by Michio Kaku
In the end, the thing that got them was climate change; trilobites died out during the end-Permian mass extinction, when gigantic volcanic eruptions raised temperatures, acidified the oceans, and killed off some 90 percent of life on Earth.
By comparison, our species seems like little more than a hiccup in the steady march of geologic time. Homo sapiens has existed for just 0.06 percent of the time trilobites survived. Given the environmental crisis we’ve created, it’s unclear how much longer we’ll be around.
Back in Washington, I head over to the Smithsonian’s National Museum of Natural History, home to tens of thousands of Burgess Shale specimens. Hans Sues, the museum’s chair of paleobiology, guides me down dimly lit hallways to the Cambrian collections, where he pulls out drawer after drawer of fossils. He handles each one like it’s a relic.
The events of 500 million years ago are just the beginning of the Burgess Shale’s story, he explains. What happened after scientists uncovered them is perhaps even more profound.
It was a secretary of the Smithsonian, Charles Doolittle Walcott, who first excavated the fossil site in 1909. The extraordinary find was announced without fanfare; “A most interesting discovery of unique Cambrian fossil,” was all Walcott wrote in an initial scientific report.
Walcott spent fifteen field seasons at the shale, but he was so busy digging up fossils he didn’t have much time to decipher them. It wasn’t until decades later that scientists began to realize how unusual and diverse the Burgess Shale specimens truly were. Paleontologist Stephen Jay Gould found the fossils so strange, he believed that many of them couldn’t belong to any known animal group. In his 1989 book, Wonderful Life, he speculated that Cambrian animals were part of an exceptionally experimental period in Earth’s history. Far from being “primitive,” these creatures and their ecosystem were as complex as anything we see today. If we were to rewind the geologic clock, Gould argued, perhaps evolution would take an entirely different course. In place of humans, the world could be dominated by Hallucigenia’s many-legged descendants.
More recent research has shown that Gould’s theories weren’t quite correct, Sues says; most of the Burgess Shale specimens do fit into existing categories on an evolutionary tree. But the idea still stands that evolution is unpredictable and undirected, that humanity is a fluke outcome rather than the inevitable result of millennia of increasing complexity. “There were all these other worlds out there,” Sues says. Someday, “ours is going to be just another one of them.”
Still, a few traits have staying power. The most common type of Cambrian creatures were arthropods, or joint-legged invertebrates. This same group, which includes insects, spiders, and crustaceans, still accounts for more than 80 percent of all known animal species. There are probably millions more arthropods that remain undiscovered and unnamed.
In other words, Sues says, if the world of the Burgess Shale seems utterly alien, it’s only because we haven’t been paying enough attention to our own world.
The price of our ignorance about life’s current diversity will be a duller, poorer future, because our inattention has led us to undermine the conditions that make Earth’s extraordinary variety possible. Recent studies have found that arthropod populations, survivors of so many millions of years of tumult, are in “hyperalarming” decline in the human era. Flying insects have vanished from German nature preserves. Huge numbers of bugs have disappeared from a pristine forest in Puerto Rico. A catastrophic combination of habitat loss and climate change is transforming ecosystems faster than scientists can study them.
“We’re losing things we don’t even know about,” Sues says. “If we don’t understand this world, if we don’t appreciate how this world came into being, how can we be capable stewards of it?”
* * *
Since the moment the Burgess Shale organisms began crawling out of the mud, living things on this planet have never been stagnant. They’ve been bombarded by asteroids, numbed by ice, eclipsed by competitors, even suffocated by the products of their own metabolisms. Yet, no matter how terrible the transformation, life has always emerged—altered, yet undeterred.
The world we love, the very fact of our existence, is contingent upon that process. Change is why we are here. And change will happen again.
But at this moment, Earth’s climate is changing at a pace unmatched in the planet’s 4.6-billion-year history. The systems on which species depend are vanishing. Living things as large and charismatic as whales, as delicate as orchids, as anonymous as tiny gray lichen growing on some remote Arctic tree, are dying out at a rate approaching the scale of the biggest extinctions.
The planet is hurtling toward “the point of no return,” UN Secretary General António Guterres said last weekend at the opening of the COP 25 climate change summit. It is the last such meeting before the Paris climate agreement goes into effect, but global leaders still have not agreed on a mechanism for achieving the emissions reductions needed. The biggest source of cumulative greenhouse gases in history—the United States—refuses to cooperate on climate change mitigation at all. Meanwhile, unprecedented wildfires have burned millions of acres in Australia, Venice is underwater, hundreds of Bahamians are still missing after Hurricane Dorian devastated the island nation in August. Like the creatures of the Cambrian, humans are entering a world utterly unlike the one in which we evolved. Our species may not die out, but life as we know it cannot go on.
While the trilobites had no hand in their fate, we brought this revolution on ourselves. And we can still shape its course. We already know what must be done to avert the worst effects of warming: starting next year, global greenhouse gas emissions must fall by 7.6 percent annually, reaching zero by the middle of the century. And although the scale of such action would be unprecedented, we already know how to achieve it: put a price on carbon, replace fossil fuels with renewable energy sources, restore nature landscapes that act as carbon sinks, equip ordinary people with the tools to adapt to a transformed world. No new technologies need to be invented to meet the terms of the Paris climate agreement. All we are waiting for is the will to change.
