Quantum physics is our most cherished description of Nature, our deepest understanding of the world. If you play with subatomic particles and smash them into one another, theory will tell you what happens, what new particles emerge, and some of their properties. And you can delight in that. But most of us don’t play around with small things. We don’t really care. We have practical things to do. We have real jobs.
What we long for, however, is a better understanding of the nature of reality. And people who spend time probing Nature on the smallest scales, see things we don’t. But tread with caution because if you ask about reality in most of academia, you probably won’t make many friends. In some academic spaces, the notion itself is viewed with suspicion. But if you insist, your instinct will prove right and find yourself directed to the physics department where you quickly learn that most people working in quantum physics don’t want to talk to you, that they’re too busy, or something. But from the way they attempt to squirm out of the room, it becomes clear they’re hiding something. If you don’t relent, someone will eventually point you to a remote corner of the department where a shabby office awaits you and entering occurs at your own peril, and inside you’ll finally find your holy grail, the person working on quantum foundations. These people live at the intersection of physics and philosophy and chances are therefore good that you will regret asking, but you’ve come too far to give up now. If being cornered and bombarded with terms like ‘quantum counterfactuals’ or ‘self-locating uncertainty’ fails to scare you off, you are mere words from reaching your goal. But you must press for those that actually exist in dictionaries, and then you will finally discover that ontologies of quantum physics exist. The theory is actually about something! But that sense of relief is fleeting. To your dissatisfaction, you quickly learn that explanations are numerous and surprisingly disparate.
From particles clinging onto ghostly waves that accompany them, protect and guide them through life, to our twin brothers and sisters making themselves briefly available to us by way of small things launched through small holes, to metaphysical abstractions about the notion of being in space and time, the assortment on offer is so vast that the differences between the explanations are as indigestibly large as the ideas themselves. It now finally dawns on you why the people in the large, shiny offices at the department entrance, were hoping you would just shut up and calculate all along. And perhaps why the father of quantum theory was always whispering. But please, oh future quantum expert, put us straight if you can.