Going the Nostalgic Route
For my contribution to our class’s children’s book about Galileo, I think I would like to focus on Galileo’s “tower experiment,” where he dropped two weights of different masses off the Tower of Pisa to show that the speed of their descent was unrelated to their respective weights. (The weights hit the ground simultaneously.) This was important because at the time it was believed that heavier objects always fell faster than lighter objects. According to Wikipedia this experiment may not have actually happened—it might have been more of a thought experiment described by Galileo and/or his students but never actually performed—but either way I think it’s a good story for explaining both one of the concepts Galileo explored and how people reacted to Galileo’s ideas.
I didn’t remember this until I read about the experiment in the children’s book about Galileo I was given, but the tower experiment is actually something I can recall learning about when I was a school-aged child myself. We watched a biographical (though perhaps romanticized) movie about Galileo in history class which had a scene portraying the tower experiment. The scene that stuck in my head, though, was a scene that came afterward, where some kind of student of Galileo’s (assuming the character was even supposed to be an actual historical figure, I still can’t remember his name) who doubted the hypothesis behind the tower experiment walked into Galileo’s study and simultaneously dropped a heavy weight and a feather. Of course the weight dropped to the floor immediately while the feather floated slowly to the ground, making it seem that Galileo’s theory wasn’t so solid after all.
It took Galileo some time to come up with an answer, but eventually he figured out what we know caused the feather to float: air resistance. He added that were the weight-and-feather experiment repeated in a vacuum, they would hit the ground at the same time just like the weights dropped from the tower, but alas, this was not an experiment he could perform.
I think this sequence stuck with me because not only did it explain the ideas expressed in Galileo’s On Motion in a very easy-to-grasp manner, but it also just as clearly explained why people of the time would have trouble believing such a concept, even after seeing it seemingly proven before their eyes. When you’re young it’s hard to understand the history of science since so much of it is about people not understanding or even rejecting ideas you’ve been taught as fact; it’s hard at that age not to hear these tales as stories about people too stupid to see the obvious. I hope that, by telling this story in a way similar to the way I remember it, I might make the rest of Galileo’s story a little easier to understand.