Does gravity work at absolute zero?

[losfomot]

Would an object still be able to emit and/or absorb gravitons at absolute zero?

 

Or...

 

Would an object have the same gravitational attraction at 0 degrees Kelvin as it does at 3 degrees Kelvin?

[[Tycho?]]

Temperature has no bearing on gravity to the best of my knowledge.

[MolecularMan14]

here's my question...does gravity affect something on a molecular level? Does a molecular change, or movement need to take place for gravity to work? Not to my knowledge.

[Martin]

Would an object still be able to emit and/or absorb gravitons at absolute zero?

 

Or...

 

Would an object have the same gravitational attraction at 0 degrees Kelvin as it does at 3 degrees Kelvin?

 

Can absolute zero be attained?

 

I think according to the laws of thermodynamics it cannot. If I am right about that, then theoretically it cannot be attained.

 

I know at least that practice it never has been attained------you can get to nanoKelvins but not to zero.

 

Maybe swantsont knows otherwise.

 

So your question is meaningless.

 

But even so, I cannot see what this has to do with gravity.

 

If one COULD somehow get to zero kelvin, masses would still attract by gravity just as they do now.

 

There is something else in your question that puzzles me----it is the "gravitons" part. The most accurate model we have of gravity does not involve gravitons. it involves the curvature of spacetime. A graviton has never been observed, and it is not clear that any exist (except as a mathematical tool or approximation in certain theories.)

Some people speculate about gravitons.

However future theories of gravity may not involve gravitons either.

The idea may be of only very limited usefulness. A good mathematical tool to use in some particular contexts but not others.

 

this recent paper has excited a fair amount of interest:

From Gravitons to Gravity: Myths and Reality

http://arxiv.org/gr-qc/0409089

 

It explains that a theory which merely predicts a graviton-type particle does not therefore predict gravity as we know it (i.e. as modeled by General Relativity). String theorists have been saying for 20 years that their stringy models predict gravity, or include General Relativity----this, it appears, is wrong. the author is a recognized expert on gravity and cosmology. So the paper has made something of a splash----it proves mathematically that accepted belief is wrong and it tends to debunk String.

 

Be that as it may, I would advise not thinking of gravity as caused by matter exchanging gravitons. that picture is of limited usefulness at best

and could be confusing if you try to apply it in extreme circumstances where the picture wasnt intended to be used.

 

But if you particularly like them, imagine the world is full of gravitons buzzing around, it wont do any harm.

[swansont]

Getting to absolute zero is forbidden by the 3rd law of thermodynamics.

 

Martin's right - nanoK-ish temperatures is the best anyone's done (which is pretty darn good) in dilute gases that form Bose-Einstein condensates. I don't think anyone had tried to measure the gravitational attraction because it's so small compared to the electromagnetic interactions on that level.

 

I don't know of any theory that makes gravity vary with temperature.

[YT2095]

could a test be done in space?

 

for example a 1 metre square box inside the space station on a wall at room temp and another one outside in the cold (the dark side), and an object of known mass and distance being released. and time how long it takes for the object to hit the hull.

one is warm the other is very cold! but all other parameters are the same.

 

just an idea

[ydoaPs]

well, superconductors are affected by gravity and some of them are pretty damn close to absolute zero.

[swansont]

well, superconductors are affected by gravity and some of them are pretty damn close to absolute zero.

 

How so? And being "affected by gravity" and changing gravity aren't the same thing.

[Sayonara]

How so?

In the same way that cats and chairs are.

 

Honestly, don't you know any physics?

[losfomot]

Thanks for all the input.

 

I had thought that gravitons were commonly accepted in the world of quantum theory, which is why I posted the question here. Going by Einstein's mass warping space, I also don't see temperature making a difference.

 

Going a step in the same direction though... we know that lower temperature slows molecular motion, but what about...

 

1. Subatomic particles? (including Quarks (do they have their own motion?))

 

2. Radioactivity? (does the half life of a radioactive material extend at temperatures near absolute zero, is it possible to stabilize a radioactive material at a cold enough temp?)

 

Oh yes, one more thing... I've read (sorry don't have a reference handy I think it was in Wikpedia) that molecular motion only reaches its slowest at absolute zero... it does not stop completely. How sure are we about this, knowing that we will never be able to reach absolute zero and see for ourselves. It seems that if we interpret molecular motion as heat and ALL the heat is removed, then ALL the motion should be ceased.

 

Sorry, I know Im asking a lot in one little post.

[RICHARDBATTY]

Why not super cool the back of a cat and then drop it.

No that would be cruel. Butter some toast and then super cool the butter. You could see if the cooling over came the force of the butter.

[losfomot]

Why not super cool the back of a cat and then drop it.

No that would be cruel. Butter some toast and then super cool the butter. You could see if the cooling over came the force of the butter.

 

Are my questions that stupid?

