Do we need a Theory of Everything?

I get constantly asked if I could please comment on other people’s theories of everything. That could be Garrett Lisi’s E8 theory or Eric Weinstein’s geometric unity or Stephen Wolfram’s idea that the universe is but a big graph, and so on. First I explain what physicists mean by a theory of everything and by grand unification (or a grand unified theory, respectively). Then I explain why the current approaches are no very promising but why, forgive me, I nevertheless think it’s good to have them. You can h