Polarization was a new topic in physics at that time. Étienne-Louis Malus, a fellow Frenchman, discovered the Law of Malus, governing how much light passes through two polarizers, in 1808, just 14 years before Pasteur’s birth. Pasteur’s friend and mentor Jean-Baptiste Biot first showed that polarized light could be rotated when passed through certain crystals. Pasteur’s contribution was to prove that crystals formed from tartaric acid could rotate polarized light either clockwise or counterclockwise, depending on the chirality of the crystal (this acid is asymmetric, having two forms that are mirror images of each other, like the left hand and the right hand). In a famous experiment, he inspected the structure of each crystal under a microscope and determined if it was left or right handed. When he then separated the two types of crystals he could obtain rotation in either direction, although a mixture of the two crystals did not rotate light. This discovery, made in 1848, at first appears to arise from physics and chemistry alone, but its relation to biology is that most biological molecules exist in only one version. Handedness matters in biology. Debré writes
The Mystic: Louis Kahn
In Pennsylvania Station in New York , circumstances made it the most startling end to an eminent architect’s life, he collapsed on the floor…