Science can't solve the mystery of life, but it can make it a lot more fascinating.
There are times in life when it seems that nothing ever changes — life goes on and on in the same frustrating old way, cliché after cliché. Decades go by. Then suddenly, or so it seems, important parts of life change instantly and forever: a word processing computer replaces my clumsy typewriter, a microwave oven defrosts my food in minutes, and a cell phone makes reaching me in Lisbon, London, or Milan as easy as reaching me at home.
- The 10 Most Beautiful Experiments by George Johnson. Vintage. 208 pages. $13.95 (new in paperback).
Galileo had to roll a ball down an incline plane over and over again before he could prove that distance traveled is directly proportional to the square of time (work that overturned Aristotle’s theory that heavier objects fall faster than lighter ones do). Isaac Newton manipulated prisms endlessly in the process of discovering that color is not stained light, as once believed, but rather a ray of light “preternaturally disposed” to bend a certain way (and that white is a combination of all colors, not the absence of color). Luigi Galvani went through perhaps hundreds of frog legs while studying what made the animal jump and uncovering the electrochemical underpinnings of life. Other “beautiful experiments” described in this book led to the discovery of the speed of light, to the measurement of an electron’s charge, and to the understanding that mass cannot be created or destroyed.
Perhaps the hardest work for these scientists came after their great discoveries, when they had to convince others to embrace their new scientific theory. Like convincing people that purchasing a microwave or cell phone will change their lives, changing people’s perceptions is rarely easy.
Consider the work of William Harvey, a 17th-century physician in London. In medical school, he learned the second-century dogma that there were two kinds of blood in the body, carried by what amounted to two different vascular systems. In the bluish-colored veins coursed a vegetative fluid, “the elixir of nourishment and growth” that was made in the liver; meanwhile in the heart and arteries coursed a bright red fluid “activating the muscles and stimulating motion.” All of the fluids, supposedly, were imbued with invisible pneuma, “spirits that entered through the lungs with each breath before passing into the heart.”
When Harvey started studying the hearts of amphibians, fish, reptiles, crustaceans, mollusks, and other small animals, though, he began to realize that the heart did not actually work this way. Hearts did not expand and contract passively, as he had been taught. Instead he saw that the heart actually drove the system.
In what was at the time a radical hypothesis — remember, he was questioning 1400-year-old teachings — Harvey proposed that there was just one kind of blood, and it moved in a circle: After being pumped by the left side of the heart and moving the ends of the arteries, the veins picked it up and returned it to the right side of the heart. Experimenting on a snake, he showed how pinching off the vena cava, just before the blood entered the heart, emptied the blood from vessels downstream and made the heart beat more slowly; releasing the pressure allowed the heart to refill with blood and beat normally again. Pinching the main artery leading away from the heart made the heart grow distended with blood, and when this pressure was removed, it returned to normal functioning.
Whether or not the heart, besides propelling blood throughout the body, added anything else to it, such as “heat, spirit, perfection — must be inquired into by-and-by, and decided on other ground,” Harvey wrote at the time. But people did not want to think of the heart as so mechanical: Despite the convincing quality of Harvey’s experiments, hardly anyone believed him. He defended his findings against doubters for years to come, according to Johnson.
When reading about scientists, I am often struck by how much confidence — as well as intelligence — is required to do the job. So much of the work that goes into great discoveries is based on an anomalous idea, conducted in lonesome obscurity, and carried out through the repetition of small tasks — titrating liquid, measuring output, tracking results. There seems to be so much room for mistakes and so much time to lose faith. Johnson seems similarly awed by how it all happens, wondering how the scientists who conducted these “beautiful experiments” kept from confusing their instincts with their suppositions, “unconsciously nudging the apparatus, like an Ouija board, to come up with the hoped-for reply.” As he asserts, “the most temperamental piece of laboratory equipment will always be the human brain.” • 5 March 2009
Jennifer Fisher Wilson is the science reporter for Annals of Internal Medicine. Her stories are available at www.annals.org.