One metric that I have thought about is this: If this person had not existed, how long would it have been before someone else made the same discovery? Somethin

One metric that I have thought about is this: If this person had not existed, how long would it have been before someone else made the same discovery? Something I noticed when I was in astronomy was that the most successful astronomers tended to do work that was high impact, but also, in a sense, obvious. But they would do that work faster than anyone else, get the first paper out, and let the citations roll in. (There was a good Twitter thread about this strategy here: https://twitter.com/neurobongo/status/1404208339295350792 https://twitter.com/neurobongo/status/1404208339295350792) There is something to be said for this work! After all, it is important and someone needs to do it. But it seems to me that there have been singular figures who really discovered something that wasn't just "in the air," and that that's the sort of thing we reserve for the word "genius." I'm still not completely convinced that this is the right metric though. There have been a number of scientists who are universally regarded as geniuses who discovered things that probably would have been discovered shortly thereafter if they hadn't existed. Poincaré was close to discovering the special theory of relativity when Einstein published his work. Leibniz discovered calculus at around the same time as Newton. Hilbert discovered the Einstein field equations at about the same time as Einstein. (Some sources say Hilbert was just five days earlier than Einstein.) The whole history of quantum mechanics seems like a mad dash by a group of brilliant physicists who were discovering one thing after another nearly every week in the early 20th century. On the other hand, Poincaré, Leibniz, and Hilbert could all justifiably be called geniuses, too. So if two geniuses figure something out simultaneously, does that mean that they cancel each other out and neither of them were geniuses? Seems wrong. So I'm still not sure what the right metric is.