A wormhole is also known as an Einstein–Rosen bridge and was coined by American theoretical physicist John A. Wheeler in 1957.It is a theoretical passage through space-time that would be a "shortcut" through spacetime in another words anyone can reach one place in universe to another place just like creating a shortcut through the intervening space. Wormholes are dangerous as they can sudden collapse and have high radiation. It is like a tunnel with the two ends, each in separate points in spacetime.
The Einstein-Rosen bridge was first formalized in 1935 by Albert Einstein and Nathan Rosen. For many years the scientists believed this phenomenon as physically impossible. But recent researches by Kip Thorne proved that it could be done using exotic materials capable of withstanding the immense forces involved.
Traversable wormholes would allow to travel in both directions from one part of the universe to another part of universe very quickly. The traversable wormholes were first explained by Kip Thorne and his student Mike Morris in a 1988. The first wormhole proposed was Morris–Thorne wormhole. Later, other types of traversable wormholes were discovered in which a path through the wormhole can be made where the traversing path does not pass through a region of exotic matter.
There are several theories for how the laws of physics might not work in favor of time travel through wormholes. According to many scientists keeping a wormhole stable enough to travel requires a large amounts of exotic matter.
In general there is no account of existence of exotic matter. But exotic matter does exist. That is what from where the quantum theory starts. Quantum theory is a system for explaining the universe and it is a kind of like a lens through which scientists observe the universe. However the exotic matter has been observed in trace amounts which is not nearly enough to hold wormhole.
In 2011, Panagiota Kanti and Burkhard Kleihaus showed how it is possible to construct traversable wormholes without using exotic matter by resorting to a form of string theory. Our technology is not yet upgrade to building a wormhole passage.
The researchers stated that wormholes are actually entangled black holes. This entanglement of wormholes might be caused by two simultaneously created black holes or the radiation emitted by one black hole could be captured by another black hole, creating some kind of entanglement.