Ruminations on multiverses; denied again (Introduction)

by David Turell , Thursday, May 13, 2021, 18:11 (1289 days ago) @ David Turell

Still has proponents without any proof:

https://iai.tv/articles/the-seduction-of-the-multiverse-auid-1806?_auid=2020

"Today, physicists still lack evidence of other universes, or even good ideas for obtaining evidence. Many nonetheless insist our cosmos really is just a mote of dust in a vast “multiverse.” One especially eloquent and passionate multiverse theorist is Sean Carroll. His faith in the multiverse stems from his faith in quantum mechanics, which he sees as our best account of reality.

In his book Something Deeply Hidden, Carroll asserts that quantum mechanics describes not just very small things but everything, including us. “As far as we currently know,” he writes, “quantum mechanics isn’t just an approximation to the truth; it is the truth.” And however preposterous it might seem, a multiverse, Carroll argues, is an inescapable consequence of quantum mechanics.

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"This hypothesis, which came to be called the many-worlds theory, has been refined over the decades. It no longer entails acts of measurement, or consciousness (sorry New Agers). The universe supposedly splits, or branches, whenever one quantum particle jostles against another, making their wave functions collapse. This process, called “decoherence,” happens all the time, everywhere. It is happening to you right now. And now. And now. Yes, zillions of your doppelgangers are out there at this very moment, probably having more fun than you. Asked why we don’t feel ourselves splitting, Everett replied, “Do you feel the motion of the earth?” Carroll addresses the problem of evidence, sort of. He says philosopher Karl Popper, who popularized the notion that scientific theories should be precise enough to be testable, or falsifiable, “had good things to say about” Everett’s hypothesis, calling it “a completely objective discussion of quantum mechanics.” (Popper, I must add, had doubts about natural selection, so his taste wasn’t irreproachable.)

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"Physicists have proposed even stranger multiverses, which science writer Tom Siegfried describes in his book The Number of the Heavens. String theory, which posits that all the forces of nature stem from stringy thingies wriggling in nine or more dimensions, implies that our cosmos is just a hillock in a sprawling “landscape” of universes, some with radically different laws and dimensions than ours. Chaotic inflation, a supercharged version of the big bang theory, suggests that our universe is a minuscule bubble in a boundless, frothy sea.

"In addition to describing these and other multiverses, Siegfried provides a history of the idea of other worlds, which goes back to the ancient Greeks. (Is there anything they didn’t think of first?) Acknowledging that “nobody can say for sure” whether other universes exist, Siegfried professes neutrality on their existence. But he goes on to construct an almost comically partisan defense of the multiverse, declaring that “it makes much more sense for a multiverse to exist than not."

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"I am not a multiverse denier, any more than I am a God denier. Science cannot resolve the existence of either God or the multiverse, making agnosticism the only sensible position. I see some value in multiverse theories. Particularly when presented by a writer as gifted as Sean Carroll, they goad our imaginations and give us intimations of infinity. They make us feel really, really small—in a good way.

"But I’m less entertained by multiverse theories than I once was, for a couple of reasons. First, science is in a slump, for reasons both internal and external. Science is ill-served when prominent thinkers tout ideas that can never be tested and hence are, sorry, unscientific. Moreover, at a time when our world, the real world, faces serious problems, dwelling on multiverses strikes me as escapism—akin to billionaires fantasizing about colonizing Mars. Shouldn’t scientists do something more productive with their time?"

Comment: I'm with Horgan. Multiverse discussion is entertaining fluff, nothing more.