Spherical-Cow Philosophy

There is this joke about a dairy farmer wanting to maximize his cow’s milk production. So the farmer goes to a physicist who comes back with a stack of impressive looking equations and says, “Well, first assume a spherical cow…”

 

At first sight, it just sounds like yet another theoretical simplification to the point of absurdity. But there is a lot to this “spherical-cow philosophy”, writes Sean Carroll in The Biggest Ideas in the Universe 1. Specifically in how physics is done:

“Idealize a difficult problem down to a simple one by ignoring as many complications as you can. Get an answer to the simple problem. Then put the complications back in and calculate how they affect the answer to the simple problem.”

 

Physics is famous for this method e.g. ignore friction, build an idea, then add friction into it. For no apparent reason, this technique works in physics. Even though it obviously does not work in so many other fields:

“In fields like biology and economics, everything often depends on everything else.”

The term for that is “feedback loops”. Just a little bit of such feedback loops and even the seemingly simplest of problems becomes impossible to solve.

 

Carroll says the fact that this seemingly absurd spherical-cow philosophy works in physics is a major reason why physicists are “able to discover amazing and counterintuitive features of the world”. Because this add-one-thing-at-a-time approach makes physicists’ “lives enormously easier than they otherwise would have been”.

 

The final outcome of physics looks daunting and impressive. Which it is. Nobody is taking credit away from the flashes of genius and inspiration of so many physicists over centuries. But physicists would do well to acknowledge that it helps that the topic at hand lends itself to certain problem solving techniques, in their case the spherical-cow philosophy…