Roger Penrose has advanced the hypothesis that Godel's theorem shows that there is something non-computable (not the product of any algorithm) in the human brain. The only physical process in the universe known to be non-computable is the collapse of the wave function. This is random, and therefore not at first glance a promising mechanism for mental processes. Penrose has, however, proposed an additional form of wave function collapse for particles that are isolated from the rest of the environment. This would not be random, but would be a non-computable link to the geometry of spacetime. He further suggests that this type of wave function collapse occurs in the brain. In conjunction with Stuart Hameroff, Penrose developed the hypothesis that microtubules (skeletal structures within living cells) were suited to support such quantum activity.