Her handwriting was messy at the best of times, but now, only able to start her thinking after a long day helping the increasingly desperate Voltaire, she scrawled. She let her wide writing slip down the righthand edge of her foolscap sheets; she left drenching ink marks, but just blotted or scratched over them and kept on going.
She began with what she knew about light. It manages to rise up out of the sun and cover the immense distance to our planet in barely nine minutes. The only way it can do that is by traveling at fabulous speeds. She'd helped Voltaire with this very calculation when they were preparing their Newton book the year before, so she knew that streams of light from the sun pour down on us, and hit at a speed of close to I billion feet per second.
That's faster than anything we're used to. Put a big, half-pound charge of gunpowder in a cannon, and it can send a heavy shot hurtling out of the barrel at about 600 feet per second. Even that “slow” speed is enough to shatter anything it hits. Yet the light from the sun is hitting us a million times faster.
She started thinking about what this meant. If there were any solid particles inside those sunbeams—if light were made of miniaturized particles, as Voltaire and almost everyone else assumed must be the case—then they would utterly devastate life on our planet. Even if atoms of sunlight weighed merely 1⁄15,000 of a pound, Emilie calculated, each one would hit the Earth with the power of a full-sized cannonball. You could go further. Even if they were a billion—even a trillion— times smaller, their shatteringly fast impact would still destroy all living beings on the surface of the Earth.
Voltaire should have recognized this, but he was blocked because every authority he'd read had assumed that light had solid weight. They'd ignored the problem of how dangerous it would be to us in that case as it smashed down on our planet.
Emilie, working on her own, was different. She had the imagination and fearlessness to go past currently accepted concepts. What if—she couldn't yet say for sure, but just as something to consider— the assumption everyone made was wrong? And then—this would really be striking if it was true—what if light was something that had no mass at all?
Voltaire would never acknowledge that, least of all from her (“I was disagreeing with almost all his own ideas”). It was a breakthrough for the time. But wasn't the image of light that weighed nothing the only way to explain how the sun worked? For if light did weigh something, how would it keep on lifting out from the sun? All its weight, inside the sun where it began, would make the sun so overwhelmingly massive—and produce such an overwhelming pull of gravity—that nothing would be able to fly out. But we don't see our sun as a dark void in the daytime sky. We see it as a brilliant glowing orb. That glowing is the sign of the weightless light stuff pouring our way.
It was warm at her bedroom writing desk this August, even so long after dark when she was now working, and that made it hard to stay awake. When it got too bad she plunged her arms deep in a vase of ice water. Other times she stood and paced up and down, clapping her hands together to stay awake. Then she'd return to her desk and the rows of candles and continue.
If light really did weigh nothing, then she could work out some of its properties. It had to be very different, for example, from the heat pouring out from her candles. If she put her hand near the rows of candles on the desk now, she'd feel their heat wherever her hand was. Heat spreads slowly, and it's impossible to control its direction. But light, she knew, could be aimed far more easily. Hold a curved mirror beside one of the candles, and if you blew out the others, in the neardarkened room you'd see a single beam of light shooting away from that selected candle, in something much closer to a straight line.
With that, she was ready for her great discovery. Many researchers had used prisms to scatter a beam of light into different-colored rays. They knew it came in different colors. Researchers also accepted that light was powerful enough to heat up our entire planet; everyone knew that as well. Yet she was now insisting that, in addition to all that, it was also entirely massless. That meant that it couldn't have any hidden particles inside to carry that great power. Yet if its great power couldn't be carried along by little particles, then…
Was light's great power transmitted by its different colors? This was as extraordinary an idea as anything Locke or Newton had thought up. She must have been mulling it over in some way, even if subconsciously, for a long time, but it all burst into clarity in these hurried latesummer nights. If only she could do the experiments to confirm this now! If she was correct, then perhaps those colors would also carry heat. The different colors of light might even carry different amounts of heat. But how could she check it when Voltaire was hogging all the thermometers that Moussinot sent down from Paris? And even if she did manage to spirit one away when he wasn't looking—and even if Florent-Claude was willing to help—she still wouldn't be able to do the necessary experiments on her own.
