Can you get colder than absolute zero?

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Can you get colder than absolute zero?
« on: 26/06/2009 12:30:02 »
Yasser asked the Naked Scientists:
   Dear Dr. Smith and The Naked Scientists,
If temperature can be described as a measurement of "molecular movement", according to Steven Holzner's "Physics For Dummies", and Absolute zero occurs when the movement of molecules stop, is it a justified statement to say, "No refrigeration system in the world - or in the entire universe - can go any lower". This was in the chapter concerning Thermodynamics, but in regards to absolute zero, if you were to treat the temperature spectrum as something similar to a VCR tape, where molecules can fast-forward, is it possible for molecules to also 'rewind'?
Essentially, would breaking down the bonds, that bind molecules together, result in passing absolute zero, due to perhaps, greater exposure of the atomic structure etc. and would slowing down the movement of molecules at Location A, while increasing the rate of molecular movement at Location B result in teleportation, or potentially time-travel? I'm still having trouble believing that somewhere in the universe, "absolute zero" has not been exceeded.
Warm Regards,
Yasser in Canada

What do you think?


Offline LeeE

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Can you get colder than absolute zero?
« Reply #1 on: 26/06/2009 14:47:07 »
When you cool something, you are not adding 'coldness' (in effect, adding a negative value) to it; you are actually taking heat away from it (subtracting a positive value), which then leaves it cooler (at a lower end value).

While temperature can be described as a measurement of molecular movement, it's probably better to think of it as a measurement of kinetic energy, so that when something has 'stopped' its kinetic energy is been reduced to zero.  So, when something gets to zero, there is nothing positive left that can be further subtracted.

Another way of looking at it is that compared with something that has stopped, which represents zero, any movement at all, in any direction, represents a positive or absolute value.  This is just like when you are driving you always think of your speed in positive or absolute terms, rather than north/south and east/west vectors; if you are unfortunate enough to collide with something it won't matter which direction you're traveling in.

This is one of those instances where equivalence in maths is not matched by equivalence in physics.
...And its claws are as big as cups, and for some reason it's got a tremendous fear of stamps! And Mrs Doyle was telling me it's got magnets on its tail, so if you're made out of metal it can attach itself to you! And instead of a mouth it's got four arses!



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Can you get colder than absolute zero?
« Reply #2 on: 26/06/2009 15:57:32 »
If you have a problem of the concept of not going below zero then think of it this way. If the difficulty of getting to a temperature were proportional to 1/temperature then the lower the temperature, the harder it would get.  To get to 1/10 of the temperature would require 10 times the effort etc etc.. The actual relationship isn't as simple as that but it gives an idea.
0K represents a brick wall rather than just a point on the x axis.
It's a bit like c in that respect.