But importantly, they are accelerating downward at precisely the same rate. This idea, that objects fall at the same rate irrespective of their mass, had been known since the time of Galileo. Indeed, Vincenzo Viviani, one of Galileo’s assistants, recalled the great physicist demonstrating this property by dropping two objects of different mass from the top of the Leaning Tower of Pisa and showing that they hit the ground simultaneously.
