Pascal

Blaise Pascal was born in Clermont-Ferrand in 1623. He was a prodigy in mathematics, physics, and theology—though these disciplines were not yet separated into different corners. At eighteen, he invented a mechanical calculator. At twenty-four, he designed an experiment that shattered the medieval belief that nature abhors a vacuum.

Pascal's father, Étienne, was a magistrate fascinated by Evangelista Torricelli's barometer—a tube of mercury suspended in air that rose and fell with atmospheric pressure. In 1647, Blaise Pascal argued that if the vacuum at the top of the tube had weight, then air pressure must be real, measurable, mechanical. He convinced his brother-in-law to carry a barometer up the Puy de Dôme mountain. At higher elevations, the mercury column fell. The experiment confirmed it: the pressure of air decreases with altitude.

Pascal went on to formalize the principle of hydrostatic pressure—the foundation of modern physics. His name became attached to the unit of pressure in 1971, adopted by the International System of Units. One pascal is the pressure of one newton per square meter. It is extraordinarily small: a human breath exerts about 100 pascals.

Pascal died at thirty-nine in 1662, tortured by stomach pain he believed was divine punishment for his scientific pride. He never knew that his name would become ubiquitous—branded into aircraft wings, hydraulic systems, vacuum seals, and the pressure gauges of every engineering discipline. The man who worried about hubris became immortal through humble units.