# Why should the action be Lorentz invariant?

1. Jul 31, 2009

### pellman

Why should the action be Lorentz invariant? Every time I come across this it is assumed by the author without qualification. As too obvious to explain maybe? Ain't obvious to me.

2. Jul 31, 2009

### AstroRoyale

3. Jul 31, 2009

### pellman

i get it now. Thanks.