Michael Miner [Hot Type, October 6] suggests that the terrorist-asteroid equivalency is, for many, "a lot less illuminating than loopy." Perhaps. Perhaps it is my own actuarial training, but I find it more illuminating than loopy.
A few years ago Harper's had an article on "near earth objects"--not only did they change the course of evolution several times (when a kilometer-size asteroid hits the earth it creates enough damage to blot out the sun for several years, effectively altering evolution), but smaller impacts have had noticeable impacts on the course of human history: a smaller impact is said to have altered human behavior in the southwest, while an impact in Siberia in the early 1900s scorched thousands of acres and the glow of the fires could be seen as far away as England.
More importantly, it shows the poor ability of humans in general to weigh high damages from low-probability events. Smoking has a high likelihood of causing substantial damage; flying has a very low likelihood of killing you outright. But the number of people who view their next smoke with alarm and fear is not high. Too many people fear terrorism in the same way that they view flying: with heightened subjective probabilities and excess fear.