[fractionalhare]

Can you elaborate a bit more? I don't understand how this responds to the commenter's critique. Under the hypothesis, almost all stars in the universe would be so far from Earth that we would see at most one photon from their light by the time it reached us, for whatever the applicable time interval is. Would that single photon be sufficient to register the star's existence?

I'm not a physicist so presumably I'm wrong. But why is this wrong? As far as I understand it, this paradox is the reason we have the theory that space is expanding at a rate which makes objects in effect move away from each other faster than the light they emit.

[warent]

the point is 1 photon from a star seems like nothing, but 1 photon multiplied by infinite stars is infinite photons blinding us

[umvi]

"at most one". As you get further away zero protons are reaching you on most cases, and zero photons times infinite stars is zero, which would appear to be darkness

[andy-x]

Zero multiplied by infinity does not have to be zero, it can be anything between zero and infinity. Refresh your https://en.wikipedia.org/wiki/Calculus.

[fractionalhare]

How does calculus relate to the context of this discussion though? Photons are discrete, not continuous, so I don't see how calculus applies.

[improbable22]

The discreteness is a distraction here. You are interested in the total flux of light, from all stars in some patch of the sky. If some of them contribute on average less than one photon, that doesn't matter, it doesn't cause some sudden drop-off in intensity.

If it did, the same thing would happen not just for stars, but for all sorts of things. If you position a computer screen on a hiltop far enough away that, on a dark night, you can just make out whether it's on or off, then your eyes are getting about 6 photons per second. It doesn't matter whether these come from a million separate pixels, or from one light-bulb of similar total brightness.