L’Envoi

Churchill’s expression was glorious Rodomontade, but in the end it is still nothing but rodomontade. Understanding the causes of the First World War did not help us to understand the different factors that were operating in 1939, and understanding the results of our isolationism when Hitler began strutting around did not help us avoid the opposite mistakes we made by waging “preventive” war in Vietnam and Iraq. “The past is a different country; they do things differently there,” and we learn nothing from them except that we cannot predict the future. This is true even more with science than with politics. At the end of every century, there is a spate of experts predicting what the new century will bring. But in 1900 no one predicted radio, much less television, or antibiotics or computers or MRI or CAT scans, or cyclotrons or trips to the moon, or even that man might fly. So I cannot pretend that the history written here will tell us what breakthroughs are in store for those working with the noble gases. That’s why they call it research; if you knew what the result of your experiment was going to be, there’d be no point in doing it. I thought I knew what the result of Ray Davis’s neutrino experiment was going to be, and so I thought there was no point in doing it. I was wrong, and glad to be, for it’s the surprises that drive us forward: Rutherford’s helium particles bouncing backwards, the xenon-129 peak poking up beyond where it ought to be, the argon-39 peak appearing where it oughtn’t to be at all, the electrical currents suddenly running wild through the heliumcooled mercury, et cetera and so forth and so on. What’s coming next? I have no idea and, no matter what they tell you, neither does anyone else. Which is what makes it all so exciting. Exactly fifty years after I first met the noble gases at Brookhaven in the summer of 1958, I turned off the mass spectrometer and retired.

The Neutrino Revolution

But while all this was going on, while the noble gases were being used to work out all the details of stellar processes, a different argon-based experiment was sneaking in and threatening to upset the whole applecart. I first began to learn about it way back in the fading summer of 1958, when I pulled myself up off the Westhampton sands and sauntered back to the lab, angry—in my own self-importance—that Gert Friedlander had hopped off to Europe and left me on my own. You’ll remember Ray Davis, in whose lab I was to work on the iron meteorite K/Ar problem? Well, I first met him that summer when I found Ollie Schaeffer and his mass spectrometer. In the lab next door was this courtly, soft-spoken Southern gentleman, Raymond Davis, Junior, who was putting together a most unlikely experiment and who invited me to join him in his journey into the unknown. Except that it wasn’t really unknown. It was a basic part of quantum mechanics, the theory describing the inner workings of atomic nuclei, which was put together largely during the 1920s and ‘30s—some thirty years before my sojourn at Brookhaven, and which I considered a time of ancient history, not quite real. Oh, I accepted that the 1920s had really existed, but in an intellectual way only, as a sort of existential fantasy—they had happened before I was born. (I first noticed this in others when, in the 1980s, I referred during a class lecture to the Kennedy assassination and was received with blank, uninterested stares. The students knew about it, but it had happened before they were born and had the same status as the Lincoln assassination: it was true, certainly, but basically it was a story grown-ups told.) It’s hard to realize that I’m writing this now more than twice as far removed from my Brookhaven years as those years were from the beginnings of quantum mechanics. So anyhow, it was known back then that the nuclei of atoms were held together by a binding energy which can be expressed through Einstein’s famous equation E = mc2.

The Argon Surprise

The first thing I did in Miami was to write a proposal to the National Science Foundation for a mass spectrometer, in order to test Hess’s idea of a spreading seafloor. Funding was not a problem in those halcyon and bygone days of yore. Once, I remember, Cesare came trotting down the hall calling out that it was the end of the fiscal year and the NSF was on the phone; they were calling to say they had two hundred thousand dollars left over from the budget, and did anyone want it? No one did, we all had enough money. Lordy, lordy. (Loud sigh.) And so the money for the mass spectrometer came through, but not before summer, and I was not about to spend July and August in the Miami furnace. Instead, I arranged to go up to the State University of New York at Stony Brook, where Ollie Schaeffer had become head of a new earth sciences department, to use his mass spectrometer to measure the ages on a suite of rocks brought back by one of my new friends at Miami, Enrico Bonatti, a marine geologist who had just returned from a research cruise with ocean floor samples that were perfect for testing the spreading seafloor hypothesis. He had dredged up basalts from the flanks of the East Pacific Rise and a half dozen other samples at various distances from it. So we should see young ages on the ridge rocks, and a spectrum of increasingly older ages as we moved outwards. Basalts are good material for normal potassium-argon dating, and those on the seafloor, we thought, should be even better. The basis of K/Ar dating is that you have a magma region somewhere inside the earth, with potassium continually decaying to argon. When the magma erupts, throwing out molten basaltic rocks, all the argon previously produced will bubble out and be lost to the atmosphere; as the lava cools into basaltic rocks, they will have potassium in them, but no argon, effectively setting the dating clock to zero.

