Je n’ai fait celle-ci plus longue que parce que je n’ai pas eu le loisir de la faire plus courte.
(translation: I made this too long because I didn’t have the leisure to make it short.)
–Blaise Pascal, June 19, 1623-August 19, 1662
Blaise Pascal, French physicist-mathematician-philosopher-gambler-hypochondriac-etc., was born on this day (June 19) in 1623. Like many Renaissance figures, which of his many accomplishments is most important depends on who you ask: he is probably best and most enduringly known for his mathematical work and his incomplete philosophical text, Pensées (or Thoughts, if you want the rare literal translation). As a physicist, I tend to rank his contributions to the physics of gases and fluids high on the list: he showed that vacuum (absence of air) is possible, and also that air has mass. The existence of vacuum was a strike against the classical physics model, where the elements permeate everything; Pascal pointed out that the phrase “nature abhors a vacuum” is not so much scientific as it is wishful thinking.
The mass (and weight) of air is significant for astronomy: if air has weight, then Earth can hold it even as it orbits around the Sun and rotates on its axis. Using language Pascal himself didn’t possess, we understand air has inertia, so it isn’t spun off the planet. The full understanding of atmospheres came later, along with gravity—Newton, after all, published his law of gravitation in 1687, after Pascal’s death in 1662.
I think honestly that may be Pascal’s greatest accomplishment: not so much his specific achievements, but the groundwork he laid for later theories. His work with Pierre Fermat on probability theory in combination with his work on gas laws led to the great 19th century science of Maxwell, Boltzmann, and others, in ways he couldn’t have seen at the time. In a world where determinism and adherence to ancient Greek thought still held sway, he showed you could still be scientific (as much as it was possible at the time) and accept the existence of random processes.
Oh yes, and I named my cat after him, since le chat a ses raisons, que la raison ne connaît point.