Roger Penrose and Stuart Hameroff would go on to write several papers together about microtubules, which are small tubes of proteins that can be found in cells, including neurons. The idea is that collections of microtubules in neurons can display quantum behavior. When these quantum states of the microtubules are reduced—that is, the quantum effects disappear—conscious awareness arises and free will becomes possible. This conjecture is called orchestrated objective reduction, or Orch OR for short.
