It looks like this thread has reached its end, so I'll summarize what was learned for those who might still peruse it, or be curious about the validity of the Carter catastrophe conjecture. The idea behind the catastrophe is that if each person has x humans born up to their own birth, then they can be 95% certain they are not in the first 5% of humans, in the absence of any other information. This would seem to suggest that the 95% confidence extended to the idea that humanity would not outlive a count of 20 times x, but the primary debate centered on whether or not it was allowed to set x=10 billion (or so, for us), and still expect the 95% confidence to apply to the number 20x = 200 billion. To have this work, most felt it would have to be argued that setting x=10 billion did not constitute any extra information. But since 10 billion must have some relationship to the actual expected number of humans (i.e. high or low in relation to it), in a situation of complete knowledge of all the contributing factors, so most felt that using any actual value of x (such as 10 billion) did constitute extra information, invalidating the Carter confidence interval. This was not a unanimous view. No doubt the Carter conjecture will continue to be debated, but probably not on this forum!