Q. Lady Traveller, where have you been? Why no posts?
A. 1. Helping to install a new museum. 2. Sleeping. 3. See #1
Q. What is a Black Swan Event?
A. Something that comes as a surprise (that may even have been postulated to be impossible) but, once observed, makes sense in hindsight. For example, for centuries Europeans believed that it was impossible that a black swan could exist ... until settlers came across the birds in Australia.