Math and the Ether

There were two things I really liked in chapter 2.

First, the ether. I remember the ether from my Philosophy of Science class; I've always been fond of it. The physicists of the 19th century assumed that, just as sound moves through things like air or water, light must also move through something. They called that something "the ether" and worked diligently to find some evidence of its existence. Chapter 2 describes some of that painstaking work, and reveals that no evidence could be found.

Our prof asked us what this meant, and we said it meant that the ether didn't exist. He corrected us: you can't prove that something doesn't exist, he said, but it did prove that it didn't matter. If something has no observable effects, then it doesn't matter whether it exists or not.

The other thing I liked in this chapter was the discussion of the place of math in physics. I've always had some trouble with the idea that having the math come out right proves something about the universe. I particularly have trouble with the idea that having the math come out wrong allows us to posit random stuff (multiple universes, for example) to make the math come out right, and then behave as though it must actually exist in reality.

Isn't that sort of like deciding that the existence of an extra chair at the table proves that there must actually be another dinner guest?