Interlude: Helium, Argon, and Creationism

Henry M. Morris, widely regarded as the founder of the modern creationist movement, died February 25, 2006, at the age of eighty-seven. His 1961 book The Genesis Flood, subtitled, The Biblical Record and Its Scientific Implications, was a cornerstone of the movement. Many more books followed, including Scientific Creationism; What Is Creation Science?; Men of Science; Men of God; History of Modern Creationism; The Long War Against God; and Biblical Creationism. In 1970 he founded the Institute for Creation Research, which continues to be a leading creationist force, now headed by his sons, John and Henry III. In 1982 I debated the subject with him at the Coral Ridge Presbyterian Church in Fort Lauderdale in front of a sellout crowd of several thousand. He had emphasized in our initial contacts that the debate would be based on science, not religion, but when he opened his remarks with this same statement and the audience responded with loud cries of “Amen!” and “Praise Jesus!” I knew I was in for a long night. Both of us steered away from the biological arguments, I because I’m not a biologist and he presumably because the Biblical side of that is so evidently silly—if he had tried to describe how Noah brought two mosquitoes or two fleas aboard he might have got away with it, but the whole panoply of billions of species of submicroscopic creatures was obviously a problem. Instead he concentrated on the physical side, in particular on the age of the earth, and that was fine with me. As noted in the previous chapters, the earth’s age is central to Darwin’s argument. A strict interpretation of the Bible gives a limit of thousands of years, which is clearly not enough time for evolution to take place. Radioactive dating, on the other hand, gives Darwin his needed time span of billions of years, and so a cornerstone of the creationist argument is its necessary destruction. Morris was a wonderful motivational speaker, and spent a long introduction wandering through the Bible to show how wonderfully reasonable it is.

Helium

Today we learn at such a young age about the periodic properties of the elements and their atomic structure that it seems as if we grew up with the knowledge, and that everyone must always have known such basic, simple stuff. But till nearly the end of the nineteenth century no one even suspected that such things as the noble gases, with their filled electronic orbits, might exist. Helium was the first one we at Brookhaven looked for in our mass spectrometer, and the first one discovered. This was in 1868, but the discovery was ignored and the discoverer ridiculed. He didn’t care; he had other things on his mind. His name was Pierre Jules César Janssen, and he was a French astronomer who sailed to India that year in order to take advantage of a predicted solar eclipse. With the overwhelming brightness of the sun’s disk blocked by the moon, he hoped to observe the outer layers using the newly discovered technique of absorption spectroscopy. Nobody at the time understood why, but it had been observed that when a bright light shone through a gas, the chemical elements in the gas absorbed the light at specific wavelengths. The resulting dark lines in the emission spectrum of the light were like fingerprints, for it had been found in chemical laboratories that when an element was heated it emitted light at the same wavelengths it would absorb when light from an outside source was shined on it. So the way the technique worked, Janssen reasoned, was that he could measure the wavelengths of the solar absorbed lines and compare them with lines emitted in chemical laboratories where different elements were routinely studied, thus identifying the gases present in the sun. On August 18 of that year the moon moved properly into position, and Janssen’s spectroscope captured the dark absorption lines of the gases surrounding the sun. It was an exciting moment, as for the first time the old riddle could be answered: “Twinkle twinkle, little star, how I wonder what you are.” The answer now was clear: the sun, a typical star, was made overwhelmingly of hydrogen. But to Janssen’s surprise there was one additional and annoying line, with a wavelength of 587.49 nanometers.

