Dear Robert,
I appreciated the expertise and data about catastrophic events of the past, and the relatively wide spectrum of topics that you cover in the limited space of the essay.
I am curious about the estimate by physicist Richard Gott. Do you know whether this a purely abstract argument (reasoning in `geometric` terms of where a point might be on a segment, given that the segment be finite, etc.), or one more concrete and subtle, based on specific (historical) data?
You wrote:
`If we are really special it is also good news for us, because it means that the most stringent filtering steps - and therefore the greatest dangers - are already behind us.`
This triggers the discussion about the fact that we may be special/non-special. You seem to prefer the Copernican, NON-special option, but you also seem to argue about the opposite. I am definitely for the NON-special option, for the following reason.
We could only be special if we assumed that there is a threshold after which extinction becomes much more unlikely, but I do not see why this should be the case. Consider a remote village in which you find an unusual number of ultra centenary people. This does not guarantee to these very old people the chance to have more years left to live than the average person from a `normal` village. And if this example is not convincing, I would just say, more generally, that we cannot anticipate the nature and frequency of (natural or auto-induced) causes for the extinction of humanity that will occur in the future.
Best regards
Tommaso