To conduct her test she'd need to pass a single beam of bright sunlight through a prism. That would produce a rainbow splay of colors on the far wall of whatever room she was doing the experiment in. The upstairs room they'd shuttered off the year before for optical research would be ideal for it. Everyone knew that light had great power, as with its ability to create heat, and what she was proposing now was that different colors of light would carry different amounts of that heating power. To test it, all she'd have to do was hang a series of thermometers on the wall, and see if in fact the different colors of light made the different thermometers heat up differently. But it all depended on a bright sunbeam, and that meant she could only do it during the day. The setup would take hours, and Voltaire would certainly find out. She realized, with disappointment, that she couldn't do it. Her idea would have to stay untested.
In the final report she wrote up—sprinting to make the September I deadline—she was reduced to suggesting that “fruitful experiments could be conducted concerning the distinctive heating power” of different-colored light. It wouldn't be till more than seventy years later, in 1800, that the famous astronomer Herschel actually carried out those experiments at his home beside the giant forty-foot-long telescope he operated in Slough, England. His procedure was almost exactly what Emilie could have followed, and he used thermometers of no greater sensitivity than Moussinot had in fact sent to Cirey. For whenever one sets up a series of thermometers side by side and lets a prism burst of light shine on them, the sun's position will gradually shift. A thermometer that had been recording the heat of the red part of the rainbow will soon be left in the dark. But its temperature doesn't go down—even though there's no light we can see shining on it. Seemingly invisible light really could carry the power to do that. What Herschel's experiments led to—following, although unknown to him, what Emilie had foreseen at Cirey—was the realization that there are more types of light beams than we can see with our naked eye.
Herschel discovered infrared light, and other investigators at about his time discovered ultraviolet light, and in time it became clear that our universe is full of a tremendous range of “lights,” only very few of which are visible to us. Photography, electromagnetic theory, and almost all of modern science and technology developed from or used that result.
Emilie was far from any of those great conclusions. But in those August weeks alone in her candlelit room after midnight, developing her reasoning in step after step, she prepared the paper that was a first, crucial step along that path. (She even put in a suggestion that there might be solar systems where suns glow with colors unknown on Earth—a further hint in the direction of Herschel a century later looking for types of light beyond anything previously known.) Voltaire sent his own paper off with a great flurry, amidst demands for proper sealing wax and envelopes, and no doubt elaborate instructions to the postal couriers. Emilie, however, had to send hers in without anyone knowing, and so probably either rode herself to the nearby town of Vassy or had her husband send it.
Then they waited for months and months as the Academy deliberated
, and Voltaire asked everyone he knew what was going on. Emilie had to pretend that although she too wanted to get an early hint, it was only for the sake of supporting Voltaire. Maupertuis was back from the Arctic now, and her husband was one of the many dignitaries who met him, but she knew that noble families understood about loyalty. “M. du Châtelet,” she proudly told Maupertuis, when it all came out the next year, “…kept my secret so well! He never said anything about it to you, did he?”
Instead, Emilie had to go through all the forms of daily life. There was a new tutor to try to find, and never-ending construction work to supervise, and the painter who insisted on putting scaffolding up in her bedroom to finish the mural on the ceiling, and the other painters, from Watteau's workshop, who wanted to put more touches on the panels beside her desk. There was the way the big mastiffs that slept outside would try to mate with the daintier house dogs that guests brought, and so she'd need to have a word with the groundsman, to keep the mastiffs tied up when the house dogs were in heat, and then a word with the guests, to placate them despite their thoughtlessness. There also was Voltaire spilling oil from the slide-projecting lanterns he liked to entertain guests with all over his hand, and needing to be succored, for the burn could—and he knew how easily this could happen!—lead to a grievous infection unless she ministered to it. It went on and on; it never ended.
