Due to the influence of gravity, the Earth's core is 2.5 years younger than its crust
https://fermatslibrary.com/s/the-young-center-of-the-earth
* scientists revisit claim by Richard Feynman
* famously suggested, 1960s Caltech lecture, gravitational time dilation (general relativity)
* would make the Earth's core younger than crust by "day or 2"
* gen. concept correct h/e estimate wrong
* pedagogical value: any number/observation, by whomever, must be critically examined

