I just briefly looked into what Jonathan Oppenheim is working on, and I’d say he’s part of the problem. More speculative work that might or might not be testable in a distant future.
It used to be that there was some experimental result or other phenomena that required explanation which lead to a theoretical model that could be tested. That worked very well.
Now there’s some theoretical considerations that leads to a theoretical model that can’t be tested. It didn’t work for Aristotle and it doesn’t work for string theorists (and similar).
Why doesn't this experimental result count as requiring explanation?
We know (for example) silver atoms have mass, and that massive objects exert gravity (which we understand as warping of space-time according to GR).
We know that we can put silver atoms in quantum superpositions of being in different positions (for example in a sequential Stern-Gerlach type experiment).
We have (essentially) absolutely no theoretical understanding of what is going on to space-time when a thing with mass is in such a superposition. Quantum mechanics does not successfully model gravity, and general relativity contains no superpositions, so the situation is completely beyond our theoretical understanding. This isn't a theoretical consideration, this is something real that you can do in an undergrad physics lab experiment pretty easily.
Now the problem is that the models we have developed so far to deal with this situation turned out to be (wildly) too difficult for us to test. I think it is very far from clear that the Oppenheim & co model falls into this category - imo its completely reasonable for them to be spending theoretical effort working out what is needed to test their model.
Because it's not an experimental result. There are two disparate experimental results, one about superpositions and one about gravity. There's no experimental result about gravity being or not being in superpositions. What will happen to gravity (if there is any) in a double split experiment is pure theoretical speculations.
And I readily admit that it would be interesting to know what would happen. But many decades of more or less convoluted hypotheses has proved to be unfruitful. We need a new way to do fundamental physics, or if possible go back to the old way, because the current one clearly doesn't work.
