#2: One of the first experimentalists was Galileo, who supposedly dropped a feather and a hammer simultaneously from the Leaning Tower of Pisa in order to demonstrate that the two would hit the ground at the same time. Approx. 400 years later that trick still works. (courtesy NASA, 1971)

#10: The California Academy of Sciences in San Francisco houses this particular Foucault’s Pendulum, where one can go to watch the Earth spinning, by deduction.