Stephen Hawking, one of the most brilliant physicists ever to have lived, used to publicly say this every year or two, because it is perhaps the most important thing humanity should be doing but is only barely/slowly doing. Now that he is gone, I’ll repeat it: for the survival of our species, humans really need to leave this tiny, fragile little planet as quickly as possible. At national and global levels, instead of putting resources into fighting with each other and building things on this planet, we should be focusing on building space stations, fast ships, and colonies on other planets and in other solar systems. Currently, our entire species could be wiped out by global warming, over-population, nuclear war, one large epidemic, asteroid, solar flare, and on and on. We need to go and spread out, now.