Einstein’s Rosen Bridges
Einstein’s Rosen Bridges is described as a black hole that is a portal to an infinite parallel universe.
For example, an empty space-time is flat, but curved by objects on it. If we compress that object, space-time gets more curved around it. Eventually, space-time becomes too warped that it collapses into a black hole. A one way banner forms, which anything can enter but nothing can escape; everything that goes through it is trapped at its singularity–at its core.
But maybe there is no singularity here. One possibility is that the other side of the event horizon looks like our universe, but mirrored upside down where time runs backwards. In our universe, things fall into the black hole, in the parallel universe with backwards times, the mirror black hole is spewing things out much like a Big Bang. This is called a white hole.
Unfortunately, Einstein Rosen Bridges cannot be crossed. It takes an infinite amount of time to crossover into the opposite universe and it is closed chit in the middle. If you go into a black hole you will not come out the white hole the same, instead you will be dead. To travel the cosmos in a blink of an eye, humans need a different kind of wormhole – a traversable wormhole.