Schwarzschild solution

Karl Schwarzschild, in 1916, gives us the very first description of a black hole in general relativity. Schwarzschild published this result just months after Einstein published his theory of general relativity. Schwarzschild solved Einstein’s equations for the gravitational field of a massive (stationary) star. This black hole has some features, for example, the point of no return known as the event horizon, or simply, horizon. Any physical information that goes beyond this horizon will be sucked into the black hole with no chance of escape. This region beyond the horizon is known as the Schwarzschild radius and once you enter you will be crushed to death. However, there was another interesting property of this black hole. If one could pass the event horizon they would become aware of a kind of “mirror universe”. Einstein figured that communication with this mirror universe was not possible. Any kind of physical information that fell into this black hole would be crushed to death at infinite spacetime curvature at a nasty singularity. This is where the strength of the gravitational field becomes infinite. This is sufficient strength to crush any kind of matter. Atoms would literally be ripped apart. It also should be noted that if one wanted to penetrate to the other side to the mirror universe, one would have to move faster than the speed of light. This is of course forbidden by the theory of relativity. Thus, we could never observe this mirror universe physically, despite the fact that its existence is necessary for the consistency of the Schwarzschild solution mathematics.

The Einstein-Rosen bridge connects two different universes. However, according to Einstein, communication between these two universes would be impossible since any rocket ship that tried to travel through it would be crushed. However, this kind of travel may be possible with some new physics. However, it would be quite difficult.