Multiple universes

Playwright, novelist, and philosophy Michael Frayn offers this critique of David Deutsch’s claim that quantum mechanics implies multiple, perhaps infinite, worlds: “If only we knew what proportion of David Deutsches was putting forward each of these theories we should be able to judge which of them correct. Sadly since we can’t know anything whatsoever about any of these other universes the question must remain forever undecidable; though I have a sneaking private suspicion, unsupportable by any possible evidence, that however many trillions of David Deutsches are putting forward however many trillions of millions of theories, not a single one of those theories can be as daft as this one.”