Science Friction_ Where the Known Meets the Unknown - Michael Shermer [32]
There are several heretics who champion the multiverse. The maverick Oxford University physicist David Deutsch applies the “many worlds” interpretation of quantum mechanics to the cosmos, where he argues that there are an infinite number of universes in which every possible outcome of every possible choice that has ever been available, or will be available, has happened in one of those universes. This idea is based on a spooky experiment with light that is passed through two slits and forms an interference pattern of waves on a back surface (like throwing two stones in a pond and watching the concentric wave patterns interact, with crests and troughs adding and subtracting from one another). The eerie part is when you send single photons of light through the slits they still form an interference wave pattern even though they are not interacting with other photons. One explanation for this oddity is that the photons are interacting with photons in other universes!
In this theory of “parallel universes” you could actually meet yourself and, depending on which universe you entered, your parallel self would be fairly similar or dissimilar to you. In an early episode of Star Trek (the original series) Mr. Spock met his doppelgänger, who sported a goatee and exhibited a rather truculent temperament. In another Star Trek episode (the next generation), the Enterprise and her crew arrived at a quantum junction at which they experienced a multitude of other Enterprises and crews, all having made slightly different choices with their correspondingly different outcomes (one was destroyed by the Borg, another defeated the Borg, etc.).
A different form of multiverse is suggested by the Astronomer Royal of Great Britain, Sir Martin Rees. The expansion of our bubble universe may be just one “episode” of the bubble’s eventual collapse and reexpansion in an eternal cycle. Or, an “eternally inflating multiverse” may sprout other bubble universes out of collapsing black holes, all with slightly different configurations. We know that our universe can sustain life because, well, here we are! But our universe could be impoverished compared to others that might be teeming with life. This rnultiverse model is used by the American cosmologist Lee Smolin, who adds an evolutionary component to it that resembles Darwinian “natural selection.” Like its biological counterpart, Smolin thinks that there might be a selection from different “species” of universes, each containing different laws of nature. Universes like ours will have lots of stars, which means they will have lots of black holes that collapse and create new baby universes similar to our own. By contrast, universes without stars cannot have black holes, and thus will not hatch any baby universes, and thus will go extinct. The result would be a preponderance of universes like ours, so we should not be surprised to find ourselves in a universe suitable for life. There may very well be many such biophilic universes.
Much of this speculative cosmology is in the realm of what I call borderlands science because it has yet to be tested. But that does not mean that it cannot be tested. The theory that new universes can emerge from collapsing black holes may be illuminated through additional knowledge about the properties of black holes. Other bubble universes might be detected in the subtle temperature variations of the cosmic microwave background radiation left over from the big bang of our own universe, and NASA recently launched a spacecraft constructed to study this radiation. Another way to test these theories might be through the new Laser Interferometer Gravitational Wave Observatory (LIGO), which will be able to detect exceptionally faint gravitational waves. If there are other universes, perhaps ripples in gravitational waves will signal their presence. Maybe gravity is such