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Contest! Explain this "temperatures below absolute zero" thing in a way that makes SENSE.


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Showing 1-21 of 21 posts in this discussion
Initial post: Jan 7, 2013, 7:33:53 AM PST
Ambulocetus says:
Scientists have recently gotten a gas to go below absolute zero (-459 degrees F). Apparently, this gas has NEGATIVE pressure, unlike gases above absolute zero. Oh, and this below-zero gas is actually HOTTER than anything which is ABOVE absolute zero since, apparently, temperature goes in some kind of a loop (wtf?).

This discovery allows for a possible explanation of dark matter, as well as the possibility of creating engines with better than 100% efficiency (wtf?).

The problem: science journalists are not explaining this story very well. This story, for example, needs revision for coherence between sentences and between paragraphs, and makes a dog's breakfast of explaining the inverted Boltzmann distribution:
http://www.sciencedaily.com/releases/2013/01/130104143516.htm

So here's the contest: pick some aspect of this amazing science story, and explain it better than the pros in FOUR HUNDRED WORDS OR LESS. Some aspects to explain might include:
1) why temperature can't just be defined as a linear measure of the energies of atoms in a substance, but should rather be seen as in some sense circular;
2) the inverted Boltzmann constant;
3) why a negative-temperature gas has a negative pressure;
4) how this discovery could yield engines with over 100% efficiency,

etc. Winners (to be decided by number of Yes votes) will receive adulation, respect, and little else, but hey, fun contest, right?

Posted on Jan 7, 2013, 8:01:39 AM PST
Last edited by the author on Jan 7, 2013, 1:47:54 PM PST
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In reply to an earlier post on Jan 7, 2013, 8:31:53 AM PST
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Posted on Jan 7, 2013, 8:44:03 AM PST
Last edited by the author on Jan 7, 2013, 8:49:05 AM PST
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In reply to an earlier post on Jan 7, 2013, 8:45:32 AM PST
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Posted on Jan 7, 2013, 8:50:57 AM PST
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In reply to an earlier post on Jan 7, 2013, 10:09:12 AM PST
Doctor Who says:
Here is part of the answer in the form of partial differential calculus.

T = temperature
S = entropy
V = volume
U = energy
W = work

1) 1/T = (dS/dU)
2) No idea at the moment
3) P = T (dS/dV)
4) maximum efficiency = 1 - (T_cold)/(T_hot)

Posted on Jan 7, 2013, 1:16:03 PM PST
Last edited by the author on Jan 7, 2013, 1:35:05 PM PST
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In reply to an earlier post on Jan 7, 2013, 1:38:06 PM PST
The Weasel says:
Lol was going to respond with an attempt, but I see this is one of those creationist thread so forget it! Good luck to you!

Posted on Jan 7, 2013, 1:50:44 PM PST
Last edited by the author on Jan 7, 2013, 3:57:14 PM PST
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In reply to an earlier post on Jan 7, 2013, 1:53:18 PM PST
Rev Otter says:
i'm still trying to figure out how it ties in with dark matter.

In reply to an earlier post on Jan 7, 2013, 2:10:53 PM PST
The Weasel says:
Rev. Otter says:
i'm still trying to figure out how it ties in with dark matter.
***
Just the shared property of negative pressure but not collapsing.

Posted on Jan 7, 2013, 2:11:47 PM PST
[Deleted by the author on Jan 7, 2013, 2:12:34 PM PST]

In reply to an earlier post on Jan 7, 2013, 2:18:03 PM PST
Seeker says:
As in all things human, we don't really know much. There are several things that we have placed limits on, which have later been found to have been severely in error. Welcome to reality.........

In reply to an earlier post on Jan 7, 2013, 2:21:38 PM PST
Seeker says:
The only hole I can put in your desciption is that our present equipment can't adaquately measure zero energy.

Posted on Jan 7, 2013, 2:34:49 PM PST
Last edited by the author on Jan 7, 2013, 8:23:26 PM PST
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Posted on Jan 7, 2013, 4:18:56 PM PST
Ambulocetus says:
Creationists have opinions about thermodynamics? Wonderful!

Okay, so, anybody with science education want to chime in?

In reply to an earlier post on Jan 7, 2013, 6:52:20 PM PST
Last edited by the author on Jan 7, 2013, 6:53:05 PM PST
if it has mass it has energy
e=mc2
you are confused about the form of the energy

a pile of uranium could release a lot of energy
even if you cool it to absolute zero by your silly defintion

Posted on Jan 8, 2013, 4:44:14 AM PST
Jamie says:
You can't think of a typical system to understand this. You have to imaging a different kind of system. For example, a number of elementary particles with only one of two possible states, say spin. Now imagine half are spinning 'up' and half are spinning 'down'. forget the kinetic energy of the particles (this doesn't work on typical systems). So then you apply energy from a magnetic field, and the particles start to change to one kind of spin, say 'down'. So there is more order in the new system (instead of a 50/50 distribution). The entropy has gone down. Second Law... So now you have added energy, entropy has gone down. If you accept second law, that system must have negative temperature for the equation to work. dS=dQ/T. So dS is negative (the system is more orderly), dQ is positive (you've added energy). Therefore T has to be negative.
I've never heard of a system like this that exists, but I don't read Thermodynamics Monthly, My thermo prof mentioned it in a class once - long enough to say this. I don't think you can get any work from it.

In reply to an earlier post on Jan 8, 2013, 9:12:44 PM PST
Re OP: I have a copy of a paper on the subject, which (of course!) I can't find. Jamie, above, basically has it right. It is a quantum-mechanical phenomenon, which means that macroscopic physics does a lousy job of dealing with it. One starts with a system a tiny fraction of a degree above absolute zero, and changes the magnetic field; the result is a system which has an apparent temperature a tiny fraction of a degree below absolute zero. The effects are weird -- to put it mildly. There is no conceivable practical application for this effect. Google turns up a number of references; I suggest spending some time on these.

Posted on Jan 14, 2013, 7:58:54 AM PST
Last edited by the author on Jan 14, 2013, 8:35:17 AM PST
That's wrong
"Ahem the result is a system which has an apparent temperature a tiny fraction of a degree below absolute zero."

That guy was talking about electron spin systems
Take it from us Creationists.
Them spin systems, you get negative infintity temperatures.

Now we dont got a paper on this:
But here's what we figure:
Infinity, that's not "a tiny fraction of a degree"
What do you figure?
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Discussion in:  Science forum
Participants:  9
Total posts:  21
Initial post:  Jan 7, 2013
Latest post:  Jan 14, 2013

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