Play ping pong in my head most every day.

No, I would say the conservation laws

Are what bedevil … puzzle … give me pause.

Momentum (straight and round) and Energy

Seem destined always just the same to be.

Like quick-change artists, morphing shape and form,

Their underlying constancy the norm.

The other laws, ‘though priceless they may be

Pay homage to these arch conservers three.

They seem so fixed for all eternity …

Momentum (straight and round) and Energy.