[swansont]

In the same way that cats and chairs are.

 

Honestly' date=' don't you know [u']any[/u] physics?

 

No...I've been faking it.

[RICHARDBATTY]

Are my questions that stupid?

No, just a bit of my insanity leaking out again.

[5614]

sayo: In the same way that cats and chairs are.

Honestly, don't you know any physics?

 

swansont: No...I've been faking it.

 

richard: No, just a bit of my insanity leaking out again.

 

awww gawd... how i just love you guys!!

____________________

 

"Subatomic particles? (including Quarks (do they have their own motion?))"

yes if you hit one with a baseball bat it would have its own motion!

 

"Radioactivity?"

radioactivity is not affected by temperature as you mention (nor pressure or any external environmental thingys!)

 

"that molecular motion only reaches its slowest at absolute zero... it does not stop completely."

called zero point energy:

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

[timo]

Are my questions that stupid?

 

Not really stupid but hard to tackle. For your question about gravitation at T=0 I can´t really give an answer because it´s hard for me to imagine such a system. But generally, the laws of physical interactions are unchanged by temperature - just the set of possible effects and their probabilities are (that´s very losely speaking, of course).

 

 

To refer to your question about molecular motion stops/doesn´t stop:

 

- Strictly speaking saying that temparature is a measure for motion is not even correct. You can consider spin-systems and threat them with thermodynamical methods (assign a temperature to them). But there is no motion involved at all.

 

- In Classical Mechanics, which is a bad approximation for very low temperatures, T=0 would mean "stop of all motion" if a system where this term makes sense is considered.

 

- In Quantum Mechanics I would have problems defining what I mean by motion of the particles (actually, I could think of a few ways but that discussion would lead way too far). However, for common systems (probably all) the kinetic energy will be >0 even at T=0. That´s probably what the guy from wikipedia meant by saying that molecular motion does not stop completely - which is, imho, a false statement.

[swansont]

"Radioactivity?"

radioactivity is not affected by temperature as you mention (nor pressure or any external environmental thingys!)

 

There is an exception. Electron capture' date=' which happens in proton-rich nuclei, has a small dependence on environmental effects. Under high pressure, you basically squash the orbits a bit, so the electron spends more time closer tothe nucleus and thus increasing the capture cross section.

 

 

"Hensley et al. (1973) demonstrated that the electron capture decay of 7Be to 7Li is increased by 0.59% when BeO is subjected to 270 " 10 kbars pressure in a diamond anvil." (from this link)

[swansont]

Oh yes' date=' one more thing... I've read (sorry don't have a reference handy I think it was in Wikpedia) that molecular motion only reaches its slowest at absolute zero... it does not stop completely. How sure are we about this, knowing that we will never be able to reach absolute zero and see for ourselves. It seems that if we interpret molecular motion as heat and ALL the heat is removed, then ALL the motion should be ceased.

[/quote']

 

But we can't get there, so it's a moot point.

[jdurg]

This is a good theoretical question. In order to observe that gravity exists, you need to observe an object being moved towards another object. If something is at absolute zero, then it wouldn't be moving, would it? The act of it moving would bring it right above absolute zero. So couldn't we conclude that at absolute zero gravity would not affect that object? (ARRGGGHH!!!! Brain seizing cuz of quantum mechanics! heh. Kind of like how my p-chem professor mathematically showed that it is theoretically possible for someone to run straight into a wall and actually go through it. However, the probability of that happening is so infantessimally small that they don't even have a number for how small it is. lol. But it's not zero!)

[noz92]

Well, gravity would cause the object to moove, creating heat. So, I guess, it can, yet it can't. The second the gravity effects the object, it would no longer be at absolute zero.

[JaKiri]

Gravity doesn't necessarily cause something to move.

 

Lagrange points.

[noz92]

oh

[maverick88]

Would an object have the same gravitational attraction at 0 degrees Kelvin as it does at 3 degrees Kelvin?

 

As far as I know, though it is impossible to reach absolute zero, theoretically the closer you approach the a.z. the less mass the material has.It was proved when scientists where very very very close to a.z. the saw that the hellium that was frozen started losing his mass.

 

So I don't understand WHAT can be affected by gravity at a.z.

[JaKiri]

As far as I know, though it is impossible to reach absolute zero, theoretically the closer you approach the a.z. the less mass the material has.

 

That's true, but the change of mass between something at 3K and 0K is negligable. It's the same change in mass if you cool something by 3 degrees.

[maverick88]

If you cool something by 3 degrees and it's not even near the a.z. then it doesn't lose mass I think (maybe I'm wrong),(It seems that when something is far away from the a.z. it is not affected by special properties that another material that is closed to the a.z. has, otherwise I think that the scientists would have noticed the loss of the mass in warming up from solid to gas (much more significantly) and not only while closed to the a.z.), does it?