Some 550 years ago the last of the great city-states of the Maya civilization that had flourished in the Americas for centuries met their demise. As drought and warfare tore apart the social and political fabric and the Spanish conquistadors began claiming Maya land for plantations and subjugating Maya people to work on them, many residents of storied stone cities such as Yaxchilan and Palenque fled to the countryside in search of a better life. Ultimately they founded a host of new Maya cultures. Some people, known as the Lacandon Maya, established themselves in the forests around Lake Mensabak in the southern Mexican state of Chiapas. Their descendants still live in this region today. They are the Hach Winik, “the true people” in Yucatec Mayan.
Life’s up and downs may seem as inevitable as gravity, but somehow 2020 feels worse than usual. Just as a thought experiment, what if this year actually did get so weird that it even ushered in a change in how gravity affects our material universe?
In the video Did the Universe Have to Be the Way That It Is? we examine what our universe—and more specifically, our lives—might look like with some tweaks to the physics responsible for the world as we know it.
If gravity were just a little stronger in our own three-dimensional world, the curvature of spacetime would be greater, and matter could more easily collapse in on itself. This arrangement would make stars, galaxies and planets extremely diminutive, compared with the ones in our reality. Not only would we have less space on Earth, but our sun would deplete its nuclear fuel much more rapidly—meaning that evolution, and life itself, would be greatly curtailed.
If gravity were weaker, Earth would be gigantic, and it might be oddly shaped like some asteroids—or a potato. And rather than walking on the surface of our planet, we might find ourselves, say, jumping to grab a rebound in a basketball game, only to accidentally end up in the upper atmosphere or orbiting the globe as a tiny human space station.
What if we weren’t three-dimensional at all? (Imagine people as paper cutouts.) If we lived in two dimensions, gravity would act very differently. Although we would still have the spacetime curvature noted in Einstein’s general theory of relativity, such curvature would no longer produce gravitational forces. For this sort of flattened universe, we could instead have “scalar gravity,” in which Newton’s description of gravity would have been the final word, and black holes would be relegated to science fiction.
Thankfully, even though 2020 seems topsy-turvy, we still have gravity to keep us grounded.
The Americas’ western oak woodlands are fragmented into territories that are often fiercely contested—by groups of acorn woodpeckers. In each location, generations of the birds have transformed the oaks into granaries that store thousands of acorns. They nest in groups of breeding and nonbreeding members, which cooperatively raise chicks; when one of the breeding pair in a granary-rich area dies, rival teams of nonbreeding birds sweep in from surrounding territories to fight for a chance to fill it. These internecine struggles can be deadly, involve multiple coalitions of warriors and last for days. Scientists have studied the skirmishes for more than 50 years—but they only recently discovered other woodpeckers were keenly observing the battles, too.
Sahas Barve, an avian biologist at the Smithsonian National Museum of Natural History, was the lead author of a recent study that tracked this behavior and was published in Current Biology. He and his colleagues discovered the spectator phenomenon by fitting dozens of birds with ultralight solar-powered radio trackers and monitoring their positions. “Power struggles are so chaotic that you can’t really [visually] track the movements of any one animal,” Barve says.
Biologists have seen news of a breeding opportunity travel through the woods with astonishing speed. “Because animals don’t have language, we often assume it’s harder for them to transmit information,” says Christina Riehl, an evolutionary biologist at Princeton University, who was not involved in the study. “They’re not posting about it on Facebook or talking about it in the streets.” Researchers do not yet understand how woodpeckers in surrounding territories find out about these openings, which can trigger battles within minutes.
The researchers were surprised that the combat attracted not only fighters but also birds that apparently came just to watch—sometimes from kilometers away—for up to an hour at a time. These spectators left their own granaries undefended, which suggests that the value of the intelligence they can gain about rival coalitions outweighs the risks of gathering it. “It helps you judge what you should do in a given situation,” Riehl says.
Monitoring the relationships between individuals in other groups (a trait biologists call triadic awareness) has rarely been seen among birds, according to Barve. The new observations show that the woodpeckers “have a very high-level understanding of social dynamics in their population,” he says. “It highlights how much we don’t know about how animals perceive and navigate a complicated social system.”
This month I learned that senior editor Jen Schwartz is an evil genius at media manipulation. She produced our cover package about misinformation, including a story about her own role in an Election Day drill in which she demonstrated how easily bad actors can disrupt honest news coverage. It’s funny and chilling and a little too real for comfort, and I’m more grateful than ever that she is working for the side of truth and reality rather than disinformation.
Misinformation is one of the hottest areas of research right now—unfortunately because there’s just so much to study. With the pandemic, election season, trolls who weaponize confusion and the massive influence of social media platforms, conspiracy theories and quackery are spreading more quickly and widely than ever. We hope that understanding the science of misinformation will help us all tell sense from nonsense and find the best ways to resist and debunk dangerous myths.
During the pandemic shutdown, lots of people are discovering the joy of watching birds. Senior editor Kate Wong was inspired by the goldfinches at her feeder to look into how birds evolved such spectacular diversity. As a longtime birder, I’m delighted to see this hobby becoming more popular. It’s now hawk migration season, so when you’re outdoors, look up, and you might see raptors heading south in a hurry.
You might not expect a story about space war to be … charming? And amusing? Satellites fighting satellites is a serious issue, and science writer Ann Finkbeiner is a serious person, but she also knows how to bring out the absurdity of a situation and get experts to tell us what they really think. Enjoy an amazing graphic within.
Rocket science may be challenging, but brain science is immeasurably more complicated. Journalist Diana Kwon offers a possible explanation for how psychological trauma can cause neurological symptoms in a feedback loop that scientists are just starting to piece together. The mysterious condition is called functional neurological disorder.
