Is a Multiverse Detectable?
The idea of a multiverse (an ensemble of universes like our own visible one) has been criticized as unscientific because it would be unobservable, even in principle. Now, however, some theoretical physicists are claiming that bubble universes beyond ours could be detected in the cosmic microwave background radiation – provided they collide with our universe. Does this bring multiverse theory back into the realm of science?
National Geographic News, posting an article on this idea, said, “The multiverse, if it exists, may have sprung out of a chaotic fluctuation of empty space.” Chaotic motions from other bubble universes might “bruise” our universe and leave telltale patterns in the cosmic microwave background (CMB). Matthew Johnson, a theoretical physicist at the Perimeter Institute, with colleagues, is working on an algorithm to find the patterns.
But what to look for? Sean Carroll, physicist at Caltech, warned that “People tend to recognize patterns whether or not they are there.” Trouble is, nobody knows what the needle in the haystack would look like. “Even with better data from Planck” (a new space telescope measuring the CMB in finer detail), “finding evidence of a universe-to-universe smashup is a game of chance, thanks to the nearly infinite possible outcomes.”
For this reason and the fact that any deviations in the CMB are likely to be extremely subtle, Carroll thinks the quest is “a long shot”. But the implications would be so earth shattering, he is eager to see what Johnson and team find.
They don’t know what they are looking for, they don’t know what they might expect to find, and they won’t be able to confirm it when they see it. Imagine looking for a what-not in a pile of whatever, that might leave an infinite set of possible outcomes. You could claim success and nobody could ever confirm or deny it. NG unabashedly stated another piece of nonsense: “The multiverse, if it exists, may have sprung out of a chaotic fluctuation of empty space.” The whatever, if it exists, might have spring out of a chaotic what-not. Isn’t science wonderful.
The elephant in the room that Carroll, Johnson, Hawking and all the other multiverse advocates are overlooking is the question of ultimate origins. Even if, in their wildest dreams, in spite of overwhelming odds, they had some basis for claiming that some other bubble is pushing on our bubble, they would merely displace the question of ultimate origins to another location. Let them start with what Francis Schaeffer called “nothing nothing” – no space, no time, no laws of nature, no fields, no categories. From absolutely nothing, get them to derive not only a universe, but reasoning beings questioning its origin and destiny. The folly of such a quest is self-evident.
Exercise. See if Ethan Siegel in “The Physics of Nothing, The Philosophy of Everything” on ScienceBlogs.com succeeded in building a universe out of nothing nothing. (Hint: philosophy and laws of physics are something.)