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Absolute Zero

  1. Sep 9, 2003 #1


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    What would happen to an object if it reached the temperature of absolute zero? Would it just freeze? Explode? Or does it depend on the object?
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  3. Sep 9, 2003 #2


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    it would be immediately arrested by the police and cited
    for a flagrant disregard of thermodynamic law
  4. Sep 9, 2003 #3


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    At Absolute zero all electronic motion ceases. All of the electrons in the atom will be in the lowest possible orbitals.

    Zero motion of a subatomic particle violates Heisenberg Uncertainty Principle, so it is not possible to achieve this state.
  5. Sep 9, 2003 #4
    "The statement that is found so often in elementary books and newspaper articles, that at the temperature T = 0 all molecular activity ceases, is entirely erroneous. Modern atomic theory shows that the atoms of a solid (or a liquid in the case of helium) at absolute zero have a store of kinetic energy, called zero point energy, which may be considerable. As a matter of fact, the zero point energy of liquid helium is so large (three times as large as the heat of vaporization) that a crystal of helium under its own vapor pressure would be unstable. Under pressure, however, the reduction in volume brings the helium atoms nearer together so that the fields of force may interlock and a crystalline solid may form."

    Mark W. Zemansky, Temperatures Very Low and Very High

    Temperatures very close to absolute zero have been achieved. Wear your mittens and galoshes so you don't get frostbite.

    "The limit of all temperature is absolute zero. For many years physicists have been closing in on absolute zero. No one will ever succeed in reaching it, but many have come very close. To reach a very low temperature, such gases as helium have to be liquefied and such a methods have been used by physicists in Bell Labs in Holmdel, NJ. In 1987 physicist Steven Chu, a former Bell Labs scientist, and other physicists by the names of William Phillips and Claude Cohen-Tannoudji who also worked in the same lab came up with the idea of trapping atoms with lasers by lowering the temperature during their conversation over a lunch table in the lab's cafeteria. Chu and his companions, Phillips and Cohen-Tannoudji, figured out a way to lower the atom's temperature to one ten-millionth of a Kelvin above absolute zero or 0.1 µK. In 1997, ten years after patenting the idea of trapping atoms with lasers by lowering the temperature, he honored with a Nobel Prize in physics for all his work in Bell Labs. After 20 years of constant research the Low Temperature Lab at the Helsinki University of Technology managed to reach 280 pK or 280 trillionths of a Kelvin. However, in the year 2000 that record was surpassed when a piece of rhodium metal was cooled to 100 pK or 0.000,000,000,1 degrees above absolute zero by a team of physicists at this same lab."

    "In laboratory tests, Hinton (1960) found that dehydrated larvae of the African chironomid Polypedilum vanderplanki (Diptera) could survive submersion in liquid helium (-270 C). This phenomenon seems related to its ability to tolerate extreme desiccation."


    Temperature is defined formally in thermodynamic terms (partial derivative of internal energy with respect to entropy at constant volume, for example), so descriptions rendered in terms of molecular motion and such are likely to be slightly off the mark, and thermodynamic definitions incomprehensible.
    Last edited: Sep 9, 2003
  6. Sep 9, 2003 #5
    This is an interesting subject. This got me wondering what affect this would have on 'time', relating to an object approaching absolute zero. Isn't absolute zero diametrical to the speed of light?
  7. Sep 10, 2003 #6


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    No, "absolute zero" has nothing whatsoever to do with the speed of light OR relativity. Or are you trying to freeze light?
  8. Sep 10, 2003 #7
    What I'm asking is the affect this will have on an electron's velocity that's occupying a space approaching absolute zero. Wouldn't the electron in this environment be operating at a much reduced energy level, which I take as a reduction in velocity? Isn't an electron velocity at or near the speed of light? Doesn't time theoretically slow down as an object approaches the speed of light?. As such, would time be accelerating for an electron that's decelerating as it approaches absolute zero?
  9. Sep 13, 2003 #8
    At absolute zero all atoms and molecules will completely stop moving, but these atoms/molecules have a mass. Photons and waves however don't have a mass and will do what they normally would do...
  10. Sep 13, 2003 #9
    Temperatures below absolute zero.

    By fiddling with the definition of temperature, physicists can come up with negative temperatures--one of many subjects I mean to study some day and never get around to, but here is some discussion from Temperatures Very Low and Very High by Mark W. Zemansky.
    Achievement of negative temperatures.

