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I Inflation and expansion of the universe

  1. Dec 12, 2016 #1
    We know from observations that the universe is expanding and that the speed of recession of celestial objects increases the further we look back in space.
    However, looking further in space is also looking back in time, so does this mean that we are looking at the end of inflation ?
  2. jcsd
  3. Dec 12, 2016 #2


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    Staff: Mentor

    We can't see that far back in time, phtdegroot. The furthest we can see back is to about 379,000 years after the big bang. At this time, the hot plasma that permeated the universe reached a lower enough temperature for protons to combine with electrons to form neutral atoms. This is important because plasma interacts very strongly with EM radiation such as light, absorbing or scattering it before it can travel far. As a consequence, prior to this point in time light could not travel very far and it is impossible to see any further back in time using EM radiation. The CMB was created by this recombination event, and represents the furthest we can see at this time. To see further we could use neutrinos, except that they interact so weakly with other matter that it's essentially impossible to focus them down to a single spot like we can do with light and EM radiation.
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