discovery of radioactive heat was a battering ram

An example of metaphor in a scientist's writngs:

"As far as Earth's age is concerned, in fact, the discovery of radioactive heat is principally of historic interest: it was simply the first battering ram that ruined the mathematical construction that Kelvin had bitterly defended."

Hubert Krivine

Krivine, H. (2015). The Earth. From myths to knowledge [La Terre, des myths au savoir] (D. Fernbach, Trans.). Verso. (2011)

[Lord Kelvin had proposed an age for the earth much less than is now accepted, on the basis that it was a cooling ball of matter]