ABSTRACT
Galileo asked us to image the following experiment: Take aboard a ship (which is initially tied up at a pier on the shore) some butterflies and a
fishbowl (with fish). Go below deck and shut yourself up, along with the butterflies and fish, in a cabin and close the shutters on the windows. With the ship at port, notice how the butterflies fly around the cabin, and how the fish swim around in the bowl equally freely in all directions. Now, set the ship in motion. The motion is to be uniform velocity. Observe your butterflies and fish again. Do the butterflies all clump towards the stern? Do the fish get left behind and gather towards one end of the bowl? No. The butterflies fly around as before and the fish swim to and fro without any preference for being towards the front or the back of the bowl.
