# Energy and Momentum

1. Nov 29, 2006

### actionintegral

Gentlemen,

I see where there is a relationship between energy and momentum in

$$E=\frac{p^2}{2m}$$

Ok. And I also see where there is a different relationship between energy and momentum in

$$E^2 = p^2c^2 + (m_{0}c^2)^2$$

fine. So there must be some abstract concept where E=E(p) in general. What is that concept called? And what do I search on to learn about it?

2. Nov 29, 2006

### vanesch

Staff Emeritus
"dispersion relation"