While I have to admit that his fiction was sometimes a bit wooden, Sir Arthur C. Clarke, who died today, was one of the true visionaries of the last century. Geostationary telecommunications satellites—the ones we all use now for all sorts of things—were his idea. He helped with the deployment of radar in World War II. And in novels like Rendezvous With Rama and Childhood's End, he imagined how humans might react if we find out we aren't alone in the universe.
In many ways, he helped build the frame around our modern ideas about astronomy, cosmology, and space travel. He was no doubt disappointed that we didn't pursue the kind of space program started in the 1950s and '60s. We're certainly far from the routine orbital and lunar trips he and Stanley Kubrick forecasted in 2001.
He was, in many ways, an eccentric, married only once, briefly, decades ago, and spending the last 50 years of his life in Sri Lanka after leaving his native Britain. He was also a master of pithy quotes: "Any sufficiently advanced technology is indistinguishable from magic." "If there are any gods whose chief concern is man, they cannot be very important gods." "Any teacher that can be replaced by a machine should be!" "There is hopeful symbolism in the fact that flags do not wave in a vacuum." "I don't believe in astrology; I'm a Sagittarian and we're sceptical."
I read a lot of his stuff when I was young, and he is one reason I turned into a geek and a science major. He lived a long life, to 90, but it's still a sad day that he's gone.