G. H. Hardy wrote: "Mathematics is a young man's game." Of course, you can continue to be a mathematician later, but for top performance, especially in terms of novelty, you have to start early.
Individual examples do not contradict the general statement. Galois was dead at an age when I wasn't even at university. Abel a bit later (so avoid groups if you want to have a long life), same with Ramanujan (which incidentally may be a factor in Hardy's comment). And so on, just as singular at the first glance.
As a mathematician, however, I continue to argue Hardy's point, both for the present and for the past as a general and observable phenomenon.
And the number of books as a measure of quality, really? I think that view is skewed by today's “publish and perish” environment (nothing against Euler).
There's no suggestion that Euler is anything but an individual example however it is explicitly stated that number of works was a measure of productivity not quality.
Not all Groupies die young, https://mathematical-research-institute.sydney.edu.au/news/p... is still grinding along having created and steadily expanded on a system from 1980 through to today that is still actively used to beat quantum cryptographic cipher candidates.
> it is explicitly stated that number of works was a measure of productivity not quality.
I have noticed that. But my entire posting, to which you replied, had the subtext of excellence - in this case, the comparison of professional basketball and mathematics. And in the latter at least, quality and originality plays first fiddle. In this respect, I would be reluctant to shift the discussion to other qualities such as “productivity”. For me, this is not the relevant measure in this context and, as I said, I also view it critically as a criterion for whatever.
As for Tao, I knew the picture and the story. Yes, an old and a young one. So what? It's not countering my or Hardy's point. These are statements from experience about a whole profession.
Admittedly some of that was playing a Swiss Charles Dodgson to 15 and 10 year old girls.
~ https://en.wikipedia.org/wiki/Letters_to_a_German_Princess