We just need to understand how the planets in our solar system formed over the last 100 years. In the extract below from “What got into you” (HarperCollins, 2023), Dan Levitt focuses on the Soviet mathematician who spent a decade working on a problem that most astronomers had abandoned and who, when he finally solved it, was greeted with disinterest and skepticism.
More than 4.8 billion years ago, the atoms that would create us were sailing in great clouds of gas and dust, toward… well, nothing. There was no solar system, no planets, no Earth. In fact, for a long time, scientists could not explain how our solid planet, let alone one so hospitable to life, came to be. How was our now rocky planet created, as if by magic, from an ethereal cloud of gas and dust? How and when did the Earth become so welcoming to life? And what trials were our molecules forced to face until life could evolve?
Scientists would learn that our atoms could finally create life only after undergoing harrowing collisions, meltdowns, and bombardments—catastrophes that surpass any destruction humanity has ever seen.
Explaining how our planets were created seemed so difficult that by the 1950s most astronomers had given up. Their theories seemed to lead nowhere. Two centuries earlier, the German philosopher Emmanuel Kant and the French scholar Pierre-Simon Laplace had begun, quite promisingly, by correctly theorizing that gravity swirled in a huge cloud of gas and dust rotating so tightly that temperatures and fierce pressures ignited it into a star. – our sun. But how were the planets formed? They postulated that a disk of stray dust and gas was always orbiting the Sun, and that it was breaking up into smaller clouds that created the planets. However, no one has been able to convincingly explain how the disk broke up or how the planets formed from these small clouds.
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In 1917, the Englishman James Jeans adopted an inventive approach which, as we have seen, was approved by Cecilia Payne’s contemporaries. Jeans hypothesized that the gravitational pull of a passing star was so strong that it tore huge chunks of gas from the surface of the sun – and these became the planets. Others thought our planets were debris left behind by star collisions. But no one could guess how nine distant planets would have formed as a result of such a collision. It seemed as likely as if you had put wet laundry in a dryer and then opened it to find your clothes not only dry, but neatly folded. Only a few astronomers continued to take the question seriously. It was a question worthy only of “innocent entertainment” or “scandalous speculation,” observed astronomer George Wetherill. It just wasn’t clear that we could ever go that far back in time.
However, in the Soviet Union in the late 1950s, at the height of the Cold War, a young physicist decided to tackle the problem head on – with mathematics. His name was Viktor Safronov. Safronov was small and battled malaria, a legacy of his military training in Azerbaijan during World War II. He was modest, humble and exceptionally intelligent. At Moscow University he distinguished himself with advanced degrees in physics and mathematics. Recognizing his talent, the mathematician, geophysicist and polar explorer Otto Schmidt recruited him to the Soviet Academy of Sciences.
Schmidt himself, like Kant and Laplace before him, was sure that our planets were created from a disk of gas and dust orbiting the Sun. He wanted someone with the technical skills to help him figure out how, and the soft-spoken Safronov was a brilliant mathematician.
In fact, his lack of a computer may have even helped, by forcing him to sharpen his already formidable intuition.
In an office at the Academy of Sciences, Safronov started at the beginning. He took on the daunting task of trying to explain how billions and billions of gas and dust particles could build a solar system. He would try to do this with mathematics – mainly statistics and the equations of fluid dynamics, which describe the flow of gases and liquids. All this without a computer. In fact, his lack of a computer may have even helped, by forcing him to sharpen his already formidable intuition.
Safronov began by assuming that our solar system first took shape when the vast primordial cloud of dust and gas, which we left floating in space in the previous chapter, was transformed by the relentless pull of star gravity. Almost everything (99%, we know now) has become our sun. But the lingering remains were too far away to be dragged toward the sun, but not far enough to completely escape its clutches. Instead, gravity and centripetal rotational force flattened this cloud into a disk of dust and gas orbiting the sun.
Safronov, who dazzled his colleagues with his gift for making rapid mathematical estimates, set out to calculate what happened when tiny particles inside the disk collided with each other and then hit their neighbors. With pencil, paper and a slide rule, perhaps in the quiet of a library where Soviet scientists often retreated from the hubbub of large shared offices, he stubbornly attempted to estimate the effects of trillions of collisions . It was an incredibly arduous undertaking, with or without a computer. In comparison, you might think that calculating the path of a hurricane from the first water droplets that form in clouds would be child’s play.
Safronov realized that the swarm of cosmic dust and gases orbiting the sun would move at approximately the same speed and in the same direction. Sometimes, when the particles collided with their neighbors, they stuck together like snowflakes. More and more collisions gave rise to larger and larger clusters, until they became as big as rocks, ocean liners, mountain ranges, and eventually mini-planets. Drawing on his insight, Safronov single-handedly exposed most of the major problems that scientists would need to solve to explain the origin of our planets. And with mathematical bravado, he won over many.
For years he had the area of planetary formation he had created virtually to himself. Most Soviet colleagues were skeptical and indifferent; his research seemed so speculative, so far removed from any proof. Then, in 1969, Safronov published a small paperback, a retrospective of his decade of solitary work. He presented a copy to a visiting American graduate student, who passed it on to NASA with the recommendation that it be published. Three years later, an English version appeared in the West.
This would revolutionize our understanding of the creation of Earth and all planets.
Text of What’s Getting to You: The History of the Atoms in Your Body, From the Big Bang to Last Night’s Dinner. Reprinted with permission from HarperCollins Publishers.
