We just have to deal with how the planets in our solar system have formed over the past 100 years. In the excerpt below from “what’s wrong with you” (HarperCollins, 2023), Dan Levitt looks at a Soviet mathematician who spent a decade working on a problem most astronomers had given up on, only to be met with disinterest and skepticism when he finally solved it.
More than 4.8 billion years ago, the atoms that made us floated in great clouds of gas and dust toward… well, nowhere. 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, appeared in the first place. How was our now stony planet conjured as if by magic from an ethereal cloud of gas and dust? How and when did Earth become so friendly to life? And what hardships were our molecules forced to face until life evolved?
Scientists would learn that our atoms could finally create life only after surviving massive collisions, meltdowns, and bombardments—catastrophes that would claim any destruction humanity has ever seen.
Explaining how our planets were formed seemed so difficult that by the 1950s most astronomers had given up. Their theories seemed to lead nowhere. Two centuries ago, the German philosopher Immanuel Kant and the French scholar Pierre-Simon Laplace began, promisingly enough, with the correct theory that gravity coiled a massive rotating cloud of gas and dust so tightly that the wild temperature and pressures ignited it into a star. — our sun. But how did the planets form? They hypothesized that a disk of stray dust and gas was still spinning around the Sun, and this broke up into smaller clouds that formed the planets. However, no one has been able to convincingly explain how the disk broke up or how planets formed from these smaller clouds.
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In 1917 the Englishman James Jeans took an inventive new approach which, as we have seen, was supported by Cecilia Payne’s contemporaries. Jeans believed that the gravitational pull of the passing star was so strong that it ripped massive chunks of gas from the sun’s surface—and these became planets. Others thought our planets were debris left behind by star collisions. But how nine distant planets formed from such a collision was anyone’s guess. It seemed as likely as putting wet laundry in the dryer and then opening it to find the clothes not only dry but neatly folded. Only a few astronomers continued to take the question seriously. It was a matter fit only for “innocent amusement” or “outrageous speculation”, noted astronomer George Wetherill. It was simply not clear that we could ever see 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 in stature and battled malaria, a legacy of his military training in Azerbaijan during World War II. He was humble, unassuming and extraordinarily clever. At Moscow University, he earned advanced degrees in physics and mathematics. Mathematician, geophysicist and polar explorer Otto Schmidt recognized his talent and recruited him to the Soviet Academy of Sciences.
Schmidt himself, like Kant and Laplace before him, was certain that our planets were formed from a disk of gas and dust orbiting the Sun. He wanted someone with technical skills to help him figure out how, and the soft-spoken Safronov was a brilliant mathematician.
In fact, he may have been helped by the absence of a computer, forcing him to sharpen his already formidable intuition.
In the office of the Academy of Sciences, Safronov started from scratch. He took on the daunting task of trying to explain how trillions and trillions of particles of gas and dust could build the solar system. He would try to do this with mathematics — primarily statistics and the fluid dynamics equations that describe the flow of gases and liquids. All this without computers. In fact, he may have been helped by the absence of a computer, forcing him to sharpen his already formidable intuition.
Safronov began by hypothesizing that our solar system first formed when the huge primordial cloud of dust and gas we left floating in space in the previous chapter was transformed into a star by the inexorable gravity. Almost all (99%, we now know) became our sun. But the lingering remnants were too far to be drawn to the sun, yet not far enough to escape its clutches entirely. Instead, gravity and the centrifugal force of rotation flattened this cloud into a disk of dust and gases orbiting the Sun.
Safronov, who had dazzled his colleagues with his knack for quick mathematical guesses, set about calculating what happened when tiny particles in the disk bumped into each other and then hit their neighbors. With pencil, paper and a logarithmic ruler, perhaps in the quiet of a library where Soviet scientists often retreated from the bustle of large communal offices, he frantically tried to estimate the effects of trillions upon trillions of collisions. It was an incredibly daunting endeavor, with or without a computer. By comparison, one would think that calculating a hurricane’s path from the initial water droplets forming in the clouds would be child’s play.
Safronov realized that a swarm of cosmic dust and gas orbiting the Sun would move at roughly the same speed and direction. Sometimes, when the particles collided with their neighbors, they stuck together like snowflakes. Further collisions spawned larger and larger clumps until they were as large as boulders, ocean liners, mountain ranges, and eventually mini-planets. Based on his findings, Safronov single-handedly outlined most of the major problems that scientists would have to solve in order to explain the origin of our planets. And with mathematical bravado he conquered many of them.
For years, he had the planetary formation field he created practically to himself. Most Soviet colleagues were skeptical and disinterested; his research seemed so speculative, so far from any proof. In 1969, Safronov published a slim paperback, a retrospective of his decades of solitary work. He gave a copy to a visiting American graduate student, who gave it to NASA with a recommendation that it be published. Three years later, the English version appeared in the West.
It would change our understanding of how the Earth and all the planets were created.
Text from What’s Gotten Into You: The Story of Your Body’s Atoms, From the Big Bang to Last Night’s Dinner. Reprinted by permission of HarperCollins Publishers.
