ... If you want to learn about nature, to appreciate nature, it is necessary to understand the language that she speaks in.


Science is the belief in the ignorance of experts.


You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing — that's what counts. I learned very early the difference between knowing the name of something and knowing something.


?I don't know what's the matter with people: they don't learn by understanding, they learn by some other way — by rote or something. Their knowledge is so fragile!


?Poets say science takes away from the beauty of the stars — mere globs of gas atoms. Nothing is "mere". I too can see the stars on a desert night, and feel them. But do I see less or more? The vastness of the heavens stretches my imagination — stuck on this carousel my little eye can catch one-million-year-old light. A vast pattern — of which I am a part... What is the pattern or the meaning or the why? It does not do harm to the mystery to know a little more about it. For far more marvelous is the truth than any artists of the past imagined it. Why do the poets of the present not speak of it? What men are poets who can speak of Jupiter if he were a man, but if he is an immense spinning sphere of methane and ammonia must be silent?


I think I can safely say that nobody understands quantum mechanics.


?For those who want some proof that physicists are human, the proof is in the idiocy of all the different units which they use for measuring energy.


?I'd hate to die twice. It's so boring.

-------------

That dude defined science for me, and why I loved it in a way I have never forgotten. His ability to embrace the humility of it as well is something I have always loved, and it's quite telling when you see a scientist flaunt their knowledge for no reason other than to look big. It's usually a sign he's an idiot.

[shaewyn]

Hm, I have no actual knowledge but the way it worked in my head was that time slows down as you get closer to the speed of light. As acceleration is distance/time/time when time is at a crawl you can't really 'speed up' by expending more energy, because the rate of expenditure goes down over relative time. As time would effectively stop at the speed of light it's not possible to accelerate up to there, because time is so closed to stopped as for acceleration to no longer be possible.

Don't forget that as you approach the speed of light a whole other shitload of fun stuff happens, such as your ship getting shorter along the axis of travel (a.k.a. length contraction).

[Pacefalm]

?For those who want some proof that physicists are human, the proof is in the idiocy of all the different units which they use for measuring energy.
1 degree kelvin = about 0.7/cm

true story

[Chakrai]

Hm, I have no actual knowledge but the way it worked in my head was that time slows down as you get closer to the speed of light. As acceleration is distance/time/time when time is at a crawl you can't really 'speed up' by expending more energy, because the rate of expenditure goes down over relative time. As time would effectively stop at the speed of light it's not possible to accelerate up to there, because time is so closed to stopped as for acceleration to no longer be possible.

Don't forget that as you approach the speed of light a whole other shitload of fun stuff happens, such as your ship getting shorter along the axis of travel (a.k.a. length contraction).

To be fair, if you're on the ship you don't get to enjoy the fun stuff. It's only the people on the ground watching you that see the comedy.

[omeg]

Can I build a working double-slit experiment using the electron gun from old CRT monitor?

[balistic void]

CRT vacuum tube is very dangerous to tamper with, they can explode and will spray glass in your face.

But yeah you probably could, but it would be so much easier to do with normal light.

[Viper Shizzle]

does the plane take off

[KKassandra]

Hm, I have no actual knowledge but the way it worked in my head was that time slows down as you get closer to the speed of light. As acceleration is distance/time/time when time is at a crawl you can't really 'speed up' by expending more energy, because the rate of expenditure goes down over relative time. As time would effectively stop at the speed of light it's not possible to accelerate up to there, because time is so closed to stopped as for acceleration to no longer be possible.

Don't forget that as you approach the speed of light a whole other shitload of fun stuff happens, such as your ship getting shorter along the axis of travel (a.k.a. length contraction).

To be fair, if you're on the ship you don't get to enjoy the fun stuff. It's only the people on the ground watching you that see the comedy.

Watching the entire universe contract along your axis of travel isn't fun stuff?

[Stoffl]

CRT vacuum tube is very dangerous to tamper with, they can implode and will spray glass in your face.


nyp*




*nitpicked your post

[smagd]

So, Earth is in fact flat after all, if you're just going at the right speed?

[Stoffl]

Why does my cup of coffee taste like black pepper ?


I had to use fairly old powdered sugar because we ran out of crystal sugar, but apart from that no changes.

[balistic void]

Ok Stoff you got me. Supernovas are also implosions you know? :) They collapse so violently that the "rebound" hurls all the stuff into space.

[sassy b]

Why does my cup of coffee taste like black pepper ?
I had to use fairly old powdered sugar because we ran out of crystal sugar, but apart from that no changes.
hypothesis: there is pepper in your sugar

[Stoffl]

unpossible!

My tinfoil hat tells me it's sabotage.

[Yuto]

does the plane take off

http://www.gifsforum.com/images/gif/trolling%20gifs/grand/545454288.gif

[Hellkyte]

Can I build a working double-slit experiment using the electron gun from old CRT monitor?

While it's not exactly the same experiment I believe you can see some of the same effects by reflecting a pen laser off of a CD or a DVD. It's hard to get the angle right but you end up with a diffraction pattern. It's a neat trick for talking about diffraction.

[vackris]

Can I build a working double-slit experiment using the electron gun from old CRT monitor?

While it's not exactly the same experiment I believe you can see some of the same effects by reflecting a pen laser off of a CD or a DVD. It's hard to get the angle right but you end up with a diffraction pattern. It's a neat trick for talking about diffraction.

While true, this is what's expected from the diffraction pattern of a laser.

The wacky unexpected part is when you fire single electrons and it still does it :ohnoes:

[Frug]

Can I build a working double-slit experiment using the electron gun from old CRT monitor?

While it's not exactly the same experiment I believe you can see some of the same effects by reflecting a pen laser off of a CD or a DVD. It's hard to get the angle right but you end up with a diffraction pattern. It's a neat trick for talking about diffraction.

While true, this is what's expected from the diffraction pattern of a laser.

The wacky unexpected part is when you fire single electrons and it still does it :ohnoes:
Yeah I'm pretty sure his point was if it will work with electrons.

Now my question is that I heard a while back that everything exhibits wave properties, though on larger scales it stops being measurable. So would the double slit experiment work with everything?

[KKassandra]

Can I build a working double-slit experiment using the electron gun from old CRT monitor?

While it's not exactly the same experiment I believe you can see some of the same effects by reflecting a pen laser off of a CD or a DVD. It's hard to get the angle right but you end up with a diffraction pattern. It's a neat trick for talking about diffraction.

While true, this is what's expected from the diffraction pattern of a laser.

