|MadSci Network: Physics|
Hello, Lucasz. Yes, light speed is constant. Also, it's direction of travel is constant. Gravity really doesn't bend light, or slow it down. What gravity does is bend spacetime. Let's imagine that spacetime is a sheet of paper, and a ray of light is a straight line drawn on the paper. Gravity curves the paper. Really strong gravity, like black holes, curve the paper so much that the the paper is rolled up into a cylinder, and the straight line never escapes its confines. The line is still strait. It hasn't moved on the paper. But the paper has been rolled up, unless you're inside the cylinder, you can't see the line. Once the paper has been rolled into a cylinder, new lines drawn on the inside curve of the paper wouldn't be seen from the outside. So a flash of light inside a black hole wouldn't be seen outside of it. Actually, with the incredible amounts of heat and energy contained in a black hole, they're extremely bright stars. They're probably the brightest objects in the universe, but their light will never be seen outside their event horizons. Kind of a shame, isn't it? Remember, it's the fabric of the universe, spacetime, that is curved by gravity. Light doesn't alter its speed or direction as it travels through the universe, but it appears to do so near objects with lots of gravitational pull. What's actually being altered is time and space, not speed and direction. Thanks for the question, Layne Johnson
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