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Can bodies be made to radiate at one freq.

  1. Jan 21, 2013 #1
    If two bodies could be made to radiate at only one frequency a radiation heat pump could be made by having radiation sent by the colder body but having none received from the hotter to the colder by placing the colder body in a zone in a resulting inference pattern of zero net radiation. I don't know how I thought a answer may be in quatum physics as I understand that when electrons change valancy they put out radiation at a certain frequency ( or perhaps it is a certain range of frequency I don't know) Can anyone Dream up any ideas?
  2. jcsd
  3. Jan 21, 2013 #2
    It is possible for something to only radiate at one frequency if it is a two-level quantum system. A system of very cold spin-1/2 particles in a magnetic field is one possibility.

    However, I have no idea what the rest of your question is describing.
  4. Jan 22, 2013 #3
    I was blubbering about a idea along the lines that since everthing in a vaccuum emits radiation (unless a body is at absolute zero I guess) that if one somehow had a hot body( say with a hot junction of a thermocouple) and a colder body(say with a cold juction of the said thermocouple) in a sphere made of say a perfect mirror. That if the radiation of the hot body could be made to not hit or be absorbed by the cold body but radiation from the cold body transmitted to the hot there would be a radiation heat pump ( yeah I'm dreaming about beating Carnots efficency) ( and yes the thermocouple can make electricity without the heat dumped in the cold sink been lost.

    I'm fishing because I don't know how it could be done but have the notion that if a inference pattern could be established ( probably needing the hot and cold bodies to radiate at one frequency) maybe there could be spots in the sphere where the net radiation is zero . I don't know just that we are burning more oil than ever and for all the talk there is little hope of not doing so.
  5. Jan 22, 2013 #4
    Quantum mechanics and electromagnetism are proven to obey the Second Law of Thermodynamics directly from their fundamental postulates. It doesn't matter how Byzantine a scenario you imagine is; it won't exceed the Carnot efficiency.
  6. Jan 22, 2013 #5
    Electromagnetism is. Quantum mechanics, however - cannot see how.

    Second Law of Thermodynamics follows from T reversal symmetry.

    T reversal symmetry applies if every pair of states which has any process connecting them also has a reverse process and the ratio between the rates of process and reverse process is at all times equal to the ratio between phase spaces of second and first states.

    Is the restatement above correct?

    Now, T reversal or microscopic reversibility causes Second Law of Thermodynamics by forbidding Maxwell demons.

    You can put any sort of frequency selectors between two radiating bodies. Refracting prisms, diffraction gratings... whatever you like, or the bodies themselves may be absorbing and THEREFORE emitting in a narrow spectrum range and transparent or reflective at all wavelength... but in whatever window is available, the hotter body would be emitting back more light than the cooler body can be sending out.

    Note that quantum mechanics is not limited to electromagnetism.

    Strong interation obeys T reversal symmetry, and therefore Second Law.

    But weak interaction includes CP violation, which is allowed and included in quantum mechanics.

    Quantum mechanics is supposed to observe CPT symmetry.

    And from observed violation of CP symmetry, it is claimed that T reversal symmetry should also occur.

    If so, then weak interaction should permit operation of CP violating Maxwell demons.

    Therefore allowing violations of 2nd Law of Thermodynamics, and operation of perpetuum mobiles of 2nd kind. Not 1st kind, of course, because weak interaction does conserve energy even in CP violating interactions.
  7. Jan 22, 2013 #6
    Any unitary process—which time evolution in QM is—obeys the second law. This is a completely general result and doesn't require any other assumptions about QM besides its unitarity.

    Every current theory used in physics is provably entropic, and the sooner people accept that and stop trying to find sneaky loopholes, the sooner we can collectively stop wasting a lot of time.
  8. Feb 8, 2013 #7
    I´d like to see the derivation for that.

    As far as T reversal symmetry, I can follow.

    But how does "unitarity" allow T reversal violation?
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