Discussion

geometric optics

Crepuscular rays show that light travels in straight lines with relatively little diffraction.

Charlottesville, Virginia

New York, New York

Paris, France

Pierre deFermat (1601–1665) France, "principle of least time". Pierre LouisMaupertuis (1698–1759) "principle of least action" in 1747 or 1750? Maupertuis hoped that the principle might unify the laws of physics and support his proof of the existence of God.

The wisdom of Beekman. "We don't see things. We see light bouncing off things."

reflection

A plane mirror produces only one inversion: front-to-back. This is called aperverted image. The pair of warning signs on the right illustrateslateral inversion.

The law of reflection

θ_i = θ_r