Category: Non-Fiction; Rating: 3 out of 5; Tags: Cosmology, Physics, Science
The Multiverse is a weird idea. There could be regions of spacetime, out of our reach, in which different physical parameters cause different rules to apply, and in which complex life as we know it could not develop. These regions of spacetime could be separated from us by time, distance, or other dimensions. We cannot communicate with them, yet there are interactions that suggest they must exist.
First, some definitions. If the universe includes “all that there is,” then any other “universes” must really be just part of the larger universe, so we need to define some terms. Following modern usage, Gribbin chooses “Universe” with a capital ‘U’ to indicate “everything…of which we could ever, in principle, have direct knowledge – our component of the Multiverse.” A mathematical or computer model of spacetime is a “universe” with a small ‘u’, and may describe parts of the Multiverse that we cannot access. So it’s really the “Multiverse” that includes “all that there is.”
There are different kinds of Multiverse. Coming to grips with them means first delving into quantum physics and cosmology. The weirdest might be the many worlds interpretation of quantum events, in which the universe splits every time a quantum event occurs – one universe with one outcome, another with the opposite. Or one can think of an infinity of parallel universes, with some evolving very much like ours, but in ours the event turns out one way, and in the other it turns out the other way. This interpretation explains the strange results of the double slit experiment, in which a single photon is interfered with in some mysterious way to deflect it depending on which slit is open. David Deutsch, in “The Fabric of Reality”, says these mysterious interfering entities act just like invisible photons, and actually are photons in adjacent, parallel universes, interacting with ours only under these special circumstances. It makes me wonder whether some clever coding scheme could be devised to communicate with, or at least prove the existence of at least one parallel universe.
Other parts of the Multiverse might just be too far away for us ever to observe them. Still others might have been born from a bubble of quantum foam, conjured from the nothing of a vacuum fluctuation, and developed differently from ours, with different physical constants and ratios which could never lead to the evolution of life. These could appear within our own Universe, or outside it. Or perhaps our Universe was created by the collision in some higher dimension of two other universes – there are models and math to support all these theories.
As I read the book, I confess that the mind-expanding challenge of grasping the concept of yet another infinity of universes, or series of infinities of universes, with some infinities bigger than others, left me nodding in my chair. Perhaps my powers of abstraction are not up to the task, or maybe I just had too much turkey over the Christmas break.
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