Colder than Absolute Zero?

[Dragoncaviar]

I just wanted to post a thread discussing the different ways of looking at why it is not possible for anything to reach temperatures below absolute zero.

 

Look at it this way:

Molecules have energy

they have to do something with this energy though, so they make themselves vibrate and move to different degrees depending on how much energy they have.

If they lost all of the energy, they wouldn't move - i.e. there's no energy for them to do work with to actually move.

Cooling is a process of slowing the movement of molecules in a substance,

but if you cool things down, the energy has to be removed somewhere.

The energy can't be removed without movement though - otherwise it would just sit there, so the movement gives energy, and warms it up again.

 

Look at it another way:

You say - I'm not going to stop them moving by taking their energy away, I'm going to stop them moving physically, and make them lose their energy

O.K. - so you invent something small enough to hold one atom still

that one atom loses all its energy

This means it is the coldest thing in existance

colder than EVERYTHING else, even if only by a little.

this means there's an energy imbalance - nature like equilibrium

So the atom absorbs energy from the thing holding it.

The holder moves a little less, having lost energy, but the atom starts again.

 

So you say - well what if the holder could have less energy than the atom

That means the holder would be the coldest thing, and that it would absorb energy from the atom.

 

alternatively - what if we could stop the holder moving, as well as the atom,

so we make a bigger holder to hold the first holder, to hold the atom, and run into the same problem.

You would need a holder entirely made up of atoms that were the coldest thing on the earth, but all those atoms would need to be held by the coldest thing on earth, and all the holders held by something colder, and the holders holders held by something even cooler, etc. etc.

Leaving you with nothing more than an infinite chain of infinitely impossible possibilities.

 

Are there any other ways of looking at it?

 

Sorry people, I only just realised I am in the Chemistry forum, and this should be in Quantum Physics. Advanced apologies!

[admiral_ju00]

I believe that Swansont said that to reach the Absolute Zero is to break either the 2nd law of thermodynamics or 2nd law of Newton.

[pulkit]

A better way to understand is too look at how the concept of temperature and how / why the absolute scale of temperature is defined and how it were initially though of (Courtesy Lord Kelvin).

 

The concept of heat and temperature only becomes clearer at an advanced stage of thermodynamics.

 

You can find this stuff in an any advanced book on thermodynamics and complete understanding generally requires a small amount of knowledge of quantum mechanix.

[ed84c]

I believe that Swansont said that to reach the Absolute Zero is to break either the 2nd law of thermodynamics or 2nd law of Newton.

 

The 2nd law of Thermodynamics has already been broken by QED.

[swansont]

The 2nd law of Thermodynamics has already been broken by QED.

 

To what are you referring?

[budullewraagh]

it's impossible to divide by zero...plus, even if you could make something that would "hold" an atom in place, that atom would get pissed off so to speak and meander through that "container"