- #1
Happiness
- 679
- 30
To show that the Lagrangian ##L## is invariant under a rotation of ##\theta##, it is common practice to show that it is invariant under a rotation of ##\delta\theta##, an infinitesimal angle, and then use the fact that a rotation of ##\theta## is a composite of many rotations of ##\delta\theta##. But a rotation of ##\theta## is a composite of an infinite number of rotations of ##\delta\theta##. If ##L## is invariant under a transformation ##R##, is it still invariant under an infinite composite of ##R##?
Is 0 + 0 + ..., added infinitely, or ##\infty\times0## still 0?
Is 0 + 0 + ..., added infinitely, or ##\infty\times0## still 0?