If photons have no mass, how are black-holes able to suck in light?
In: Physics
Before Einstein, we assumed that gravity was like an invisible rope between objects with mass that pulled them together. Under this sort of understanding, light wouldn’t be affected by gravity at all.
One of Einstein’s biggest contributions to science is what we now call “general relativity”. Put very simply, he theorized that objects with mass are actually fundamentally curving space around them slightly in the 4th dimension. This means that as objects move through this space in a straight line, they will end up moving towards the center of this curve, kind of like rolling a marble into a funnel. Incredibly fast moving things like light are still absurdly hard to trap; using the marble analogy, if you throw a marble into that funnel as hard as you can it’ll just bounce out. However, with a big and steep enough funnel it can be done, and that’s what a black hole is.
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