10 February 2007
Any spacecraft with sufficient alacrity to journey to the stars will have to have to travel some large fraction of the speed of light. That would mean of course that a round trip would likely leave most or all of the astronauts youthful while their relatives or friends on Earth would have aged and died by the time of their return. Indeed, significant geopolitical or environmental changes might have occurred since their departure, leaving the Earth a far different place from what the astronauts left. It is an idea that fascinates me and creeps me out at the same time.