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
The light doesn’t reach us from 46B light years away. What we are seeing is the light from close to year 0 in your example which was emitted ~13B years ago, but we know that the objects which emitted that light are currently 46B light years away so we can say that the observable universe is 46B light years across
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