Galileo’s Relativity
Reasoning from principle of Superposition: All Motion is Relative
No experiment inside a steadily moving ship will show that is is moving. Only by looking outside can one detect motion -- i.e., relative motion.
Therefore there’s no reason to expect to sense that the Earth is moving. There is no reason to say the earth is at rest!
No reason to put the earth at the center of the universe!
Profound consequences upon the world view --- for which Galileo was persecuted