It’s a Mishmash Out There
This year marks the 300th anniversary of the publication of Isaac Newton’s “Principia Mathematica,” one of the great milestones of science and of all thought. In this book (which, like too many other great books, is hardly read anymore) Newton established the idea that the same law of nature that governed falling bodies on Earth also governed the motion of planets and comets in the universe.
The idea that nature obeys the same laws everywhere is one of the basic tenets of science. Along with it is the notion that the universe is basically simple, which was expressed in the 14th Century by William of Ockham, who said, “What can be done with fewer assumptions is done in vain with more.” This principle, now called Ockham’s Razor, says that a simpler explanation of a given set of facts is always preferable to a more complicated one.
At the time that William of Ockham lived, people believed that the Earth was the center of the universe and that the sun, stars and planets went around it, which is certainly consistent with an ordinary observation of the sky.
The geocentric model of the universe was propounded by Ptolemy in the 2nd Century. But, in order to make this model mesh with careful observation of the stars, Ptolemy had to add many complications to it, which were called epicycles. These epicycles had no function and no purpose other than to make things come out right. More than 1,000 years later, Copernicus overthrew the entire model and substituted a simpler one: The sun is in the center of the solar system, and all of the planets--including the Earth--go around it. Epicycles were brushed aside, and Ockham’s Razor had triumphed. Newton’s “Principia” followed a century and a half later.
All this comes to mind now because of the current state of affairs in physics, which more and more resembles the Ptolemaic system and less and less resembles Ockham, Copernicus and Newton. The number of subatomic particles has swelled to 19 at last count--some of which have been observed and some of which have been invented by physicists for the purpose of making the mathematics come out right.
On top of this bevy of particles we now have the spectacle of superstring theory, which posits that the universe is ultimately made out of long, thin strings. Not that anybody has actually ever seen these superstrings, mind you, but, once again, they function mathematically. They also have the interesting property that they require that the universe contain 10 dimensions, which are no fewer than seven more than we observe. Most people struggle to understand what the fourth dimension might be, much less the 10th.
As if that’s not enough, we now find physicists who are talking about “superconducting cosmic strings,” about which the British science publication Nature says, “This hybrid animal has recently joined the bulging bestiary of imagined fauna with which high-energy physics might populate the cosmos.”
It is time to wonder whether this whole picture has gotten out of hand. Is each new imagined particle, superstring and superconducting cosmic string just one more epicycle on the body of physics? Where is the contemporary Copernicus who can propose a new and simpler theory and make sense of this mishmash?
In this tricentennial of Newton’s great achievement, physicists should rededicate themselves to straightening things out. Much has been learned, but much more remains obscure. Nature is probably simpler than contemporary physics would have us believe.
