Physics is the study of very tangible things. The equations are imbued with the same sensory emotions as the universe they describe. Variables click into place, brackets swing open and shut, integrals compound their integrands, and derivatives rip through constant terms. It’s the same connection you make when drawing the path of a ball on a chalkboard. Your fingers press harder and your hand swings faster as the ball falls from its apex. You trust that by imitating an actual ball you will somehow better represent its behaviour abstractly in the diagram.
Physics gets its direction from desire. We desire the world to be simple to understand and manipulate. A simple universe is a little closer to everyday life and little easier to feel in control of. But of course this is never the case, we are inundated in data that makes little sense and theories far beyond interpretation. Naturally then, when a monstrous elliptic integral or PDE appear in a theory we can only hope that all those terms go to 0. It feels uneasy to have such uncontrollable and complicated effects contribute to our universe. Maybe it’s why multiplying by 0 feels like cleaning to me. At all times, though, you know what you are looking for, carefully balancing your trust in your methods with your desires about the universe.
- Gross!
However, it’s the most exotic places and conditions that I think tell us most about the fundamentals. The inside of a black hole is my favourite, but the insides of stars, the tiny spaces inside atoms, the beginning and end of time are equally crazy. What is most exciting is that all of the most extreme objects in the galaxy do actually exist, and so they absolutely must be described by the same language we use to talk about dropping tea cups, running taps, kicking footballs and getting into car accidents. String theory’s contribution to our experience of black hole singularities is equally insignificant to it’s contribution to our experience of kicking footballs. We will never use strings to score goals and we will never travel into the centre of a black hole. Merely the fact that it’s the same string theory that describes both is enough to make it worth studying.