K/Ar and the Irons

One day at Ithaca I had screwed my courage to the sticking point, hopped on my Honda scooter, scooted over to the Ithaca airport, and joined the East Hill Flying Club, an organization that owned a Piper Cub and a Tri-Pacer, and I learned how to fly. I had taken a few lessons at the age of fourteen, but quit when we began to do stalls and my stomach had dropped faster than the plane. Now I found that although I was still scared, I could handle it, and I progressed quickly. Probably the single most terrifying, exhilarating moment in my life was my first solo. I hadn’t yet earned my private pilot’s license, but I was able to fly by myself and was allowed, even encouraged, to take short crosscountry trips. For this—and for me—Ithaca was ideally suited. The Tri-Pacer had a four-hour range at 120 knots cruising speed, and Ithaca was well within flying range of Washington, New England, New York—and Brookhaven. I took off and was soon approaching Long Island Sound, and having second thoughts. Whenever I flew out of sight of the Ithaca airport I not only continually looked around the skies to be sure there were no other planes anywhere near me, I also kept my eyes on the ground, picking out level places where I could put the plane down if the motor in front of me ever quit. Now, approaching the Sound, it looked vast and never-ending, with Long Island nothing but a dim, dark line on the horizon. If the engine quit over that water, if I went down … I turned around, was ashamed of myself, turned back again, turned around again, took a deep breath and headed out over that endless expanse of water. Ten minutes later I was approaching Long Island. I skimmed over Port Jefferson, found the little airport that served the lab, and set her down smoothly. A cab took me to Brookhaven, I said hello to everyone, found Joe Zähringer’s notebooks, and was amazed.

The Strange Case of Helium and the Nuclear Atom

It is often taken as a matter of established fact that the difference between a good scientist and a great scientist is the ability to distinguish in advance which problems are going to be the important ones. I think this belief is a reflection of the fact that history is written by the winners: Professor X chooses a problem and with much hard work solves it, but it turns out not to have important consequences, so it and he are forgotten; Professor Y does the same, but this time the result spurs further work or even opens new and unforeseeable regions of science, so he naturally feels that his “intuition” was correct. But how do you distinguish his intuition from a lucky guess? I suggest that a study of the history of science tells us that luck plays a significant part. Consider, for example, Lord Rutherford’s discovery of the nuclear atom—perhaps the most important experimental discovery of the twentieth century, in that it led to quantum theory and the whole of nuclear physics. To set the stage: By the first few years of the twentieth century it had been determined that there were three kinds of radioactive emissions, termed alpha, beta, and gamma rays. The gamma rays were electromagnetic in nature, the beta rays were electrons, and Rutherford had just shown that the alpha rays were in fact helium; or rather, as he put it, the alpha rays were a stream of particles zipping along at roughly 10,000 miles per second which, after they slowed down and lost their electric charge, became helium atoms. (He didn’t realize at the time that they “lost” their positive electric charge by picking up negatively charged electrons.) What next? Well, the natural thing to do was to see how these radioactive emissions interacted with matter. This had already been done with the beta and gamma radiations: a stream of these radiations had been directed at various targets, and such parameters as their depth of penetration and ionizing capabilities had been measured, with no particular insights gained (an example of Professor X’s work).

