Absolute of Zero

Are you talking about absolute zero, the temperature?

All motion expends energy, some of which is given off as heat.

At higher temperatures, the molecules making up a substance, move about more actively, than they do at lower temperatures.

Water, for example, at 100 degrees celsius, begins to boil; that is it changes into a gas.

Going the other way, water again, at 0 degrees celsius freezes; that is it changes from a liquid, to a solid - ice.

Other chemicals 'freeze' at much lower temperatures; nitrogen, and oxygen, for example.

If we examine matter at lower, and lower temperatures, it is observed that the molecular motion slows, as the temperature drops.

Following this to the extreme point, it has been found that at minus 273 celsius, all motion stops, and there is no heat being given off at all.

This defines absolute zero, the point where all motion stops.

[even here, where their is apparently no motion, the subatomic particles are still doing their various 'dances'!]

http://www.pa.msu.edu/~sciencet/ask_st/012992.html

Check this out.

I'm not sure anything can ever achieve *true* absolute zero without matter and space ceasing to have definition.

As you approach absolute zero, you run into weird things like Bose-Einstein Condensates; a very strange form of matter... http://www.colorado.edu/physics/2000/bec

You can't reach absolute zero due to the Uncertainty Principle. This would indicate an exact location and velocity for the matter. All matter has a probability distribution of energy called it's Ground State Flucation.

I was just reading about this yesterday and came across a good link that put it into perspective for me.

temperature scales

Particularly what I took from the link..

"The graph of volume vs temperature for a sample of gas forms a straight line. (This assumes that you keep the pressure constant.) The lower the temperature, the smaller the volume. If you extend this line to low enough temperatures, it will eventually hit zero volume. Scientists noticed that, for all gasses, the temperature at which the graph said they would reach zero volume was about -273 Celsius (about -460 Farenheit). This temperature became known as absolute zero, and is today the zero for the Kelvin and Rankine temperature scales"

I will be the first to admit I have a lot to learn on these subjects. Thought this might be of some use.

Hamal

Hi Hamal, welcome to A2K. It's nice to know how the Kelvin "0" was originally projected. Thanks

Hi rosborne,

Thanks for the welcome.

I thought that was very interesting too. I have read that labs have been able to come to within a small fraction of 'absolute zero' and find that simply amazing. Must make these guys feel pretty sastisfied that even if we can never actually prove it, it really explains things very nicely for what we see in action and that they came up with the idea even before it was possible to test. If those that came up with it are still around. I gotta say, I really dig this stuff

Hamal

I almost forgot. If you like this, you might find the link at the bottom of that page interesting as well. I had read about absolute temperature before, but Negative Absolute Temperature was a totally new concept to me. Not sure I have my brian wrapped around this one yet. Heres the link..

negative absolute temperatures

I think scientists have achieved states of temperature a thousandth of a degree Kelvin. Theoretically we would really like to see a 10 millionith of a degree kelvin to see quantum jostling.

True absolutle zero within our Universe is held by Stephen Hawkings as being unachievable:

- It would invalidate the uncertainity principle - by giving matter a precise location and momentum ( = 0).

The mechanism stopping this ultra low energy state in our Universe is the quantum foam of virtual particle / anti-particle pairs that pop into and out of existence very rapidily. They can jostle an almost zero energy atom into slight motion (theoretically).

Tests to see this would have to be able to lower and atom to one ten millionth of a degree Kelvin - four orders of magnitude lower than we can yet achieve.

Hope this helps!