The Trouble with Physics: The Rise of String Theory, The Fall of a Science and What Comes Next

by Lee Smolin

Faraday and Maxwell were themselves mechanists, and they devoted a lot of time and trouble to addressing this problem. They were not alone; young gentlemen made good careers at renowned institutions by inventing elaborate constructions of the microscopic gears, pulleys, and belts that they posited underlay Maxwell’s equations. Prizes were given for those who could solve the convoluted equations that resulted. There was one big and obvious manifestation of the problem, which is that light travels to us from the sun and stars, and outer space is empty of any matter. Were there any matter in space, it would retard the motion of the planets, which would thus have long since fallen into the sun. But how could electric and magnetic fields reside in a vacuum? So the mechanists invented a new form of matter—the aether—and filled space with it. The aether had paradoxical properties: It had to be extremely dense and stiff, for light was to be essentially a sound wave through it.