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Thread: How was the visible horizon measured?

  1. #1 How was the visible horizon measured? 
    Forum Professor Daecon's Avatar
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    If the very edge of the visible Universe is 13.8 billion light-years away, how exactly was such a vast measurement calculated? What clues led us to figure out that's how far away in the cosmic distance we can see?

    I'm not sure if I'm phrasing the question accurately enough.


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    Quote Originally Posted by Daecon View Post
    If the very edge of the visible Universe is 13.8 billion light-years away, how exactly was such a vast measurement calculated? What clues led us to figure out that's how far away in the cosmic distance we can see?

    I'm not sure if I'm phrasing the question accurately enough.
    Although the universe is 13.8 billion years old, the radius of the visible universe is roughly 46 billion light-years (thanks to expansion). A reasonably good introduction to where this figures come from is, surprisingly, a wikipedia article: Observable universe - Wikipedia, the free encyclopedia

    The short answer to how these calculations are performed is that the CMB redshift contains vast amounts of information that can be used to fix parameters in cosmological models. The current best model is the lambda-CDM model. When used in conjunction with the best CMB data, one obtains the current estimate for the age of the universe. (I'm leaving out a great many details, but that's the basic outline.)

    Wikipedia again has a reasonably good overview: Age of the universe - Wikipedia, the free encyclopedia


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