Live from Spooky Action at a Distance: Question: Don't decoherent branches of an Everettian wave function recohere every time somebody runs a quantum eraser? In what sense is testing the existence of decohered states "hopelessly impractical"? Sean Carroll: Beyond Falsifiability: Normal Science in a Multiverse: "(3) There exist tests that are possible to do within the laws of physics, but are hopelessly impractical...

...We can contemplate building a particle accelerator the size of our galaxy, but it’s not something that will happen no matter how far technology progresses; like- wise, we can imagine decoherent branches of an Everettian wave function recohering, but the timescales over which that becomes likely are much longer than the age of the universe...


Yoon-Ho Kim, R. Yu, S.P. Kulik, Y.H. Shih, Marlan .O. Scully (1999): A Delayed Choice Quantum Eraser: "This paper reports a 'delayed choice quantum eraser' experiment...

...The experimental results demonstrated the possibility of simultaneously observing both particle-like and wave-like behavior of a quantum via quantum entanglement. The which-path or both-path information of a quantum can be erased or marked by its entangled twin even after the registration of the quantum...


John A. Wheeler (1978): The “Past” and the “Delayed-Choice” Double-Slit Experiment

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