The Hidden Reality_ Parallel Universes and the Deep Laws of the Cosmos - Brian Greene [124]
Figure 8.14 (a) A schematic illustration of the evolution, dictated by Schrödinger’s equation, of the combined probability wave for all the particles making up you and the measuring device, when you measure the position of an electron. The electron’s own probability wave is spiked at Strawberry Fields.
Figure 8.14 (b) The corresponding physical, or experiential, story.
Figure 8.15 (a) The same type of mathematical evolution as in Figure 8.14a, but with the electron’s probability wave spiked at Grant’s Tomb.
Figure 8.15 (b) The corresponding physical, or experiential, story.
Figure 8.16 (a) A schematic illustration of the evolution of the combined probability wave of all the particles making up you and your device, when measuring the position of an electron whose probability wave is spiked at two locations.
Figure 8.16 (b) The corresponding physical, or experiential, story.
If the electron’s original probability wave had, say, four spikes, or five, or a hundred, or any number, the same would follow: the wave evolution would result in four, or five, or a hundred, or any number of universes. In the most general case, as in Figure 8.11, a spread-out wave is composed of spikes at every location, and so the wave evolution would yield a vast collection of universes, one for each possible position.7
As advertised, though, the only thing that happens in any of these scenarios is that a probability wave enters Schrödinger’s equation, his math goes to work, and out comes a wave with a modified shape. There’s no “cloning machine.” There’s no “splitting machine.” This is why I said earlier that such words can give a misleading impression. There’s nothing but a probability-wave-evolution “machine” driven by the lean mathematical law of quantum mechanics. When the resulting waves have a particular shape, as in Figure 8.16a, we retell the mathematical story in type-two language, and conclude that in each spike there’s a sentient being, situated within a normal-looking universe, certain he sees one and only one definite result for the given experiment, as in Figure 8.16b. If I could somehow interview all these sentient beings, I’d find each to be an exact replica of the others. Their only point of departure would be that each would attest to a different definite result.
And so, whereas Bohr and the Copenhagen gang would argue that only one of these universes would exist (because the act of measurement, which they claim lies outside of Schrödinger’s purview, would collapse away all the others), and whereas a first-pass attempt to go beyond Bohr and extend Schrödinger’s math to all particles, including those constituting equipment and brains, yielded dizzying confusion (because a given machine or mind seemed to internalize all possible outcomes simultaneously), Everett found that a more careful reading of Schrödinger’s math leads somewhere else: to a plentiful reality populated by an ever-growing collection of universes.
Prior to the publication of Everett’s 1957 paper, a preliminary version was circulated to a number of physicists around the world. Under Wheeler’s guidance, the paper’s language had been abbreviated so aggressively that many who read it were unsure as to whether Everett was arguing that all the universes in the mathematics were real. Everett became aware of this confusion and decided to clarify it. In a “note added in proof” that he seems to have slipped in just before publication, and apparently without Wheeler’s notice, Everett sharply articulated his stance on the reality of the different outcomes: “From the viewpoint of the theory, all … are ‘actual,’ none any more ‘real