5 July 23

Isaac Newton's revolutionary book "Principia" was first published on 5 July 1687. "No work was more seminal in the development of modern physics and astronomy than Newton's 'Principia.' Its conclusion that the force retaining the planets in their orbits is one in kind with terrestrial gravity ended forever the view dating back at least to Aristotle that the celestial realm calls for one science and the sublunar realm, another." In other words, Newton proved that the force of gravity is the same everywhere in the universe. (Albert Einstein introduced general relativity 228 years later!) My tie shows some of Newton's equations, along with the legendary apple that triggered Newton's experiments and calculations.