With regard to the multiple universe theory - one physicist whose name I cannot recall said something like “That is not a very efficient use of universes.”
There’s still a lot to learn. We have not yet quantized gravity so as to fit with quantum descriptions of the other three forces. We have no idea what “dark matter” is. And all quantum descriptions for “dark energy” produce numbers which are literally billions of times greater than the one we think we are measuring.
Methinks the ‘theory of everything” is still a bit far off.
Perhaps so far off that we’ll never get there.
The most dangerous game is when such big ideas are used to limit the freedom of everyday people. A separation of science and state is as beneficial as a separation of church and state.