All the fifty years of conscious brooding have brought me no closer to the answer to the question, “What are light quanta?” Of course today every rascal thinks he knows the answer, but he is deluding himself.
—ALBERT EINSTEIN, 1951
I therefore take the liberty of proposing for this hypothetical new atom, which … plays an essential part in every process of radiation the name photon.
—G.N. LEWIS IN NATURE, DECEMBER 18, 1926
We can wax eloquent: Light is universally revered. It represents illumination and understanding. It represents our greatest treasure, as in the “light of our lives.” We believe that bad things happen under cover of darkness, and evil works cannot stand the light of day. Light sets the ...