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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

Comments     Threshold


RE: As long...
By Kurz on 1/9/2013 11:08:12 AM , Rating: 2
The fact you downplay the profit motive and Monetary system almost leads me to discredit everything else you said.

RE: As long...
By deksman2 on 1/10/2013 1:49:25 PM , Rating: 2
The profit motive and the monetary system ARE part of the problem (a huge part actually).
Nobody asks a question: 'do we have the resources and technology to make something happen' (you know, the things we actually NEED) - to which the answer is practically always 'yes'.
Instead, people usually ask: 'how much does it cost and is it profitable?'.

This is why a re-education of society is required.
Social awareness has to be brought up to our latest scientific knowledge.
So many people claim things are 'impossible' and the main reason they do so is due to lack of exposure to relevant general education and critical thinking.

Right now, people are prone to being manipulated and used because their information is limited to specific sources/opinions.
Questioning pre-established things is discouraged because today, everything is monetized, and unless its profitable or usable within the current structure, it won't be discredited anytime soon, and those who try to at least encourage others to take into consideration the possibility that established notions could be in error, they are sooner ridiculed (because society or 'accredited' individuals are never considered to be prone to making mistakes).

Multi-billion dollar industries in some cases would end up going under if the underlying theories that allowed their existence came into question.
You have any idea how many people could lose their jobs in such a scenario?

There is no conspiracy necessary in a system where common interests converge on a daily basis (in capitalism, they converge on a daily basis).

I'm just appalled that numerous people are AWARE that these things are happening and they couldn't care less (at least until they start losing their confidence in the system and those they elected, and everything they have - which is when they start to 'care' - of course, by the time that happens, its already too late).

