One big problem with theories of everything is that their predictions of how space-time behaves at the smallest scales are way beyond the reach of our experiments. At least, that is the common wisdom. Now it seems that certain properties of space-time predicted by these theories may have already influenced experiments without anyone noticing.
The challenge for a theory of everything is to unify Einstein’s description of gravity with quantum mechanics into a successful theory of quantum gravity. There are many candidate theories that predict that space-time fluctuates rapidly on so-called Planck scales of about 10-35 metres, but…
