In his book, The Beginning of Infinity, Oxford physicist David Deutsch writes:
If a one kilometer asteroid had approached the Earth on a collision course at any time in human history before the early twenty-first century, it would have killed at least a substantial proportion of all humans. In that respect, as in many others, we live in an era of unprecedented safety: the twenty-first century is the first ever moment when we have known how to defend ourselves from such impacts, which occur once every 250,000 years or so.
Documentary filmmaker Errol Morris wants to know what you think of Deutsch’s claim, and has set out a brief survey on his blog at the New York Times. Morris told me, "It may seem like another innocuous Internet quiz, but take my word for it—it isn't one." He also said, "There is a hidden question, which I’m not at liberty to reveal, that I think will interest you." and on his blog, he writes "When the results are announced, there will be a surprise."
I'm intrigued! I love surprises, even when they involve killer asteroids.