July 5, 1687: When Newton Explained Why You Don't Float Away

Summary

The Day the Universe Got Organised (Mostly) People were worried, mostly about everything, but particularly about why things stayed on the ground. Apples fell. Horses galloped. Cannonballs soared (briefly) and came crashing down. But no one was quite sure why the moon didn’t join in and plummet to Earth in the same enthusiastic fashion. And then on July 5, 1687, Isaac Newton published a book with a title so long it felt like a Latin riddle: Philosophiæ Naturalis Principia Mathematica. In three volumes, Newton calmly explained how the universe kept its house in order. Why apples fall, why planets don’t wander off, and why we aren’t all quietly drifting into space every time we sneeze. It Almost Didn’t Happen The Principia might never have seen the light of day if not for Edmund Halley—the comet chap—who personally bankrolled the printing. Newton, brilliant as he was, had managed to fall out with the only other mathematician capable of understanding him. (This was the 17th-century version of crowdfunding, only with fewer emails and more quills.) Halley’s intervention saved science from being reduced to “things fall down because they do” for another century. How We’ve Used It Ever Since In the 337 years since, Newton’s ideas have been used for all sorts of fussy yet vital activities: building bridges that don’t collapse, plotting planetary orbits, and explaining why toast inevitably lands butter-side down. NASA still uses Newton’s framework today. They strap adventurous humans into enormous cylinders, set off controlled explosions underneath, and fling them into space—because three centuries later, it’s still the best idea we’ve got. Why It Matters (Even if You Don’t Think It Does) We treat the Principia as a sacred text, but it’s really just a rulebook for how objects behave. Big ones, like moons and planets. And small ones, like apples, cannonballs, and the pen you dropped under the fridge last week. Newton’s laws gave us a universe that made sense—mostly. They made p...