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B Was the Big Bang a quantum mechanical vacuum fluctuation?

  1. May 10, 2018 #21
    No, not yet, I’ll read the article soon (probably tomorrow), I hope it’s going to be an interesting one.

    Just to be clear, I’m not saying that my description above is a true description of nature, but I don’t yet see why this way of reasoning should be wrong. I’m looking for a fact/law/equation/anything why it can’t be true. So I’m actually looking for evidence against my own reasoning, not in favour of it, I want to understand why my description can’t be right. But while I’m explaining myself quite extensively and detailed, I’m receiving a rather short answer as a counter-argument, which isn’t overwhelming me with persuasion, if you don't mind me saying it.
    I've tried my best, but I can't follow you there. The photon seems to be only changing, not disappearing.
    I’m arguing against "established science"? I’m referring to dark matter and dark energy. The scientific community don't know what both dark matter and dark energy are, so there is no established science yet about these topic, in order to be able to argue against it.

    I’ll read this article, which is in disfavour of the law of conservation of energy, concluding that it's not a universal law. But what about entropy, is that also an approximate/statistical conservation law, instead of a universal one? Or what about the conservation of charge?
     
  2. May 10, 2018 #22

    phinds

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    The recent discussion has been about conservation of energy. Nikkkom's comment was pointing out that energy density is decreased because photons lose energy and it doesn't go anywhere, it just evaporates.

    The best way to "get" the argument against your line of thinking is to learn the actual physics. Then your misunderstanding will evaporate like the energy of EM radiation as it travels over cosmological distances.
     
    Last edited: May 10, 2018
  3. May 11, 2018 #23
    Your description is handwavey. Nothing wrong with doing that as the first approximation (more like "zeroth" one), but you should be ready to start looking at the rigorous description as you test your theories against evidence and other well-known physics.

    The energy of plasma in thermodynamic equilibrium is equally distributed across all available degrees of freedom. Therefore energy can't be only in photons, unless temperature (nee "average energy of particles") is much below 2*511 keV. Such "low" temperature was reached only at about 10 seconds "after BB". Before that, energy was distributed among photons _and_ electrons/positrons. Before 0.1s, energy was distributed also across muons and pi-mesons. And so on. "Pure photon epoch" has no basis in known physics.
     
  4. May 11, 2018 #24
    Photon's energy is decreasing. Where does it go?
     
  5. May 13, 2018 #25
    I’ve read the article. To summarise it, “Energy isn’t conserved; it changes because spacetime does”.

    But the energy itself is still there. No boson or fermion has disappeared. So therefore, from that point of view energy ("stuff" on the Standard Model) “has been conserved”. But of course, something has changed, due to this dark energy (not "stuff" on the Standard Model), so the Universe is not the same any more as it was before, something has definitely been added, so from that point of view energy “has not been conserved”. It’s a matter of terminology, if you also include "gravitational energy" when you're referring to “energy”, then energy is indeed not conserved. But energy from the Standard Model is different from gravitational "energy".

    A photon has no charge/mass, but both the matter/antimatter particles do have charge/mass, but together still cancel out to 0. The electron and positron pair still have that same dualistic nature. Maxwell's 2nd law of electromagnetism clearly shows the symmetry in the wave function of the photon, whereas the Schrödinger equation shows symmetry in the wave function of the electron. In other words: it doesn’t matter how often you divide an electromagnetic particle, it will always conserve a north and a south pole, because there is no such thing as a monopole.

    Therefore, I’m still a supporter of the zero-energy Universe, and the quantum mechanical vacuum fluctuation to explain the mechanism of the Big Bang, because I’m not aware of any other, more plausible, explanation for the Universe we live in today. Should/shouldn’t I be?
     
    Last edited: May 13, 2018
  6. May 13, 2018 #26

    DaveC426913

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    It gets attenuated.

    Think of the universe as analogous to an ideal gas in a closed vessel. The temperature will change in inverse proportion to the volume change.
    i.e. increase the volume, and the temperature drops, though no energy has left the system.
     
  7. May 14, 2018 #27
    Wrong - energy and number of particles are completely different concepts.

    Also, number of particles is not a conserved quantity at all. Say, one gamma-ray photon can be converted to millions of visible and infrared photons. Stars do this all the time.
     
  8. May 14, 2018 #28
    Are you referring to this:
    Energy has changed, yes, but it wasn't created or destroyed. You can divide '1' into 1/2 and 1/2, or into 1/4, 1/4, 1/4 and 1/4, but that doesn't mean that energy has been added. It still has been conserved.
     
