Richard A. Posner, whom I recently defended at Sean Carroll's blog, studies various catastrophes in the New York Times:
He evaluates whether it makes sense to try prevent various catastrophes, and the most serious examples of catastrophes are the following:
- a high energy accelerator seems to be the biggest disaster ;-) because it kills 6 billion people with the probability of "1 in 5 million per year", as the leading U.S. newspapers argue
- global warming
- colission with an asteroid
Let me assume that Prof. Posner got the idea to multiply the probability that something happens with the cost of this catastrophe, to get the expected cost, which should be compared with the cost of the prevention. One can argue that it is better to be insured against something, and therefore it may be useful to pay a little bit more than the amount calculated in the previous sentence - to protect life against major disasters. Obviously, there is no objective calculation that should tell you how perfectly should you be insured.
Well, this was the easy part of the story. The hard part of the story is to actually calculate the probabilities of various catastrophes and their total cost. I apologize, but Prof. Posner seems to believe that this is the less intellectual part of the task. The reality is that this is more or less the whole task, and all the answers he obtained seem to be flawed, at least partially. If someone from Brookhaven told him that the annual probability that they would create "strange matter" that will eat up the planet is 2 x 10^-7, then they were either joking, or they lost their minds. This would be statistically equivalent to murdering 1,200 people a year! ;-)
The probability can be argued to be smaller than 10^-15 per the whole lifetime of our civilization, just by observing that the stars around don't seem to be eaten, and the only explanation consistent with the predicted catastrophe would be that the "strange matter core" actually stops growing when it's as large as Earth. But even if this matter existed, such a conspiracy would require fine-tuning equivalent to the ultrasmall probability mentioned previously.
Frank Wilczek et al. argued that the process is most likely excluded because otherwise the high energy cosmic rays would have already destroyed the Moon and other things:
The probability of colissions with the superlarge asteroids are also infinitesimal - one per tens of millions of years. I have wasted more time than appropriate with the "problem" called global warming, so let me not open this again. But Prof. Posner also wants to impose new censorship laws in science to fight against bioterrorism. I can imagine circumstances under which this is a very reasonable proposal; it just does not seem to be the case right now.
He only wants to investigate the big questions, and therefore he does not intend to waste his time with "details" such as 9/11 or - apparently - the recent earthquake in Asia that has probably killed as much as 500,000 people: Indonesia now estimates 400,000 casualties in this country itself.