Helgoland: Making Sense of the Quantum Revolution

by Carlo Rovelli

I see a rock falling toward me.124 If I move, I will survive. There is nothing mysterious about the fact that I move. It is explained by Darwin’s theory: those who did not move were crushed and killed; I am a descendant of those who move out of the way. But in order to be able to move, my body needs to know that the stone is heading for me. For it to know, there must be a physical correlation between a physical variable inside me and the physical state of the rock. This correlation is there, obviously, because the visual system does precisely this: it correlates the surrounding environment with neural processes in the brain. There are all sorts of correlation between internal and external, but this one has a particular characteristic: if it was not there, or if it was not well adjusted, I would be killed by the rock.