For as long as there’s been an ocean, there have been tides. Twice a day, every day. By now, you’d think we’d have a pretty good scientific handle on tides. And we do. But there are still plenty of questions, even mysteries.
In his new book Tides: The Science and Spirit of the Ocean, Jonathan White weaves a tale of our changing understanding of the tides. It's a story that goes back millenia, but our modern understanding of tides is closely tied to the emergence of modern science.
1. Aristotle tried - and failed - to understand the tides in the Euripus Strait. While he is generally thought to have died of a disease of the digestive system, a few accounts say he became so frustrated that he killed himself by jumping into the ocean, yelling “Comprehend me, since I cannot comprehend thee!”
2. Galileo used tides to argue that the Earth moves (around the sun). In fact, tides were so essential to his argument that he originally titled his book The Flux and Reflux of the Tides. But he misunderstood what drives tides. He thought they were the ocean sloshing around, like water in a swinging bucket, and he actively opposed the idea of an invisible force or attraction (a.k.a. gravity).
3. Descartes was equally unhappy with the concept of an invisible force, and instead, suggested that a soupy ether surrounded the planet and was compressed against the ocean by the moon.
Even Newton wasn't fond of the idea of an invisible force, but he found it unavoidable. Thus was born gravity, and our modern understanding of tides. The subject received a three page treatment in Newton's famous Philosophiæ Naturalis Principia Mathematica.