Absolute Zero - how low can you go?

[alexdouglas1969]

Can anyone help me with this - as I understand it at
-273K all motion stops at the molecular level and therefore no heat / energy can be present. However, I have recently been told that both Nitrogen and Helium can be taken below -273K.

a. Why is absolute zero given as -273K?
b. What is the lowest temperature for N2 / Helium?

[The MG Pony]

We've never reached absolute dam close but never been.

Helium is a couple Kalvin above absolute, LN2 is much warmer then Helium.

And at absolute Zero we Canadians might say it's cold out

[Paulajayne]

Hi

Your understanding of the kelvin scale is slightly out.

Zero degrees Kelvin is Absolute Zero and is -273.16 C



Kelvin is a temperature scale designed so that zero degrees K is defined as absolute zero (at absolute zero, a hypothetical temperature, all molecular movement stops - all actual temperatures are above absolute zero) and the size of one unit is the same as the size of one degree Celsius. Water freezes at 273.16K; water boils at 373.16K.

HTH

Paula

[Josip]

Hi, alexdouglas1969

Can anyone help me with this - as I understand it at
-273K all motion stops at the molecular level and therefore no heat / energy can be present. However, I have recently been told that both Nitrogen and Helium can be taken below -273K.

a. Why is absolute zero given as -273K?
b. What is the lowest temperature for N2/Helium?

Wrong

Please read this:

http://en.wikipedia.org/wiki/Absolute_zero
http://www.colorado.edu/physics/2000...mperature.html

Best regards, Josip

[nh3simman]

I think that this is a very interesting subject.

From the laws of thermodynamics, the lowest possible temperature is Zero Kelvin (or -273.15 degC).

Actually reaching this limit seems to be like reaching the speed of light. Having said that, there have been some remarkable attempts at reaching this limit.

Mark Zamansky has written a very good book "Temperatures, very low and very high", where he gives some of the history. The lowest temperature was

1960, Kurti, England, Nuclear cooling methods, 10^-6 (1 millionth of a degree)

I was told by Prof Rallis that in theory, it is possible to "bounce" below Zero Kelvin. How this works, I would not even speculate.

[nh3simman]

http://www.colorado.edu/physics/2000...mperature.html

Hey Josip, thanks for this link. It looks worth reading.

[Athanatos]

Absolute zero is the lowest possible temperature, occurring when no heat energy remains in a substance. Absolute zero is the point at which particles have a minimum energy

from that statement alone reaching that point will be impossible

[nh3simman]

from that statement alone reaching that point will be impossible

Then you would be interested to read "Beyond infinity to negative temperatures" by Zemansky.

The definition of absolute temperture is purely a "large scale" concept. No reference is made of molecules or to molecular energy. The statement that all molecular activity ceases at zero Kelvin is wrong. Modern atomic theory has shown that atoms of a solid at abs zero have a store of kinetic energy called "zero point energy", which may be considerable.
Quote: Mark Zemansky

[US Iceman]

Here is an interesting link for those inclined to read theoretical physics.

http://freeenergynews.com/Directory/ZPE/index.html

[nh3simman]

Here is an interesting link for those inclined to read theoretical physics

One of the things that I like the most about the Refrigeration Engineer web site is the free association of ideas. You start out thinking you know about something and are often treated to ideas that you never even considered.

I invariably end up reading something completely different and this freeenergynews site looks like one of those sidetracks.

[US Iceman]

You start out thinking you know about something and are often treated to ideas that you never even considered.

That's what I like about this business. It is NEVER boring.

If you want some other fascinating information look for Einsteins' refrigerator and the notion of a bubble pump. The other topic is related to Tesla and his idea of how a refrigeration system should work.

Not quite on par with zero point energy, but close!