As I have mentioned before, I always have several books on the go at any one time, but still find there is not enough time to read everything I want. Top this off with the vast amount of information out there on the Internet and some times you think you might need several lifetimes to digest it all.
One of the books I am reading at the moment is titled: "Parallel worlds:a journey through creation, higher dimensions and the future of the cosmos." It was published in 2005 by Doubleday, New York and written by Michio Kaku who is the Henry Semat Professor of Theoretical Physics at the Graduate center of the City University of New York.
He explores many of the areas of modern cosmology, including the big bang, inflation theory, black holes and the idea of the multiverse. Also covered are quantum mechanics, string theory and particle physics.
In examining these areas he ties them all in to the concept of an existence in which a number of parallel universes are created.
Following on from this "...is the possibility of parallel universes and gateways connecting them." p112.
Although the idea of parallel universes is still hypothetical, it appears scientifically possible. Whether or not you can move from one to another is even more speculative. However, this hasn't stopped a number of UFO researchers postulating parallel worlds as a potential source for the UFO phenomenon.