Life 3.0: Being Human in the Age of Artificial Intelligence

by Max Tegmark

The first challenge is that our Universe is expanding, which means that almost all galaxies are flying away from us, so settling distant galaxies amounts to a game of catch-up. The second challenge is that this cosmic expansion is accelerating, due to the mysterious dark energy that makes up about 70% of our Universe. To understand how this causes trouble, imagine that you enter a train platform and see your train slowly accelerating away from you, but with a door left invitingly open. If you’re fast and foolhardy, can you catch the train? Since it will eventually go faster than you can run, the answer clearly depends on how far away from you the train is initially: if it’s beyond a certain critical distance, you’ll never catch up with it. We face the same situation trying to catch those distant galaxies that are accelerating away from us: even if we could travel at the speed of light, all galaxies beyond about 17 billion light-years remain forever out of reach—and that’s over 98% of the galaxies in our Universe.