    Last edited: May 14, 2018
  9. May 15, 2018 #29
    Saying that it "evaporates" is not the same thing as saying it "is not conserved". Vaporization is readily recognizable as a disaggregation and not as a non-conservation of the vaporized matter.

    Bare remarks to the effect that on a cosmic scale energy isn't conserved are jarring to the sensibilities of many. The expression "is not conserved" is insufficient to account for what happens to the 'not conserved as such' energy. It dis-integrates and dissipates, and although not 'conserved as such', it is nonetheless 'conserved not as such', as a difference in a quantity of a different suchness that is proportional to the difference in the 'not entirely conserved as such' energy.

    It goes not from somethingness to nothingness; it goes from a thisness to a thatness, just as everything else in flux does.
     
  10. May 15, 2018 #30
    In this context, phinds did mean that energy disappears. All CMB photons redshift everywhere.

    Facts don't care about your sensibilities.

    If it is "conserved not as such", whatever that means, where, in your opinion, energy of redshifting photons goes?
     
  11. May 15, 2018 #31
    He said evaporates. I replied to what he said. Just as water seems to disappear from a dish left in open air, but is in fact somewhere else rather than simply gone, the energy diminution we encounter in our observations of photons should not be presumed to be un-accounted-for in the grand ledger of the universe.
    I'm fairly confident that for the most part you're right about that. :wink:
    I suspect that it goes somewhere other than nowhere. We can observe that it doesn't appear to us to continue to inhere in or exhere from the photons we measure. We cannot thereby infer that it is leaked out of the entire universe.
     
  12. May 16, 2018 #32
    Perhaps its useful to think about this photon energy question in a simpler setting. Consider photons emitted from someone speeding away from you. They arrive at a different frequency, which can be calculated based on relativistic doppler formulas.

    However, the intensity of the light is also influenced. I think since E gets multiplied by gamma for a lorentz boost, the intensity should be reduced by gamma squared?

    Can anyone fill in the dots? I'm interested to see whether photon number is actually conserved- if someone speeding away emits 10^10 photons at a certain wavelength over a finite period of time, does the stationary observer really see that same number? I don't think so. Photon numbers depend on choice of basis for hilbert spaces which can be done differently. This is part of the story behind spontaneous particle creation in Hawking radiation for example.

    Related would be to do this for gravitational redshift.
     
  13. May 16, 2018 #33
    That meander does not serve to clarify. It's clear that there's an energy loss that is not fully accounted for merely by the accepted paradigms. Although I've stated that I think that the energy must go somewhere rather than nowhere, I confess that I think that I'm as much at a loss to explain exactly where, as are the proponents of nowhere to explain exactly how.
     
  14. May 16, 2018 #34

    phinds

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    But there is no NEED to explain "how" since that question only arises if you insist on applying a local principle (conservation of energy) in a domain (large scale cosmological distances) where it does not apply.
     
  15. May 16, 2018 #35
    If you insist that energy exits the universe, when all you can show is that it became no longer to you findable, while I insist that it must be somewhere, when all I can show is that historically, energy once reported as missing usually turns up somewhere else, I think it's at least as incumbent upon you to account for how energy leaves the universe, as it is on me to account for where it went.
     
  16. May 16, 2018 #36
    It's not a "he said, she said" competition. Energy conservation is a theorem. For time-translation invariant spacetime, energy must be conserved.

    Since our local conditions, to a very high precision, are time-translation invariant, we should, and we are, observing that energy is conserved in all processes.

    At the same time, on a cosmological scale, we observe that Universe is not time-translation invariant. Therefore, energy conservation on that scale is not required by any theorem.
     
  17. May 16, 2018 #37

    fresh_42

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    I cut off the discussion about energy conservation at this point, because this post summarizes it all:
    Everything else I've read so far is an argumentation about phrasing it. It is furthermore off topic, resp. will become off topic if we go on with it. So please return to the question, whether the big bang can be considered a quantum fluctuation, on which scale ever, i.e. possibly a real giant one. Otherwise we will be forced to close the thread, as personal debates about wordings won't help anybody to understand what has been going on before inflation.

    Thank you.
     
  18. Jul 28, 2018 #38
    That is true in General Relativity which is not the full picture .. maybe energy will be conserved in a quantum theory of gravity.
     
  19. Jul 28, 2018 #39

    phinds

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    Nothing about a quantum theory of gravity would change the fact that photons lose energy as they travel in an expanding universe, so no, it would not.
     
  20. Jul 28, 2018 #40
    It might explain where that energy goes.
     
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