Dropping a light and heavy ball from the Leaning Tower of Piza
Galileo Galilei was the first to demonstrate that bodies of different mass fall equal distances in equal times. He did this very dramatically by dropping a light and heavy ball from the Leaning Tower of Piza before an assembly of students and skeptical faculty of the University of Pisa. The balls reached the ground at the same time, thereby proving Aristotle’s physics wrong.
Galileo wasn’t the first to do this.
Flemish engineer/mathematician Simon Stevin (1548-1620) did the experiment.
Even earlier, the 7th century Byzantine scholar John Philloponus (John the Grammarian) described the experiment in detail, in language that leaves no doubt that he had actually done it.
To make matters worse, Galileo probably didn’t even do the experiment himself, at least he never claimed he did.
No document of the University of Pisa mentions it, nor does any other independent source.
The story was likely a fictional invention of Vivani, Galileo’s pupil and biographer. Galileo did describe such an experiment, and used it when arguing against Aristotelian mechanics.
The myth still shows up in textbooks. It should have died when Lane Cooper demolished it in a pahmphet titled Aristotle, Galileo, and the Tower of Pisa (Ithica, 1935; Kennakat Press, 1972).