This is about the horizon which divides us from stuff that is too far to see because it's moving away from us faster than the speed of light.

If point $A$ and $B$ are so far away that $B$ is a bit outside $A$'s horizon, what if I look at the point $C$ that's midway between them? It will get light from $B$, because there's nothing from stopping that happening. However, any light at $C$ must be moving with speed $c$ with respect to $A$ while $C$ itself is moving slower. Therefore, any light that is at $C$ should also reach $A$ if the direction is right (and it is, if it came from $B$).

Where is the flaw?


Why should light that can reach C also have time to reach A?

It does not, because B is so far away that light from there did not have time to reach us.
No problem that light from C had time to reach B and A - but that is unrelated.

You placed C near enough that it's light can reach us - we see C how it looked very long ago, We will see B if we wait another long time while light that already reached C travels towards us between C and A.

(The actual flaw un your argument is probably related to not taking the timing into account in some way.)


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