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In 1935, physicists Albert Einstein and Nathan Rosen used the theory of general relativity to propose the existence of "bridges" through spacetime. These holes, called Einstein-Rosen bridges or wormholes, can connect two different points in spacetime, theoretically creating a shortcut (bridge) that could make possible time and distance travel. A wormhole, or Einstein-Rosen Bridge, is a theoretical bridge through space-time that could create shortcuts for long journeys across the universe and connect between two separate points in spacetime, theater they are extremely far such as a billion light years or more, or close such as a few feet.

To simplify, space can be visualized as a 2D surface - a wormhole would appear as a hole in that surface, lead into a 3D tube which is ending at another location on the 2D surface with a similar hole. Wormholes contain two points - entrance and exit, with a tunnel connecting the two. An actual wormhole would be analogous to this, but with the spatial dimensions raised by one. The tunnel might be a straight stretch, but it could also wind around, taking a longer path than a more conventional route might require. The entrance and the exit points could be visualized as spheres in 3D space. Certain solutions of general relativity allow for the existence of wormholes where the entry or exit point of each is a black hole. "A wormhole is not really a means of going back in time, it's a short cut, so that something that was far away is much closer", NASA's Eric Christian wrote.