When Vilenkin talks about “quantum tunneling,” he is referring to the spooky phenomenon in quantum physics in which objects can perform such magic feats as passing through a mountain and suddenly appearing on the other side, without ever going over the top. That mystifying ability, which has been verified in the laboratory, follows from the fact that subatomic particles behave as if they could be in many places at once. Quantum tunneling is common in the tiny world of the atom but totally negligible in our human world—explaining why the phenomenon seems so absurd.
