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Mass<-> Energy

  1. Apr 15, 2010 #1
    In the universe, we can see mass gets converted to energy almost everywhere. Does the energy get converted to mass naturally? From an answer to a question I posted many months ago, I understand that it is possible to convert energy to mass. But does it happen in the same rate as mass to energy conversion?

    If there is more mass to energy conversion occurring in the universe, will the universe become massless eventually?

    When we think about the origin of universe, we start with a point mass or no mass concept. Shouldn't it be the other way? Initially the universe was of infinite mass and most of the mass got converted to energy, something like that...:)
  2. jcsd
  3. Apr 15, 2010 #2


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    Energy to mass conversion doesn't occur nearly as regularly as the other way around, and even when it does occur the products usually don't last long.

    The main problem with energy to mass conversion is the immense amount of energy you would need to pack into a tiny portion of space for matter to be created. The energy densities you need are pretty huge. In the cores of some very massive stars this can actually happen.

    In vacuum this also happens...the energy is "stolen" from the universe...and "given back" within a short period of time as constrained by the Heisenberg Uncertainty Principle.

    The other problem with energy to mass conversion is that every particle you create is always paired with an anti-particle. When you create an electron, you necessarily create a positron as well. In this way, the particles you create usually annihilate each other soon after they are created (this is what happens to nearly all of the particle-antiparticle pairs created in vacuum). They don't last.
  4. Apr 16, 2010 #3


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    http://en.wikipedia.org/wiki/Baryogenesis" [Broken]was large scale matter production. Things have calmed down a bit since then, however.
    Last edited by a moderator: May 4, 2017
  5. Apr 16, 2010 #4
    Did not understand a single bit of the wiki page :) well, that's not surprising :)
    Last edited by a moderator: May 4, 2017
  6. Apr 16, 2010 #5


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    Well, the article is about something that physicists don't really understand, too.
    In short: it is believed that some all-pervading field decayed, released an immense amount of energy, which somehow got converted to stable matter. That was the Big Bang (or, precisely: "reheating")
    From Wikipedia:
  7. Apr 17, 2010 #6
    OK. About the future of the universe - are we going massless?
  8. Apr 17, 2010 #7
    You might want to re-think the effect of the process of expansion?
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