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To: traderrob6

“The comoving distance from Earth to the edge of the observable universe is about 14.26 gigaparsecs (46.5 billion light years or 4.40 x 1026 meters) in any direction.”

https://en.wikipedia.org/wiki/Observable_universe#Size
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“In standard cosmology, comoving distance and proper distance are two closely related distance measures used by cosmologists to define distances between objects. Proper distance roughly corresponds to where a distant object would be at a specific moment of cosmological time, which can change over time due to the expansion of the universe. Comoving distance factors out the expansion of the universe, giving a distance that does not change in time due to the expansion of space (though this may change due to other, local factors such as the motion of a galaxy within a cluster).

Comoving distance and proper distance are defined to be equal at the present time; therefore, the ratio of proper distance to comoving distance now is 1. At other times, the scale factor differs from 1. The Universe’s expansion results in the proper distance changing, while the comoving distance is unchanged by this expansion because it is the proper distance divided by that scale factor.”

https://en.wikipedia.org/wiki/Comoving_distance


41 posted on 11/17/2015 12:42:30 PM PST by ETL (Ted Cruz 2016!! -- For a better and safer America)
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To: traderrob6

“corresponds to where a distant object would be at a specific moment of cosmological time, which can change over time due to the expansion of the universe.”

I think I know what they mean now. For example, when we observe this galaxy it is where it WAS 2 billion years ago. But due to the expansion of the universe it is actually much further away than that now.


43 posted on 11/17/2015 12:59:57 PM PST by ETL (Ted Cruz 2016!! -- For a better and safer America)
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To: traderrob6

“Comoving distance is the distance between two points measured along a path defined at the present cosmological time.”

https://en.wikipedia.org/wiki/Comoving_distance#Comoving_distance_and_proper_distance


44 posted on 11/17/2015 1:05:09 PM PST by ETL (Ted Cruz 2016!! -- For a better and safer America)
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