# Can you move particles by cooling them?

1. Jun 20, 2011

### Negeng

Can you "move" particles by cooling them?

Suppose you have an object made of particles and you cool it down alot. I would assume then that the average momentum of the particles would be reduced therefore we could know more about the particles' momentum and therefore less of the particles' postion. For example if the momentum of the particles could be say any where between 100-1 (I know those are not realistic numbers) and then if they are cooled down they could be between say 50-1. If we then check the particles postion we may find then some of them end up far away from the object they made up thereby particles would be moved (though I am sure the object would be heated up again).

If there is a flaw in my logic please let me know.

2. Jun 20, 2011

### San K

Re: Can you "move" particles by cooling them?

not sure what you mean...

have you read on Bose–Einstein condensate?...http://en.wikipedia.org/wiki/Bose–Einstein_condensate

3. Jun 20, 2011

### agentredlum

Re: Can you "move" particles by cooling them?

I think i understand what you are talking about. De-Broglie wavelength right? L=h/p Planck's constant (h) divided by momentum (p=mv) Theoretically if p -> 0 the particles wavelength becomes infinite. If you have a particle whose wavelength is THE ENTIRE UNIVERSE where is that particle? I would like to know. Is it on one end? is it on the other end? is it in the middle? is it everywhere? is it nowhere?

Suppose it's everywhere and suppose you are 100 km away and have a way of collapsing the wavelength. (Maybe all you have to do is LOOK for it, keeping in tradition with Q.M.) Then my dear fellow we have achieved TELEPORTATION. Someday I may be able to send you a BEER this way.

The big problem is Planck's constant because its very small. If the mass is 1 kg the velocity has to be equal in magnitude to the Planck's constant so that you can make the objects wavelength 1m (if the equation holds for objects composed of 'zillions' of particles. You may have to put a 'force field' around the object in order to 'fool' the laws of physics into thinking it is a single particle)

h~10^-33 mass of electron~10^-30 so if you can make velocity of electron 10^-3 wavelength should become close to 1m. This is not easy since electrons travel close to speed of light but recent developments in LASER COOLING may be able to do this. (Using LASER to cool particles, NOT heat them, amazing eh?)

Perhaps Planck's constant is different if you use another medium, the way speed of light and index of refraction is different when using different medium. Could a medium be constructed which has Planck's constant equal 1? How about 10^-20? That would still be enough to transport 'ordinary' electrons over great distances INSIDE this medium.

OPEN TO SUGGESTIONS

Last edited: Jun 20, 2011
4. Jun 20, 2011

### agentredlum

Re: Can you "move" particles by cooling them?

oops...got the Planck's constant wrong...forgive me oh great one...

6.62606957 x 10^-34 Js

5. Jun 20, 2011

### maverick_starstrider

Re: Can you "move" particles by cooling them?

The mental image you have in your head is essentially that of "Heisenberg's Microscope" (wiki it). The fact is that isn't really how Quantum works at all, and it's a shame that incorrect picture is the go to explanation used in science popularizer stuff (Heisenberg himself proposed it in the early days then later recanted, yet it still persists). Also, even within that picture it is not that the greater one knows the position the greater the momentum. It is that as the UNCERTAINTY in the particles momentum lessens the UNCERTAINTY in the position grows. And this actually isn't a statement of quantum mechanics at all (despite being called Heisenberg's Uncertainty Principles), it's actually just a property of waves, all waves (water, sound, etc.). The real conceptual leap is that particles exists as WAVEfunctions, once you have that the uncertainty principal is an obvious mathematical result.

So if you move away from incorrectly thinking of particles as zooming little billiard balls but instead of as sort of blurred/smushed out wavefunctions (or excitations of a quantum field) then yes, as the momentum is lowered (i.e. their velocity from cooling), their position becomes more blurred out. This has nothing to really do with "moving" though, how much they're "moving" relates to their momentum so as you cool them they "move" less. If you imagine the probability curve for a particle is something like a bell curve from school then as the energy is lowered it becomes shorter and more stretched out

6. Jun 21, 2011

### Negeng

Re: Can you "move" particles by cooling them?

I am feel more uncertain than ever now.

I have been told many times that recognizing that particles have wave like properties is the key to understanding the uncertinty princaple and yet when I look at an ocean wave I clearly see its crest, trouph, where they are and where they are going.

Further more if momentum is the only factor that determines where a particlewave goes then I could predict where a particlewave would be based on that; and I am certain I cannot do that.

As I understood HUP is that if a particlewave has diffinitive postion to measure, than it simply does not have a diffinitive momentum to measure and vis versa; is that true at least?

7. Jun 22, 2011

### Negeng

Re: Can you "move" particles by cooling them?

Ok then lets look at a situation that is the reverse. In a neutron star particlewaves are compressed to a very diffinitive postion so then the momentum of the particleswaves must become less diffinitive. Assuming the neutron star is less than 3 times the mass of the sun it does not collapse; is this because the average momentum of the particlewaves rises and therefore resist the intence gravitational pull?

8. Jun 24, 2011

Re: Can you "move" particles by cooling them?

Well, we cool alot of compounds (example LiAlh4) under alomst zero temp, different pressure using computing, use PV=NRT. If new equlibrium reached then properties of matter changed (electronic, magnetic, almost all), otherwise it release heat/wave and come back again during relaxing. Does not matter what matter, this this is true, from one energy equalibrium to another or excited state to back to normal state.
I hope it helps.

9. Jun 27, 2011

### Negeng

Re: Can you "move" particles by cooling them?

I suppose it does, but what I really am asking about is HUP.