Index Key:  PHY059
Author:     Vitale
Subject:    Absolute zero and Absolute Infinity.
Text:       I have heard of Absolute zero where all motion ceases.  Is there a 
maximum temperature that objects can attain so that molecules reach a velocity 
approaching the speed of light?

Response #:  1 of 2
Author:      A. Smith
Text:        Temperature scales are organized to be proportional to the energy 
of the matter involved.  Since, as particles approach the speed of light, 
their energy increases without bound, the maximum temperature you are 
interested in, is in fact infinity.  Actually, for an isolated system of 
spins, it turns out there are some temperatures higher than infinity.  Since 
what is really important there is particle over the temperature, called beta, 
that means beta values lower than zero, and therefore negative temperatures.  
I am not sure that anybody has ever succeeded in preparing a system in a 
negative-temperature state, but it would not last long.

Response #:  2 of 2
Author:      Robert Topper
Text:        I would like to expand a little.  At absolute zero, all motion 
does not cease, at least not in a finite system.  This is a quantum mechanical 
effect; closed systems have a zero-point motion, and are always in motion.  
This is easy to understand; if the system were motionless, you would be able 
to predict all the atomic positions and momenta simultaneously, which violates 
the Heisenberg Uncertainty Principle.  Thus, the "perfect, motionless crystal" 
in the Nernst postulate (the "third law" of thermodynamics") does not actually 
exist; it is a mathematical abstraction used as a reference for entropy.  
Finally, lasers are an example of a system at infinite temperature; you have a 
population inversion in a finite-level system.  The spin system defined by the 
spins of Li in LiF(s) will undergo population inversion if you just put the 
crystal in a magnetic field, then suddenly reverse it.  So systems with 
(infinite temperature" are all around!  In fact, I think that NMR spectroscopy 
works by population inversion, which is the basis of MRI imaging in medicine 
and chemistry.