Question about the universe expansion

fantom42

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us in the Milky way
2 galaxy A and B at 100 millions light year in opposite direction, go farther to us at 0.1 % of speed of light
2 galaxy C and D at 1 billions light year in opposite direction, go farther to us at 1 % of speed of light
2 galaxy E and F at 10 billions light year in opposite direction, go farther to us at 10 % of speed of light
and we declare. because of the red shift bigger for E and F than C and D than A and B, the universe is in accelerating expansion!

My problem:
I will agree if the speed of light was infinite, but
E and F are 10 billions year in the past and are more red shifted,
C and D are 1 billions year in the past less red shifted,
A and B are 100 millions year in the past even less red shifted
and for me that mean the universe expansion is slowing, not accelerating!

Where am I wrong ?
 

Urwumpe

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Well - I am likely oversimplifying things a bit but: Lets assume, redshift is proportional to velocity. If a galaxy that is ten times further away has ten times more redshift than another galaxy, the expansion would not accelerate: It must have been the same in the past as it was now, because the older light shows the same redshift/distance ratio.

Would the expansion accelerate, the more distant galaxies show a lower redshift/distance ratio as closer galaxies, because the newer light that arrives at our position shows signs of a faster expansion.

Again, its oversimplified - in reality, the light we observe would have to travel through accelerating or decelerating space, which would mean some sort of exponential relation between observed redshift and distance.
 

Sbb1413

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I will agree if the speed of light was infinite, but
Speed of light can't be infinite, otherwise photons would be unstoppable from the infinite speed*, and thus we could not see any light, which is contrary to the reality.

*If they are stoppable, then it would require an infinite amount of energy to stop them, but the universe has a finite amount of energy to waste, according to the first law of thermodynamics.
 
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