Physics & Space · From gravity to galaxies — the laws of the universe
Newton's Law of Universal Gravitation
1687
Isaac Newton explained why apples fall and planets orbit — with one elegant law.
In his Principia Mathematica, Isaac Newton showed that the same force pulling an apple to Earth also keeps the Moon circling our planet and the planets orbiting the Sun. He proposed that every particle attracts every other particle with a force proportional to their masses and inversely proportional to the square of the distance between them. This unified celestial and terrestrial mechanics for the first time in history, giving humanity a mathematical key to predict eclipses, tides, and spacecraft trajectories centuries later.