The Best American Science and Nature Writing 2020

by Michio Kaku

  In the summer of 1961, Hamilton moved on to another project, but not before training her replacement. Two years after Hamilton first stepped on campus, Ellen Fetter showed up at MIT in much the same fashion: a recent graduate of Mount Holyoke with a degree in math, seeking any sort of math-related job in the Boston area, eager and able to learn. She interviewed with a woman who ran the LGP-30 in the nuclear engineering department, who recommended her to Hamilton, who hired her.

  Once Fetter arrived in Building 24, Lorenz gave her a manual and a set of programming problems to practice, and before long she was up to speed. “He carried a lot in his head,” she said. “He would come in with maybe one yellow sheet of paper, a legal piece of paper in his pocket, pull it out, and say, ‘Let’s try this.’”

  The project had progressed meanwhile. The twelve equations produced fickle weather, but even so, that weather seemed to prefer a narrow set of possibilities among all possible states, forming a mysterious cluster which Lorenz wanted to visualize. Finding that difficult, he narrowed his focus even further. From a colleague named Barry Saltzman, he borrowed just three equations that would describe an even simpler nonperiodic system, a beaker of water heated from below and cooled from above.

  Here, again, the LGP-30 chugged its way into chaos. Lorenz identified three properties of the system corresponding roughly to how fast convection was happening in the idealized beaker, how the temperature varied from side to side, and how the temperature varied from top to bottom. The computer tracked these properties moment by moment.

  The properties could also be represented as a point in space. Lorenz and Fetter plotted the motion of this point. They found that over time, the point would trace out a butterfly-shaped fractal structure now called the Lorenz attractor. The trajectory of the point—​of the system—​would never retrace its own path. And as before, two systems setting out from two minutely different starting points would soon be on totally different tracks. But just as profoundly, wherever you started the system, it would still head over to the attractor and start doing chaotic laps around it.

  The attractor and the system’s sensitivity to initial conditions would eventually be recognized as foundations of chaos theory. Both were published in the landmark 1963 paper. But for a while only meteorologists noticed the result. Meanwhile, Fetter married John Gille and moved with him when he went to Florida State University and then to Colorado. They stayed in touch with Lorenz and saw him at social events. But she didn’t realize how famous he had become.

  Still, the notion of small differences leading to drastically different outcomes stayed in the back of her mind. She remembered the seagull, flapping its wings. “I always had this image that stepping off the curb one way or the other could change the course of any field,” she said.

  Flight Checks

  After leaving Lorenz’s group, Hamilton embarked on a different path, achieving a level of fame that rivals or even exceeds that of her first coding mentor. At MIT’s Instrumentation Laboratory, starting in 1965, she headed the onboard flight software team for the Apollo project.

  Her code held up when the stakes were life and death—​even when a misflipped switch triggered alarms that interrupted the astronaut’s displays right as Apollo 11 approached the surface of the moon. Mission Control had to make a quick choice: land or abort. But trusting the software’s ability to recognize errors, prioritize important tasks, and recover, the astronauts kept going.

  Hamilton, who popularized the term “software engineering,” later led the team that wrote the software for Skylab, the first U.S. space station. She founded her own company in Cambridge in 1976, and in recent years her legacy has been celebrated again and again. She won NASA’s Exceptional Space Act Award in 2003 and received the Presidential Medal of Freedom in 2016. In 2017 she garnered arguably the greatest honor of all: a Margaret Hamilton Lego minifigure.

  Fetter, for her part, continued to program at Florida State after leaving Lorenz’s group at MIT. After a few years, she left her job to raise her children. In the 1970s, she took computer science classes at the University of Colorado, toying with the idea of returning to programming, but she eventually took a tax preparation job instead. By the 1980s, the demographics of programming had shifted. “After I sort of got put off by a couple of job interviews, I said forget it,” she said. “They went with young, techy guys.”

