Quantum Physics: More causality weirdness (General)

by David Turell , Saturday, August 20, 2016, 21:43 (2798 days ago) @ David Turell
edited by David Turell, Saturday, August 20, 2016, 21:48

Who or what came first can be confusing in this experiment:-https://www.newscientist.com/article/2101749-quantum-trick-sees-two-things-happen-before-and-after-each-other/-"You may have heard of the double-slit experiment, in which a single particle fired at two small gaps appears to interfere with itself, as if it had passed through both slits at once. That happens because, until it is measured by a detector on the other side, the particle is in a quantum superposition of two states. In some sense it is able to take both paths.-"It's weird, and difficult to wrap your head around, but now a team at the University of Vienna in Austria have performed a different kind of experiment that is even more mind-bending: putting the order of events into a superposition.
 
Normally, it's easy for us to say that event A happens before event B, or vice versa. But Giulia Rubino and her colleagues have created a superposition in which these seemingly contradictory scenarios are in superposition. “If you put together quantum mechanics and causal relations, a situation arises in which there is no pre-defined causal order,” she says. “It's counter-intuitive.”-"Their experiment involves sending a photon through two collections of optical devices, labelled Alice and Bob. These devices transform the quantum state of the photon in different ways, so that going through Alice, then Bob produces a different outcome to Bob, then Alice. “The fact that A is applied before B or B is applied before A actually changes the results,” says Rubino.-"To picture how that works, imagine the photon is a present intended for a third party. Alice likes to wrap presents, while Bob prefers a simple ribbon tied into a bow. If Alice gets her hands on the present first, she wraps it and then passes it to Bob, who puts a bow on. If Bob gets it first, Alice's wrapping covers the bow, resulting in a different outcome. Things are slightly more complicated for the photon, as Alice and Bob can perform different actions with a certain probability, so there are more than two possible outcomes.-"In the team's experiment, a kind of quantum switch controls which path the photon takes, and thus the order in which Alice and Bob act. To mess with causality, they place this switch itself in a superposition, meaning that in a sense, both act first.-"Of course, that's not quite what's happening, just as the particle in the double slit experiment doesn't truly go through both slits at once - it's just we don't have the language to describe the truly weird nature of the quantum realm that bubbles beneath our layer of reality. (my bold)
“'Time itself might be undefined in these situations,” says team member Mateus Araújo. “The whole confusion with quantum mechanics is unfamiliarity, something that just doesn't match our macroscopic, classical experience.”-***-"We're really pushing the mysteries and confusion of quantum physics to the absolute limit,” says Matty Hoban at the University of Oxford. “We don't have a good picture of what reality is.” (my bold)-Comment: the two bolds are exactly my point. It seems as if the reality we experience is grounded in quick sand. The comment I heard years ago that God must exist because of quantum mechanics as the basis of everything, somehow makes sense to me as God remains effectively cancelled from us.-This setup totally confused the concept of causality and time. But since quantum particles are connected all over the universe, in that sense the speed of light to communicate information, and the sense of elapsed time are not necessarily present