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SubjectRe: temperature standard - global config option?
On Thu, Jun 07, 2001 at 09:30:54PM +0000, mirabilos {Thorsten Glaser} wrote:
> It was posted by L. K. where I now add my 0.02 EUR...
> > On Thu, 7 Jun 2001, Albert D. Cahalan wrote:
> > > Negative temperatures do not really exist.
> > Are you really sure about this ?

> I am. I made Abitur (german degree after 13yrs of school)
> with physics being an important course, and there can not
> be any temperature less than 0 K (or -273.15°C if you want).
> This is because temperature is nothing but the movement of
> pieces of materie (and even photons, ergo energy).

Then you must have blown your quantum finals. Royally. ESPECIALLY
after that statement about "temperature is nothing but the movement of
pieces of materie". Not even close, once you get into the quant.

Mathematically and quantum mechanically, negative absolute
temperatures do exist. In quantum mechanics, temperature is expressed as
probability populations in various quantum states.

Absolute zero is the quantum state were all particles are in
the ground state. An infinite temperature is, quantum mechanically,
the condition where all states, ground and energetic, have an equal
probability of population.

A "population inversion" (a condition where the energized states
are more likely to be populated than the ground states) is at the heart
of many things we take for granted today such as lasers, masers, leds,
NMR (Nuclear Magnetic Resonance) and MRI (the medical use of NMR).

Those "population inversions" represents an "energized state"
that is more energetic than the state that would be present in a steady
state infinite temperature.

Mathematically, those states can actually be treated as negative
absolute temperatures. IOW, negative absolute temperatures are actually
hotter than infinite.

It's true that these are not STEADY STATE conditions or in
equilibrium (which is how we take advantage of populations inversions -
by their actions in returning to equilibrium), but the math still works.
Just check out a few issues of Scientific American from the mid 1970's
on "Negative Absolute Temperatures in Nuclear Magnetic Resonance" and
to the scientific journals they reference. I won an argument with
a physics prof (PhD in high energy physics) over that very issue when
I did the same thing in a 400 level senior level physics lab on NMR back
then. It's actually pretty damn simple, once you work the math, and it
agravated him that he didn't believe it but couldn't argue with the math
till he saw the work and publication from someone else. Then he conceeded
that I had him and I had been right.

IAC... Negative absolute temperatures are about as meaningless
to this particular discussion as is expressing the temperature in 1/100s
of a Kelvin which would have a precision than exceeds the accuracy of
the measuring chips by two orders of magnitude. IOW... Both are silly
and meaningless to this case. One is out of range in magnitude and one
is out of the range of accuracy.

> -mirabilos
> --
> C:\>debug
> -e100 EA F0 FF 00 F0
> -g
> --->Enjoy!

Michael H. Warfield | (770) 985-6132 |
(The Mad Wizard) | (678) 463-0932 |
NIC whois: MHW9 | An optimist believes we live in the best of all
PGP Key: 0xDF1DD471 | possible worlds. A pessimist is sure of it!

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