  Chaos only reentered her life through her daughter, Sarah. As an undergraduate at Yale in the 1980s, Sarah Gille sat in on a class about scientific programming. The case they studied? Lorenz’s discoveries on the LGP-30. Later, Sarah studied physical oceanography as a graduate student at MIT, joining the same overarching department as both Lorenz and Rothman, who had arrived a few years earlier. “One of my office mates in the general exam, the qualifying exam for doing research at MIT, was asked: How would you explain chaos theory to your mother?” she said. “I was like, whew, glad I didn’t get that question.”

  The Changing Value of Computation

  Today, chaos theory is part of the scientific repertoire. In a study published just last month, researchers concluded that no amount of improvement in data gathering or in the science of weather forecasting will allow meteorologists to produce useful forecasts that stretch more than fifteen days out. (Lorenz had suggested a similar two-week cap to weather forecasts in the mid-1960s.)

  But the many retellings of chaos’s birth say little to nothing about how Hamilton and Ellen Gille wrote the specific programs that revealed the signatures of chaos. “This is an all-too-common story in the histories of science and technology,” wrote Jennifer Light, the department head for MIT’s Science, Technology, and Society program, in an email to Quanta. To an extent, we can chalk up that omission to the tendency of storytellers to focus on solitary geniuses. But it also stems from tensions that remain unresolved today.

  First, coders in general have seen their contributions to science minimized from the beginning. “It was seen as rote,” said Mar Hicks, a historian at the Illinois Institute of Technology. “The fact that it was associated with machines actually gave it less status, rather than more.” But beyond that, and contributing to it, many programmers in this era were women.

  In addition to Hamilton and the woman who coded in MIT’s nuclear engineering department, Ellen Gille recalls a woman on an LGP-30 doing meteorology next door to Lorenz’s group. Another woman followed Gille in the job of programming for Lorenz. An analysis of official U.S. labor statistics shows that in 1960, women held 27 percent of computing and math-related jobs.

  The percentage has been stuck there for a half-century. In the mid-1980s, the fraction of women pursuing bachelor’s degrees in programming even started to decline. Experts have argued over why. One idea holds that early personal computers were marketed preferentially to boys and men. Then when kids went to college, introductory classes assumed a detailed knowledge of computers going in, which alienated young women who didn’t grow up with a machine at home. Today, women programmers describe a self-perpetuating cycle where white and Asian male managers hire people who look like all the other programmers they know. Outright harassment also remains a problem.

  Hamilton and Gille, however, still speak of Lorenz’s humility and mentorship in glowing terms. Before later chroniclers left them out, Lorenz thanked them in the literature in the same way he thanked Saltzman, who provided the equations Lorenz used to find his attractor. This was common at the time. Gille recalls that in all her scientific programming work, only once did someone include her as a co-author after she contributed computational work to a paper; she said she was “stunned” because of how unusual that was.

  Since then, the standard for giving credit has shifted. “If you went up and down the floors of this building and told the story to my colleagues, every one of them would say that if this were going on today . . . they’d be a co-author!” Rothman said. “Automatically, they’d be a co-author.”

  Computation in science has become even more indispensable, of cours
e. For recent breakthroughs like the first image of a black hole, the hard part was not figuring out which equations described the system, but how to leverage computers to understand the data.

  Today, many programmers leave science not because their role isn’t appreciated, but because coding is better compensated in industry, said Alyssa Goodman, an astronomer at Harvard University and an expert in computing and data science. “In the 1960s, there was no such thing as a data scientist, there was no such thing as Netflix or Google or whoever, that was going to suck in these people and really, really value them,” she said.

  Still, for coder-scientists in academic systems that measure success by paper citations, things haven’t changed all that much. “If you are a software developer who may never write a paper, you may be essential,” Goodman said. “But you’re not going to be counted that way.”

