In the 'Dialogues concerning two new sciences' [1] Galileo (1564-1642) wrote: "I, Simplicio, who have made the test, can assure you that a cannon ball weighing one or two hundred pounds, or even more, will not reach the ground by as much as a span ahead of a musket ball weighing only a half a pound." Whether or not this experiment was performed before the doubting professors of the University of Pisa by dropping weights from the Leaning Tower is still being discussed by historians. The debate takes away nothing from the stunning discovery by Galileo which will forever remain a landmark of science. What kind of force counteracted the force of gravitational attraction to the center of the earth by just the right amount to make the heavy object fall no faster than the light object?
