# The journey to the other side of absolute zero

##### November 4, 2014 by Tapio Simula, The Conversation

Absolute zero is the temperature (-273.15C) at which all motion in matter stops and is thought to be unreachable. But recent experiments using ultracold atoms have measured temperatures that are, in fact, negative in absolute temperature scale.

The journey there, however, is quite the opposite to what you might expect. Simply removing heat from the equation to make things colder and colder is not the answer. Instead, you need to heat things hotter than infinitely hot!

Understanding temperature

The concept of temperature is intimately connected to the concept of disorder. Typically, a high degree of order corresponds to a . A perfect order is tantamount to absolute zero and a maximum possible disorder corresponds to an infinite temperature.

Ice crystals are more ordered than boiling water and, as intuition tells us, ice is indeed colder than hot water. By adding more energy in the water molecules will cause their motion to become ever more chaotic and disordered, thus increasing their temperature.

But under certain very special circumstances, a system may become more ordered when more energy is added beyond a critical value which corresponds to an infinite temperature.

Such a system is then characterised by negative absolute temperature. Continuing to add more energy in such a system would ultimately render it perfectly ordered at which point it would have reached negative absolute zero.

If the positive absolute zero is the point at which all motion stops, then the negative absolute zero is the point where all motion is as fast as it possibly can be.

In the image (above), at positive absolute zero the blue marbles on the left have minimum possible energy and they are sitting in the bottom of the container whereas at negative absolute zero, the now red hot marbles on the right have the maximum possible energy and are sitting at the ceiling of the container.

Since at negative absolute temperatures the average energy of the particles is higher than at any positive absolute temperature of the same system, it means that at negative absolute temperature the system is in fact hotter (in the sense that it is more energetic) than what it could be at any positive absolute temperature.

Sounds impossible? Well, let us explore further.

Into the maelstrom

The concept of negative absolute temperature was originally introduced by Nobel Prize winning chemist and physicist Lars Onsager in the context of turbulence in fluids. Notwithstanding centuries of research initiated by Leonardo da Vinci, turbulence itself remains an open problem to date.

Onsager predicted that in turbulent two-dimensional fluid flows, small eddies – rather than fading away – would spontaneously begin to grow in size forming ever larger and larger giant vortex structures. This process would then lead to the emergence of order out of turbulence.

Such enormous vortices that bring about order amid chaos are so energetic that the system reaches temperatures hotter than hot and enters the absolute negative temperature regime (red marbles). The enormous turbulent whirlwinds would support extremely fast fluid motion and correspondingly high energies of the system.

Such a phenomenon is thought to underlie many naturally occurring maelstroms such as the Gulf Stream or the Great Red Spot on the surface of Jupiter.

Now our work, published in the Physical Review Letters, has predicted that similar Onsager vortices characterised by absolute negative temperature could also emerge in planar superfluids. These are fluids with the ability to flow without friction.

Like classical viscous fluids, superfluids too can be made turbulent. Studies of the resulting "superfluid turbulence" are anticipated to yield new insights to Onsager's original predictions of absolute negative temperatures and emergence of order out of chaos.

But following the recent experimental observation of negative absolute temperatures of ultra-cold atoms, the very existence of thermodynamically consistent negative temperatures has been questioned. While the debate continues, it is clear that once the dust settles, many textbooks should be revised.

Nevertheless, whatever temperature should be used for describing certain experiments, the fact remains that such novel states of matter are a feat of experimental physics and may potentially be useful for applications of emergent future technologies such as Spintronics or Atomtronics. These propose replacing the information carriers (electrons) used in electronics by more efficient quantities such as spins, which are sort of elementary magnets, or whole atoms.

Meanwhile, we may rest assured that no thermometer should ever be able to reach —positive or negative.

