Paul Bratermag, writing for Scientific American:
Nevertheless, by the late 19th century the geologists included here had reached a consensus for the age of the earth of around 100 million years. Having come that far, they were initially quite reluctant to accept a further expansion of the geologic timescale by a factor of 10 or more. And we should resist the temptation to blame them for their resistance. Radioactivity was poorly understood. Different methods of measurement (such as the decay of uranium to helium versus its decay to lead) sometimes gave discordant values, and almost a decade passed between the first use of radiometric dating and the discovery of isotopes, let alone the working out of the three separate major decay chains in nature. The constancy of radioactive decay rates was regarded as an independent and questionable assumption because it was not known—and could not be known until the development of modern quantum mechanics—that these rates were fixed by the fundamental constants of physics.
Interesting read. I’m a little sad now that basically all of physics is pretty much understood.
But at least there’s chemistry and biology to pick up the slack!
I wish I could read the full series without paying $9.99 though.