I’m just a dumb dog, but I’ve never understood why we couldn’t predict the spin of a particle (or why its spin is important). Like… It sounds like a weird philosophical thing more than actual physics and, to my limited understanding, boils down to “we don’t know the truth until we see it.”

Which, I mean… No shit? Is there an easier way of explaining WTF it means in a practical application? Or is that really what it comes down to?

What mechanism actually makes knowing or accurately predicting this information about particles impossible that it isn’t just a measurement issue?