I will explain what I mean.
Assumptions to help simplify: Point A is stationary, point b is moving away from it. And the expanding universe is moving point b away 1 light year in a year at point “a’.
Year 0 we see nothing
Year 1 we see point “b” 1 ly away
In year 1 point “b” is already 2 years away because universe expanded.
So it will take 2 years for the light from point “b” to hit observers eye in point “a” (year 3)
In that 2 years point “b” would have moved 2 more light years away.
In year 3 point “b” is observed as being 2 ly away but is 4 ly away.
In year 7 point “b” would be observed as being 4 years away. But in Year 7, the point “b” would actually be 8 ly away.
Based on this, how do we know age of universe is 13B+ light years and observable universe radius is 46B+ light years?
Since we are only at 13B years old, how does the light reach us from 46B light years away?
Also, since we haven’t been observing the process from beginning how do we know if a star was moving away from us at x light years per year or w/e? Things can change directions in those billions of years as galaxies merge or w/e, right?
In: Physics
No no no. You see, we see the oldest light is 13,8 billion years old. The CMB. How far its coming form is a different question since space have expended since the formation of the CMB we can calculate how far it is. Thats the 46 billion light years. The light can reach us no problem but we see the past when we look super far. See a galaxy 36 billion light years away, the light you see was emailed when it was a lot closer. So you see how the galaxy looked like but since space expanded we know that it’s in fact 36 billion light years away.
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