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Q & A: light and black holes

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Most recent answer: 09/07/2009
Q:
If nothing can travel faster than the speed of light, than how do black holes have a stronger gravitational field than the speed of light?
- John (age 13)
Cincinnati, Ohio
A:
I don't follow this question. Nothing can travel faster than the speed of light in the following sense: whatever your point of view, any object traveling past you nearby will not be traveling faster than the speed of light from your viewpoint. There is no contradiction whatever with the existence of regions from which neither light nor anything else can escape. The size of the gravitational effects is not itself a speed, so it can't be faster than the speed of light, or even compared with it in any way.

Mike W,

(published on 09/07/2009)

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