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I've enjoyed thinking about the following: It must be almost impossible to time travel back in time. But it could be possible, given unlimited time. Thus, give

• testing3212 12y ago
  > But it could be possible, given unlimited time. Just because time is infinite, does not mean that all things are possible. My understanding is that the universe is in a bounded random walk. As space-time moves, the unexplored potential state space increases more quickly than can be explored. If there are multiple universes, then each universe could explore one of these states. So if there are more states than universes, not all things are possible. But if there are more universes than states, all things would be possible. Though there are infinite potential states and infinite universes, I feel like the potential states expand faster than the number of universes. This means that our likelihood of living in a universe where something like like time travel is possible, is incredibly low.