Wasn't something similar said about atoms? (Not that this is proof,
more a "they laughed at Copernicus, and now they're laughing at me, so
I must be right too" sort of argument). But as (or if) I understand
it, multiverses are speculations that reduce problems elsewhere. To
loosely quote Max Tegmark, an M-theory multiverse goes some way
towards answering the question "why these particular laws of physics?"
while a quantum multiverse rigorously answers the question "why this
particular history?"
On Sun, 19 Nov 2023 at 00:58, John Clark wrote:
>
> I read an article called The multiverse is unscientific nonsense by Jacob
> Barandes, a lecturer in physics at Harvard University, and I wrote a letter
> to professor Barandes commenting on it. He responded with a very polite
> letter saying he read it and appreciated what I said but didn't have time to
> comment further. This is the letter I sent:
> ===
>
> Hello Professor Barandes
>
> I read your article The multiverse is unscientific nonsense with interest and
> I have a few comments:
>
> Nobody is claiming that the existence of the multiverse is a proven fact, but
> I think the idea needs to be taken seriously because:
>
> 1) Unlike Bohr's Copenhagen interpretation, the Many Worlds theory is clear
> about what it's saying.
> 2) It is self consistent and conforms with all known experimental results.
> 3) It has no need to speculate about new physics as objective wave collapse
> theories like GRW do.
> 4) It doesn't have to explain what consciousness or a measurement is because
> they have nothing to do with it, all it needs is Schrodinger's equation.
>
> I don't see how you can explain counterfactual quantum reasoning and such
> things as the Elitzur–Vaidman bomb tester without making use of many worlds.
> Hugh Everett would say that by having a bomb in a universe we are not in
> explode we can tell if a bomb that is in the branch of the multiverse that we
> are in is a dud or is a live fully functional bomb. You say that many worlds
> needs to account for probability and that's true, but then you say many
> worlds demands that some worlds have “higher probabilities than others" but
> that is incorrect. According to many worlds there is one and only one
> universe for every quantum state that is not forbidden by the laws of
> physics. So when you flip a coin the universe splits many more times than
> twice because there are a vast number, perhaps an infinite number, of places
> where a coin could land, but you are not interested in exactly where the coin
> lands, you're only interested if it lands heads or tails. And we've known for
> centuries how to obtain a useful probability between any two points on the
> continuous bell curve even though the continuous curve is made up of an
> unaccountably infinite number of points, all we need to do is perform a
> simple integration to figure out which part of the bell curve we're most
> likely on.
>
> Yes, that's a lot of worlds, but you shouldn't object that the multiverse
> really couldn't be that big unless you are a stout defender of the idea that
> the universe must be finite, because even if many worlds turns out to be
> untrue the universe could still be infinite and an infinity plus an infinity
> is still the an infinity with the same Aleph number. Even if there is only
> one universe if it's infinite then a finite distance away there must be a
> doppelgänger of you because, although there are a huge number of quantum
> states your body could be in, that number is not infinite, but the universe
> is.
>
> And Occam's razor is about an economy of assumptions not an economy of
> results. As for the "Tower of assumptions" many worlds is supposed to be
> based on, the only assumption that many worlds makes is that Schrodinger's
> equation means what it says, and it says nothing about the wave function
> collapsing. I would maintain that many worlds is bare-bones no-nonsense
> quantum mechanics with none of the silly bells and whistles that other
> theories stick on that do nothing but get rid of those pesky other worlds
> that keep cropping up that they personally dislike for some reason. And since
> Everett's time other worlds do seem to keep popping up and in completely
> unrelated fields, such as string theory and inflationary cosmology.
>
> You also ask what a “rational observer” is and how they ought to behave, and
> place bets on future events, given their self-locating uncertainty. I agree
> with David Hume who said that "ought" cannot be derived from "is", but
> "ought" can be derived from "want". So if an observer is a gambler that WANTS
> to make money but is irrational then he is absolutely guaranteed to lose all
> his money if he plays long enough, while a rational observer who knows how to
> make use of continuous probabilities is guaranteed to make money, or at least
> break even. Physicists WANT their ideas to be clear, have predictive
