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I was reading about Professor Finkelstein's speech at Cambridge University back in the 50's. He was explaining the dual reference frame of a black hole's event horizon. (A person falling in has one reference frame, and a person watching has a second.).... This I understand. My question is about the person watching reference frame...

It is my understanding that a person watching someone fall into the black hole would never actually see the person disappear. My question is how is this possible? THe photons coming from the person at the edge of the event horizon are only given off while the person is on this side of the EH. Once the person crosses the horizon, then the photons should not be there anymore for me to see. I know that time is slowed... but if I stared for 1000 years would I ever see the person cross the threshold? If not, where are these photons coming from?

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  • $\begingroup$ Maybe belongs on Physics SE? $\endgroup$
    – WarpPrime
    Commented Jan 3, 2021 at 1:27

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From the distant observer's perspective the person falling in becomes more and more time dilated and redshifted. As a result you see fewer and fewer photons from them and eventually none at all (although you never have any way of knowing that one more, very redshifted photon isn't going to arrive some time). So there are no extra photons.

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  • $\begingroup$ Thanks that make sense..... $\endgroup$
    – Rick
    Commented Jan 3, 2021 at 0:28

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