The best theories are non-deterministic, but of course we don’t know if they are the last word about reality. To put it another way, we don’t know why the math is non-deterministic in our best equations.
The old equations were deterministic, but they turned out to be wrong. Something similar may happen here.
I drove by a house in my neighborhood. There was a pure white van, no windows, license was VAN 3. A man was walking towards the van dressed in white coveralls and gloves.
As I passed, I stared at him. He stared at me with cold murderers eyes. I’ve seen that look twice before and both guys turned out to be murderers.
A personal library. A room dedicated to the purpose.