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Can High-Energy Photons Escape a Black Hole that Absorbs Low-Energy Photons?

-- Chuck | March 4, 2021

EHT image of event horizon in the central supermassive black hole of M87

Question:

There may be so many ways to ask this that your archive could not find a match, so apologies if the answer is already in there somewhere: Is there a mass that is nearly black hole ‘size’ at which lower energy photons may be ‘trapped’ but not higher energy ones? Or is this question meaningless in the strange realm of BH mechanics?

-- Chuck

Answer:

Any object, including light, that exists inside the event horizon of a black hole is doomed never to escape the black hole, no matter what its mass or energy is. If an object is just a bit lighter than, but not quite a black hole, all wavelengths and energies of light can escape.

-- Jeff Mangum

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