"Imagine returning from an exhausting adventure only to find that your home is abandoned, empty. Not just your home, but your neighborhood, your city, in fact, everyone, everywhere, seems to be missing. This is what happens to the crew of the first manned mission to Barnard's Star -- they return after awakening from suspended animation to find that their ship-board AI has sent them on a relativistic tour of the stellar neighborhood while they slumbered, dilating time so severely that nearly 200 years have passed on Earth. After coming to, they discover their vessel is adrift at LaGrange point 5, within visual range of a vast O'neill cylinder-colony." More.