iws
On Sat, Nov 18, 2023, 6:58 AM John Clark
<johnkcl...@gmail.com> wrote:
/I read an article called The multiverse is unscientific
nonsense
<https://iai.tv/articles/the-multiverse-is-unscientific-nonsense-auid-2668> 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 provenfact, 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 power, and to
conform with reality as described by experiment;
therefore I think they OUGHT to embrace the many world's
idea.
*
*
*
*And yes there is a version of you and me that flips a
coin 1 million times and see heads every single time even
though the coin is 100% fair, however it is extremely
unlikely that we will find ourselves that far out on the
bell curve, so I would be willing to bet a large sum of
money that I will not see 1 million heads in a row. You
also say that "the Dirac-von Neumann axioms don’t support
oft-heard statements that an atom can be in two places at
once, or that a cat can be alive and dead at the same
time", but there are only two possibilities, either there
is an alive cat and a dead cat in two different places or
there is a live/dead cat that instantly snaps into being
either alive or dead by the act of "measurement" even
though the standard textbook Copenhagen interpretation
can't say exactly what a measurement is, or even
approximately what it is for that matter. In many worlds
a measurement is simply any change in a quantum system,
it makes no difference if that quantum system is a human
being or an unconscious brick wall. So in that sense many
worlds is totalitarian because everything that is not
forbidden by the laws of Quantum Physics and General
Relativity must exist.
*
*
*
*You correctly point out that nobody has ever "seen an
atom in two places at once, let alone a cat being both
alive and dead", but nobody has ever seen infinite
dimensional operators in Hilbert space that the Dirac-von
Neumann axioms use either, all they've seen is ink on
paper in mathematical books. And you can't get milk from
the word "cow". *
*
*
*I'll close by just saying although I believe there is
considerable evidence in favor of the many worlds view I
admit it falls far short of a proof, maybe tomorrow
somebody will come up with a better idea but right now
many worlds is the least bad quantum interpretation
around. And speculation is not a dirty word, without it
science would be moribund, Richard Feynman said science
is imagination in a tight straight jacket and I agree
with him.
Best wishes
John K Clark*
*=========*
lis