  SHANNON STIRONE

  The Hunt for Planet Nine

  from Longreads

  At 9,200 feet, there is 20 percent less oxygen than at sea level, enough to take all the air from my lungs after just three steps. But it didn’t stop Mike Brown and Konstantin Batygin from hastily shuffling into the lobby of Hale Pōhaku to check the weather forecast. They stared at the TV monitor, craning their necks, suitcases in one hand, fingers pointing to the screens with the other. “It’s Sunday,” Brown said, “there’s no new forecast until tomorrow. Damn.” We were at base camp on the dormant volcano Mauna Kea, on the Big Island of Hawaii. The pair were here to use one of the most powerful telescopes in the world, called Subaru. Tomorrow night, December 3, marked the start of their sixth observing run and their next attempt to find the biggest missing object in our solar system, called—​for the moment—​Planet Nine.

  The Onizuka Center for International Astronomy, located at Hale Pōhaku, looked exactly as you might imagine a Hawaiian dormitory built in the early 1980s would. Each table was covered in an azure nylon tablecloth with salt and pepper shakers. The backs of the chairs depicted scenes from around the island: Mauna Kea, palm trees, snow-capped volcanoes, sandy beaches. It was 7 p.m. when we arrived, and most everyone who lived and worked at these dorms was asleep. (In astronomers’ quarters, most people sleep during the day or wake at odd hours of the night to go to work.) The cafeteria was empty. “Oh my god, they have Pop-Tarts! They haven’t had Pop-Tarts here for ten years!” said Brown as he unwrapped the shiny foil package to put one in the toaster. This was a good sign—​Pop-Tarts are the nonsuperstitious tradition of astronomical observing—​and also dinner.

  We would have a snack and go over the game plan for tomorrow night. Brown and Batygin sat down at one of the round tables, laptops out. Brown, a professor of planetary astronomy at the California Institute of Technology in Pasadena, felt optimistic. Batygin, a theoretical astrophysicist and professor of planetary sciences at Caltech, guessed it would take them ten more years of observing. This is their dynamic. If the planet they’re looking for exists, it is likely six times the mass of Earth, with an atmosphere made of hydrogen and helium covering its rock-and-ice core. What makes it hard to find is its likely location: at least four hundred times farther away from the sun than our own planet, and fifteen to twenty times farther out than Pluto. As a theorist, Batygin feels that he’s already mathematically proven its existence. But it’s generally accepted that for a planet to be considered discovered in the field of astronomy, the theory must also be accompanied by a photograph. This is where the Subaru Telescope comes in. They know that Planet Nine is somewhere in between the constellation Orion and Taurus, but that’s about as exact as they can get, and they’ll need good weather to locate it. Right now the last predicted forecast showed fog. Even at six times the mass of Earth, Planet Nine is so far away that it would appear as a barely visible point of light, even through the lens of the most powerful telescope they could get their hands on.

  Though it was only 7 p.m. it was time to settle in for the night. We took a series of wooden bridges faintly illuminated with reddish light to the dorms. (Red light does not affect night vision.) Because of the reduced oxygen, the carry-on-size suitcase I had with me might as well have been the dead body of a weightlifter. We stopped to take a break to catch our breath, and looked up. There is hardly any light at Hale Pōhaku after sundown. An hour away from Kona or Hilo, there are no streetlights, no real building lights, no car lights, it’s just dark. What can be easy to forget for anyone that lives in or around a city is that the night sky is not black, but gray. We are drowning ourselves with so much light that we don’t realize how much light the darkness really contains. Wherever Planet Nine is—​if Planet Nine even is—​its surface is touched by the sun’s light just like our planet, and as a result some of it is illuminated. The physical particles of light that travel the billions of miles between both bodies also move through space. Their journey begins at the sun, stirring around deep inside the core for thousands of years, moving eventually to the surface where they are finally released. This newly exposed light travels out into the cosmos and to distant unknown worlds. This is why we came, we had to escape the light in order to find it.

