Mathematicians sometimes bemoan the early death of Évariste Galois,
who invented group theory and died in a pointless duel immediately
after, at the age of twenty. I am more saddened by the early loss of
Niels Henrik Abel (26) and Jacques Herbrand (23).
But if I had to pick one scientist or mathematician to rescue from a
premature death, it would be Henry Moseley.
Here's what I wrote about him on The Universe of
Moseley is better-known for discovering that atoms have an atomic
number, thus explaining the periodic table. The periodic table had
previously been formulated in terms of atomic mass, which put some of
the elements in the wrong order. Scientists guessed they were in the
wrong order, because the periodicity didn't work, but they weren't
sure why. Moseley was able to compute the electric charge of the
atomic nucleus from spectrographic observations. I have often
wondered what else Moseley would have done if he had not been killed
in the European war at the age of 27.