I am trying to grasp the concept of cosmic background radiation, specifically why we can still see it today. As the name implies, it is very faint radiation from the very early universe.
What I don’t get: if a very distant star stops emitting radiation then it will disappear from our view.
As far as I understand it, CBR originated with the recombination. That phase took a few hundred thousand years, then it stopped. So why can we still see the photons emitted then?
Thanks for illuminating me.
In: 6
Sorry for late reply.
You can still see the light because the universe expanded faster than the speed of light. Yes, speed of light is the fastest something can move, but realitivly and through some magic of general realitivty, the universe expanded faster.
So the light that was created during the Big Bang, is still traveling towards us. The redshift is just the result of the light “slowed down” by the expansion after the BB.
If you google “observable universe” or “edge of the universe”
You get a circle or part of a circle that looks like a human Iris. As it goes further out away from the center, it also goes back in time. Cuz thoes photons still be travelling, just having to go a further distance before reaching us.
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