We began this introduction by talking about how physics began as philosophy, a sort of thinking that tries to understand things more deeply, and doesn't have a results-oriented focus. But soon the first natural philosophers crossed a divide which continues to separate physics and all the sciences from philosophy. This divide has three hallmarks: experimental observation of nature's actual behavior, complete control over experiments including the ability to repeat them at will, and always using numbers to describe nature. We started by talking about experimental observation, and more recently discussed the focus on experimental control, how it results in a corresponding narrowing of "scientific truth" to those things that can be controlled and repeated at will, and how it unfortunately can be part of a vicious cycle which focuses on power and abuses both man and nature. Now we will turn to the third hallmark of natural philosophy: its focus on numbers.
Numbers and the things we can do with them will be the daily bread of the rest of this blog. (That's why I discussed this hallmark last.) But before we get to know numbers I want to point out that there is a great mystery here: why are numbers useful for describing nature? Certainly this doesn't seem like a mystery today, when the success of numbers is a fact of life. The movie reproductions we watch via DVD or high definition television are composed of billions of numbers; indeed any image can be represented by numbers, as are the voice signals that we listen to on our cell phones and the songs we listen to on CDs. Mapquest and GPS have quantified our moving around: 5.3 miles north, then turn right and 1.4 miles east. And time also: we watches to tell the exact date and time. Clearly numbers have been very very successful, but their success alone does not explain why you're successful. If we think that the utility of numbers is obvious, it is only because we are prejudiced by our daily experience.