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Name: Jacques
Status: other
Age: 50s
Location: N/A
Country: N/A
Date: 8/22/2004

Light is bent by gravitational force. Can a light wave traveling near a black hole, not at its singularity but very close to it be bent in a permanent spherical trajectory?

Yes, I believe it could travel in a circular or elliptical trajectory much as the planets circle the sun. It would not be permanent and might be quite short lived since the gravitational attraction of the black hole will increase as it gobbles up more matter. Also the photon might collide with some bit of matter being swallowed by the black hole and itself be swallowed.

Also, if the orbit is small enough in diameter, quantum mechanical effects could become dominant as they are for an electron circulating a proton in a hydrogen atom. Remember that black holes are small in size, but not, I believe as small as atomic dimensions. It is also relevant that time is slowed drastically in the enormous gravitational fields near the event horizon of a black hole.

My expertise is not sufficient to know exactly what would happen. I have never seen a discussion of this problem.

Good Question!

Best, Dick Plano, Professor of Physics emeritus, Rutgers University

You are apeaking of a very specific case where the energy of light and the gravitational force of the Black Hole are in perfect balance. Dr. Stephen Hawking does a pretty good job of explaining about black holes and light in his book "A Brief History of Time."


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