Among his numerous other findings and theories, Einstein uncovered some significant findings about the nature of gravity. Gravity isn't just a force of attraction among two objects with mass; it's bending of space-time. Just like exactly how a satellite circles the Earth, if light approaches into the gravitational field of a gigantic object it will also curve to follow the curvature of space-time. The Earth itself can essentially cause light to bounce away from its original path as Earth distorts space-time, just like the sun.
|Image Credit: ESO/L. Calcada.|
But what's more exciting is the question of whether a black hole can reason the similar thing to occur, which was questioned to Fraser Cain from Universe Today. A black hole has such a tough gravitational pull that it halts everything from escaping counting light, which also can't be redirected, therefore it is designated as "black", but they're truly invisible to our eyes. The extremely strong gravity of black holes result in a area surrounding them called the "photon sphere" where certain enough, light is directed into orbit. The nearer the object to the black hole, the quicker it needs to go; photons of light in the photon sphere move at light speed. This describes that if you stood inside this photon sphere area and shined a torch in a specific path, you might essentially see the light behind you as it would be in orbit.
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