The News & Observer

August 5, 2001


The history of, well, everything


By Phillip Manning

In his seminal 1962 book, "The Structure of Scientific Revolutions," Thomas Kuhn posited that science advances in fits and starts. The most important discoveries, he argued, change the paradigm in which science operates. These paradigm shifts share as much with philosophy as they do with hard science, for they make us see the world anew. But such tidal waves are rare and are usually followed by long periods of ripples or "normal science," during which scientists fill in the gaps left after the previous major advance. Jonas Salk's development of the polio vaccine, for example, saved countless lives, but it did not alter the course of science as did Isaac Newton's law of gravity and James Watson and Francis Crick's discovery of the structure of DNA.

In three engaging new books, a trio of British science writers show us how rare moments of insight sparked a revolution in our understanding of the chemical elements -- what they are and where they come from.

In "Mendeleyev's Dream: The Quest for the Elements" (St. Martin's Press, $23.95, 309 pages), Paul Strathern traces the history of how chemists discovered and classified the elements. An element is composed of atoms with the same atomic number. Hydrogen, for example, the lightest atom with one proton in its nucleus, has an atomic number of one. Helium has two protons in its nucleus and an atomic number of two, and so on. At first, Strathern notes, chemistry was stifled by the existing paradigm, the one provided by Aristotle. He said that matter was composed of four elements -- earth, air, fire and water. And who was going to argue with him? This premise proved deadly to chemistry. For almost 2,000 years alchemists tried to figure out how to combine those elements to make gold.

The science of chemistry languished until Robert Boyle -- a brilliant, fanatically religious celibate -- wrote "The Sceptical Chymist" in 1661. He gave scientists a new way of seeing the world by defining an element as any substance that could not be broken down into a simpler substance, an idea that closely coincides with today's notion of what an element is. Boyle's insight led chemists back to their labs, where they heated solids and evaporated liquids and analyzed the gases that boiled off and residues that remained behind. They isolated a flood of elements and found, ironically, that gold was one of them.

Two centuries later, chemists had identified more than 60 of the 92 naturally occurring elements. But they had no useful way of organizing them, no overriding system that would allow them to understand the elements' relationship to each other. Did the elements have any order? The question stumped the world's best chemists until the Russian scientist Dmitri Mendeleyev solved the problem in 1869. His eureka moment did not come in his lab but in his bed. "I saw in a dream," he wrote, "a table where all the elements fell into place as required." He called this arrangement The Periodic Table, a copy of which adorns virtually every chemistry classroom and textbook on the planet. By explicitly showing the relationship between the elements, Mendeleyev was able to predict the existence and properties of elements that had not yet been discovered. For example, he theorized that an undiscovered element should fall between silicon and tin on the periodic table. In 1880, a German chemist isolated a new element, which he named germanium, that had exactly the properties that Mendeleyev predicted.

The other two books address a more fundamental question about the elements: Where do they come from? The answer is simple and surprising. We -- you, me and everyone else on Earth -- are made out of stardust. This is not a figure of speech; it is literally true. Every atom on Earth, the constituents of every rock and every river, came from the stars, except perhaps for a smattering of hydrogen and helium left over from the Big Bang. John Gribbin's "Stardust" (Yale University Press, $24.95, 238 pages) and Marcus Chown's "The Magic Furnace" (Oxford University Press, $25, 232 pages) tell how scientists reached this startling conclusion.

By the 1920s, scientists were beginning to understand that our sun was made mostly of hydrogen and helium. Then, in 1928, the flamboyant Russian physicist George Gamow used the new science of quantum mechanics to make a startling discovery: He showed how hydrogen nuclei could fuse together to make other elements. Fusion, Gamow said, could happen only if the hydrogen nuclei were moving at very high speeds, as they do in the intensely hot interior of an active star. Soon afterward, physicists figured out the chain of events that power the sun's magic furnace. Hydrogen nuclei fuse together to form a helium nucleus. Some mass is lost in this process, and in accordance with Albert Einstein's famous equation, E=mc2, energy is given off as heat. When the sun has converted most of its hydrogen to helium, it will collapse and become hot enough to fuse helium. When three helium nuclei collide with sufficient force, carbon forms; and when a carbon nucleus meets a helium nucleus, oxygen is created.

So, from the hydrogen and helium produced in the Big Bang, our sun will eventually create atoms of carbon and oxygen. Then, after it has consumed all of its helium, the sun will shrink further and become a white dwarf. Before that happens, however, some of the atoms that have formed in sun's interior will be blasted into space in a final convulsion. In this stardust are the elements for a new generation of life.

But some elements are heavier than carbon and oxygen. Where do they come from? The mercury, the gold and the iron that the alchemists knew? It turns out they come from stars, too, but from ones that are much more massive than ours that end their lives differently and far more spectacularly. Because they are heavier, they release great gobs of gravitational energy when they collapse. The result is a supernova, the most spectacularly violent event in the universe. In a fraction of a second, a supernova releases 100 times as much energy as our sun will generate in its entire life. Temperatures climb to billions of degrees, and in this super hot maelstrom, nuclei of all sorts fuse together, forming every known element. Then, an explosion so powerful that one can detect it across one-third of the observable universe scatters the newly formed elements into space.

When these atoms coalesce, new stars and planets form. We are all children of the stars, made from the recycled elements created in yesterday's suns. And our understanding of the relationship between those elements and their origin has revolutionized our world -- and the way we think about the universe.

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