Newton: A Tale of Two Isaacs: Sir Isaac and The Apple
Physics → Gravity → Introduction to Gravity
Physics → Classical Mechanics → Newton's Law of Universal Gravitation
History → Age of Enlightenment → Isaac Newton
Sir Isaac Newton ponders why the planets orbit the sun and what allows them to maintain that orbit. Very soon after he sits down under an apple tree, Humphrey bangs his head against one of the limbs, causing an apple to fall on Newton's head. It is at this moment that Isaac Newton has an epiphany and starts to develop the concept of gravity.