Brian Greene: When we talk about vibration in physics, we have an interesting set of equations, mathematical equations that govern how a system vibrates. So if we have a string on a violin, we have an equation for how that string will vibrate. And that equation is one we can study mathematically and predict for a given string, what it will sound like based in the mathematics. And this set of equations, the equations for what we call simple harmonic motion are the most ubiquitous equations in all of physics. They’re the ones we deal all the time in a wealth of different systems, in cosmology we deal with them, in astrophysics we deal with them, in everyday settings we deal with them. Those equations are the bread and butter of physics.