No one really knows what a photon or electron does when both slits are open. This is an unsolved mystery of quantum theory. It seems incorrect to say it goes through A, through B, through both, or through neither. Physicists just say that its path is a superposition of A and B. This just means we don’t know what’s happening, even though we can write down simple formulas, involving linear combinations called superpositions, that accurately model the results of experiments. And it’s not just tiny particles, like photons and electrons, that do this magic with double-slits. In 2013, Sandra
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