The wacky unexpected part is when you fire single electrons and it still does it :ohnoes:
Yeah I'm pretty sure his point was if it will work with electrons.

Now my question is that I heard a while back that everything exhibits wave properties, though on larger scales it stops being measurable. So would the double slit experiment work with everything?

On anything that had a coherent wave function, yes. It has been done with atoms and molecules, for example (http://www.julianvossandreae.com/Work/C ... rticle.pdf (http://www.julianvossandreae.com/Work/C60article/c60article.pdf)). You couldn't do it with a person because of decoherence.

[balistic void]

Can I build a working double-slit experiment using the electron gun from old CRT monitor?

While it's not exactly the same experiment I believe you can see some of the same effects by reflecting a pen laser off of a CD or a DVD. It's hard to get the angle right but you end up with a diffraction pattern. It's a neat trick for talking about diffraction.

Did experiment in lab like this, but we bounced laser off an engineers metal ruler (has grooves marking millimetres etc). From the diffraction bounced onto sheet of graph paper we could measure the wavelength of light :D Measuring wavelength of light with a ruler!!

[omeg]

Reminds me I need to finish building power source for my dvd-ripped laser...

[Frug]

You couldn't do it with a person because of decoherence.
...

Now I want to start dropping people from a cliff onto a floor with two holes in it to test your theory. There are some posters here I would like to volunteer.
These people suffer from vast amounts of incoherence, which I think means they are excellent candidates.


Now that I have googled quantum decoherence, it brings another old question to mind. What would you say is the best physical experiment to date that demonstrates a quantum effect in an understandable way?
Last time I checked, they were all too confusing or unclear to be used as a LOOK! ITS BEING IMPOSSIBLE. Except for wave/particle duality which is easily demonstrated with thin slit experiments and... whatever the particle showing experiments are.
Have we got a half dead cat in a box or a cat in two places at once that is mind blowing to look at (for an amateur scientist)? Or is it still relegated to conjecture and math?

[MortyM]

You couldn't do it with a person because of decoherence.
...

Now I want to start dropping people from a cliff onto a floor with two holes in it to test your theory. There are some posters here I would like to volunteer.
These people suffer from vast amounts of incoherence, which I think means they are excellent candidates.


Now that I have googled quantum decoherence, it brings another old question to mind. What would you say is the best physical experiment to date that demonstrates a quantum effect in an understandable way?
Last time I checked, they were all too confusing or unclear to be used as a LOOK! ITS BEING IMPOSSIBLE. Except for wave/particle duality which is easily demonstrated with thin slit experiments and... whatever the particle showing experiments are.
Have we got a half dead cat in a box or a cat in two places at once that is mind blowing to look at (for an amateur scientist)? Or is it still relegated to conjecture and math?
I'd say the sun is a pretty decent example.
Classical mechanics can not explain nuclear fusion, it would infact be impossible. It can only be explained with quantum tunnelling.

[KKassandra]

You couldn't do it with a person because of decoherence.
...

Now I want to start dropping people from a cliff onto a floor with two holes in it to test your theory. There are some posters here I would like to volunteer.
These people suffer from vast amounts of incoherence, which I think means they are excellent candidates.


Now that I have googled quantum decoherence, it brings another old question to mind. What would you say is the best physical experiment to date that demonstrates a quantum effect in an understandable way?
Last time I checked, they were all too confusing or unclear to be used as a LOOK! ITS BEING IMPOSSIBLE. Except for wave/particle duality which is easily demonstrated with thin slit experiments and... whatever the particle showing experiments are.
Have we got a half dead cat in a box or a cat in two places at once that is mind blowing to look at (for an amateur scientist)? Or is it still relegated to conjecture and math?
I'd say the sun is a pretty decent example.
Classical mechanics can not explain nuclear fusion, it would infact be impossible. It can only be explained with quantum tunnelling.

Indeed - if you mean 'stuff that can only be explained using QM' then the sun, radioactive decay or anything with a diode in it (i.e. pretty much everything electronic nowadays). None of these things have a classical explanation. Or indeed 'why doesn't the electron spiral into the nucleus?', which was the question that led to the development of QM in the first place.

Perhaps a more obviously 'quantum' example would be spectral lines - why does a sodium lamp only give off light at such specific frequencies? Why is the emission spectrum of different elements different?

Or if you want visually cool stuff, think of something like a superconductor or levitating a frog with an intense magnetic field.

[Frug]

Neither of those examples are particularly interesting unless you're versed and absorbed in the technical details of the effects you're talking about. I mean, neither of those challenges how I see things, although I'm sure they're both very valid pieces of evidence.
The double slit experiment is a tangible way of showing something that makes no sense and is plainly visible, but those examples are both obscured in technicalities to most people (including me).
I mean, you're seeing an effect and providing an explanation for it that fits the data, which is great. I know that lots of different effects are best explained with the quantum model. But things like particle duality being apparent actually hurts the brain to think about.

Probably the presence of quanta isn't that mind blowing to me. It... is as good an explanation for infinite smallness as anything else ever was. Something being two things at once, or neither at the same time, or changing itself because my consciousness is aware of it... that's very different. Am I making sense?

[KKassandra]

I do see what you mean. I'm struggling to think of anything that's inherently 'woah' without having some understanding of what's going on though.

However, I would argue that lots of those examples in the last post only seem normal and don't challenge people's worldview because they're so common. Show an educated guy from the mid-19th century an LED or a fluorescent lamp and he'd be :psyduck:. A incandescent lamp he gets, because it's the same principle as a fire ( make thing hot, it glows). But an LED, glowing brighter than any lamp he's ever seen whilst remaining cool to the touch? :psyduck: :psyduck: Meanwhile, we see things like this every day so it's no big deal.

Similarly, Edison would probably not have a big conceptual problem with a computer built out of valves because it operates entirely using physics he knows and understands. An integrated circuit, OTOH?


Finally, the bit about 'consciousness being aware of it changing stuff' is taking the Copenhagen interpretation a bit too literally, in my view. I prefer to view the whole thing as a black box where we understand how to turn the handle and get predictions that apply to (our observations of) the real world. Trying to draw conclusions about the 'nature of reality' from it is in danger of delving into the bullshitty end of philosophy. All IMO, of course.

[Frug]

What would you say the reason why a lot of smart guys do take the interpretation that literally though? Are they being fanciful or are you evading it because it's too weird?

I strongly agree that the whole purpose of a model is only to provide predictions and not talk about the nature of what we're predicting. But don't they have evidence to support that weird interpretation? Or is it all part of this confusing mess nobody understands correctly?

