In the universe as we know it, there are no interstellar planets close enough to Earth that is reachable by man. What if there was a theoretical short cut that we could take that could make traversing the universe more possible for humans? This is what the wormhole theory says. The concept of a wormhole is based on the belief that space time is not in a singular plane like we believe but instead is curved and has folds. Then, there is a hole between two different points in space time that creates a shorter distance between those two points.
The diagram above best shows the concept of a wormhole. The movie Interstellar is very heavily based on the assumption that wormholes are real. In the movie, the astronauts try to find a suitable habitable planet for humanity by traveling through a wormhole. In the movie and in reality, the only way for humans to get outside our solar system and reach another planet is to find a short cut because they would be many light-years away. To put that in perspective, the closest plant to our solar system is Proxima Centauri, which is 12 light-years away, which would take 12 years of travel to reach and that is assuming the person is travelling the speed of light, which is impossible. A more realistic estimate would be if we could get the ship to one percent the speed of light, the trip would take 1200 years to complete. While the theory of wormholes is an intriguing one to think about, there is no hard physical evidence to support this theory.