QUANTUM physics – known to practitioners as quantum mechanics – is a subject that physicists learn in a rather peculiar way. We all learn to calculate using its mathematical framework, but that doesn’t mean we can really explain what it all means. If we go far enough in our education, we get the opportunity to see just how accurately these calculations match experimental results, so we learn to trust that they are correctly describing reality.

But how can a cat be both alive and dead inside a box before we look at it? We can do calculations that are consistent with this …