[MortyM]

What would you say the reason why a lot of smart guys do take the interpretation that literally though? Are they being fanciful or are you evading it because it's too weird?

I strongly agree that the whole purpose of a model is only to provide predictions and not talk about the nature of what we're predicting. But don't they have evidence to support that weird interpretation? Or is it all part of this confusing mess nobody understands correctly?
I don't think many people would say that 'your consciousness becoming aware' is what causes the wave function to collapse, but rather the interaction that is needed for observation.

[Frug]

I don't think many people would say that 'your consciousness becoming aware' is what causes the wave function to collapse, but rather the interaction that is needed for observation.
Oh I've heard the stronger interpretation of the Copenhagen interpretation many times. It's not about the physical means of measurement or interaction, but the acquisition of the information itself. Hence why it being a cat, or a person, in the box, makes the mindfuck so obvious.
I don't know how many people think it's weird spooky consciousness stuff but I'm sure I've heard enough well versed people say it. I guess the jury's still out in the end though.

[elmicker]

Neither of those examples are particularly interesting unless you're versed and absorbed in the technical details of the effects you're talking about....

The closest you'll get to a tangible effect that demonstrates a quantum effect is something that exploits band gaps and photon emission. The most common of these will obviously be LEDs, but the usual one used in schools to demonstrate the quantum, dual nature of light is a demonstration of the photoelectric effect with a gold-leaf electroscope.

The electroscope shows the presence of charge by making a piece of gold leaf hover away from an electrode, in this case one with a negative charge. The photoelectric effect, whereby electrons can be freed (kind of boiled) away from the surface of the metal by absorbing the energy of incoming light, can be used to reduce the magnitude of that negative charge, neutralising the electrode and causing the leaf to fall back to its resting position.

Classical physics, where light is a wave, would have light absorbed regardless of its wavelength, and the number of electrons that "boiled off" would simply be a function of the intensity of the light. This isn't the case. The absorbance of light is dependent entirely on the wavelength. Light outside the required frequencies will not cause emission of electrons, no matter how intense it gets.

If light were just a wave, this could not happen; under classical physics electrons, like a mass of water, could sit there and absorb continuous wave energy until they popped out. Instead, for this to work, light has to be a series of discrete particles with specific energies, energies determined by planck's equation e=hf.

This is as simple as a demonstration gets to prove light's dual nature: it still behaves as a wave when it reflects off the electrode, but it has to behave as a particle when interacting with the electrons on the surface. The nature of the light doesn't change, all thar changes is what it interacts with, what "observes" it. The change in the nature of the observer demands a change in the nature of the light.

Simple as it is, even this demands a pretty comprehensive understanding of band gaps and metallic bonding.

[Frug]

Thanks elmicker, for going over things I thought i made clear I already know. Maybe someone else will find it useful.

edit: for MortyM

Here let me quote all knowing wikipedia to show what I mean:


This experiment makes apparent the fact that the nature of measurement, or observation, is not well-defined in this interpretation. The experiment can be interpreted to mean that while the box is closed, the system simultaneously exists in a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat", and that only when the box is opened and an observation performed does the wave function collapse into one of the two states.

However, one of the main scientists associated with the Copenhagen interpretation, Niels Bohr, never had in mind the observer-induced collapse of the wave function, so that Schrödinger's Cat did not pose any riddle to him. The cat would be either dead or alive long before the box is opened by a conscious observer.[5]
They use the term "conscious observer" for a reason.

As in, the whole system remains in an undefined state regardless of measurement, because all of the devices making measurements likewise will just assume a dual nature (the cat, if you like, is a measuring device) and that this duality converges only when you, yourself, or some other conscious observer, forces it to be one or the other.

Like, what would be the difference between the cat and some other measuring device? Only that it's in a box which you can't see. So everything in the box is two things at once. This seems to me to be the crux of the experiment.

[MortyM]

I don't like the inclusion of consciousness, because it requires you to attribute special status to consciousness and humans, and that is something were most physicist do not want to go. That just opens up an even bigger can of worms than quantum mechanics aleady is.

Edit: actually it would be rather easy to show with quantum entanglement experiments whether it is human observation that matters. I'll have to delve a bit deeper into the precise mechanics of those experiments.

[Frug]

I don't like the inclusion of consciousness, because it requires you to attribute special status to consciousness and humans, and that is something were most physicist do not want to go. That just opens up an even bigger can of worms than quantum mechanics aleady is.
Yes but it's bad science to discount it because it's uncomfortable.

I edited a bunch of crap into my post because I like to do that a lot. But basically, you've got to answer schrodingers' cat to come to a conclusion about this. So if you're saying I won't find many people saying it's eerie consciousness stuff, then you're likewise saying the thought experiment is resolved and that the cat is already either dead or alive before you open the box.


Edit: actually it would be rather easy to show with quantum entanglement experiments whether it is human observation that matters. I'll have to delve a bit deeper into the precise mechanics of those experiments.
That's the good stuff man.

[elmicker]

I've always like Bell's quote on the consciousness causes collapse interpretation: "Was the wave function waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some highly qualified measurer - with a PhD?"

What physical boundary is there between an "observer" and a plain' ol "interaction"? I've always thought the consciousness interpretations were a little too philosophical to have any grounding in reality.

[Jason Marshall]

Why is finding the Higgs so damn important? Will it really change anything in industry? or is it just to prove/disprove theories?

[shaewyn]

Re: Observation and QM effects:

be careful what you define as "observation". that term is a special one in physics, and in particular, refers to specifically measuring a particle's state. Schrodinger's Cat is an analogy used to make it easier to understand. Now, the weird thing about quantum mechanics is that not only is it theoretically the case that a particle exists in a superposition of states, but that particle is able to act as if it were both/all states simultaneously. Think: Not only do we not know whether Schrodinger's Cat is alive or dead, but it is able to both decompose (action only available when dead) and eat tuna (action only available when alive) at the same time. But only if we're not watching.

also, news that I found quite interesting recently: The electron has been determined to be an (almost) perfect sphere.

[elmicker]

Wouldn't it be more precise to say it's been almost found to be a perfect sphere? They determined it to be a perfect sphere within 0.00000000000000000000000000001m (28 zeros), which is as good as you're realistically ever going to get to to measuring a perfect sphere in the real world.

