[ExI] THE MANY WORLDS OF HUGH EVERETT

[John Clark]

Back in 2010 on this list I posted a review of Peter Byrne's book "THE MANY
WORLDS OF HUGH EVERETT", this seems like a good time to re-post it:

==

*I've just finished **this book and it's one of the most enjoyable things
I've read in a long time. Being a staple of science fiction and the only
interpretation of quantum mechanics to enter the popular imagination it's a
little surprising that "The Many Worlds of Hugh Everett '' by Peter Byrne
is the first biography of the originator of that amazing idea. Everett
certainly had an interesting life, he was a  libertarian and a libertine,
became a cold warrior who with his top secret clearance was comfortable
with the idea of megadeth, became wealthy by starting one of the first
successful software companies until alcoholism drove him and his company
into the ground. Everett died of heart failure in 1982 at the age of 51, he
was legally drunk at the time. He requested that his body be cremated and
his ashes thrown into the garbage. And so he was.*

*Byrne had an advantage other potential biographers did not, the
cooperation of his son Mark, a successful rock musician and composer whose
music has been featured in such big budget movies as American Beauty,
Hellboy, Yes Man, all three of the Shrek movies and many others. Mark gave
Byrne full access to his garage which was full of his father's papers that
nobody had looked at in decades.  *

*Everett was an atheist all his life, after his death Paul Davies, who got
1,000,000 pounds for winning the Templeton religion prize, said that if
true Many Worlds destroyed the anthropic argument for the existence of God.
Everett would have been delighted. Nevertheless Everett ended up going to
Catholic University of America near Washington DC.  Although Byrne doesn't
tell us exactly what was in it, Everett as a freshman devised a logical
proof against the existence of God. Apparently it was good enough that one
of his pious professors became very upset and depressed with "ontological
horror" when he read it. Everett liked the professor and felt so guilty he
decided not to use it on a person of faith again. This story is very
atypical of the man, most of the time Everett seems to care little for the
feelings of others and although quite brilliant wasn't exactly lovable.*

*Everett wasn't the only one dissatisfied with the Copenhagen
Interpretation which insisted the measuring device had to be outside the
wave function, but he was unlike other dissidents such as Bohm or Cramer in
that Everett saw no need to add new terms to Schrodinger's Equation and
thought the equation meant exactly what it said. The only reason those
extra terms were added was to try to rescue the single universe idea, and
there was no experimental justification for that. Everett was unique in
thinking that quantum mechanics gave a description of nature that was
literally true.*

*John Wheeler, Everett's thesis advisor, made him cut out about half the
stuff in his original 137 page thesis and tone down the language so it
didn't sound like he thought all those other universes were equally real
when in fact he did. For example, Wheeler didn't like the word "split" and
was especially uncomfortable with talk of conscious observers splitting,
most seriously he made him remove the entire chapter on information and
probability which today many consider the best part of the work. His long
thesis was not published until 1973, if that version had been published in
1957 instead of the truncated Bowdlerized version things would have been
different; plenty of people would still have disagreed but he would not
have been ignored for as long as he was.*


*Byrne writes of Everett's views: "the splitting of observers share an
identity because they stem from a common ancestor, but they also embark on
different fates in different universes. They experience different
lifespans, dissimilar events (such as a nuclear war perhaps) and at some
point are no longer the same person, even though they share certain memory
records." Everett says that when an observer splits it is meaningless to
ask "which of the final observers corresponds to the initial one since each
possesses the total memory of the first" he says it is as foolish as asking
which amoeba is the original after it splits into two. Wheeler made him
remove all such talk of amebas from his published short thesis.*


*Byrne says Everett did not think there were just an astronomically large
number of other universes but rather an infinite number of them, not only
that he thought there were a non-denumerable infinite number of other
worlds. This means that the number of them was larger than the infinite set
of integers, but Byrne does not make it clear if this means they are as
numerous as the number of points on a line, or as numerous as an even
larger infinite set. Neill Graham tried to reformulate the theory so you'd
only need a countably infinite number of branches and Everett at first
liked the idea but later rejected it and concluded you couldn't derive
probability by counting universes. Eventually even Graham seems to have
agreed and abandoned the idea that the number of universes was so small you
could count them.*


*Taken as a whole Everett's multiverse, where all things not forbidden by
quantum mechanics happen, probability is not a useful concept and
everything is deterministic. However for observers like us trapped in a
single branch of the multiverse, observers who do not have access to the
entire wave function and all the information it contains but only a small
sliver of it, probability is the best we can do. That probability we see is
not part of the thing itself but is just a subjective measure of our
ignorance.*


