Assuming the Big Bang was 13.8 Billion Years ago: Is it possible to observe a Galaxy's redshift showing distances slightly greater than that, like 48 Billion Light Years away? I understand that in a static universe, light traveling in a straight line would only be visible at less than 46.6 Bly. But, can Hubble's constant distort this number? Also, do we assume some error due to the light taking a non-linear path because of lensing? If so, is it possible to have an error of several hundred million years?
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2 Answers
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The edge of the observable universe is actually 46.6 billion light years away, despite the Big Bang being only 13.8 Billion years ago. This is because the light which we are now receiving as the furthest visible stuff had to travel through ever expanding space in between, being redshifted down into what we call the Cosmic Microwave Background Radiation (CMBR). There is a little bit further than that which we are technically receiving, but it has been redshifted infinitely.
To see anything further away than 46.6 Bly, it would have had to existed literally before time itself, or travelled faster than the speed of light. Two highly improbable things
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$\begingroup$ I understand that bc of expansion the object is actually, at this time, 46+B ly away but that doesn't answer my original question. When we measure the light (and its redshift), we measure as it left the source 13+ B years ago and thus we are seeing a photo of it as it was then, regardless of where it is now. So, when calculating the distance for it we consider distance based on the point and period at which the light was emitted. However, that light still has to travel through expanding space on a curved path. How do we resolve these variables and to what degree of error? $\endgroup$– NotSoSNCommented Apr 23, 2016 at 16:22
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$\begingroup$ The actual object is much further away than 46.6 Bly away now. The light has traveled that far, but during that time, the space between the light and the originator source has moved even further away still. That's if I understand your question correctly $\endgroup$ Commented Apr 23, 2016 at 17:11
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No that would be impossible. Even if we were to observe a galaxy that is basically infinitely redshifted it would not be interpreted as having its light sent out earlier than 13.72 billion years ago or now being more than 47 billion light years away. This is because of how the formula for how to calculate distance from redshift is designed.
Answer: No matter how redshifted a galaxy we find, it will never, using our current model, be interpreted to be more than 47 billion light years away.