[Frug]

Re: Observation and QM effects:

be careful what you define as "observation". that term is a special one in physics, and in particular, refers to specifically measuring a particle's state. Schrodinger's Cat is an analogy used to make it easier to understand. Now, the weird thing about quantum mechanics is that not only is it theoretically the case that a particle exists in a superposition of states, but that particle is able to act as if it were both/all states simultaneously. Think: Not only do we not know whether Schrodinger's Cat is alive or dead, but it is able to both decompose (action only available when dead) and eat tuna (action only available when alive) at the same time. But only if we're not watching.

also, news that I found quite interesting recently: The electron has been determined to be an (almost) perfect sphere.
See, there are people who believe in the creepy consciousness version of the Copenhagen interpretation all over.

It's nice of you to state all that, but if you read up, this subject was brought up because I was asking for some tangible evidence of that. Something not buried in technicalities and math, but something concrete and accessible. I also should mention that everything I've ever read says that your above claim isn't quite agreed upon.

[omeg]

Accessible and QM? Does not compute :P

[Belid Hagen]

Why is finding the Higgs so damn important? Will it really change anything in industry? or is it just to prove/disprove theories?

if the Higgs-Boson doesn't exist, then we have to scrap our current models for understanding how the universe works. I don't think you quite get how big a deal that is.

[Frug]

Accessible and QM? Does not compute :P
I know /o\ It's a pipe dream I know. But for someone to make the claim that consciousness determines reality kind of begs for tangible, understandable evidence, doesn't it?
I mean it sounds so bloody outlandish and yet there's people in here arguing that it is the case, so I'm just getting riled up about this again and begging for someone to explain to me why they believe something like that.

how about this, now that I have had time to make my thoughts more coherent and specify my request:
What part of QM draws the conclusion that a waveform does not collapse until a conscious observer views it? What part of QM says that the cat is both alive and dead until it is measured? What reason is there to accept the bizarre interpretation of the nature of measurement over saying that the cat was already either dead or alive before you looked?

I'm begging for kassandra or mortyM to prod into this for me because I tried quite diligently in the past and was never able to get anywhere. I promise not to be an ass if I don't like the answer.

[Tarminic]

I thought it was a bit weirder than the actual concept of a particle needing to by "consciously observed" to collapse from superposition.

I don't really understand this, but from what I read the reason that the particle needs to be interacted with is due to the nature of "information" in the universe. It's not possible to measure it without interaction it because until we interact with it, the attribute we're trying to measure really doesn't exist. As if that attribute simply doesn't exist within the known universe until that photon hits that particle.

[omeg]

Cogito ergo sum! Descartes was right! :psyduck:

[Frug]

I thought it was a bit weirder than the actual concept of a particle needing to by "consciously observed" to collapse from superposition.

I don't really understand this, but from what I read the reason that the particle needs to be interacted with is due to the nature of "information" in the universe. It's not possible to measure it without interaction it because until we interact with it, the attribute we're trying to measure really doesn't exist. As if that attribute simply doesn't exist within the known universe until that photon hits that particle.
But at what point do you make the leap from saying that measurement requires interaction, to saying that no measurement implies nonexistence of the value to be measured?

[Tarminic]

I thought it was a bit weirder than the actual concept of a particle needing to by "consciously observed" to collapse from superposition.

I don't really understand this, but from what I read the reason that the particle needs to be interacted with is due to the nature of "information" in the universe. It's not possible to measure it without interaction it because until we interact with it, the attribute we're trying to measure really doesn't exist. As if that attribute simply doesn't exist within the known universe until that photon hits that particle.
But at what point do you make the leap from saying that measurement requires interaction, to saying that no measurement implies nonexistence of the value to be measured?
Because without interacting with the particle, the property we're trying to measure doesn't actually exist. Or it exists as every possible value of that property. I'm not sure. :psyduck:

[KKassandra]

I thought it was a bit weirder than the actual concept of a particle needing to by "consciously observed" to collapse from superposition.

I don't really understand this, but from what I read the reason that the particle needs to be interacted with is due to the nature of "information" in the universe. It's not possible to measure it without interaction it because until we interact with it, the attribute we're trying to measure really doesn't exist. As if that attribute simply doesn't exist within the known universe until that photon hits that particle.
But at what point do you make the leap from saying that measurement requires interaction, to saying that no measurement implies nonexistence of the value to be measured?
Because without interacting with the particle, the property we're trying to measure doesn't actually exist. Or it exists as every possible value of that property. I'm not sure. :psyduck:

Well, the 'collapse' of the wavefunction is a real thing with observable consequences - when you have a wavefunction that is a superposition of states (e.g. up and down for the spin of a particle), it evolves with time in a way that is well known. Thus (given the right experimental setup) you can have something where the probability distribution of your measurements will change with time if the wavefunction has not collapsed to one of the eigenstates (that is, a state that corresponds to a 100% chance of a given result from your measurement). Thus, by waiting different amounts of time you can confirm that the wavefunction really does not collapse to an eigenstate (that is, the observable you measure really does only possess a probability distribution rather than a single fixed but unknown value) until you actually make the measurement.


One thing you have to bear in mind with QM is that is completely deterministic at all levels except the result of an indiviual measurement. The wavefunction describes the probability distribution of the results of a measurement, and this wavefunction behaves in a way that is completely deterministic - from a given setup and wavefunction, we can predict perfectly how it will evolve with time (modulo uncertainties in how we set the experiment up). The only time the dice are rolled is when you actually make a measurement.


Edit: that said, my knowledge of this stuff is old and rusty enough that we've pretty much hit the limits of my knowledge. So I can't really provide the answers you're looking for, beyond saying that those sayings about 'If someone says he understands QM, he doesn't' and so forth exist for a reason.

[Frug]

Thus (given the right experimental setup) you can have something where the probability distribution of your measurements will change with time if the wavefunction has not collapsed to one of the eigenstates (that is, a state that corresponds to a 100% chance of a given result from your measurement). Thus, by waiting different amounts of time you can confirm that the wavefunction really does not collapse to an eigenstate (that is, the observable you measure really does only possess a probability distribution rather than a single fixed but unknown value) until you actually make the measurement.

I understand a wavefunction collapsing to a value upon inspection as narrowing the probability of possible values as you gather more information, but not the second part about confirming that it does not collapse prior to any observation. It seems to me like if this is possible, it should be fairly straightforward to explain with a thought experiment or whatever.

