As far-fetched as the idea of a multiverse might seem, “it’s not like we come up with these crazy ideas and try to shove them into our theories,” said theoretical physicist Brian Greene at Columbia University, author of “The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos,” which explores a range of possible multiverses. “Our mathematical theories naturally yield these unfamiliar notions of other universes, and we’ve got a great deal of respect for mathematics, because over the centuries it’s proven itself a very potent guide to reality. This doesn’t mean the conclusions of mathematics are necessarily right, but they’re sufficiently compelling to make us willing to investigate them.”
This is just the thing to go down well with the PBS audience. Theory rather than evidence.
Here’s a theory currently being flown past the PBS audience:
The quilted multiverse
Not convinced? There’s more than one way to build a multiverse, and the quilted multiverse starts with the simple assumption that the universe goes on forever. If the universe is really infinite, then it contains infinite variations—and infinite copies—of everything. You know the one about the monkey typing Shakespeare? Given enough time, he won’t peck out just one edition of the Complete Works; he’ll bang them out infinitely. “You can imagine there are realms out there that are close copies or identical copies of ours somewhere else in the universe, or versions of ours that are modified in mind-bending ways,” Greene said. “These chunks of space would be like patches in a quilted patchwork, which is where the name for this idea comes from.”
To test the quilted multiverse hypothesis, scientists have to find out if space really is infinite. “There have been suggestions that space might not go on forever, but might, for instance, have the shape of a giant donut, or torus as we call it,” Greene said. “In this configuration where the universe does not go on forever, if you look at distant stars or galaxies, the light from them can travel multiple cycles, yielding multiple images of the same object, and if one sees those, that would be pretty strong evidence the universe does not go on forever.” More.
Hey wait a minute: Would infinite space not run into the same problems as infinite past time? Hilbert’s Hotel, anyone? If not, please write in and explain.
Why past time cannot be infinite.
Note: As I have noted earlier, the likely reason for all this is that the only plausible evidence basis for a faint hope for a multiverse just got discredited. (Planck satellite data says that big BICEP2 cosmic inflation multiverse was just dust.)
So now the hype is all about how believing in a multiverse is somehow an advantage to us, or reasonable on non-evidence-based grounds. Note: The fact that a given state of affairs, unsupported by evidence, would be more favourable to a widely accepted theory, is not in itself evidence for the existence of that state of affairs. The theory could just be beset by an ongoing weakness.
Anyway, for a quick rundown on why this is happening now, see The Science Fictions series at your fingertips (cosmology).