In his General Theory of Relativity, Einstein stated that time and space are not two different things. Rather they are just two aspects of a single thing called space-time.
He stated that near the objects in a gravitational field, this space-time bends. The solutions to the equations of the General Theory of Relativity have proof of wormholes. A wormhole is a corridor from one point in space-time to the other. A wormhole joins two universes, two planets, and any such super long distances or even very short distances.
The idea of wormholes is also very much used in the fictions. Scientists believe in it. A long distance could be covered through a shortcut and that reduces time and distance. Wormholes could allow faster than light speed in effect. This is even more surprising. Actually, the speed of light is not exceeded locally. The travel through a wormhole is done at a slower-than-light speed.
A wormhole may connect two spacetime points such that the distance between them through the wormhole is shorter than that outside the wormhole. In that case, in effect, a light beam traveling outside the wormhole from one point to the other may be slower than the speed of the traveler inside the wormhole.
The wormholes could collapse quickly, they are filled with radiation and there is a danger of exotic matter. And also, the dimension of a wormhole is predicted to be of the order of 10-33, and it is not possible for us to enter it.
But there is the possibility of traversable wormholes also. These are the wormholes through which travel is possible. But such wormholes are possible only if the exotic matter with negative energy density is used to stabilize them.
Wormholes are exciting as we can do time-travel through them. Think, how enchanting it could be if we reach some remote past or future and participate in the events. Not only this, but space travel also would become extremely easier if wormholes are understood and controlled properly.
This mysterious corridor opening a very wide spectrum of possibilities of space-time travel is yet to be understood.