[MortyM]

I'm begging for kassandra or mortyM to prod into this for me because I tried quite diligently in the past and was never able to get anywhere. I promise not to be an ass if I don't like the answer.
Gona have to dissapoint you there, as I not really able to get anywhere either and am running into the limits of my knowledge of QM :(

[Twaddle]

Thus (given the right experimental setup) you can have something where the probability distribution of your measurements will change with time if the wavefunction has not collapsed to one of the eigenstates (that is, a state that corresponds to a 100% chance of a given result from your measurement). Thus, by waiting different amounts of time you can confirm that the wavefunction really does not collapse to an eigenstate (that is, the observable you measure really does only possess a probability distribution rather than a single fixed but unknown value) until you actually make the measurement.

I understand a wavefunction collapsing to a value upon inspection as narrowing the probability of possible values as you gather more information, but not the second part about confirming that it does not collapse prior to any observation. It seems to me like if this is possible, it should be fairly straightforward to explain with a thought experiment or whatever.
I'm not sure I understand exactly what you're asking, so this might not help, but the evidence that it doesn't collapse until measured is in the fact that if you calculate the probabilities for individual parts of / paths through a system, but don't measure the outcomes you get the wrong answer for the system as a whole. You have to calculate amplitudes until you get to the point you're measuring.

[Simokon]

My dumb science question (going back to speed of light stuff again)

How come light travels the speed it does and why does it not use infinite amounts of energy to travel such?

[Tarminic]

My dumb science question (going back to speed of light stuff again)

How come light travels the speed it does and why does it not use infinite amounts of energy to travel such?
Oooh, ooh, I can answer this one!

Because photons have no mass, and the amount of energy to accelerate a particle is a direct function of its mass.

[Frug]

I'm not sure I understand exactly what you're asking, so this might not help, but the evidence that it doesn't collapse until measured is in the fact that if you calculate the probabilities for individual parts of / paths through a system, but don't measure the outcomes you get the wrong answer for the system as a whole. You have to calculate amplitudes until you get to the point you're measuring.
I'm asking for something like what you said in a more understandable and concrete fashion, like a thought experiment. For example, it sounds like what you're saying is that if I roll a (lets say weighted) die 100 times without looking at it, and I use the expected probabilities to draw conclusions about the results, it will be wrong and the results will have been something totally random. But if I roll it while watching, i get something else.
If I'm getting this right, then what experiment does this? And if I'm getting this completely wrong, I think I need an understandable example. Because you can refer to "the wrong answer for system as a whole" but you're still being very vague about systems and paths and what I want is experiments and data, or at least concrete logical steps.

[KKassandra]

I'm begging for kassandra or mortyM to prod into this for me because I tried quite diligently in the past and was never able to get anywhere. I promise not to be an ass if I don't like the answer.
Gona have to dissapoint you there, as I not really able to get anywhere either and am running into the limits of my knowledge of QM :(

Same.

I'll have another go at answering your last question tomorrow, but I suspect that even if I somehow managed to put what I was trying to say into a more coherent form it wouldn't really address your problem anyway.

Edit: Okay, I'll have a go now

What you're asking basically gets to the heart of an unresolved problem, the Measurement Problem.


The measurement problem in quantum mechanics is the unresolved problem of how (or if) wavefunction collapse occurs. The inability to observe this process directly has given rise to different interpretations of quantum mechanics, and poses a key set of questions that each interpretation must answer. The wavefunction in quantum mechanics evolves according to the Schrödinger equation into a linear superposition of different states, but actual measurements always find the physical system in a definite state. Any future evolution is based on the state the system was discovered to be in when the measurement was made, meaning that the measurement "did something" to the process under examination. Whatever that "something" may be does not appear to be explained by the basic theory.

To express matters differently (to paraphrase Steven Weinberg [1][2]), the wave function evolves deterministically – knowing the wave function at one moment, the Schrödinger equation determines the wave function at any later time. If observers and their measuring apparatus are themselves described by a deterministic wave function, why can we not predict precise results for measurements, but only probabilities? As a general question: How can one establish a correspondence between quantum and classical reality?[3]

Your dice rolling example isn't quite what it's about. Try this for an analogy:

Take a roulette wheel, then put superglue in the very base of the holes the ball falls in so that when a ball finally comes to rest it can never move again no matter how many times you spin the wheel. Now, instead of 'measurement', we 'spin the wheel'. The result of our 'measurement' will be a random rumber (pretend this is a magic roulette wheel that does actually generate random numbers - it's an analogy :)) with a known probability distribution - we know what this distribution is with certainty, but can't predict the result of any individual measurement. In effect, the ball has a 'wavefunction' which gives it equal probability of being in each of the holes.

Got that? Okay - now suspend the roulette wheel from the ceiling by the centre axis and set it swinging side to side, like a pendulum. Now, what distribution of results we get depends when in teh swing we spin the wheel / make our measurement. The proability distribution changes with time, but in a completely deterministic way (if we know when we started it swinging and how long a swing takes). However, once a measurement has been made, any further measurements/spins will always get the same answer (because the ball is stuck in the hole / the wavefunction has collapsed into an eigenstate).

Thus, when we make measurements we can tell if someone else has spun the wheel after we started it swinging, because the probability distribution of our results will be different from what it ought to be for a spin at the point in the swing we are spinning it. Instead, we will get the distribution for wherever they spun it.

Whew.


Now, replace our roulette wheel with an electron in a box (or some other such 'quantum' thingy) whose spin we measure at different times. Our knowledge of how the swinging biases the roulette wheel is replaced by our knowledge of how the electron wavefunction evolves over time (using the time-dependent schroedinger equation or :hard maths here:).

If you want actual detail on how to build such an experiment, sorry. I've no clue, beyond knowing that it can be done.


Whew, I need to lie down.

(If it feels like I've dodged your question, answered a different question or just plain not made any sense whatsoever - which I suspect I may have done - then I apologise. I was always crap at this stuff anyway. In the end it's all wibbly-wobbly quantumy-bullshitty, an extremely mathematically elegant way of making very accurate predictions about teh real world that makes no intuitive sense whatsoever, in any way).

[Frug]

Gona have to dissapoint you there, as I not really able to get anywhere either and am running into the limits of my knowledge of QM :(

Same.

I'll have another go at answering your last question tomorrow, but I suspect that even if I somehow managed to put what I was trying to say into a more coherent form it wouldn't really address your problem anyway.
I dunno.

I found this http://www.sciencedaily.com/releases/20 ... ce+News%29 (http://www.sciencedaily.com/releases/2011/04/110405084252.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily% 3A+Latest+Science+News%29)

And after reading that and a bit on quantum superposition I'm starting to understand what they mean. I should probably shut up and read more. But I have a dreadful feeling this will all come back to the question of what it means to observe something.

