Welcome to DU! The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards. Join the community: Create a free account Support DU (and get rid of ads!): Become a Star Member All Forums Issue Forums Culture Forums Alliance Forums Region Forums Support Forums Help & Search
 

stevenleser

(32,886 posts)
Mon Jan 7, 2013, 09:45 AM Jan 2013

Absolute zero temperature barrier breached by scientists with interesting implications

http://www.sciencedaily.com/releases/2013/01/130104143516.htm

Jan. 4, 2013 — What is normal to most people in winter has so far been impossible in physics: a minus temperature. On the Celsius scale minus temperatures are only surprising in summer. On the absolute temperature scale, which is used by physicists and is also called the Kelvin scale, it is not possible to go below zero – at least not in the sense of getting colder than zero kelvin.

According to the physical meaning of temperature, the temperature of a gas is determined by the chaotic movement of its particles – the colder the gas, the slower the particles. At zero kelvin (minus 273 degrees Celsius) the particles stop moving and all disorder disappears. Thus, nothing can be colder than absolute zero on the Kelvin scale. Physicists at the Ludwig-Maximilians University Munich and the Max Planck Institute of Quantum Optics in Garching have now created an atomic gas in the laboratory that nonetheless has negative Kelvin values. These negative absolute temperatures have several apparently absurd consequences: although the atoms in the gas attract each other and give rise to a negative pressure, the gas does not collapse – a behaviour that is also postulated for dark energy in cosmology. Supposedly impossible heat engines such as a combustion engine with a thermodynamic efficiency of over 100% can also be realised with the help of negative absolute temperatures.

In order to bring water to the boil, energy needs to be added. As the water heats up, the water molecules increase their kinetic energy over time and move faster and faster on average. Yet, the individual molecules possess different kinetic energies – from very slow to very fast. Low-energy states are more likely than high-energy states, i.e. only a few particles move really fast. In physics, this distribution is called the Boltzmann distribution. Physicists working with Ulrich Schneider and Immanuel Bloch have now realised a gas in which this distribution is precisely inverted: many particles possess high energies and only a few have low energies. This inversion of the energy distribution means that the particles have assumed a negative absolute temperature.
20 replies = new reply since forum marked as read
Highlight: NoneDon't highlight anything 5 newestHighlight 5 most recent replies
Absolute zero temperature barrier breached by scientists with interesting implications (Original Post) stevenleser Jan 2013 OP
Cool dipsydoodle Jan 2013 #1
yet it was achieved. AngryAmish Jan 2013 #13
Read some of the comments in the earlier post in the Science forum. dipsydoodle Jan 2013 #15
Whoa. Achieveng better than 100% thermodynamic efficiency is almost as good as perpetual motion. Ikonoklast Jan 2013 #2
This would have huge implications for information theory... Recursion Jan 2013 #3
Fox News viewers don't count? Fumesucker Jan 2013 #7
Now all we need is a nice hot cup of tea to make an infinite improbability drive. nt Xipe Totec Jan 2013 #4
I thought that was a piece of fairy cake? kentauros Jan 2013 #9
No you need the tea to create it. The fairy cake to run it. /nt TheMadMonk Jan 2013 #10
Okay, it's been a while since I read the book. kentauros Jan 2013 #12
A cupcake. JoeyT Jan 2013 #16
Must be a British thing kentauros Jan 2013 #17
I think that is the Bistromath Drive TheKentuckian Jan 2013 #14
Pushing the limits of gods creation... Victor_c3 Jan 2013 #5
How can something have negative kinetic energy?? Saboburns Jan 2013 #6
The definition of temperature is based on atoms being billiard balls Recursion Jan 2013 #8
the strange thing is negative potential energy which is seen in bound nucleons. Sirveri Jan 2013 #18
NOVA did an interesting episode called 'Absolute Zero' five years ago. Make7 Jan 2013 #11
On another front, faster-then-light neutrinos have been debunked by physicists Brother Buzz Jan 2013 #19
My brain hurts now. Odin2005 Jan 2013 #20

Ikonoklast

(23,973 posts)
2. Whoa. Achieveng better than 100% thermodynamic efficiency is almost as good as perpetual motion.
Mon Jan 7, 2013, 10:03 AM
Jan 2013

The next century will be interesting, once we break our shackles to last century thinking.

Recursion

(56,582 posts)
3. This would have huge implications for information theory...
Mon Jan 7, 2013, 10:06 AM
Jan 2013

...since a Boltzmann crystal at 0K has 0 entropy. If it could have negative entropy, then we have a true information sink.

kentauros

(29,414 posts)
12. Okay, it's been a while since I read the book.
Mon Jan 7, 2013, 11:29 AM
Jan 2013

I only knew that "fairy cake" was used somewhere in it.

What is fairy cake, anyway?

kentauros

(29,414 posts)
17. Must be a British thing
Mon Jan 7, 2013, 03:15 PM
Jan 2013

like "biscuits" for cookies.

I wonder what they think of the "fairy cake" craze in the states right now...?

Victor_c3

(3,557 posts)
5. Pushing the limits of gods creation...
Mon Jan 7, 2013, 10:17 AM
Jan 2013

This can't be a good thing. When god created us 6,000 years ago I don't think he intended us to do this.

Look out for the next super-storm or sinkhole. There'll be divine retribution for this - I'm sure.

(I hope you guys can pick up on my sarcasm)

Saboburns

(2,807 posts)
6. How can something have negative kinetic energy??
Mon Jan 7, 2013, 10:31 AM
Jan 2013

Temperature is a measure of kinetic energy, at absolute zero there zero kinetic energy.

But, how can something have negative kinetic energy??

I don't get it.

Recursion

(56,582 posts)
8. The definition of temperature is based on atoms being billiard balls
Mon Jan 7, 2013, 10:40 AM
Jan 2013

Since they instead occupy a range of states among several probability distributions, you can get weird stuff like that (from the article, you get negative absolute temperature by, oddly enough, superheating gas).

Sirveri

(4,517 posts)
18. the strange thing is negative potential energy which is seen in bound nucleons.
Tue Jan 8, 2013, 01:32 PM
Jan 2013

So it's possible... I guess. If you hit the 'I believe' button.

Make7

(8,543 posts)
11. NOVA did an interesting episode called 'Absolute Zero' five years ago.
Mon Jan 7, 2013, 11:24 AM
Jan 2013

It was two parts, so it's about an hour and forty five minutes. There is a long history on the quest of scientists to reach lower and lower temperatures - it becomes really interesting when they get to temperatures where the normal properties of matter break down and weird things start to happen.

The full program is on YouTube:

http://www.youtube.com/watch?v=y2jSv8PDDwA


Or if you want to skip ahead to where I think it starts to get really interesting:

http://www.youtube.com/watch?v=y2jSv8PDDwA#t=4458s

Latest Discussions»General Discussion»Absolute zero temperature...