Humans are the first species with not just the power to alter the planet on a geologic scale but also the capacity to predict the consequences. We understand the connection between our actions and each of Earth’s possible futures.
What a profound responsibility that is. What a beautiful gift.
First published in Washington Post, December 6, 2019. © 2019 The Washington Post. All rights reserved. Used under license.
ADAM MANN
Intelligent Ways to Search for Extraterrestrials
from The New Yorker
Suppose you’re a space-faring alien society. You’ve established colonies on a few planets and moons in your solar system, but your population is growing and you’re running out of space. What should you do? Your brightest engineers might suggest a radical idea: they could disassemble a Jupiter-size planet and rearrange its mass into a cloud of orbiting platforms that encircles your sun. Your population would have ample living area on or inside the platforms; meanwhile, through solar power, you’d be able to capture every joule of energy radiating from your star.
The laws of physics suggest no reason why this plan wouldn’t work; they merely require that all the energy collected be radiated out again as heat, lest the whole construction melt. This, in turn, means that your cloud of platforms should softly glow. A distant observer training a telescope on your solar system might see something like a hot, opaque screen encircling a dimmed star—a spherical entity, curiously bright at certain wavelengths.
The theoretical physicist Freeman Dyson first speculated about the existence of such structures in 1960. In the decades since, astronomers on Earth have looked repeatedly for so-called Dyson spheres, and nobody has seen one. There are different ways of interpreting this result. Jason Wright, an astrophysicist at Pennsylvania State University, told me that Dyson wrote his original paper while contemplating an abstrac
t idea—that “the fundamental limit to an energy supply that a species could have is all of the starlight in their system.” The fact that Dyson spheres haven’t been found, Wright said, doesn’t prove that aliens don’t exist. It might just mean that astronomers should start looking for evidence of less ambitious alien projects.
In 1623, Johannes Kepler wrote that, through his telescope, he had observed towns with round walls on the moon. In 1877, Giovanni Schiaparelli reported seeing what might have been massive canals on Mars. The same year that Dyson described his spheres, the astrophysicist Frank Drake started Project Ozma, an attempt to detect radio signals from aliens living around two nearby stars—the first modern experiment in the enterprise now known as the search for extraterrestrial intelligence, or SETI. Like his forebears, Drake was influenced by his times: he was born during the golden age of radio. Kepler spent his days in walled European cities; Schiaparelli witnessed a worldwide canal-building spree. Their efforts were simultaneously cosmic and provincial. It’s hard to say anything about organisms on other worlds that doesn’t reflect life on ours.
Wright, a cheerful, apple-cheeked, forty-two-year-old professor with wispy brown hair, is at the vanguard of a new movement in SETI. Its goal is the rationalization of a speculative endeavor. “We’re trying to formalize it,” he told me. “We’re trying to get a canon of papers that my peers have read and understood.” In a number of articles published over the past five years, Wright and his collaborators have tried to build frameworks and standards that could provide a more objective basis for SETI. In one paper, a table enumerates “Ten Anomalies of Transiting Megastructures That Could Distinguish Them from Planets or Stars.” In another, Wright and his co-authors show, by making a series of calculations, that “galaxy-spanning civilizations” may be easier to detect than those that remain clustered around a single star—a finding that has implications for how astronomers might search for aliens in the future. By approaching SETI in a more rigorous way, Wright hopes to make it more respectable. His aim is partially earthbound: he wants to win the search for aliens the government funding that it’s long been denied.
* * *
The last time the U.S. government appropriated funds for SETI was in 1992. That year, NASA spent $12.25 million on the search for aliens—its highest ever expenditure on such research, as part of a planned ten-year, $100 million investment. The next year, Richard Bryan, a Democratic senator from Nevada, led an initiative to kill the program. (“Millions have been spent and we have yet to bag a single little green fellow,” he said.) Bryan made it clear that attempts to revive SETI would be bad for NASA’s funding in general, and SETI advocates have relied on private donations ever since.
In the decades that followed, the scientific landscape shifted. By the early nineties, astronomers had confirmed the existence of only two planets outside our solar system. Today, they know of more than 4,000 “exoplanets,” and are discovering more all the time. Judging by their sizes and temperatures, many of these exoplanets could be capable of supporting life. The same is true within our own solar system. There is ample evidence that Mars, which was once considered a barren desert, was wet and warm in the past, and planetary scientists talk with some urgency about sending spacecraft to survey the oceans of the moons Europa, Titan, and Enceladus. The idea that simple organisms, such as bacteria, might exist on other worlds seems eminently reasonable.
The sheer size of the exoplanetary bounty has raised questions both astrobiological and statistical. Assuming that conditions are ripe for life, how often do living organisms tend to arise on a given world? How many biospheres produce creatures capable of communicating across space and time? The paucity of data on either of these questions allows equal freedom for optimists and pessimists.
