My interest in learning more about the idea of parallel universes led me to In Search of the Multiverse; Parallel Worlds, Hidden Dimensions, and the Ultimate Quest for the Frontiers of Reality by John Gribbin, a physicist and popular science writer. He discusses all of the above. Apparently the Multiverse is a widespread idea among physicists today, which has gained a lot of support. There are several different theories about how this would have evolved and what it would be like.
Some of the theories involve more dimensions than our accepted three of space and one of time – most commonly eleven. Six of these may be “compactified”, or rolled up to make them invisible. The eleventh would lie in a spatial dimension at right angles to those we know. The number of possible kinds of universe in the Multiverse could be 10 to the 500th power (there are only 10 to the eightieth power atoms in our entire visible Universe) or infinite. But who’s counting? If you read this book you’ll learn about Schrodinger’s cat who is alive and dead at the same time, and about the possibility of a cup of coffee as a super-fast quantum computer.
Universes may branch off every time a different choice is made (even at the quantum level, which, in physics, refers to the very smallest things). This is the idea I mention in Wandering Time. Another idea is that they may be born in black holes, defined as regions of spacetime which are bent around on themselves by gravity. In that case, a Universe like ours with lots of black holes, could produce many “baby universes”.
Sound far-fetched? I’m fascinated. But could we ever travel to other universes? Probably not. Unless we step through one of the mirrors in Wandering Time, which can only happen for those who’s minds are able to wander or, as Barbara says in my book, “You have to be open to a different way of thinking about the world.” Granny Rae quotes Fred Alan Wolf in Parallel Universes, who says our minds are time machines. “The freely associating mind is able to pass across time barriers.”