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Lasers, magnetic fields coax lattice-arranged potassium gas into a bizarre state

Scientists have demonstrated a feat that your physics teacher may have told you was impossible -- they have created a material with a temperature below absolute zero.  And the world below absolute zero is an unusual place indeed.  

I. It's a Very, Very Mad World

Atoms float upwards, ignoring gravity.  In a phenomenon that theoretical physicists believe mimic "dark energy", the atoms even stabilize in conditions that would normally crush inwards.  It's as if gravity itself is being overridden and energetic arrangements that would normally create instability, instead stabilize.  In short, we've entered the Twilight Zone of particle physics.

Massachusetts Institute of Technology professor Wolfgang Ketterle was a pioneer in the field of negative absolute temperatures.  He remarks, "[With negative absolute temperatures it is] as though you can stand a pyramid on its head and not worry about it toppling over."

The MIT professor in a new interview with Nature lauds the new work by Ulrich Schneider of Munich, Germany's Ludwig Maximilian University and colleagues.  In the work Professor Schneider demonstrates the first-ever peer-reviewed instance of a negative absolute temperature material breaking the absolute zero behavior.

The work began with Professor Schneider creating a peculiar quantum gas, using lasers and magnets.  Composed of potassium atoms the gas was arranged into a lattice structure.  A radical adjustment in the magnetic fields switches the atoms from the lowest energy state possible to the highest energy state possible.

Potassium atoms
The quantum gas is composed of potassium atoms. [Image Source: MaterialScientist]

Here is where the special behavior takes hold.

Normally the stabilizing repulsion of the original configuration would be replaced with an immense attraction, causing the system to collapse and implode.  But thanks to the trapping lasers, the lattice instead remains stable in the new super-energized state.  Comments Professor Schneider, "This suddenly shifts the atoms from their most stable, lowest-energy state to the highest possible energy state, before they can react.  It’s like walking through a valley, then instantly finding yourself on the mountain peak."

The result is a gas that by the formal definition of the Kelvin scale is a few billionths of a degree Kelvin below absolute zero (0 K).

II. Negative Absolute Temperatures?  That's Really Cold, Right?

But don't be confused.  The below-absolute-zero system is not cold.  It is in fact very, very hot -- hotter than any positive Kelvin system.  In cooler positive temperature systems, the numbers of particles in low-energy states outnumber those in high-energy states, giving rise to the formal quantum mechanics definition of temperature.  Typically entropy pushes atoms to occupy lower energy states, on average.

Lord Kelvin
Lord Kelvin's temperature scale is formally based on probability, not necessarily heat.
[Image Source: Unknown]

But in certain specialized quantum mechanical systems, the entropy actually decreases as the system energy (and "heat") increase, giving rise to a negative quantum temperature.

In other words, to understand this wild breakthrough, you must abandon your traditional notions of negative being cold and positive being hot and think in quantum terms.  This isn't your high school physics teacher's negative temperature.  It's a bizarre exercise in inverted entropy.

Could such a state be possible for the faster-than-expected expansion of the universe (a phenomena cosmologist attribute to so-called "dark energy", a poorly understood mechanism)?  Professor Schneider argues the idea is worth exploring.  He comments, "It’s interesting that this weird feature pops up in the Universe and also in the lab.  This may be something that cosmologists should look at more closely."

Negative temperature materials could be a boon to both theoretical particle physics and quantum computing.  But much work needs to be done to understand their bizarre new spin on physics.

The work by Prof. Schneider and his colleagues was published in the highly prestigious peer-reviewed journal Science.

And if that makes your brain hurt, take a break and read the classic college urban legend of a physic professor's exam question of whether hell is exothermic or endothermic and his student's epic response.

Sources: Science, Nature



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RE: As long...
By JoseMaria on 1/9/2013 6:55:26 AM , Rating: 2
What a sad little man you must be ...


RE: As long...
By FITCamaro on 1/9/2013 8:42:38 AM , Rating: 3
The sad thing is that you were to anti-religious to realize that the satire was laid on so thick that it slapped you in the face but you still didn't catch it.


RE: As long...
By JoseMaria on 1/9/2013 10:53:54 AM , Rating: 4
I didn't catch what exactly again? The fact that someone went and got religion into an article 100% not related to religion just to vent a little and take a jab at Christians? Oh I sure did get that, and that's what led me to write what I did write, that the poster must be a sad little man if he needs to reaffirm his stance against religion in one such article.
Got it? Or need a map to navigate it?

Ah the Internet, where continuous posting on a website magically confers someone the ability to know whether I am a churchgoer or not.


RE: As long...
By Tupoun on 1/9/2013 1:29:43 PM , Rating: 2
Hehehe ... guys seriously?

First of all, when I made this little note I had a picture of "Sheldon Lee Cooper, M.A., Ph.D., Sc.D" in my mind and his dearest mother "Mary Cooper" from "Galveston, Lord's blessed town in Texas". The show is called ... wait for it ... "It's Always Sunny in Philadelphia!" ... noo ... darn it! "The Big Bang Theory" (Amy sucks).

I am not taking a jab at anybody, don't take yourself too seriously. I'm Christian as well and I "believe" in Physics and Maths or whatever other scientific discipline is there (is it called Scientology?).

And second of all little citation of yours:
quote:
Ah the Internet, where continuous posting on a website magically confers someone the ability to know whether I am a churchgoer or not.

just ... did the Internet confer it to you? Doing this assumption? Towards me ... exactly in the same way, you described it ;)?

Bu who cares. I am only little sad man (me and Dr. Evil and Cartman). Gang. Our time is coming. Again!


RE: As long...
By Luticus on 1/9/2013 2:23:09 PM , Rating: 2
Hah, apologies then. it is unfortunately hard to sometimes convey sarcasm and such in text because the inflections just aren't there. At any rate, you hear so much of this kind of thing going on so often that it just hits one a lot of people’s nerves I suppose. I guess I'm so proactive about tolerance toward other people’s beliefs that I assumed it was a sarcastic jab at religion. That and I don't watch the big bang theory... so it was lost on me. :) again, apologies.


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