[KKassandra]

But I have a dreadful feeling this will all come back to the question of what it means to observe something.

It does :)

Read the stuff on the measurement problem and quantum decoherence in wiki - there are lots of ways of lookign at it, some of which have arbitary 'measurements' or consciousness having magic properties. Others avoid this, but at the cost of meaning that the whole universe is actually nothign more than a probability field with mathematical properties that make it 'look' classical. In the end, which one you pick doesn't actually affect what answers you get when trying to make a cellphone, so I don't woryy about it too much :)

[Frug]

(If it feels like I've dodged your question, answered a different question or just plain not made any sense whatsoever - which I suspect I may have done - then I apologise. I was always crap at this stuff anyway. In the end it's all wibbly-wobbly quantumy-bullshitty, an extremely mathematically elegant way of making very accurate predictions about teh real world that makes no intuitive sense whatsoever, in any way).
You're not bad at it. I just think I'm going to stop spamming this thread while i read things though.

[shaewyn]

A book I once read said it like this: "If you're feeling like you're going crazy, that's good, and you're not. It's just the physics that's crazy."

I really like that article on demonstrating quantum effects with a mirror (and laser diffraction grating) - it clarifies quite nicely what they mean by "observing" the system. In their example, "observing" means "determining, or being able to determine" the position of the atom that emitted the light. Try this as an analogy: in a room, there are two switches separated by a distance (so one person can't push both). One switch make a light turn blue. The other switch makes it turn yellow. The light is only on when one or the other switch is activated. Put a person in the room and tell them to push a button and, according to classical mechanics, you get a blue or yellow light. According to quantum mechanics, you put a person in the room and you get a green light... until you check where the person is. Then you get the blue or yellow light.

As for an example that demonstrates the pre- vs post- collapse behaviour, check out the double slit experiment, in particular for electrons. Essentially, if you do not observe the particle before it passes through the slits, it behaves in a different manner than if you do observe it. If you observe the particle, it produces a simple two-band pattern (i.e., the particle passed through either the left or the right slit). If you do not observe the particle, it creates an interference pattern, which can only happen when the electron interacts with other particles. But there was only a single electron fired at the screen. In this experiment, "measuring the particle" means placing a detector between the electron gun and the slits. By definition, for a detection to happen the electron must interact with and cause a change in the detector. This "interacting with" usually means bonking into something.

As for why... f*ck if I know... 0.o And unfortunately these effects really only manifest at the "Very tiny" level so it's really hard to get an "interactable" quantum demonstration. Also, this is why newton's laws and physical models were so successful for so long.

(dunno if this helps... This is pretty much where my brain starts hurting)

[Frug]

Try this as an analogy: in a room, there are two switches separated by a distance (so one person can't push both). One switch make a light turn blue. The other switch makes it turn yellow. The light is only on when one or the other switch is activated. Put a person in the room and tell them to push a button and, according to classical mechanics, you get a blue or yellow light. According to quantum mechanics, you put a person in the room and you get a green light... until you check where the person is. Then you get the blue or yellow light.
I understand that and the other analogies given as explanations of what QM is saying. I have been reading explanations of what you're talking about, which is quantum superposition, the ability of something to have two contradictory values simultaneously until you 'observe' it (by which they generally mean interact with in some deterministic fashion, either directly or indirectly through a chain of measurements and/or implications) at which point you essentially become entangled with it and relative to you it assumes one specific value (if you want to go with the multiple universes explanation which to me seems the easiest to believe).

I don't have a problem with that. What I have a problem with is why this conclusion is drawn. The best I've heard so far is that they extended equations they came up with explaining particle wave duality in the two slit experiments to allow every measurable value, like position and velocity, to likewise assume a superposition of values and, since the math holds, they seem to have concluded that reality follows suit (I even vaguely understand what is meant by a sum of linear equations all being solutions). But there doesn't seem to be any physical implication of this in regards to things actually being in two places at once.
As in, they run some math that assumes multiple values, and it holds true once you measure it (and have collapsed the waveform) but there still seems to me to be this leap of faith that says this is not just a mathematical tool or anomaly, and that it does actually represent reality. This doppleganger particle that ceases to exist (relative to you) when you pinpoint the position of a particle might as well never have existed and is only in the numbers?

I'm not getting why these ghost particles or multiple universes can't be discarded as mathematical anomalies. Where's the proof. Why can't i touch it. WHY GOD WHY

[Tarminic]

I'm not getting why these ghost particles or multiple universes can't be discarded as mathematical anomalies. Where's the proof. Why can't i touch it. WHY GOD WHY
This is again territory where my knowledge is extremely sketchy and basic, but I believe there are certain real-world phenomena where you can observe the physical existence of these ghost particles, where particles essentially become "disentangled" and can me measured separately.

Essentially, at the event horizon of a black hole, if one potential state (but not both of them) of a superpositioned particle crosses the event horizon of a black hole it kind of snaps off from the other one, with one particle being sucked into the black hole and the other going about its merry way, both of the particles becoming real. Because you can't have two "real" particles from a single one without violating the law of conservation, the particle that escapes the black hole has positive energy and mass, while the particle that falls into the black hole actually has negative energy and mass. By this process, black holes can actually, over time, "evaporate", i.e. lose enough mass that their singulaties collapse (or...uncollapse? dear god my brain).

This is referred to as Hawking Radiation (http://en.wikipedia.org/wiki/Hawking_radiation).

[Dregek]

ok

the earth rotates on its axis at 1041.7 MPH if i had a plane going in the opposite direction exactly on the circumference of the planet at 1041.7 MPH would i be moving or would i '"hover" graphically over the same spot

[walrus]

ok

the earth rotates on its axis at 1041.7 MPH if i had a plane going in the opposite direction exactly on the circumference of the planet at 1041.7 MPH would i be moving or would i '"hover" graphically over the same spot
you would be moving across terrain @ 1041.7 MPH, but the stars would seem to be static.

[Jason Marshall]

[quote="Jason Marshall":2mgi8w20]Why is finding the Higgs so damn important? Will it really change anything in industry? or is it just to prove/disprove theories?

if the Higgs-Boson doesn't exist, then we have to scrap our current models for understanding how the universe works. I don't think you quite get how big a deal that is.[/quote:2mgi8w20]

Ok. So if its not found Science in the field of physics has to pretty much stop and come up with a new way to look at things? When will they know its not there? Seems like they are hunting for something, that, if they do find it they wont really know that they have found it.

[TurielD]

Even Einstein had trouble with this.

