Question

Why can't light escape from a blackhole if they have no mass?

Answer 1

Light can escape from a black hole an image result for light can escape from a black hole A black hole is an area of space that is so distorted that not even light can escape. Nothing can escape a black hole because nothing can travel faster than the speed of light. If light could travel faster than the speed of light, it would be able to exit the event horizon and no longer be considered a black hole.

Complete answer:
Newtonian gravity describes gravity as a force which is related to mass. This is not actually true, particularly close to a black hole.
Explanation: According to Newton, gravity is a force. This was proven erroneous by Einstein.The fabric of 4 dimensional spacetime is curved by mass, energy, and velocity. Gravity is also the same as acceleration. Gravity is the result of all bodies moving in a gravitational field adhering to geodesics. A straight line in four dimensions is called a geodesic.

Because photons have no mass, they travel at the speed of light. In fact, as a result of this, they are oblivious to the passage of time. They must also adhere to geodesics, which is why light bends due to gravity. Every object has a velocity of escape. This is the speed at which you must travel to completely escape from a gravitational field.

For any object of mass $M$ smaller than its Schwarzschild radius $r$ , the Schwarzschild solution to Einstein's field equations of General Relativity seems to have a singularity.
${r_s} = \dfrac{{2GM}}{{{c^2}}}$
The gravitational constant is $G$ , and the speed of light is $c$. The event horizon of a black hole is defined as the Schwarzschild radius of a body less than ${r_s}$ . No geodesic may leave the black hole if it is within or near the Schwarzschild radius. As a result, the escape velocity is effectively equal to the speed of light. This means that nothing, not even light, can escape a black hole.

Note: The interaction of a black hole with other stuff and electromagnetic waves such as visible light can be used to infer its presence. Quasars are some of the brightest objects in the cosmos, formed when matter falls upon a black hole and forms an exterior accretion disc heated by friction. Stars that pass too close to a supermassive black hole can be shredded into dazzling streamers before being "swallowed."