*Infinity can cause problems in figuring out probability but Everett said
his theory could calculate what the probability any event could be observed
in any branch of the multiverse, and it turns out to be the Born Rule
(discovered by Max Born, grandfather of pop singer Olivia Newton John)
which means the probability of finding a particle at a point is the square
of the amplitude of the Schrodinger Wave function at that point. The Born
Rule has been shown experimentally to be true but the Copenhagen
Interpretation just postulates it, Everett said he could derive it from his
theory it "emerges naturally as a measure of probability for observers
confined to a single branch (like our branch)." He proved the mathematical
consistency of this idea by adding up all the probabilities in all the
branches of the event happening  and getting exactly 100%. Dieter Zeh said
Everett may not have rigorously derived the Born Rule but did justify it
and showed it "as being the only reasonable choice for a probability
measure if objective reality is represented by the universal wave function
[Schrodinger's wave equation]". Rigorous proof or not, that's more than any
other quantum interpretation has managed to do.*


*Everett wrote to his friend Max Jammer:*

*"None of these physicists had grasped what I consider to be the major
accomplishment of the theory- the "rigorous" deduction of the probability
interpretation of Quantum Mechanics from wave mechanics alone. This
deduction is just as "rigorous" as any deductions of classical statistical
mechanics. [...] What is unique about the choice of measure and why it is
forced upon one is that in both cases it is the only measure that satisfies
the law of conservation of probability through the equations of motion.
Thus logically in both classical statistical mechanics and in quantum
mechanics, the only possible statistical statements depend upon the
existence of a unique measure which obeys this conservation principle."*


*Nevertheless some complained that Everett did not use enough rigor in his
derivation. David Deutsch has helped close that rigor gap. He showed that
the number of Everett-worlds after a branching is proportional to the
conventional probability density. He then used Game Theory to show that all
these are all equally likely to be observed. Everett would likely have been
delighted as he used Game Theory extensively in his other life as a cold
warrior. Professor Deutsch gave one of the best quotations in the entire
book, talking about many worlds as an interpretation of Quantum Mechanics
"is like talking about dinosaurs as an interpretation of the fossil
record".*


*More recently Sean Carroll and others have pointed out the only assumption
that many worlds makes is that everything evolves according to the
Schrodinger equation, and Occam's Razor is about an economy of assumptions
not an economy of results, and all those worlds are not an assumption, they
are just the result of what happens if you think Schrodinger's equation
means what it says. However Schrodinger's equation is completely
deterministic so the real question is not why does the Born rule work but
why do we need to use probabilities at all?  Carroll says the reason is
"self location". Many Worlds says that if somebody flips a coin then the
universe branches, in one branch the coin lands heads and the other tales,
but until you actually look at the coin you won't know which branch you're
on so you'd have to resort to probability, in this case 50-50.  *


*Everett was disappointed at the poor reception his doctoral dissertation
received and never published anything on quantum mechanics again for the
rest of his life; instead he became a Dr. Strangelove type character making
computer nuclear war games and doing grim operational research for the
pentagon about armageddon. He was one of the first to point out that any
defense against intercontinental ballistic missiles would be ineffectual
and building an anti-ballistic missile system could not be justified except
for "political or psychological grounds". Byrne makes the case that Everett
was the first one to convince high military leaders through mathematics and
no nonsense non sentimental reasoning that a nuclear war could not be won,
"after an attack by either superpower on the other, the majority of the
attacked population that survived the initial blasts would be sterilized
and gradually succumb to leukemia. Livestock would die quickly and
survivors would be forced to rely on eating grains, potatoes and
vegetables. Unfortunately the food would be seething with radioactive
Strontium 90 which seeps into human bone marrow and causes cancer". Chemist
Linus Pauling credited Evertt by name and quoted from his pessimistic
report in his Nobel acceptance speech for receiving the 1962 Nobel Peace
prize.*


*Despite his knowledge of the horrors of a nuclear war Everett, like most
of his fellow cold warrior colleagues in the 50's and 60's, thought the
probability of it happening was very high and would likely happen very
soon. Byrne speculates in a footnote that Everett may have privately used
anthropic reasoning and thought that the fact we live in a world where such
a war has not happened (at least not yet), not even in 1962 during the
Cuban missile crisis where the human race came closer to extinction than it
ever has before, was more confirmation that his Many Worlds idea was right.
Incidentally this is one of those very rare books where the footnotes are
almost as much fun to read as the main text. *


*Hugh's daughter Liz Everett killed herself a few years after her father's
death, in her suicide note she said "Funeral requests: I prefer no church
stuff. Please burn and DON'T FILE ME. Please sprinkle me in some nice body
of water or the garbage, maybe that way I'll end up in the correct parallel
universe to meet up with Daddy". And so she was.*


*  John K Clark*
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