“There's so much to do when you have a family, and a house to run,” Emilie wrote, “so many unimportant details and obligations, that I barely get any time to read new books. I give up at how ignorant I am. If I were a man I'd… just get rid of all the useless things of my life.”
Voltaire desperately wanted the Academy's highest acclaim, for that was the one thing that would justify his shift into science. Emilie, by contrast, knew she'd never get the top prize—“the originality of my ideas,” she wrote, “would keep me from winning, aside from the other reason [i.e., being a woman].” A few science researchers accepted her at face value, but most weren't going to let a woman try to outthink a man. It reversed all the categories of nature: men, and especially upperclass men, were supposed to take command and explore things; women were not. If by awful chance a woman were to be seen to succeed, it would upset everything. Even so, to Emilie an honorable mention would be fine: “I wanted to stand out from the crowd, and…to be taken seriously by the judges.”
Finally, in April 1738, the Academy announced its results. All submissions had been numbered, to reduce bias by the judges. By chance, Voltaire's had been logged in as number 7 when it arrived; Emilie's had been logged as number 6. Neither of them was given the top prize— anything linked to Newton's foreign and disturbingly new system was blocked by the old guard, which was still fond of the Frenchman Descartes's vague whirlpools—but both were given special commendations. “The one and the other [of those two essays],” the Academy's formal report stated, “demonstrate wide reading, and a great knowledge of the best works of physics… besides, number 6 is by a lady of high rank, Madame du Châtelet, and number seven is by one of our best poets.” (The top prize was actually divided. Part went to a minor French researcher, who merely repeated unimportant—though patriotic—pre-Newtonian work; part, though, did go to the important mathematician Leonhard Euler, who offered useful calculations on the speed of sound.)
As other researchers began to read the papers, it became clear which submission had been best. Maupertuis was becoming France's best-known scientist, after his triumphant return from the polar circle, and the Royal Society in London hung on his words. “Mr. Algarotti is leaving for London,” he wrote to James Jurin, a noted English mathematician, a bit later, “and I've given him this work to pass on to you. Its author is a young woman, of the highest merit, who's worked on science for several years now, leaving the pleasures of the city and court behind. She wrote it for the French Academy's prize—when you read it, you will find it hard to believe they gave the prize to anyone else.”
Soon there were positive mentions at the Sorbonne, and word of Emilie's fame—and how she'd had to accomplish it—began to spread. The international network of letters and research societies and important friends was in full operation. Cirey—and the model of Emilie and Voltaire's willfully independent life—became even more esteemed.
Before too long, Emilie's reputation had extended from researchers to the top salons, and then to the less esteemed salons, and finally even to provincial courts—including the one not far from Cirey in Lorraine, where one voluble future houseguest resided. Addressing her boyfriend, who was nicknamed Panpan, Madame de Graffigny wrote:
Oh my God, Panpan, I began to read the dissertation on fire that Madame wrote—the one Monsieur her husband bragged about. It is so clear! So precise! I apologize to Monsieur de Voltaire, but it's much better than his…. And when did she write this discourse? At night, because she was hiding from Voltaire!
14
New Starts
CIREY, 1738
Voltaire tried to pretend Emilie's success didn't matter. He complimented her; he laughed at the way other researchers were ranked higher than themselves simply because those researchers had followed the outdated style of Descartes, which the Academy still officially supported. He had important work to do in science, he let Emilie and Florent-Claude know: there were the page proofs for the Dutch and a possible French edition of his Newton text, astronomical observations to make, other experiments to plan. The fact that Emilie had entered against him was of no importance, he insisted: merely a mark of her lively spirit.
