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Did all 10^80 particles exist after the first 3 minutes?

  1. Jul 16, 2012 #1
    I'm a little skeptical that all 10^80 particles could fit inside a universe as small as it was after the 3rd minute. I know there is a lot of empty space inside a particle so maybe in the beginning that empty space was not there, but I'm still skeptical. I'm still confused about whether or not the conversation of baryon number really holds. Is it ever the case that virtual particle get promoted to real particle hood, after the 3rd minute? Here's a passage from Paul Davies' The Last Three Minutes:
    And here is a quote from Steven Weinberg's The First Three Minutes concerning the conservation of Baryon number:
    Again, I find this hard to believe. How could all 10^80 particles fit into such a small size? But yet S.W. says it right there in black and white.

    Also, are hyperons some jargon from the 70's that no one uses anymore?
     
  2. jcsd
  3. Jul 16, 2012 #2
    Particle physics/cosmology is far from my forte, but I will point out that we don't know the size of the Universe at the third minute; it may very well have been infinite (which it must have been if the present Universe is infinite in size, which is by no means settled).
     
  4. Jul 16, 2012 #3
    I believe the OP's 10^80 number refers to the number of particles in the observable portion of the universe - which is always finite regardless of whether or not the whole of the universe is infinite or not.
     
  5. Jul 16, 2012 #4
    Yes, I'm referring to the observable portion.
     
  6. Jul 17, 2012 #5
    Here's a quote from Weinberg on the size of the Early universe

    I don't see how they can figure out the temperature of the early universe unless they know the size.
     
  7. Jul 17, 2012 #6

    Chronos

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    The size of the universe was around 50 light years 3 minutes after the big event. That may not seems like much, but, 50 light years is a lot of space and the universe was still expanding rapidly. Still, it was hot and crowded - enough so that primordial nucleosynthesis continued for another dozen or so minutes.
     
  8. Jul 17, 2012 #7

    mfb

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    @Chronos: The size of the observable universe.


    10^80 particles in a ball with 50ly diameter (?), neglecting curvature, is ~1/nm^3, which is less than the density of atoms in solid objects. And if you compare regular matter with neutron stars, there is a lot of space left, even if the particles would be solid objects (they are not). While Fermions cannot occupy the same state with multiple particles, if you increase the energy you also increase the available states and therefore the allowed density - without a theoretical limit.

    Still used
     
  9. Jul 17, 2012 #8

    Chalnoth

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    This shouldn't be a surprise. This was long before atoms formed, when our universe was just transitioning from a quark-gluon plasma as protons and neutrons first started forming.
     
  10. Jul 17, 2012 #9
    do string theorists believe there is one string with width 10^-35 m inside one quark with width 10^-19 m? If so then it would be slightly easier to imagine all matter compacted inside a very small space?
     
  11. Jul 17, 2012 #10
    No. In string theory all particles are strings. They aren't made of strings, they literally are strings. In the SM, particles have no size, they're zero dimensional. I'm not sure where you got that number, but it is most likely how far we can confirm the quark has no size.
     
  12. Jul 17, 2012 #11

    mfb

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    The 10^(-19)m is just an upper limit. If it would be larger than that, we would have seen a substructure. It is impossible to give a lower limit.
     
  13. Jul 17, 2012 #12

    Dotini

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    Doesn't pair production mean that more particles are being created all the time, even as energy is being conserved?

    Respectfully submitted,
    Steve
     
  14. Jul 17, 2012 #13

    Chalnoth

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    Well, when our universe was at extremely high temperatures, particles would be produced just as often as they would annihilate with one another. As our universe cooled so that the production rate slowed, they would tend to annihilate with one another more than they would be produced, reducing the number of particles.
     
  15. Jul 17, 2012 #14
    The OP is referring to Baryons, particles produced in the early universe that are made of quarks (protons, neutrons, etc.). This doesn't include elementary particles (e.g. the leptons)
     
  16. Jul 18, 2012 #15
    I meant that the string's size is 10^-35 m and its Pauli Exclusion domain is 10^-19 m. I got the size of quarks from wiki's article of orders of magnitude


    http://en.wikipedia.org/wiki/Orders_of_magnitude_(length))

    Maybe the size of the Pauli Exlusion domain was different during the first few seconds.
     
  17. Jul 18, 2012 #16
    We know from accelerator physics that baryon number is conserved in interactions between particles for collision energies that existed in 3-minute-old universe. Therefore the particles must have been created earlier, to account for the fact that there is more baryons than antibaryons around.
     
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