CONSIDERING HOW MUCH and the extent to which so many college-credentialed Americans are obsessed with demanding a proof of the existence of God that they are rather remarkably free in giving their credulity away in so many things other than that. If Sean Carroll or one of the other imaginary, would-be Lords of Creation came up with a theory of everything, I would bet you that a small fraction of one percent of those who would embrace it on the basis of the meat-headed claim that it would finally dispose of God - probably why Carroll et al want them to believe they've almost got one nailed down - would begin to understand it. I'm sure I wouldn't. The many true believers in it would be as reliant on the Lords of Creation as they like to imagine medieval Catholics were reliant on the faith which they so despise - one which is largely a fiction created out of Brit anti-Catholic propaganda and a few details added by later atheists but which didn't much exist.
I wonder if any of the people who demand "prove it" would be any more open to having that proof presented to them or if they'd reject it in pretty much the same way that Trump cultists are still Covid skeptics or QAnon lunatics reject reality on an even more comprehensive basis.
I doubt one in a hundred of you guys could say what you mean by "exists," to start with. I'd have a hard time saying what that means and, unlike you, I've thought about it.