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Big Bang

  1. Jul 5, 2005 #1
    I was reading some stuff about the big bang and about the singularity. When the big bang happens, is a whole lot of matter just created?


    Are Photons counted as matter?

  2. jcsd
  3. Jul 5, 2005 #2


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    What happened at the big bang and where the stuff came from is an open question. After the big bang the universe consisted mostly of energy (photons) which interacted (it takes at least 2) to form matter-antimatter pairs. For reasons not fully understood, the subsequent particle reactions were such that there was a slight excess of baryonic (ordinary) matter, which is why we're here.
  4. Jul 5, 2005 #3
    i think the matter particles had a slightly longer half life, hence when all the matter/anti-matter had collided and anihilated (producing photons) there was an excess of matter (since some of the antimatter had decayed already).
  5. Jul 5, 2005 #4


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    There is a limit to how far back toward the Big Bang modern physics can describe (something like 10^-43 seconds after the beginning). So we can't tell what was going on at Time = 0. However, physics can describe what happened after that (with varying degrees of certainty).

    To say the least, the Big Bang was an energetic event. The Big Bang was not an explosion of stuff into empty space but was the rapid expansion of all space. As space expanded, the energy therein cooled. At about 10^-36 seconds after the beginning, elementary particles like quarks and electrons were able to form. At about 10^-6 seconds, the quarks were able to combine into protons and neutrons. But the universe was still too hot for atoms to form. It took another 300,000 years for things to cool down enough to form atoms (throughout the universe, since that original energy was already throughout the whole universe). At this point, gravity pulled this matter together to form stars and galaxies (throughout the universe).
  6. Jul 5, 2005 #5

    so matter was just, made after "phlanks minute" (sorry about spelling)?

    Can Photons turn into matter?
  7. Jul 6, 2005 #6


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    As I tried to explain in my previous note, a single photon by itself can't turn into matter (conservation of momentum). However two photons can collide and turn into a matter-antimatter pair.
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