"I think that a particle must have a separate reality independent of the measurements.
That is an electron has spin, location and so forth even when it is not being measured.
I like to think that the moon is there even if I am not looking at it."

[balistic void]

Here's another famous QM experiment, the Stern-Gerlach one: http://en.wikipedia.org/wiki/Stern%E2%8 ... experiment (http://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experiment)
Don't fucking ask me to explain tho :D

[vackris]

[quote="Belid Hagen":3rie6syq][quote="Jason Marshall":3rie6syq]Why is finding the Higgs so damn important? Will it really change anything in industry? or is it just to prove/disprove theories?

if the Higgs-Boson doesn't exist, then we have to scrap our current models for understanding how the universe works. I don't think you quite get how big a deal that is.[/quote:3rie6syq]

Ok. So if its not found Science in the field of physics has to pretty much stop and come up with a new way to look at things? When will they know its not there? Seems like they are hunting for something, that, if they do find it they wont really know that they have found it.[/quote:3rie6syq]

It doesn't really have to stop, but the current way we understand the Standard Model would change a lot. The interaction of the Higgs field/particles with other particles is what gives them mass. Not finding it would require theory people to find a different way to understand how things get mass.

[EchoEpsilon23]

How does artificial gravity work by centrifugal force?

[Frug]

I'm not getting why these ghost particles or multiple universes can't be discarded as mathematical anomalies. Where's the proof. Why can't i touch it. WHY GOD WHY
This is again territory where my knowledge is extremely sketchy and basic, but I believe there are certain real-world phenomena where you can observe the physical existence of these ghost particles, where particles essentially become "disentangled" and can me measured separately.

Essentially, at the event horizon of a black hole, if one potential state (but not both of them) of a superpositioned particle crosses the event horizon of a black hole it kind of snaps off from the other one, with one particle being sucked into the black hole and the other going about its merry way, both of the particles becoming real. Because you can't have two "real" particles from a single one without violating the law of conservation, the particle that escapes the black hole has positive energy and mass, while the particle that falls into the black hole actually has negative energy and mass. By this process, black holes can actually, over time, "evaporate", i.e. lose enough mass that their singulaties collapse (or...uncollapse? dear god my brain).

This is referred to as Hawking Radiation (http://en.wikipedia.org/wiki/Hawking_radiation).
Okay. I read about that a couple years ago as it was a solution to the issue of black holes breaking the law of entropy, destroying information, and being the death of us all.

Apparently it hasn't been observed yet but I suppose if it was, it sounds like the sort of thing that would convince me. I mean that's some decent physical evidence. :| I hope it turns out wrong because this stuff is creepy and i don't like it.

[Frug]

How does artificial gravity work by centrifugal force?
http://imgs.xkcd.com/comics/centrifugal_force.png

Are you asking about why centrifugal force happens conceptually? Because using it for artificial gravity is nothing special, you just spin a space station around and the people inside stick to the walls, which become floors.

[EchoEpsilon23]

How does artificial gravity work by centrifugal force?
http://imgs.xkcd.com/comics/centrifugal_force.png

Are you asking about why centrifugal force happens conceptually? Because using it for artificial gravity is nothing special, you just spin a space station around and the people inside stick to the walls, which become floors.

Yeah, I just can't get my head around if you just spin something round and round how does that simulate gravity since gravity is usually produced theoretically by mass, a lot of mass. Whether that mass is a large core of iron, or few tons of neutronium, but I guess I'm having hard to conceptualizing something spinning creates gravity.

[MortyM]

I doesn't create gravity, it just creates a force. This force can be used to have things stick to a surface, just like gravity does. So you have a sort of simulated gravity, but ofcourse it is no actual gravitational force.

Edit, basically it is this:
http://regentsprep.org/regents/physics/phys06/bartgrav/spacesta.gif

[Frug]

Yeah, I just can't get my head around if you just spin something round and round how does that simulate gravity since gravity is usually produced theoretically by mass, a lot of mass. Whether that mass is a large core of iron, or few tons of neutronium, but I guess I'm having hard to conceptualizing something spinning creates gravity.
It's simulating the effect of gravity by simulating a force, but it's not creating gravity.
It's like when you're in a car and it speeds up really fast, you experience g-force pulling you back. It's not creating gravity, it just feels like gravity to you because you feel gravity as a force pulling you somewhere.

That works in space too. You could simulate gravity on a station by speeding it up forever, but that's not really an option so instead they spin it around to get the same effect.

[Tarminic]

Gravity is experienced by us as a force vector, ie an acceleration in a direction. The acceleration is based on the mass of the object and the direction is based on the center of mass of that object.

Centrifugal force doesn't create gravity, it simulates it by creating a force that is indistinguishable (by our fallible meat brains) from gravity. The illusion breaks down when we realize that the force is pulling us out instead of down, at which point our brain assumes we're hallucinating and makes us want to vomit or shit so we can expel whatever poisonous food we ate to cause said hallucinations.

[Frug]

Someone needs to edit morty's animation to illustrate the vomiting and shitting.

[EchoEpsilon23]

Thanks, that helped a lot.

[Wrack]

ok

the earth rotates on its axis at 1041.7 MPH if i had a plane going in the opposite direction exactly on the circumference of the planet at 1041.7 MPH would i be moving or would i '"hover" graphically over the same spot
you would be moving across terrain @ 1041.7 MPH, but the stars would seem to be static.

Well, you'd still be moving around the sun at 2*pi*AU/year = 66,600 MPH. Plus whatever velocity the sun has relative to other stars. So the stars wouldn't stay static in the sky, you'd still see the same yearly parallax as a telescope on land.

[Jason Marshall]

What does dumb science question thread think of Khan Academy?

[youtube:119wuk32]2WS1sG9fhOk[/youtube:119wuk32]

[walrus]

ok

the earth rotates on its axis at 1041.7 MPH if i had a plane going in the opposite direction exactly on the circumference of the planet at 1041.7 MPH would i be moving or would i '"hover" graphically over the same spot
you would be moving across terrain @ 1041.7 MPH, but the stars would seem to be static.

Well, you'd still be moving around the sun at 2*pi*AU/year = 66,600 MPH. Plus whatever velocity the sun has relative to other stars. So the stars wouldn't stay static in the sky, you'd still see the same yearly parallax as a telescope on land.
I assumed the plane would have to refuel before the parallax shift would be noticable :P

[Belid Hagen]

How does artificial gravity work by centrifugal force?
http://imgs.xkcd.com/comics/centrifugal_force.png[/img.]

