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From: Beth on 7 Mar 2005 03:33
wolfgang kern wrote:
> John Smith asked:
> | Could one achieve absolute zero inside an absolute vacuum? With no
matter,
> | there would be no atomic fluctuations. Though in practise, I suppose
it
> | would be useless...and you could never knw for sure you achieved
it...but
> | you seem to like to think.
>
> To reach 0ýK you must totally empty the whole universe ...
> somehow close to it is possible, but an absolute zero wont.

Yeah, from all I've heard, it's simply an impossibility...the laws of
thermodynamics prohibits it (by the same principle that prohibits
"perpetual motion devices" being possible, in fact)...

"With no matter, there would be no atomic fluctuations"?

With no matter - including no stray particles - there would be no
"temperature" to measure in the first place! As such, I suppose it's "kind
of" absolute zero when you empty out the entire universe because there's
now no "temperature" you could possibly measure..."no temperature" =
"absolute zero"...but, in a sense, that's kind of "cheating"...

By every source I've ever seen, it's simply considered
"impossible"...they've actually got within billionths of a degree of
absolute zero but, a bit like "lightspeed" (which requires "infinite
energy" to accelerate up to, making it equally impossible to reach in every
practical sense), you can't actually ever exactly reach it...

Beth :)


From: Beth on 7 Mar 2005 03:33
Arargh wrote:
> Beth wrote:
> <snip>
> >But, of course, the _REAL_ way to measure temperature is in
Kelvin...based
> >on "absolute zero" - the lowest temperature that can possibly be - but,
> >otherwise, is completely "compatible" with Celsius (literally, add 272
to
> >"convert" from Kelvin to Celsius :)...always a positive too ("absolute
> >zero" is technically unachievable because tiny "fluctuations" at the
atomic
> >level keep it from ever being _exactly_ "absolute zero" :)...
>
> 273.15 according to
> http://www.ph.rhbnc.ac.uk/schools/ZeroT/Absolute.html

Ah, yes...I made an "out by one" and inappropriate conversion to integer
there...well, going from memory, as I was, that wasn't far wrong :)...

Beth :)


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