Absolute zero is the temperature (-273.15C) at which all gesture in material stops and is supposed to be inaccessible. But fresh experiments using ultracold atoms have dignified temperatures that are, actually, negative in absolute temperature scales.
The ride there, however, is quite the contrary to what you might assume. Simply eliminating heat from the situation to make things cooler and cooler is not the answer. In its place, you must to heat things hotter than enormously hot!
The idea of temperature is closely linked to the concept of disorder. Normally, a high degree of order relates to a small temperature. A flawless order is equal to absolute zero and an extreme possible disorder relates to an unlimited temperature.
Ice crystals are more orderly than boiling water and, as instinct tells us, ice is certainly cooler than hot water.
By adding more energy in the water particles will cause their motion to become ever more messy and chaotic, thus cumulating their temperature. But under definite very special conditions, a system may become tidier when more energy is added outside a critical value which relates to an infinite temperature.
Such a system is then categorized by negative absolute temperature. On-going addition of energy in such a system would eventually render it impeccably ordered at which point it would have stretched to negative absolute zero. If the progressive absolute zero is the point at which all gesture stops, then the deleterious absolute zero is the point where all gesture is as fast as it perhaps can be.
In the picture (above), at positive absolute zero the blue glass ball on the left have least possible energy and they are meeting in the bottom of the vessel whereas at negative absolute zero, the now red hot glass balls on the right have the extreme imaginable energy and are sitting at the ceiling of the vessel.
As at negative absolute temperatures the average energy of the atoms is greater than at any positive absolute temperature of the similar arrangement, it means that at negative absolute temperature the arrangement is in fact hotter (in the logic that it is more active) than what it can be at any constructive absolute temperature.
Sounds terrible? Well, let us discover further.
Into the vortex:
The idea of negative absolute temperature was initially presented by Nobel Prize winning chemist and physicist Lars Onsager in the background of disorder in fluids. Nevertheless centuries of study started by Leonardo da Vinci, disorder itself remains an open problem to date.
Onsager forecasted that in turbulent two-dimensional fluid currents, small whirlpools – rather than disappearing away – would instinctively begin to grow in size founding ever larger and larger giant whirlpool arrangements. This procedure would then lead to the appearance of order out of disorder.
Such huge whirlpools that bring about order among chaos are so active that the arrangement reaches temperatures warmer than hot and goes in the absolute negative temperature system (red marbles). The massive turbulent tornadoes would support tremendously fast fluid motion and consistently high energies of the system.
Such a occurrence is supposed to underlie many naturally happening vortexes such as the Gulf Tributary or the Great Red Spot on the exterior of Jupiter.
Now our work, issued in the Physical Review Letters, has foreseen that like Onsager vortices considered by absolute negative temperature could also arise in planar superfluids. These are fluids with the aptitude to flow deprived of friction.
Like standard viscous fluids, superfluids too can be through turbulent. Studies of the subsequent “superfluid turbulence” are expected to yield new insights to Onsager’s original forecasts of absolute negative temperatures and appearance of order out of chaos.
But subsequent the fresh experimental statements of negative absolute temperatures of ultra-cold atoms, the very presence of thermodynamically steady negative temperatures have been questioned. While the debate lasts, it is clear that once the dust relaxes, many textbooks should be studied.
However, whatever temperature should be used for defining certain tests, the fact remains that such novel states of matter are a achievement of experimental physics and may possibly be useful for applications of developing future machineries such as Spintronics or Atomtronics. These suggest substituting the information carriers (electrons) used in electronics by more well-organized amounts such as spins, which are sort of basic magnets, or whole atoms.
Temporarily, we may rest certain that no thermometer should ever be able to touch absolute zero — positive or negative.
Tapio Simula accepts finance from Australian Research Council (ARC). He is associated with American Physical Society (APS). He works for Monash University.