Absolute Zero

[JocktheMotie]

Does space have energy? It doesn't have mass at all, so it has no Kinetic Energy, and hence reaches absolute zero right? Are people saying that you can only apply temperature when/where there is mass?

*is yet to read most of ygolo's refered post which probably contains the answer*

While vacuum has no intrinsic energy, there is a small amount of electromagnetic radiation present almost uniformly throughout the universe, and I think it's something like 2 kelvin. Vacuum won't transfer it's absolute zero temperature to you...because there's nothing there. Your temperature in that vacuum is going to be determined by the amount of light energy on you at the time. Like Halla said, "sunny sides" of planets can be 200 degrees and then the dark sides are -200 degrees because there's no atmosphere to hold the sun energy.

 

[Asterion]

While vacuum has no intrinsic energy, there is a small amount of electromagnetic radiation present almost uniformly throughout the universe, and I think it's something like 2 kelvin. Vacuum won't transfer it's absolute zero temperature to you...because there's nothing there. Your temperature in that vacuum is going to be determined by the amount of light energy on you at the time. Like Halla said, "sunny sides" of planets can be 200 degrees and then the dark sides are -200 degrees because there's no atmosphere to hold the sun energy.

That makes sense, temperature is really just a classification then. Thanks Jock

 

[erm]

Thermal energy is kinetic energy but on a small scale. Something with zero thermal energy essentially has not kinetic energy so would be still. (simplified but serves a theoretical purpose)

The first problem with that is relativity. There is no evidence for the existence of absolute motion, so for something to be absolutely still seems impossible/not worth speculating on past emotional reasons.

For something to be still in a particular frame of reference has it's own problem. Notably that a single particle is always absolutely still in reference to itself, so presumably something being still to just a select few frames of reference causes nothing special to happen.

Then there's the uncertainty principle. Something with zero energy would have zero momentum, if it's momentum can be measured with such certainty, it's location is infinitely unknown, meaning it exists everywhere/doesn't exist anywhere or something trippy like that. The fact that it exists in a probabilistic sense alone is already trippy enough for me.

There's a whole list of other complications regarding absolute zero. A lot of which are to do with what happens at the smallest scales ever measured, where energy and such start behaving unusually. Someone has already mentioned how energy is not required for motion, but classical temperature does align more with motion than energy, but could go either way.

 

[Katsuni]

Absolute zero only means no vibration in an atom or particle, or whotever.

If yeu bump something into it, the laws of motion and thermodynamics still apply... it would just bump into it and one would gain some vibration, the other would loose some. It's not like it's some mass plague that would wipe everything out.

Yeu're thinking grey goo, which's a totally different scenario.

 

[BlueScreen]

Given it can be anywhere in the universe when you get to absolute zero, you'd have trouble not bumping it into stuff on the way.

 

[JocktheMotie]

What happens at absolute zero? - physics-math - 17 February 2010 - New Scientist

New Scientist article on it, easy to read and not a terrible summary.

 

[Octarine]

I found this thread kind of interesting, well certain responses anyway.

I think it is best just to consider Absolute Zero to be a mathematical place-holder, rather than a real physical state.

Absolute zero only means no vibration in an atom or particle, or whotever.

Which seems impossible to me - matter without inherent angular momentum?

Actually, even approaching zero, things get somewhat strange. I wish I understood it better.
http://en.wikipedia.org/wiki/Bose-einstein_condensate

 

[knight]

If you can imagine it, its possible. alot of things are beyound are capabliities, including ability see right now.

 

[Antimony]

Why can't you just grab a particle and stop it from moving?

 

[JocktheMotie]

Because in order to see it, you have to interact with it, with makes it "move."

 

[Antimony]

Really? Observing things means you must interact? Why is that?

 

[Eric B]

For one thing, a photon has to bounce off of it and enter your eyes (or instrument), and that right there is enough to make it move.

 

[Fluffywolf]

Really? Observing things means you must interact? Why is that?

Relativity, the observer is moving, the particle moves. Observing is interacting.

Saying you can grab a particle and stop its movements is like saying the earth rotates around the sun.

 

[Red Herring]

I might be late for the party and don't claim to have any special background knowledge to contribute, but this thread reminds me of a talk by Nobel laureate William Phillips I attended last year, sort of an Absolute Zero For Dummies introduction to his research in Doppler cooling and the possible implications.

So I tried to find a video of his talk (apparently he always does more or less the same thing with same flashy show elements, playing around with liquid nitrogen on stage, etc)...this should be it, the first few minutes are in Chinese, just ignore them.

http://www.tudou.com/programs/view/9-YO_tsssKY/

http://bigthink.com/ideas/20868

http://en.wikipedia.org/wiki/William_Daniel_Phillips

http://en.wikipedia.org/wiki/Doppler_cooling

 

[Antimony]

Relativity, the observer is moving, the particle moves. Observing is interacting.

Saying you can grab a particle and stop its movements is like saying the earth rotates around the sun.

Doesn't the earth rotate around the sun? Am I misreading this? Or did you mistype?

 

[Fluffywolf]

Doesn't the earth rotate around the sun? Am I misreading this? Or did you mistype?

Imagine the graphics to go with the text.

1. The earth rotates around the sun.
2. The sun rotates around the earth.
3. Is not standing still!?
4. Everything moves but you. Relatively forever alone!

The earth rotates around the sun as much as you can say the sun rotates around the earth. It depends what position in space you designate as a fixed point. In truth, there are no fixed points and everything moves relatively to each other.

 

[Antimony]

^lol at the forever alone hahaha.

But how does the earth not rotate around the sun? I mean, it doesn't make sense to me...

 

[erm]

But how does the earth not rotate around the sun? I mean, it doesn't make sense to me...

If you take the sun as a fixed point, then the sun is still and the earth orbits around it.

If you take the earth as a fixed point, then the earth is still and the sun orbits around it.

Neither of those have any privilege over each other, which one you favour is arbitrary. You can make countless other points fixed if you want, and have the earth and sun performing quite strange orbits relative to those points. That said, it's useful for many calculations to treat the centre of mass as the fixed point (convenient for humans, basically, but not necessary), and the sun contains the vast majority of the solar system's mass, and thus the centre of mass, if you a dealing solely with the solar system, falls well within the sun most of the time. Some arangements of the planets have the centre of mass falling outside the sun though, but not by much (relative to the solar system's size at least!).

All of that applies to all motion, essentially, including stillness. It's a bit different with acceleration, but ultimately just as arbitrary as to which point is considered not to be accelerating, if any.

 

[Fluffywolf]

Yup, but anyway, it was just an analogy, back to absolute zero, it is impossible to reach absolute zero whilest being inside the universe. Getting a particle inside a perfect container is physically impossible as you would have to account for all of the universes magnetic fields, even the ones from the furthest stars, whose magnetic influence on the particle would be a 1^-999~almost infinity. There is no way to account for all influences and create perfect order within a container.

Suppose for the sake of arguement (because its fun), that a perfect container could be made and a particle can truely be stopped and reach absolute sub-zero, the consequences could be quite dire. Impossible to predict how the particle would react because the particle would step outside of the boundaries of physics as we know it.. At absolute zero, possibilities would be endless. Maybe it causes another big bang even! That would be kind of odd though, because the big bang is more likely to be an expansion of space itself which would be impossible inside a container, unless it happens at relative levels. (ie. the space is not expanding, but matter is shrinking.)

Who knows, we might all be living and shrinking inside an existing container within another universe.

 

[Jonny]

Here is a geocentric model of planetary motion:

Here is a heliocentric model of planetary motion: