back in time, albeit as a simulation, and relive past events. This would

Free Will 317 back in time, albeit as a simulation, and relive past events. This would have no effect on the events themselves as it would be like watching a movie, but we could see every aspect of the past from any viewpoint. To perform this time travel trick for real, we would have to gather information from an enormously wide area. Information spreads out at the speed of light. One minute after the dominoes topple, the information about the event will have spread one light minute — that is over a sphere forty-million kilometers across — half way to Venus. An hour later and it would be outside the solar system. If you were to cast your net that wide, and gathered up all the information within the sphere, you could still perfectly model the moment when the dominoes were toppled. The wider you cast the net, the more information you have and the further backward in time you can travel. If you take the idea of collecting information to its logical conclusion you could gather all the information in the Universe at a moment in time. In 1814, Laplace put this idea in an essay. He proposed an immensely powerful being observes the position and momentum of every particle in the Universe. Armed with any snapshot of the Universe and the laws of physics, the entire future and the past of the Universe. The being was nicknamed Laplace’s Daemon and the idea has influenced philosophy ever since. If the Universe is predictable, our concept of time needs to be rethought. A common sense notion isthat things inthe futureare unknown and things in the past are known. But, in a deterministic Universe a daemon or a supercomputer could keep track of all the information and tell you what is inevitably going to happen. The conscious feeling we have of moving through time would be just an illusion. Past and future have no meaning and there would just be a solid, permanent block of space- time. If you stood outside the Universe and looked at this block of space- time, everything that is going to happen and has already happened is set. This is sometimes called the Block Universe Hypothesis and is the logical conclusion of any theory that imagines an entirely determined Universe. One thing that seems to throw doubt on this Block Universe Hypothesis is our personal conscious experience of the world. We experience the Universe unfolding over time. (Of course, we could have this conscious experience in a determined Universe if someone had programmed it that way. All we can say is that it seems unlikely someone would go to the trouble of giving us a completely fictitious experience. There are an infinite number of possible Universes, why pick one where we think time flows, but it does not.) HOUSE_OVERSIGHT_016007