The Coldest Place on Earth

Suddenly, at 7.30 P.M. on July 10, 1908, the coldest place on earth—the coldest place in the entire history of the earth—was inside a small glass tube in a messy laboratory in Groningen, the Netherlands, where the temperature was a cool 269 degrees below freezing. That’s centigrade; it would be minus 452° Fahrenheit. Inside the tube were 60 cc of liquid helium, produced for the first time in history by a Dutch physicist today virtually and unfairly unknown to the general public, Heike Kamerlingh Onnes—unfairly unknown, for unlike the results discussed in the last two chapters on MORB geochemistry, this feat of engineering physics has had profound practical consequences. The utilization of fire was the first giant leap for mankind, but its opposite, the search for cold, has been an ongoing human activity through recorded history. (Actually, there is no such thing as cold; there are only lesser amounts of heat. Absolute zero, minus 273° centigrade, is unattainable, as “explained” by a complex quantum theory argument, and there are no minus numbers on the Absolute, or Kelvin, scale.) But in practical terms, no one cared, the important thing was to get ice for food preservation through the hot summers, and until nearly a hundred years ago the only way to do that was to bring it down from the high northern latitudes or, in the in-between latitudes, to store the winter’s ice underground. By the last quarter of the nineteenth century, some progress began to be made in utilizing that marvelous insight into nature, the Second Law of Thermodynamics, to bring some sort of mechanical cooling into people’s lives. The law can be stated in various ways, but for this purpose the simplest is that heat flows from hot to cold. What could be simpler? And yet it has profound consequences. When you want a cold drink, you put in ice cubes and the heat flows from the warm scotch to the cold ice cubes, cooling down the scotch. But as the ice melts, it dilutes the scotch, which is a problem.

Argon and the Rest

The discovery of Argon is a great example of how little bitty precise measurements of stuff everyone knows sometimes lead to tremendous leaps of basic knowledge, because we don’t always know what we think we know. The story has a long and meandering lead-in, beginning with Aristotle’s idea that “air” was one of the four earthly primeval elements, an idea which lasted some two thousand years—until the eighteenth century, when an Englishman named Joseph Priestley began to fool around in his homemade laboratory next door to a brewery. Priestley by name, he was also priestly by nature. Educated as a dissenting minister, neither Church of England nor Roman Catholic, he taught and preached in a vigorously antiestablishment manner. Though he supported the American Revolution, he made no enemies in England for that, for there was as large a proportion of Englishmen as Americans who believed that the colonists were in the right. But when, a few years later, he sounded loud public hurrahs for the French Revolution, applauded the beheading of King Louis, and called for the same action against King George, he went a shout too far. Members of parliament called for action against the seditious minister, a mob broke into his home and ravaged it, and all in all he decided it might be time to sail away. He was welcomed in America, where he was honored more for his theology than his scientific work (an opinion which he shared), until his thoughts evolved to the realization that the Christ story was simply an old superstition dressed up in Hebraic dress: God—Zeus, Wotan, Jupiter, Jehovah, take your pick—impregnates a human woman and the resulting child is less godly than the godfather but more so than the human mother. Jesus was only the most recent incarnation of the tale; Pythagoras, Alexander the Great, and a whole host of others share the same superstitious glory. But trying to convince his new compatriots was a losing game; his popularity waned, and the model community he planned was never populated. Never mind. For us his importance lies in his chemical researches, which had been completed twenty years previously in Leeds.

Xenology

Xenon is unique among the Noble Gases in that it has an isotope, 129Xe, that is the fossil daughter of an extinct nuclide. Iodine-129, its precursor, decays to 129Xe with a half-life of about sixteen million years, and since the earth is four and a half billion years old (and since all the elements on earth were created in stars before the earth accreted), there is no 129I on earth today; after the first hundred million years of earth’s existence there would have been less than 2 percent left, after a billion years there would have been too little to measure, and by today we can safely say there is “none” left. But now let’s go back to the very creation of the solar system. We know that the elements that exist today were created earlier in stars and blown out into space, and somehow they accreted into the sun and planets. We know roughly how and in which types of stars the elements were created, but we still don’t know the details of their synthesis, and we know even less about their accretion into the sun and planets, and until the xenon studies we had absolutely no idea when they were created. Suppose that the creation of the elements took place billions of years before solar system formation (after all, the universe is nearly ten billion years older than we are). Then all the 129I would have decayed into xenon long before the sun and planets formed, the 129Xe would have mixed with all the other xenon isotopes, and upon its incorporation into the solid particles of the solar system the xenon would be isotopically homogeneous. The sun, the earth, the meteorites, and the planets and moons would have incorporated differing amounts of xenon, according to their mode of formation and evolution, but they would all have the same mix of xenon isotopes (with perhaps some easily recognized mass fractionation). But suppose instead that the elements were created just previous to solar system formation; that is, within a few half-lives of 129I—say, less than a hundred million years.