I got to thinking recently about what I suppose should be fairly obvious but I’d never thought about it much before. We measure the time from the Big Bang based on receiving in effect signals of that moment. So we can say from those observations that the universe is something like 13 billion years old.
I am wondering do we see items further out (older?) than we are in the same way as those further in? They’re moving away, but I’m guessing someone better versed in Uncle Albert’s wisdom can explain why the light they emanate covers distance the same as the light from the guys on the other side. Although I’ve never heard of a measurement of where the far end of the universe is. Can we not see it because of the expansion effect, has it just not reached us yet, or what?
In any event, what I was wondering about was, the Big Bang must have expanded as a sphere, which means we are in effect at a point in that sphere say 10 billion or so light years from its center. Which, incidentally, I get at around 6 trillion miles. It’s a lot, but I’m amazed it can even be measured.
But wait a minute. If it’s all a sphere, then there must be somebody directly across from us on the other side of the sphere, like the Indian Ocean is to the US. If that’s the case, then we’d be separated by say 20 billion light years. But that’s older than the age of the universe, so would seem to not be possible.
So how is this all coherent?