Experimental Metaphysics

[Bomb#20]

Bob isn't causing the remote correlation, but he's causing the remote bifurcation.

Under standard Copenhagen QM, Bob’s measurement of Particle One will instantaneously affect Alice’s Particle Two, even if she is on the other side of the universe, because of instantaneous wavefunction collapse. On MWI, the world “splitting” occurs independently on local observation of each particle.

Your explanation conflicts with what Dr. Vaidman wrote:

"Alice first splits the world into four different worlds according to her measurements. Each of the worlds is then split again into four worlds by Bob. Charley, however, does not make any additional splitting. In every one of the 16 worlds created by Alice and Bob, the outcomes of his two spin measurements are already fixed."​

But perhaps he was talking about what happens if Charley is inside Bob's light-cone. If that's how the contradiction is resolved, it implies that MWI's world "splitting" isn't an instantaneous process, but instead propagates outward from each local observation, presumably at the speed of light. That sounds like it resolves the spooky-action-at-a-distance problem.

But it seems to me this just replaces one QM riddle with another as usual. In the case where Bob and Charley's measurements are space-like separated, Alice created four worlds, and then Bob and Charley each independently split those worlds into 16. So five nanoseconds after their measurements there are Alice's four full-size worlds, each of which has four fast-growing ten-foot-diameter miniworlds centered at Bob like bubbles in a tortilla, and another four centered at Charley. Then Bob's miniworlds collide with Charley's and merge with them. So the new QM riddle MWI introduces is, how does one of Bob's growing miniworlds know which one of Charley's growing miniworlds to merge with? When the independent splittings run into each other there are 24 permutations, 24 possible ways to turn 8 miniworlds into 4 maxiworlds, and MWI picks the right one, apparently by magic.

Speaking of MWI-specific QM riddles, any thoughts on why high-amplitude outcomes are observed more frequently than low-amplitude outcomes? Suppose you fire a stream of photons at window glass, with detectors on both sides to pick up the transmitted and reflected photons. At each measurement there's an amplitude of 0.2 to detect a reflected photon and 0.98 to detect a transmitted photon, which the Born Rule translates into probabilities of 4% and 96%. If an observer does this 25 times in a row his detectors will typically show 1 reflected photon and 24 transmitted photons. But according to MWI at this point his universe has split into about thirty million worlds, each showing its copy of him a different combination of transmitted and reflected photons. The point is, in only 25 of those worlds is there a split-off copy of the experimenter who has seen 1 reflected photon and 24 transmitted ones. But in twenty million of those worlds there's a split-off copy of the experimenter who has seen 10 to 15 reflected photons and 10 to 15 transmitted ones. So how the heck does MWI predict that a typical observer will only get one reflected photon? It seems if MWI were correct then glass would reflect half the incident light.