Underneath, though, it had undercut his self-belief. “I am curious,” he eventually wrote to a respected physics researcher, JeanJacques de Marain, “to know if I am on the right road. That is all I desire. I do not want approbation, but a decision. Am I right? Am I wrong?…If my memoir can show that I am not absolutely a stranger in Jerusalem, be kind enough to communicate it.”
But neither Marain nor other specialists he quizzed were as fully encouraging as he needed. He'd received a high commendation in the competition, but that wasn't enough. Voltaire had always found it painful admitting errors, and as the weeks went on it became clear that he'd made numerous basic mistakes in using his expensively purchased equipment. Why hadn't he known that putting a glass thermometer, even one of toughened glass, into oil at the temperature of molten metal would burst the glass? Or that even when his thermometers hadn't broken, most of his readings had been invalid from the start because he'd sometimes recorded the temperatures of his thermometers when their bulbs were submerged, but other times when part of the bulb was exposed to the cooling air?
There had also been the embarrassing paragraph where he'd suggested—and, sadly, this was in the manuscript copy now out of his hands in Paris—that he'd found an entirely new phenomenon of nature. He'd reported that when he'd aimed a big focusing lens at a compass needle, lining it up so that sunlight poured through the lens and got concentrated, the compass needle would begin to move. Did that not show that light could create magnetism? Wits at the Academy pointed out, however, that this just showed that Voltaire's focusing lens must have been mounted on a heavy iron base. When ordinary iron is banged hard enough, it becomes partially magnetized. Voltaire must have been striking the iron base of his focusing lens. That's what had deflected the needle.
He was diminished in the educated public's view, and above all in Emilie's eyes. He began to doubt whether he should be dabbling in science at all. As a result, Voltaire responded as he always did under stress. He got ill, and insisted it was serious this time; he was unable to get out of bed, and had to be very carefully tended by everyone. Then, when he was able to croak out a few words and feebly gesture for writing paper and his quills, he started having his Paris agent Moussinot buy and sell things, expensive things: substantial bond placements, and thousands of acres of real estate. It reminded him of the power he still possessed. Only then did he do what he'd always known would lastingly cure him: he began to write.
His work in literature had placed
him at the top in Europe, so a triumphant return to the arts would be the right therapy now. At first there were just little rhyming nothings to friends. Even before the Academy's results were in, one of these friends had written to suggest that Voltaire should get out of science, and return to literature, his true occupation. Voltaire replied in a little ditty:
My friend I'll do what you advise,
Your counsel seems most sound and wise;
Besides, it suits my inclination,
That I resume my occupation.
Voltaire made it clear to everyone that he was not exactly quitting science—that would have been cowardice—but rather that he was merely going to spend a little time relaxing in other fields. He began with drama, finding himself drawn toward a story where there's a noble yet cruelly misunderstood man, and a powerful woman who doesn't recognize the man's great strengths. She can't see how truly valorous he can be, but underneath he's actually a descendant of Hercules: that's how powerful he is. As he went on with the play there were twists and turns, with critical Parisian researchers, no, with critical ancient Greek warlords trying to undercut the hero and make him look even less worthy in her eyes. He slays some of them—he's really quite impressive with a sword—and maneuvers his way around most of the others, and at the end… what?
Voltaire was stumped: it was his fifth-act problem again, and writing a satisfying ending hadn't become much easier than when he'd struggled with his earlier dramatic effort to impress Emilie, writing the Inca play here at Cirey over three years before. There he'd finally found an easy way out, especially when his wishes had come true in reality: the two lovers had embraced and prepared to go off to the jungle to live in happiness forever. In this new play—called Mérope, and destined to become one of his most frequently performed works—something different was missing, but he couldn't tell what it was. He bothered his friends, to see if they could help, and when they couldn't bear continuing to try solving it for him, he put it aside. But he wasn't too disappointed, for now he was warmed up, getting back into his stride. Plays had been his strength for years, but if he was really going to show what he could do in literature, it would be more impressive if he invented yet another new form, as he had with the Letters from England.
Passionate Minds Page 15