terça-feira, junho 05, 2018

The Many-Worlds Interpretation (MWI): "The Many Worlds of Hugh Everett III - Multiple Universes, Mutual Assured Destruction, and the Meltdown of a Nuclear Family” by Peter Byrne

“This is the mystery: when we measure the position of an atomic particle we record it as existing in a definite place, not in all of the many places it occupies according to its smoothly evolving wave function. The emergence of a single position from the set of all physically possible positions is inescapable; it creates a logical discontinuity, a gap, a fissure, an interruption in the flow of the Schrödinger equation; it creates a problem.”

In “The Many Worlds of Hugh Everett III - Multiple Universes, Mutual Assured Destruction, and the Meltdown of a Nuclear Family” by Peter Byrne

I suspect that the reason why the Copenhagen and Many Worlds interpretations of QM are the most well-known is that they are the easiest to explain in classical terms, and therefore most accessible to those who have not already completed an undergraduate level course in QM. You can also find a discussion of the different interpretations in The Road to Reality, by Roger Penrose, but it is heavy going and not recommended unless you have a background in Physics (or Math) to degree-level. Essentially, Penrose discusses both the two interpretations above and three other interpretations: environmental decoherence, consistent histories and pilot wave; and comments on the strengths and weaknesses of each. He argues that none of them adequately solve the "measurement problem" and that there must be another, either so-far undiscovered or incompletely worked out, interpretation to be found. [This is a serious simplification of what Penrose writes in the book].

Oh, and the proof for other intelligent life in the universe is simple- physicists tell us that nature is a wave particle duality, with particles being something like placeholders for natural forces, that is particles are not individual, every like particle is identical to every other like particle. the wave function that underlies reality means that events are a result of colliding wave fronts, thus they can't occur only once, events can be rare, they cannot be unique- therefore if life occurred here it has to have occurred elsewhere as a logical certainty, nature doesn't do anything just once, there are unique locations there are no unique events. The only way for intelligent if to have occurred only here would be a supernatural explanation.

Is reality the result of colliding wave fronts or entangled fields, being these fields the ones that engender elemental particles which are everywhere, and therefore the entanglement producing life must be everywhere as well? 

Not quite. It all depends on statistical probability. If the odds of a particle doing x is greater than the chances of it doing it in the lifetime of the universe, it may never do x. Me walking through a wall is a good example - all the particles in me and all the particles in wall would have to align so that none collide in the Very Long Time (for a particle or group of particles to remain in perfect alignment) it would take me to walk through the wall. The odds of that happening are greater than the lifetime of the universe (although it still could happen at any moment too...) When you're talking an almost infinite range of possibilities, but with a large, but still finite amount of matter/particles, there is plenty of room for unique events which might never repeat in the lifetime of the universe (or may repeat many times equally).

For any casual reader not familiar with the double-slit experiment, a laser beam is directed at a plate which is solid except for two parallel slits (for instance; there are many variants in the broader experimental realm). Then the light passing through the slits is observed on a screen behind the plate. These sorts of experiment yield much interesting (and initially much unexpected) data, and these data have helped to progress analysis of a variety of puzzles in physics.

So far, so good.

The problems arise when all sorts of speculations, far beyond the data, are developed into a quasi-religious dogma of reality, which can loosely be entitled the many-worlds interpretation (MWI) of quantum mechanics. Just at the level of this simple double-slit experiment, without exploring the wilder shores of MWI, the devotees of the interpretation believe that the light passing through the apparatus of whatever configuration diverges into a vast / infinite number of other universes. That is, for one given experiment - one universe, world, lab, workbench, laser, plate, screen - the output of that local experiment diverges into an infinite number of universes. One photon emitted by the laser diverges into an infinite number of universes at the point of emission from the laser, and diverges again when it passes through the slits, and even diverges again if you close one of the slits. And that the combination (the cross-product) of all of these sets of an infinite number of universes is also then real. Don't underestimate what they are claiming, an infinite number of universes is created at this point, each new universe populated with a universe-worth of matter and energy which (somehow and “somewhen” undefined by the MWI) simply appears from nowhere.

I would respectfully suggest that the MWI devotees have rather over-interpreted the data from a laser beam passing through a slitted plate.

A final coda:

“Among Everett’s basement papers were notes that he had made after the American Institute of Physics asked him to prioritize his top five scientific capabilities. At the bottom of the list, he put ‘servomechanisms.’ Followed by ‘operations research.’ Skill number three was ‘relativity and gravity.’ Two was ‘decision game theory.’ And at the top of the list, in pride of first place: ‘quantum mechanics.’”

In “The Many Worlds of Hugh Everett III - Multiple Universes, Mutual Assured Destruction, and the Meltdown of a Nuclear Family” by Peter Byrne

Bottom-line: I explained Everettian theory much better when I reviewed Adam Becker’s “What is Real - The Unfinished Quest for the Meaning of Quantum Physics”. I’m not “in the zone” today…so, this is all you get for now. I’m moving on to finish reading Wallace’s “Emergent Multiverse” now.

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