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'Unparticles' May Hold the Key To Superconductivity 48

KentuckyFC (1144503) writes One curious property of massless particles like photons is that their energy or momentum can take any value across many orders of magnitude, a property that physicists call scale invariance. By contrast, massive particles like electrons always have the same mass regardless of their energy or momentum. So massive particles are not scale invariant. The concept of unparticles is the idea that some "stuff" may have mass, energy and momentum and yet also be scale invariant. This stuff must be profoundly different from ordinary particles, hence the name: unparticles. Nobody has ever seen an unparticle but now physicists are suggesting that unparticles may hold the key to understanding unconventional superconductivity. Their thinking is that at very low temperatures, ordinary particles can sometimes behave like unparticles. In other words, their properties become independent of the scale at which they're observed. So if an unparticle moves without resistance on a tiny scale, then it must also move without resistance at every scale, hence the phenomenon of superconductivity. That could provide some important insights into unconventional superconductivity which has puzzled physicists since it was discovered in the 1980s.
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'Unparticles' May Hold the Key To Superconductivity

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  • Is scale invariant.
  • by pla ( 258480 ) on Friday August 08, 2014 @09:38AM (#47629627) Journal
    Their thinking is that at very low temperatures, ordinary particles can sometimes behave like unparticles. In other words, their properties become independent of the scale at which they're observed.

    So their properties become independent of scale... When one of their properties falls below a certain value on the scale of temperature?

    And dogs can look like lemurs, as long as they don't look too much like dogs.
    • Doesn't matter, they'll still taste like chicken!
    • It didn't say all their properties become scale invariant.

      Not understanding the concept of scale invariance, I may well be talking out of my bum, but maybe temperature is already a scale invariant property.

      • Temperature cannot possibly be Scale-Invariant. 32 != 0 != 273.15 unless you use variant scales.

        / my backside has much to say

    • So their properties become independent of scale... When one of their properties falls below a certain value on the scale of temperature?

      As long as it's cold enough, how cold doesn't matter. Why wouldn't that make sense?

      • by Anonymous Coward

        In a photon, the rest mass, energy, momentum, and temperature are always proportional.
        The physicists define an "unparticle" to have the same property and to have non-zero rest mass.
        pla is pointing out that if the property holds only below a certain temperature, then it's is not fully "scale invariant".

    • PPH [slashdot.org] seems (as far as I know) to have made a good point here, in that temperature is not a property of particles.

      • by pla ( 258480 )
        Ah, good point. Thanks!

        Although I seem to recall recently reading (on Slashdot, even) about individual particles having a "temperature", at least in the quantum if not in the thermodynamic realm, by virtue of their entropy - Clearly that concept doesn't apply as used in TFS, which means it strictly in the thermodynamic sense.
  • Are they "massive" particles, or simply "particles with mass"? Massive implies too many things, such as "huge", as opposed to merely "with mass".
    • Re:Are they (Score:4, Interesting)

      by meza ( 414214 ) on Friday August 08, 2014 @10:08AM (#47629809)

      In particle physics I believe the term "massive particle" is used to denote any particle with mass. Makes for a nice contrast to a massless particle. See for instance the wikipedia entry [wikipedia.org] or the paper in question on arXiv.

    • Compared to something with no mass, any mass is huge.

      I could be wrong, but I think "massive particles" is actually a term of art in particle physics, meaning "particle with mass".

  • Unparticles (Score:5, Funny)

    by Anonymous Coward on Friday August 08, 2014 @09:58AM (#47629745)

    Scientist 1: How about we fuck with the public again today?
    Scientist 2: What do you have in mind?
    Scientist 1: Let's invent a new term "unparticle", give it a scientific sounding description and do a press release.
    Scientist 2: You are just evil. I love it.
    Scientist 1: I can't wait to log into Slashdot and see the "geniuses" explain how it works.

  • by PPH ( 736903 ) on Friday August 08, 2014 @10:08AM (#47629811)

    at at very low temperatures, ordinary particles can sometimes behave like unparticles

    Temperature is related to the kinetic energy of a group of particles. It determines which way energy will be transfered in interactions between them. The concept of temperature for a single particle is somewhat strange. A particle doesn't know how fast it is moving (and what kinetic energy and temperature it has) until it hits something. So temperature and superconductivity are properties of the system, not each particle.

    • A single particle would have a different temperature relative to any other single particle, would it not? Essentially just the closure rate? So temperature is a relation between particles, not a property of a individual particles.
      • by PPH ( 736903 )

        Yep. Its all about frames of reference (I don't even want to think about relativistic thermodynamics).

        Aerodynamicists talk about airflow stagnation against an object as the air 'decelerates' in its vicinity. In reality, the airplane is moving through what was still air and acelerating it. But the math all works out the same.

    • I don't like calling it kinetic energy as that generally means linear motion for a particle, the particles are vibrating and that level of vibration is the temperature. The higher the vibration the more likely it is to react with surrounding particles through accidental collisions. Zero Kelvin is supposed to be the point where all the vibration stops and the particle is no longer vibrating.

      • by PPH ( 736903 )

        Linear motion vs vibration depends on whether you are speaking of a single particle (simple case) or a molecule that can store energy in its bonds (more complex case). A single particle does in fact move linearly until it hits something and simple Newtonian mechanics apply.

        Feynman's Lectures on Physics [wikipedia.org] have a pretty good rundown on the mechanics involved.

  • by Anonymous Coward

    I propose a new particle - the Unexplainon - which is responsible for all currently unexplained phenomenon.

    When do I collect my Nobel prize?

  • by Anonymous Coward on Friday August 08, 2014 @10:23AM (#47629911)

    First unpersons, now unparticles?

    The Party's meddling in physics id doubleplusungood.

  • by Anonymous Coward

    Sounds like the uncertainty principle at play. That is, at low enough temperatures you should have very high confidence of the momentum on a particle, but that inversely means you should have very low confidence on its position. Ergo, it has approaching equal probability on being located anywhere in the superconductor--just like in the double slit experiment, where multiple paths can/are taken and the derived "real" path is the result of interference patterns of all those paths.

    The only real puzzling part

  • unparticles may hold the key to understanding unconventional superconductivity

    Should it be called Unresistance?

    Would it still follow Ohm's Law? Or would it now be Un's Law?

  • by davidwr ( 791652 ) on Friday August 08, 2014 @12:25PM (#47630899) Homepage Journal

    I never thought I'd see those words used literally like that.

    Memo to self: Do NOT, repeat, do NOT call the next skinny woman I see "massive" - being technically correct won't get me a date.

  • The summary (and the referenced Wikipedia article) are sloppy about the use of the term "mass", sometimes using it when they should use the term "rest mass". Zero rest mass particles, such as photons, always move at the speed of light in vacuum. Moving at that speed, they do have mass. The relationship between their energy (E), mass (m), and momentum (p) is:

    E = pc = mc^2,

    where c is the speed of light in vacuum. They fit the definition of uniparticles because those three quantities all scale linearly relative to each othe

  • I guess if you want to study un-particles, you have to be un-interested.

    And quite possibly un-paid .

    Thanks, folks, try the veal.

"The eleventh commandment was `Thou Shalt Compute' or `Thou Shalt Not Compute' -- I forget which." -- Epigrams in Programming, ACM SIGPLAN Sept. 1982