    "To produce negative temperatures we must find a subsystem with the following properties:
    (1) The particles must have a finite number of energy levels;
    (2) The particles must come to equilibrium with one another very rapidly; and
    (3) The particles must come to equilibrium with their surroundings slowly enough to enable an experiment to be done.

    "The first subsystem that was found to satisfy these conditions is the nuclear spin system, or nuclear magnets, of the lithium ions in a lithium fluoride crystal. These nuclear magnets can have four different energy levels when in a magnetic field. The behavior of particles which may be distributed among four energy levels is similar to that of a system which has only two energy levels. To save words, therefore, let us continue to talk about only two energy levels. In a magnetic field, nuclear magnets may align themselves either in the same direction as the field, as shown in the lower diagram of Fig. 5-4, or opposite the direction of the field, a state of higher energy shown in the upper diagram of Fig. 5-4.

    "Under ordinary circumstances, there are many fewer nuclear magnets in the upper energy level than in the lower. The subsystem is in equilibrium with itself and also in equilibrium with the rest of the lattice, so that both the subsystem and its surroundings have the same positive temperature. Now suppose we quickly reverse the direction of the external field—so quickly, indeed, that the nuclear magnets are unable to follow the change of direction of the field. The large number of nuclear magnets which were formerly in the direction of the field (and in the lower energy level) now find themselves oriented opposite the field, and therefore in the upper energy level! The few nuclear magnets formerly in the upper state are now in the lower one. There has been a population inversion. After a small and rapid reshuffling, the nuclear magnets come to equilibrium with one another, and the temperature of the subsystem is negative. After a while (from 5 to 30 minutes), the subsystem cools off and comes to equilibrium with the rest of the lattice and regains its former positive temperature. This beautiful and important experiment was first performed by Purcell and Pound at Harvard University in 1951.

    "But, how can one be sure that a population inversion has taken place, that is, that there are more particles in the upper energy level than in the lower? The answer is, by measuring the absorption and re-emission of electromagnetic waves whose wavelength A is connected with the energy difference of the two levels «, by the Planck relation, e = hc/lambda. When e is the small value associated with Zeeman levels, A is large compared with visible light, and is in the region of microwaves. When a beam of microwaves with this particular A is sent through the lithium nuclei, two processes affecting the beam take place:
    (1) The beam is reduced in intensity by raising nuclei in the lower state to the upper state, the amount of reduction depending on the number of nuclei in the lower state. This is ordinary absorption.
    (2) The beam is increased in intensity by causing transitions of nuclei from the upper state to the lower state. A nucleus so lowered emits a quantum of radiation in phase with the radiation that forced it down, and the consequent increase in intensity of radiation is proportional to the number of nuclei in the upper state...."
  11. Sep 15, 2003 #10


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    Oh, is that what you mean? I'm afraid you have it very wrong. Electrons are just ordinary particles moving at ordinary speeds.
    You may be thinking of "photons" (which gets back to my original question: "Are you trying to freeze light?"!
  12. Sep 15, 2003 #11
    What kind of thermometer is used to measure absolute 0?
  13. Sep 16, 2003 #12
    Low pressure helium gas thermometers can be used down to about 0.5 degrees Kelvin. The principle is simple enough; the lower the temperature the lower the pressure exerted by the helium.

    Crystals of paramagnetic salts, especially cerium magnesium nitrate, can be used to determine very low temperatures close to absolute zero since the paramagnetic susceptibility is temperature dependent, as I understand the principle, which is not very clearly.
  14. Sep 16, 2003 #13
    by HallsofIvy Oh, is that what you mean? I'm afraid you have it very wrong. Electrons are just ordinary particles moving at ordinary speeds. You may be thinking of "photons" (which gets back to my original question: "Are you trying to freeze light?"!

    Thank you for straightening me out about the velocity of an electron. Your absolutely right. Now, the question you posed to me regarding the freezing of light is intriguing. If you could stop or significantly impede light, what effect would this have on a photons relationship with time. Since time theoretically stops for an object travelling at the speed of light, would time be accelerating for a photon approaching absolute zero?
  15. Sep 16, 2003 #14
    Absolute Zero is a phenomenon that can theoretically exist, absolutely no motion is not. Absolute Zero simply signifies the coldest something can possibly get (which is not all the way to the point of NO motion).
  16. Sep 17, 2003 #15
    At T=0 entropy vanishes. What's the entropy of a photon?
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