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No hydrogen formation

  1. May 16, 2005 #1

    wolram

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    AFAIK hydrogen was one of the first elements in our universe, i came to
    wonder, what conditions would prevent hydrogen from forming, and our
    universe consisting of only radiation?
     
  2. jcsd
  3. May 16, 2005 #2
    permanent high temperature? which would mean no expansion of the universe I suppose.
     
  4. May 16, 2005 #3

    Astronuc

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    That question may never be answered.

    One could just as well ask, why are the elementary particles the size that they are? Why is the charge what it is? and so on.

    What one may ask is - how and why were the initial conditions of the universe (or all of existence), and all of matter and energy, and for that matter time, established?
     
  5. May 16, 2005 #4

    wolram

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    If there are two ways to ask a question i always pick the wrong one :smile:
    But were the conditions for hydrogen inevitable in our universe?
     
  6. May 16, 2005 #5

    mathman

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    If you start with the big bang conditions - extremely small volume and extremely high energy density, then hydrogen formation (or more specifically quark-antiquark and electron-positron pair production) is inevitable, assuming that the laws of physics are inevitable. A still open question is how did the excess of matter over antimatter come about.
     
  7. May 16, 2005 #6

    Astronuc

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    But what preceeded the Big Bang? What were the precursors? That question will never be answered.

    That's a BIG assumption. Yes, it is an open question. But how do we know that there is an excess of matter over antimatter. We cannot see the entire universe. We may be way off center.
     
  8. May 17, 2005 #7

    SpaceTiger

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    There are answers to the first part of the question that don't lead to the second. For example, if the rate of the expansion of the universe were much slower and the density much higher, then nucleosynthesis could have led only to the formation of elements much heavier than hydrogen. There are a ton of other initial conditions one could contrive that would lead to a lack of hydrogen. Mostly notably, if matter and antimatter were exactly symmetric and in equal abundance, then all matter would annihilate and you'd be left only with radiation. Another easy way would be to simply start without any baryons.
     
  9. May 17, 2005 #8

    Danger

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    It'd be interesting to see what would happen if Planck's Constant was 5, but I don't think I'd be around to witness it.
     
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