In May, I met Wright at the headquarters of the SETI Institute, a private nonprofit dedicated to researching life in the universe. The Institute’s offices are situated in a cookie-cutter office park in Mountain View, California; Wright, who was in from Penn State, was working from a small office—gray walls, a laptop, a few books on a shelf—until that evening, when he would receive the Institute’s Frank Drake award, which recognizes exemplary contributions to astrobiology. At the ceremony, around 300 attendees would gather for hors d’oeuvres, beer and wine, Wright’s talk, and then dessert. The committee cited his commitment to approaching the search for extraterrestrial intelligence in “a rational and productive manner.”
Wright was born in 1977, and grew up in the suburbs outside Seattle. After reading a book about astronomy in elementary school, he became certain that he wanted to study the stars. He went to graduate school at the University of California, Berkeley—historically, a SETI hub—where his research focused on magnetic activity in stars that makes it hard to detect the planets that orbit them. One day, in the early 2000s, his adviser suggested that they might write a SETI paper together by combing through a recently released infrared map of the night sky—the product of an initiative called the Two Micron All-Sky Survey—to look for Dyson spheres. Wright performed a quick calculation, determining that the survey’s sensitivity had been too low to spot the work of extraterrestrial mega-engineers, and moved on.
Eight years later, he was listening to a talk at Penn State about the Wide-Field Infrared Survey Explorer (WISE), a space-based telescope. It occurred to him that WISE—which was sensitive enough to have recently discovered a number of unusual brown dwarfs that glow at room temperature—would be capable of detecting Dyson spheres. With a colleague, Steinn Sigurðsson, Wright applied for a grant from the John Templeton Foundation, which is known for supporting unusual research ideas, to conduct a new survey, called Glimpsing Heat from Alien Technologies. From 2012 to 2015, the project analyzed the light from about a million galaxies, in search of evidence that a spacefaring species had enclosed a significant fraction of those galaxies’ stars in Dyson-style spheres. (None had.)
In 2015, around the time the survey was winding down, Wright heard about a peculiar object that another astronomer, Tabetha Boyajian, was investigating. The object, which came to be known as Tabby’s Star, had been discovered using the exoplanet-hunting Kepler space telescope; it appeared to be surrounded by a swarm of material that caused its light to dim at irregular intervals—another possible Dyson sphere. Wright was among several astronomers interviewed for an article about Tabby’s Star, in The Atlantic. “Aliens should always be the very last hypothesis you consider,” he said, “but this looked like something you would expect an alien civilization to build.” The media coverage caused a sensation: Tabby’s Star became the subject of jokes on Saturday Night Live and The Late Show with Stephen Colbert. With Boyajian and another astronomer, Andrew Siemion, as co-investigators, Wright led an effort to scan the star for radio signals. The search found nothing there, either. (The entity’s flickering is now believed to stem from clouds of dust or a swarm of surrounding comets.)
One natural objection to the search for Dyson spheres is that it presupposes an endlessly consumptive technological teleology. To imagine that alien societies would construct such structures seems to assume that energy collection is those societies’ most important goal. Why couldn’t an intelligent civilization strive to use less energy, not more? Focusing on the sun may be similarly shortsighted; perhaps extraterrestrial power plants tap into some spectacular aspect of reality we have yet to discover.
“Energy use is the observable manifestation of technology, so it’s a very useful parameter,” Wright explained, leaning back in his chair and smiling. “My analogy is the sizes of mammals or plants. There’s no natural evolutionary tendency for all things to get bigger. Nonetheless, we have giraffes and sequoias and blue whales. Some of them are large, and those are the ones we will find.”
* * *
In April 2018, a draft of a NASA appropriations bill appeared in the House of Representatives containing an unexpected provision: it mandated that the agency spend $10 million over the next two years to
“search for technosignatures, such as radio transmissions.” The paragraph had been inserted by Lamar Smith, the Republican congressman who, from 2013 until earlier this year, chaired the House Science Committee. Smith, who is notorious among scientists for his climate denialism, has long been a fervent supporter of astronomical research. In 2017, he announced that he planned to retire; researchers at the SETI Institute considered the language to be a parting gift. To figure out how the money might best be spent, NASA, which had no extant SETI program, convened a conference of experts in Houston. Wright co-edited its final report, to which he wrote the introduction.
Michael New, NASA’s deputy associate administrator for research—he is in charge of ensuring the quality of the agency’s scientific portfolio—joined the researchers at the conference. He had been struck, he told them, that the term “technosignatures,” which had been used by Smith and others, hadn’t set off “antibodies” at the agency. The word, coined by the SETI pioneer Jill Tarter in 2006, is based on the term “biosignatures,” which refers to evidence—liquid water, atmospheric oxygen—that hints at the existence of living organisms on a planet’s surface. Technosignatures, by extension, suggest the presence of tool use or technology. An electromagnetic message, an artificial megastructure, or an alien monolith would be a technosignature. So would the low-tech damming of a planet’s waterways by a beaver-like species, if it could produce a measurable change detectable from far away. By artfully removing extraterrestrials, their communicative motives, and even their intelligence from the equation, the term makes SETI more flexible.
