Main Question or Discussion Point
Just for fun I wondered about how many photons hit the hubble telescope from a single star 13 billion LY away during a one day time exposure and came up with about 40 billion photons. Considering that a single star radiates light in all directions to a radius of 13 billion LY, it puts a perspective on just how many photons are out there. I'm not going to reveal how I came up with this number as I'll get laughed out of the forum . Anyone else care to come up with a number?