Random Connections, Many Worlds

Sometimes, blog material sneaks up on you unannounced: consider this chain of fortuitous connections:

1. A New York Times piece by Stephen Johnson about how TV is making us smarter, focussing in particular on the complexity of '24' in terms of its complex, intersecting plotlines and character development.
2. Stumbling on the season finale of said '24' last monday, after missing 98% of the previous 4 seasons, but triggering on one of the actresses, who looked familiar
3. An IMDB search (just type "imdb x" into google) revealing said actress as Mary Lynn Rajskub, who I had subliminally recognized from a recent Netflixing of P.T. Anderson's Punch Drunk Love.
4. I somehow triggered on a music/comedy piece that Rajskub starred in from 2001 called "Girl's Guitar Club", which I downloaded online.
5. The protagonistas in that film have a few scenes with an "Indie Rock Guy", who turns out to be Mark Everett, frontman (onlyman) of Eels.
6. (Here's where things get interesting) IMDB tells us that Everett's father is Hugh Everett, III, a once well-known physicist who introduced the "Many Worlds" interpretation of Quantum Mechanics. 

Although this reads like "six degrees of...", at the time it felt just like bumbling around.  But now even the quasi-linear progression ceases as this story bifurcates into the story of a CD and a physics paper (involving two of my favorite hobbies...):

So on Monday night, I ordered the new Eels album (Blinking Lights and other Revelations) from amazon, which arrives yesterday, just in time for a long drive home.  It's "terrific" in almost every sense listed by the definition posted on dictionary.com (splendid, awesome, terrifying, frightful...).  That is, it's a great album, albeit somewhat harrowing, especially the bits about his father, who was apparently an introverted drunk who died prematurely.  The, um, complicated family drama alluded to in various songs is corroborated by a detailed, but quirky, bio of Everett hosted here. 

But while the son wonders out loud what went on his father's mind, he never seems to allude to his father's life work.  Not surprising, since the father appears to be one of those men who left physics and entered the somewhat amorphous realm of the military industrial complex (working for the Pentagon, and various IT-related contractors).  But this seemed like a golden opportunity for me to actually learn a bit about the "Many Worlds" theory from its primary source, the single paper by Everett listed on SPIRES: "Relative State" Formulation of Quantum Mechanics, published by Review of Modern Physics in 1957, based on his thesis work at Princeton.

With all the disclaimers of an experimentalist commenting on a piece of pure theory, it's a beautiful work, carefully laid out and unflinching in following its internal logic to its end, even if the result has been somewhat overblown and subject to unnecessary mystification in the intervening years.  And in the context laid out by the nearly-random connections which led me to this paper, and in the context of an emotionally-charged album by the son of the author (which is also unflinching in its meditations on his family and its effect on the rest of his life), this one particular train of thought in the 1957 paper stood out:

It will suffice for our purposes to consider the observers to possess memories (i.e., parts of a relatively permanent nature whose states are in correpondence with past experience of the observers)...

As models for observers we can, if we wish, consider automatically functioning machines, possessing sensory apparatus and coupled to recording devices capable of registering past sensory data and machine configurations.  We can further suppose that the machine is so constructed that its present actions shall be determined noy only by its present sensory data, but by the contents of its memory as well.  Such a machine will then be capable of performing a sequence of observations (measurements), and further more of deciding upon its future experiments on the basis of past results.  If we consider that current sensory data, as well as machine configuration is immediately recorded in the memory, then the actions of the machine at a given instant can be regarded as a function of the memory contents only, and all relevant experience of the machine is contained in the memory.

I try to imagine this construction popping up in a father/son fireside chat. 

Of course, this isn't the core concept of the "Many Worlds" hypothesis, but just a definition of an observer.  In his considerations of the ensemble of "memories" of said observer in the context of quantum mechanical wave functions, he comes to the conclusion that:

The "trajectory" of the memory configuration of an observer performing a sequence of measurements is thus not a linear sequence of memory configuration, but a branching tree, with all possible outcomes existing simultaneously in a final superposition.

But for those people who are attracted to the Many Worlds interpretation since it seems to suggest a universe of endless possibilities, where everything that could have happened somehow did happen and continues on in an alternate universe, Everett is very clear (in a footnote) about the reality of these other branches:

It is unnecessary to suppose that all [branches] but one are somehow destroyed, since all the separate elements of a superposition individually obey the wave equation with complete indifference to the presence of absence ("actuality" or not) or any other elements.  This total lack of effect of one branch on another also implies that no observer will ever be aware of any splitting process.

Again, think about that fireside chat. 

So we've stumbled on an almost-heartbreaking story, with a father who seems fiercely intelligent and scientifically creative but somewhat bleak in his view of the human condition, and a son who is musically prolific and artistically creative but, well, also somewhat bleak in his view of the human condition.  It's also hard to escape a shared sense of an inescapable determinism of the past on the present.  Good thing it's a great CD, 35 tracks evincing a sharp musical sensibility in a variety of styles, all held together by Everett the Younger's voice. Clearly, if we're all trapped on our particular branch, we may as well mine it for material, and at least try to make the best of it as it develops.

Comments

[neil]

Fascinating
Thanks
N

[Paul Stankus]

P --
Another great post on the crossing of science and humanity.
Consider: in his deep thinking on the actuality of alternative
histories ("Two roads diverged in a yellow wood"), do you imagine
that the elder Everett was comforted by having a rigorous way to
believe that what might have been actually did happen, somewhere?
If he was disappointed with the way his life had gone ("and that has
made all the difference."), maybe this was his way of mourning for the
missed possibilities. You can see how this would have been rough
on his family and friends....

Meanwhile, a question to ponder: Is the "many-worlds" interpretation
truly a scientific theory? in that, is it falsifiable? We know that a variety
of experiments support Bell's conclusions, which can be said to confirm
the operation of quantum mechanics (at least for small systems), and
if this were not true then Many Worlds would have been ruled out along
with pretty much all other post-Copenhagen interpretations of QM.
But, is there some observation which could rule out Many Worlds while
allowing some other QM framework (say orthodox Copenhagen-ism, or the
"coarse-grained histories" approach of Gell-Mann and Hartle) to survive?

Let me know what you think,

Paul

[Arthur Collins]

Just remember Peter that the limits of our measurements isn't the limit of what can be understood. For what is known is far more limited by the constraints of our belief of what is possible, than that which truely really exists.