Zero - Charles Seife [38]
No matter the dimensions of the tube that Torricelli used, the mercury would sink down until its highest point was about 30 inches above the dish; or, looking at it another way, mercury could only rise 30 inches to combat the vacuum above it. Nature only abhorred a vacuum as far as 30 inches. It would take an anti-Descartes to explain why.
In 1623, Descartes was twenty-seven, and Blaise Pascal, who would become Descartes’s opponent, was zero years old. Pascal’s father, Étienne, was an accomplished scientist and mathematician; the young Blaise was a genius equal to his father. As a young man, Blaise invented a mechanical calculating machine, named the Pascaline, which is similar to some of the mechanical calculators that engineers used before the invention of the electronic calculator.
When Blaise was twenty-three, his father slipped on a patch of ice and broke his thigh. He was cared for by a group of Jansenists, Catholics who belonged to a sect based largely on a hatred of the Jesuit order. Soon the entire Pascal family was won over, and Blaise became an anti-Jesuit, a counter-counter-reformationist. Pascal’s newfound religion was not a comfortable fit for the young scientist. Bishop Jansen, the founder of the sect, had declared that science was sinful; curiosity about the natural world was akin to lust. Luckily, Pascal’s lust was greater than his religious fervor for a time, because he would use science to unravel the secret of the vacuum.
About the time of the Pascals’ conversion, a friend of Étienne’s—a military engineer—came to visit and repeated Torricelli’s experiment for the Pascals. Blaise Pascal was enthralled, and started performing experiments of his own, using water, wine, and other fluids. The result was New experiments concerning the vacuum, published in 1647. This work left the main question unanswered: why would mercury rise only 30 inches and water only 33 feet? The theories of the time tried to save a fragment of Aristotle’s philosophy by declaring that nature’s horror of the vacuum was “limited”; it could only destroy a finite amount of vacuum. Pascal had a different idea.
In the fall of 1648, acting on a hunch, Pascal sent his brother-in-law up a mountain with a mercury-filled tube. On top of the mountain, the mercury rose considerably less than 30 inches (Figure 22). Was nature somehow perturbed less by a vacuum on top of a mountain than by a vacuum in the valley?
Figure 22: Pascal’s experiment
To Pascal, this seemingly bizarre behavior proved that it wasn’t an abhorrence of the vacuum that drove the mercury up the tube. It was the weight of the atmosphere pressing down on the mercury exposed in the pan that makes the fluid shoot up the column. The atmospheric pressure bearing down on a pan of liquid—be it mercury, water, or wine—will make the level inside the tube rise, just as gently squeezing the bottom of a toothpaste tube will make the contents squirt out the top. Since the atmosphere cannot push infinitely hard, it can only drive mercury about 30 inches up the tube—and at the top of the mountain, there is less atmosphere pushing down, so the air can’t even push the mercury as high as 30 inches.
It is a subtle point: vacuums don’t suck; the atmosphere pushes. But Pascal’s simple experiment demolished Aristotle’s assertion that nature abhors a vacuum. Pascal wrote, “But until now one could find no one who took this…view, that nature has no repugnance for the vacuum, that it makes no effort to avoid it, and that it admits vacuum without difficulty and without resistance.” Aristotle was defeated, and scientists stopped fearing the void and began to study it.
It was also in zero and the infinite that Pascal, the devout Jansenist, sought to prove God’s existence. He did it in a very profane way.
The Divine Wager
What is man in nature? Nothing in relation to the infinite, everything in relation