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Q & A: light near black hole

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Most recent answer: 10/24/2017
Q:
I am aware that photons can be captured in orbit around a black hole. Would it be possible for light to hit just near the event horizon of a black hole and be sent back in the opposite direction? Almost like a cosmic mirror.
- Anthony Atchison (age 31)
Arlington, TX
A:

Light can swing gravitationally around a black hole and come back toward the source, much like how a comet can swing near the Sun and head back toward where it came from. It's not really like a mirror, however. If two light rays go past the left side of the black hole the one farther to the left will swing around and return farther to the right. For a mirror with direct reflection, that reversal doesn't happen.

Mike W.


(published on 10/24/2017)

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