[lisper]

Not a physicist, but I've been studying QM as a hobby for thirty years. The problem with superdeterminism (SD) is that if QM is true then SD is not falsifiable. SD says that all experimental outcomes are deterministic but derive from hidden state, i.e. some sort of "Cosmic Turing Machine" (CTM) calculating the digits of pi or something like that. So now what? The CTM has to be perpetually hidden from us, otherwise we could examine its state and predict the outcomes of quantum experiments, and that would violate QM. So if QM is true, then the CTM necessarily has the same ontological status as an Invisible Pink Unicorn (IPU). In fact, the deterministic calculations underlying SD may well be carried out by a literal IPU. If QM is correct then there's no way to determine this, even in principle.

[nabla9]

Bell-inequality experiments still that leave room for hidden-variable models that fall short of full superdeterminism.

Relatively recent experiment using photons from stars in the Milky Way "Cosmic Bell Test: Measurement Settings from Milky Way Stars" http://web.mit.edu/asf/www/Papers/Handsteiner_Friedman+2017.... The experiment excludes local-realist models with local hidden variable younger than 600 light years. Similar test with cosmic microwave background could push the limit to the early universe.

[corey_moncure]

How do you tell if your code is running on a virtual machine or on bare metal?

[lisper]

In our case we know we're running on "quantum bare metal" because we can do quantum mechanics experiments.