  We stood there for a moment and as our eyes adjusted, the galaxy turned on. Clusters of stars became the entire sky. Each speck of light had traveled its own distance; traversed its path through the dark void of space, some from the time of the earliest human civilizations, light that left at the dawn of the invention of agriculture and cities, at the time this mountain was last covered in lava. Mike pointed over the hills to a hazy cone of yellow light that shot up like a triangle from the Earth, explaining it was a rare astronomical phenomenon some people wait their whole lives to see: “That is the zodiacal light. It is the sunlight reflecting off of the dust that’s floating in the asteroid belt. This is the best I’ve ever seen it. Wow.” Across the sky to the right was the arm of the Milky Way galaxy. It was as though a painter had dipped their brush in starlight and clouds and smeared it ever so carefully across the universe.

  * * *

  With dozens of astronomical discoveries to his name, fifty-three-year-old Mike Brown has the distinction of having found more dwarf planets than any other human in history. Dwarf planets are hundreds of times smaller than Earth, so detecting them when they orbit so far out is extremely tricky. (Pluto, for example, is 500 times less massive than our planet.) In 2001, Brown discovered two dwarf planets called 2001 YH140 and 2001 YJ140. Two years later, using the Palomar Observatory in the mountains outside of San Diego, he caught some light from a distant Kuiper Belt object that no one had ever seen before. It was three times farther away than Pluto, and smaller too. The object was so distant that the view of the sun from its surface could be blotted out with the tip of a pen if held at arm’s length. He named it Sedna. Then, in 2005, he found another object—​more massive but just a bit smaller than Pluto. He would later name this dwarf planet Eris after the Greek goddess of strife and discord, and oh how much strife this thing caused.

  The International Astronomical Union decided that if there were other “Pluto-size” objects out there then maybe the title “planet” was not a good one for Pluto. Brown became known as the “Pluto Killer”—​though mostly by way of his adopted Twitter handle. (Brown said he actually finds Pluto quite interesting, but only admits it under his breath so as not to ruin his bad boy reputation.)

  Years later, two astronomers, Scott Sheppard and Chad Trujillo, noticed that a dozen distant Kuiper Belt objects appeared as though they were all operating in concert in the Unknown Regions of space, sharing certain orbital characteristics. Brown was intrigued by their 2014 paper, but thought something wasn’t quite right with their hypothesis. That same year Batygin, his former student, was working down the hall. Brown asked Batygin if he wouldn’t mind looking at the data with him. Though Brown briefly wondered about the possibility of a planet, he and Batygin quickly pivoted to the idea that enough collective gravity might have put the objects in this orbit. “We tried to examine every hypothesis other than a planet and took it
very seriously,” said Batygin. “This is not like you come in one day and think a little bit about it then you’re done. It takes a lot of time. I made almost complete models for every single other hypothesis before we allowed ourselves to consider the planetary explanation. You have to rule out every other possibility first.”

  They are not the first to be puzzled by oddities in the outer solar system. Not long after the discovery of Uranus in the eighteenth century, astronomers observed that the planet’s orbit wasn’t moving at the rate that predictions said it should. The planet appeared to randomly accelerate in its orbit, then decelerate. In 1846, French astronomer Urbain Le Verrier suggested this was the result of another large planet orbiting beyond Uranus that had not yet been found. As in all astronomical observation, an image must be taken in order to consider an object discovered, and no one had ever seen a planet beyond Uranus. Not only did Le Verrier suggest a planet as the cause, he predicted what he thought to be the location. As an expert in mathematics and celestial mechanics, Le Verrier was confident in his claim, so much so that he wrote to German astronomer Johann Galle, who was working at the Berlin Observatory at the time, and told him to look at a specific point in the sky. Galle opened the letter on September 23, 1846, and right away he and his assistant, fellow astronomer Heinrich Louis d’Arrest, took to the telescope. Using Le Verrier’s coordinates along with a recently updated star chart, they were able to finally compare this moving object against the tapestry of unmoving stars—​they found Neptune less than one hour later.