In physics, your solution should convince a reasonable person. In math, you have to convince a person who's trying to make trouble. Ultimately, in physics, you're hoping to convince Nature. And I've found Nature to be pretty reasonable.
Frank WilczekThe answer to the ancient question Why is there something rather than nothing would be that nothingis unstable.
Frank WilczekI went off to college planning to major in math or philosophy-- of course, both those ideas are really the same idea.
Frank Wilczek