Issues

Counting accelerated ions rather than decay events increases the sensitivity by several orders of magnitude so we can find the ages of much older and smaller samples.

Recent advances in technique have greatly increased the scope of possible studies, including tests of fundamental symmetries and the spin dependence of nuclear forces.

At the Allegheny and Lick observatories, both of which he served as director, Keeler applied physical methods to the analysis of planets, stars and nebulae.