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Suppose a boy is in a room with a bulb (no windows and other light sources). Now the boy ON's the bulb and OFFs it such that only one photon is released (hypothetical). Now the bulb is OFF. The photon should collide (elastically, so no loss in energy) with the walls and eventually after many collisions reach our eyes, the boy should be able to see the part of the wall with which the photon last collided. But this is not the case we don't see anything so what happened to the photon which was released? What happens if we replace the boy with a photon detector and repeat the above?

Edit: What happens if there are many photons and many people in the room (covering the whole room) then there is a slight probability of seeing light when the light got off, right?

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  • $\begingroup$ Does this answer your question? How are photons "consumed"? $\endgroup$
    – John Rennie
    Commented Mar 29, 2023 at 17:07
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    $\begingroup$ Re, "What happens if there are many photons (like 10^100000)?" I think you have no idea of the magnitude of that number. If you could round up all of the photons that have ever existed in the entire history of the universe, and put all of them into that closet at once, it would be utterly insignificant compared to 10^100000 photons. What would happen? It would be silly to even try to extrapolate from any existing physical theory to say what might happen. $\endgroup$
    – Solomon Slow
    Commented Mar 29, 2023 at 18:47
  • $\begingroup$ by 10^100000 I just mean "many photons" not literally the number $\endgroup$
    – vivian.ai
    Commented Mar 30, 2023 at 2:55
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    $\begingroup$ I think that if you rounded up all the photons that ever existed in the universe and put them into a closet all at once, then for any reasonably-sized closet, you'd end up with a black hole (now I want to know if this is actually the case). If no black hole was created, you'd certainly burn down your house, and possibly the planet it is on. $\endgroup$
    – TimWescott
    Commented Mar 30, 2023 at 3:03
  • $\begingroup$ The photon reflection events you have outlined actually do happen to an extent, but over a time frame on the order of $10^{-7} s$ or less. Our human reaction time for perceiving separate events is on the order of $10^{-1} s$, so to us it is completely instantaneous. Consider for example, we see a 60 frame per second movie as smooth and continuous. $\endgroup$
    – RC_23
    Commented Mar 30, 2023 at 4:15

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When the photon hits a wall, it might be reflected (in a somewhat random direction) or it might be absorbed. If reflected it will encounter another wall and again it may be reflected or it may be absorbed. It takes about ten billionths (US billions) of a second for a photon to traverse a room. In a millionth of a second the photon, if reflected at every wall, would have encountered many many many walls. It will eventually be absorbed, in a very very short time.

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