# black hole mystery

I come to know about black hole that it is invisible because light is never reflected as it gets in it , so does photon light is affected by gravitational field .But how it's possible ,photon doesn't contain any matter . If it doesn't have matter then how the gravitational field can at on it

5 years, 9 months ago

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Firstly, a black hole isn't invisible. It just absorbs all the light coming on to it, sort of like a sponge. If they were invisible, then they would let light pass right through them. Now, onto the question. Light is affected by a gravitational field because of the curvature of the space - time web (think of Minkowski diagram). Bumps in this web are caused by gravity, which means that a particle, such as light, needs to travel a further distance to get to Point B from Point A. When light reaches a black hole (such a bad name, it does reflect particles, Hawking radiation), it is literally caught into a 'whirlpool' straight to the singularity because of its momentum.

- 5 years, 9 months ago

What did you do to the word "invisible" in the first line? It doesn't show. I can only see it when I select it.

- 5 years, 9 months ago

You want to say that light too keep moving around the black hole?

- 5 years, 9 months ago

Yeah, but spirals towards the centre.

- 5 years, 9 months ago

This, is why, because gravity is not a mysterious invisible force but it is rather the shape of space time itself. Consider a football on a trampoline, what will happen? Well the ball will sink in the trampoline due to its mass. Similarly, the space-time behaves something similar like a trampoline. Thus, the black hole also make a curvature in space-time and the mass of a black hole is so large that the curvature become infinitely deep and so deep that photons cant escape trough it. We know, E=m(c^2) therefore, m[photon] = E/(c^2) We also know, F= GMm/(r^2) In this case, M is the mass of the black hole & m is the mass of the photon . So gravitational force for the photon: F = GE/(rc)^2

- 5 years, 9 months ago

OK i understand one thing that the curvature is very deep due to its mass but speed of light is very high so it should come out at some extent of time. First of all photon travels at the speed of light means the mass of photon is extremely negligeble therefore force between black hole and photon light must be less . i true words i am not satisfied so please explain me further

- 5 years, 9 months ago

- 5 years, 9 months ago

Ok thank you

- 5 years, 9 months ago

Check it out about black hole here

- 5 years, 9 months ago