There seems to be a conflation between the multiple worlds of Everett
and the eternal inflation of a multiverse.
Brent
On 11/19/2023 4:49 PM, Lawrence Crowell wrote:
The real problem is that anything involving the multiverse, say some
quantum field signature from the earliest quantum cosmology, is
stretched by inflation into a red-shifted spectrum beyond
measurability. The multiverse is consistent with inflationary
cosmology, which is supported by data, but information about the
multiverse may never be detected.
LC
On Saturday, November 18, 2023 at 5:58:15 AM UTC-6 John Clark 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*
*=========*
John K Clark See what's on my new list at Extropolis
<https://groups.google.com/g/extropolis>
lis
*
*
*
*
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