which we call a wave equation. Why?
Suppose solution is f(x, t). The left side has got to produce a c on each differentiation, right side no factor:
can do if f(x, t) = f(x - ct) or f(x + ct)
and this gives a shape that just slides along x as a function of time, what we call a wave.
As we see, f(x) can be any shape. We see that c is the speed of the wave.Maxwell said, c=1/?(??) = vlight = 3.1010m/s Hey, this is light!!