I have a vague memory that someone tested whether we can see individual photons and it turned out we can, but do not quote me on that. I’ll do some searching to see if I can find a relevant study
Despite investigations for over 70 years, the absolute limits of human vision have remained unclear. Rod cells respond to individual photons, yet whether a single-photon incident on the eye can be perceived by a human subject has remained a fundamental open question. Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance. This was achieved by implementing a combination of a psychophysics procedure with a quantum light source that can generate single-photon states of light. We further discover that the probability of reporting a single photon is modulated by the presence of an earlier photon, suggesting a priming process that temporarily enhances the effective gain of the visual system on the timescale of seconds.
At night (in the dark), everything you see has fluctuating intensity. This is change in the number of photons that you detect - when there are few photons, the number of photons per second per detection cell noticeably fluctuates, and you can see that, easily.
I have a vague memory that someone tested whether we can see individual photons and it turned out we can, but do not quote me on that. I’ll do some searching to see if I can find a relevant study
edit: well that was easy https://www.nature.com/articles/ncomms12172
At night (in the dark), everything you see has fluctuating intensity. This is change in the number of photons that you detect - when there are few photons, the number of photons per second per detection cell noticeably fluctuates, and you can see that, easily.
Change in the number of photons and noise from your wetware.
But yeah, it’s pretty neat that our peepers have a built-in gain system