Ask HN: Can you think of any positive black swans?

I read a comment on here tonight about how “no-one in 2019 would have predicted the pandemic” which is semi true, but we can hypothesise about generalised events with negative effects. Which got me to thinking about whether there are generalised positive events on the same scale. I would think that these would mainly be mathematical, scientific and technological breakthroughs but thought I would put it to the crowd to see what you all think.