Another theory is called Causal Sets. As some of the approaches mentioned above, its direct goal isn't necessarily to achieve a theory of everything but primarily a working theory of quantum gravity, which might eventually include the standard model and become a candidate for a theory of everything. Its founding principle is that spacetime is fundamentally discrete and that the spacetime events are related by a partial order. This partial order has the physical meaning of the causality relations between relative past and future distinguishing spacetime events.
another theory is called causal sets as some of the approaches mentioned above its direct goal isn't necessarily to achieve a theory of everything but primarily a working theory of quantum gravity which might eventually include the standard model and become a candidate for a theory of everything its founding principle is that spacetime is fundamentally discrete and that the spacetime events are related by a partial order this partial order has the physical meaning of the causality relations between relative past and future distinguishing spacetime events