No, it doesn’t have to happen. Consider the Elitzur-Vaidman bomb tester. The outcome depends on whether or not the bomb could have exploded, regardless of whether or not it actually does. You might object that in the Many Worlds Interpretation of quantum mechanics both happen, but the situation can equally well be described using Cramer’s Transactional Interpretation of quantum mechanics, which involves waves that propagate backwards in time, and in which only one of the two possibilities (explode or don’t explode) occurs. Whether MWI or TI or some other interpretation is the correct one, this demonstrates that backward-in-time signalling allows a “mere possibility”, that does not actually occur, to have measurable effects.
From what I can understand, Cramer’s Transactional Interpretation is basically a way to justify waveform collapse. The tester sees what he does because the plunger sent the signals causing waveform collapse. As far as I can tell, he never says what triggers the wave-form collapse. If it’s just too much stuff getting entangled, then that’s what causes the result you see, not mere possibilities.
In Eliezer’s realist, MWI interpretation, there are definitely “worlds” in which the bomb explodes; they can have small amplitude but what we see in our world is because of events that straightforwardly happen in those other worlds. And of course there aren’t really multiple worlds, there’s one world, only part of which we can see and interact with once we’ve separated through decoherence.
No, it doesn’t have to happen. Consider the Elitzur-Vaidman bomb tester. The outcome depends on whether or not the bomb could have exploded, regardless of whether or not it actually does. You might object that in the Many Worlds Interpretation of quantum mechanics both happen, but the situation can equally well be described using Cramer’s Transactional Interpretation of quantum mechanics, which involves waves that propagate backwards in time, and in which only one of the two possibilities (explode or don’t explode) occurs. Whether MWI or TI or some other interpretation is the correct one, this demonstrates that backward-in-time signalling allows a “mere possibility”, that does not actually occur, to have measurable effects.
From what I can understand, Cramer’s Transactional Interpretation is basically a way to justify waveform collapse. The tester sees what he does because the plunger sent the signals causing waveform collapse. As far as I can tell, he never says what triggers the wave-form collapse. If it’s just too much stuff getting entangled, then that’s what causes the result you see, not mere possibilities.
In Eliezer’s realist, MWI interpretation, there are definitely “worlds” in which the bomb explodes; they can have small amplitude but what we see in our world is because of events that straightforwardly happen in those other worlds. And of course there aren’t really multiple worlds, there’s one world, only part of which we can see and interact with once we’ve separated through decoherence.