Everybody believed in Æther but not God?
René Descartes (d. 1650) had some trouble trusting his senses. He coined the quintessential philosophical maxim: “I think therefore I am” because the only thing you can ever be sure even exists is yourself, since you are the one thinking that egotistical thought. Everything and everyone else in the Universe could be a figment of your imagination (or a product of the Matrix!) But that still proves that you have an imagination, and as the thinker you are thus the only one who certainly exists. I find it both bemusing and amusing that Descartes also whole-heartedly bought into the implausible notion of luminiferous æther (or ether). Æther is a “substance” that was universally believed—by everyone from any literate third grader to the auspicious father of physics, Sir Isaac Newton himself—to occupy every nook and cranny of outer space. Since light behaves like a wave, it must have a substance through which to move from the stars to earth, which “proved” space was not a vacuum. Ether ...