Are you asking about why centrifugal force happens conceptually? Because using it for artificial gravity is nothing special, you just spin a space station around and the people inside stick to the walls, which become floors.

Yeah, I just can't get my head around if you just spin something round and round how does that simulate gravity since gravity is usually produced theoretically by mass, a lot of mass. Whether that mass is a large core of iron, or few tons of neutronium, but I guess I'm having hard to conceptualizing something spinning creates gravity.


[img]http://www.transformer-ivan.net/wp-content/uploads/2011/01/gravitron.jpg

[Pacefalm]

What does dumb science question thread think of Khan Academy?
[spoiler:m8hyiy2z][youtube:m8hyiy2z]2WS1sG9fhOk[/youtube:m8hyiy2z][/spoiler:m8hyiy2z]
Pretty good tbh, he's easy to follow and has some vids also from deeper topics. Nice find

[Frug]

What does dumb science question thread think of Khan Academy?
[spoiler:jz1ivddp][youtube:jz1ivddp]2WS1sG9fhOk[/youtube:jz1ivddp][/spoiler:jz1ivddp]
Pretty good tbh, he's easy to follow and has some vids also from deeper topics. Nice find
Seen the site once before. Thought it was great.

[omeg]

Quantum physics on a macro scale:
http://i.imgur.com/sQgp2.jpg

Finally separated the bitch from the DVD head assembly. Soldering it will be a challenge, but it's still working - gives nice bright red light. I have an Aixiz enclosure with lens to mount the diode, but damn, no casing, the junction is naked and fragile. :|
I'll probably bust it in the process, but it's fun. :)

[Jason Marshall]

Quantum physics on a macro scale:
http://i.imgur.com/sQgp2.jpg

Finally separated the bitch from the DVD head assembly. Soldering it will be a challenge, but it's still working - gives nice bright red light. I have an Aixiz enclosure with lens to mount the diode, but damn, no casing, the junction is naked and fragile. :|
I'll probably bust it in the process, but it's fun. :)

is dat a laz0r?

[omeg]

Yes, the burning laser from DVD.

[Jason Marshall]

Would one be found in a CD-RW drive? =D

[omeg]

CDs have much less powerful ones and they are infrared (invisible).

[Jason Marshall]

DVD-RW I assume? or does burning take place during the reading process in regular players?

[omeg]

DVD-RW I assume? or does burning take place during the reading process in regular players?
You need a writer. It has the high-powered one for burning and an infrared for reading.

[balistic void]

That laser is powerful enough to cause serious eye damage FYI (visible spectrum, ~300mW power?).

Contrary to popular belief, ze (tinted) goggles may actually be useful.

[MyBitchIsCummin]

Gonna be one retarded first post. Oh well.



Ok. So if its not found Science in the field of physics has to pretty much stop and come up with a new way to look at things? When will they know its not there? Seems like they are hunting for something, that, if they do find it they wont really know that they have found it.

Science doesn't have to do shit. We use models whose bounds and inaccuracies we know all the goddamn time and we already know that the Standard Model does not make accurate predictions in some (rather exotic) situations. Neither do Ideal gas law, Newtonian Kinematics, Kirchhoff's Law et alia - pick a subject you think is "understood" and it is a fucking trivial matter to demonstrate that we have only models that approximate behavior in certain circumstances and by no means a method of divining fucking truth here. (Exempli gratia: Nothing besides an imaginary object on an euclidean plane really can be described by a sine function perfectly. But it can approximate almost anything really well. It's usefulness doesn't make it true, it is a complete abstraction that makes stuff comprehensible and with that predictable to a degree.)

Philosophy of science is weird shit and it doesn't help that it's tacitly taken for granted or grasped in a crude and/or horrifying manner. Underlying truth, or true nature, in as far as such a thing might even be compatible with our methods of cognition is a rather irrelevant pursuit (the idea of truth seems like kind of an anachronistic religious holdover) - because all we have is a system of verifying models (and if you're at all into the subject, that method itself is rather more chaotic than little Observation->Hypothesis->Experiment->Peer Review mantra you're expected to not look at too critically in undergrad).

CERN is a big deal because any even remotely conclusive evidence either way w/r/t Higgs-Boson is a meaningful result. This won't change the applications of the Standard Model, but will encourage the search for something to model so far inaccurately described extremes & from that stepping stone continue further.

[Pacefalm]

But you dont take into account some models that are the definition of what the "real truth" is, eg. Gauss' law of electric flux is 100% guarranteed to give the 'true value' of electric flux, simply because the definition of the electric flux is "what Gauss' law says it is".

Other than that I agree mostly with your post

[keiiko netsova]

Gonna be one retarded first post. Oh well.



Ok. So if its not found Science in the field of physics has to pretty much stop and come up with a new way to look at things? When will they know its not there? Seems like they are hunting for something, that, if they do find it they wont really know that they have found it.

Science doesn't have to do shit. We use models whose bounds and inaccuracies we know all the goddamn time and we already know that the Standard Model does not make accurate predictions in some (rather exotic) situations. Neither do Ideal gas law, Newtonian Kinematics, Kirchhoff's Law et alia - pick a subject you think is "understood" and it is a fucking trivial matter to demonstrate that we have only models that approximate behavior in certain circumstances and by no means a method of divining fucking truth here. (Exempli gratia: Nothing besides an imaginary object on an euclidean plane really can be described by a sine function perfectly. But it can approximate almost anything really well. It's usefulness doesn't make it true, it is a complete abstraction that makes stuff comprehensible and with that predictable to a degree.)

Philosophy of science is weird shit and it doesn't help that it's tacitly taken for granted or grasped in a crude and/or horrifying manner. Underlying truth, or true nature, in as far as such a thing might even be compatible with our methods of cognition is a rather irrelevant pursuit (the idea of truth seems like kind of an anachronistic religious holdover) - because all we have is a system of verifying models (and if you're at all into the subject, that method itself is rather more chaotic than little Observation->Hypothesis->Experiment->Peer Review mantra you're expected to not look at too critically in undergrad).

CERN is a big deal because any even remotely conclusive evidence either way w/r/t Higgs-Boson is a meaningful result. This won't change the applications of the Standard Model, but will encourage the search for something to model so far inaccurately described extremes & from that stepping stone continue further.

:companioncube:

[cpl_fisher]

How does artificial gravity work by centrifugal force?
It is just centrifugal force, there is no gravity, artificial or otherwise.

In before the faggots who correctly state that gravity exist between any two objects, but in this case, it is negligable.