****An infinitely old universe will have a night sky filled with light****
I have yet to see proof that light travels forever.
As it travels, it loses energy which is expressed by a lower frequency. At some point, the frequency is so low you can’t see it. I suppose then you could say is stopped. But as we can see, the surface of a star puts out a LOT of light and we can see it from incredibly far away, almost back to the ‘flash’ when light became able to ‘shine.’
When does light run out of gas?