Explore further: Researchers force a gas to a temperature below absolute zero

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##### Da Schneib
5 / 5 (4) Nov 04, 2014
Fascinating. I'll be interested to see where this leads. I'd like to see how the Fluctuation Theorem interacts with this finding.
##### SteveL
5 / 5 (4) Nov 04, 2014
Would not an infinite temperature require an infinite amount of energy? I believe the universe doesn't have an infinite amount of energy.
##### Da Schneib
5 / 5 (4) Nov 04, 2014
Actually they're saying that there is a highest temperature for any given system, represented by the highest temperature configuration of its constituents. I'm not sure you're any more justified in calling that "infinite temperature" than you would be in calling absolute zero "no temperature."
##### gculpex
2.3 / 5 (3) Nov 04, 2014
old story, ran about three years ago. nothing new here.....same goobled up junk....
##### MRBlizzard
5 / 5 (4) Nov 04, 2014
From the point of view of Mossbauer Effect, it would appear that the zero phonon component would be 0%. It would be interesting to run a spectrum, and confirm this obvious conclusion, because, if you do get a clean absorption spectrum, then it deepens our understanding, and provides new technology. (Yes, you can get a spectrum without a solid.)
##### Da Schneib
5 / 5 (4) Nov 04, 2014
The Mössbauer effect ensures that very minor changes in the frequency of an emitted gamma ray prevent it from being absorbed by an atom in the same state elsewhere. It has been used to detect minute changes in the frequency of gamma rays over a few hundred feet of vertical distance, due to GRT, and constitutes one of the terrestrial tests of general relativity.

Could you explain, MRBlizzard, why we do not have a "clean enough" spectrum from the tests of GR I have mentioned? I am sure all the amateurs here would be very interested in the reason, is why I ask.
##### Lex Talonis
1 / 5 (7) Nov 05, 2014
Why don't they just put the absolute zero equipment inside a deep freezer and that will take it to minus 25*C, below absolute zero.

I would...
##### Da Schneib
5 / 5 (5) Nov 05, 2014
Ummm, absolute zero is not the zero of the Celsius or Fahrenheit scales. At absolute zero no gases can exist.
##### big_hairy_jimbo
3 / 5 (1) Nov 09, 2014
I would have thought that the maximum temperature possible would be a particle oscillating at LIGHT SPEED. I'm lost as to why they call this negative absolute Zero.
##### tritace
Nov 09, 2014
This comment has been removed by a moderator.
##### Drjsa_oba
1 / 5 (1) Nov 11, 2014
using a nomenclature like negative absolute zero defeats the purpose of trying to improve understanding and make things clearer. Would be more sensible to say a maximum disorder temperature for the system. Starting to create negative zero values that are different for every medium is just plain crazy.
##### imido
Nov 11, 2014
This comment has been removed by a moderator.
##### animah
5 / 5 (4) Nov 11, 2014
Perendev motors

Sorry mate, perpetual motion machines and the 2nd Law don't mix. "Inventors" of these devices tend to end up in prison for embezzlement. Case in point:

http://pesn.com/2...zlement/
##### imido
Nov 11, 2014
This comment has been removed by a moderator.
##### imido
Nov 11, 2014
This comment has been removed by a moderator.
##### animah
5 / 5 (5) Nov 11, 2014
Ren82: Nonsense. Absolute zero just means where matter has zero kinetic thermal energy (no energy available to get any work done, see the 3rd Law).

This does NOT mean zero energy as the matter in question is still always subject to quantum mechanical motion (aptly named "zero point energy" / ZPE).

Absolute zero is just +as close as possible+ to absolute rest. It is not actually absolute, it's just a term.
##### imido
Nov 11, 2014
This comment has been removed by a moderator.
##### Mike_Massen
3 / 5 (2) Nov 13, 2014
Ren82 claimed
At absolute zero matter ceases to exist, but because it violates the first law of thermodynamics, it is unattainable as any absolute, whose meaning is to outline the limits of possibility.
But Ren82, you are acquainted with absolutes, elsewhere on these forms you state the "idea of a creator" as if it has any chance of being real as an absolute, so R U ill ?

Where is there any evidence that Moses was spoken to by a god to force him to write a book ?

Scientific Method Ren82 ?

Should we throw the idea of a personal creator in the dustbin of unproven ideas Eg;-
- Zeus,
- Zoraster (virgin birth)
- Nature spirits
- Ghosts
- Demons
- Devils
- Witches
- Clairvoyance
- Talking Snakes
- Talking fiery bushes

http://en.wikiped...c_method

Evidence please of your creator & his "talking" to Moses, with or without fire - okay ?