At a time when every conversation eventually turns to the pandemic, it’s hard to imagine that we will ever forget it. But collective memory for the catastrophic influenza of 1918–1919, which killed 50 million to 100 million people, was shockingly fleeting. The story is by Scott Hershberger, a summer writing fellow who worked with us through a program from the American Association for the Advancement of Science.
Plenty of other plagues have shaped history, and researchers around the world are extracting pathogens’ genetic material from their victims to show which diseases caused the worst mass deaths and how the germs spread around the world. The article by science writer James P. Close begins here. We hope that looking at the history of past plagues can help us understand the COVID-19 pandemic, which will only be ended with science, public health measures and a shared interpretation of reality.
We got more attention than we expected for our editorial in last month’s issue endorsing Joe Biden for president. More than 1,000 publications covered the endorsement, and the response was overwhelmingly positive (whew). Thanks very much to everyone who sent supportive messages, including some people who disagree with the decision but respect us for feeling a responsibility to speak up. We hope those who are disappointed in the endorsement will stick with us for everything else we have in common: a desire to understand the world, share knowledge and discoveries, and show that reality is more rich and fascinating than misinformation.
The first 2020 presidential debate did not go well for Donald Trump. Viewers were turned off by the president’s constant hectoring of Joe Biden. And many were alarmed when he not only declined to denounce white supremacists but went so far as to tell a far-right neofascist group to “stand by.” Polling by FiveThirtyEight revealed that 50 percent of people who watched the event rated Trump’s performance as “very poor.”
But while Biden clearly won the debate, this does not mean he will win the election. Studies indicate that televised presidential debates have very little, if any, impact on votes. For a variety of reasons, this observation is especially true in 2020.
“People aren’t really watching debates because they’re like, ‘I’m gonna take this time and really compare these two candidates on their merits,’” says Yanna Krupnikov, a political scientist at Stony Brook University. Most people watching have already chosen their candidate, she says, and even if that candidate does not perform well, “they already have a decision as to how they’re going to vote.”
For years, researchers have suspected presidential debates have a tiny to nonexistent influence on election outcomes. Most studies have focused on a single debate or election, however, limiting their ability to weed out potential confounding variables. “Some people are heralding the debate [in late September] as the one that mattered,” says Christopher Wlezien, a professor of government at the University of Texas at Austin. “But if you look at public opinion polls, it’s hard to really partition these things out.” The almost concurrent news that Trump and others in his administration contracted COVID-19 may have had a more consequential effect on people’s views of the candidate.
To cut through such noise, in 2019 Vincent Pons, an associate professor at Harvard Business School, and graduate student Caroline Le Pennec of the University of California, Berkeley, produced a working paper analyzing the influence of 56 TV debates on 31 elections in the U.S., the U.K., Germany, Canada and three other countries. The researchers’ data set included 94,000 respondents who were interviewed before and after an election to see who they planned to vote for and who they actually wound up choosing. The surveys took place in the two months leading up to an election, with a different set of individuals interviewed each day. This approach allowed the researchers to determine the percentage of people who had settled on their final choice as election day grew nearer and to test for any effect immediately before and after a debate.
Across all voting systems and election types, Pons and Le Pennec found that debates neither helped undecided voters to make up their mind nor caused those who had already made a decision to switch candidates. “I was surprised,” Pons says. “If you look at the numbers of people watching TV debates and at all the media attention around debates, you would think debates matter.”
Pons’s study is not the only one to conclude that debates do not, in fact, have an impact. Wlezien arrived at the same finding when he and Robert Erikson of Columbia University analyzed all available U.S. presidential election polls between 1952, when the first televised debate took place, and 2012. The best predictor for a candidate’s standing after a debate season, they found, is what it was before that person’s face-offs.
A variety of factors likely contribute to the ineffectiveness of presidential debates in helping individuals to decide how to vote. For starters, many of the people who take the time to watch debates are those heavily engaged in politics to begin with, Krupnikov says, so they have already committed to a particular candidate. In the U.S. especially, when an election actually takes place, candidates have been campaigning for months—giving Americans plenty of time to have already made up their mind. And even if something sensational does happen in a debate and causes a wider stir, the effects tend to be small and fade by the time of the election. “Debates are short-term events, so they have less effect on people’s choices,” Wlezien says. “These performances just get added into this giant pile of information.”
Also, unlike many other developed countries, the U.S. has only two major political parties—a dichotomy that contributes to deep ideological divides and a strong us-versus-them mentality. The two-party system likely lends weight to Pons’s finding: compared with citizens of other countries, American voters are significantly less likely to change their decision in the two months leading up to an election.
Given all of these observations, most people who watch debates do not view them to be persuaded but to “see how their candidate is going to dominate, smear or embarrass the other candidate,” says Jay Van Bavel, an associate professor of psychology and neural science at New York University. Regardless of what actually transpires in a debate, evidence also indicates that many viewers filter what they see in a way that aligns with their goals and identity. In unpublished results from a new study, Van Bavel found that, depending on which political party they belong to, people shown clips from a 2016 debate between Hillary Clinton and Trump selectively paid attention to different parts and remembered what happened differently. “When partisans tune into a debate, they often walk away with an opinion that just confirms what they believed before the debate began,” Van Bavel says.
Presidential debates for the current U.S. election are probably even more subject to these forces than usual. Political polarization is at an extreme high, and voters are already well acquainted with both candidates from their years in office. “The more knowledge you have of someone, the more crystalized your attitude about them is,” Van Bavel says. Additionally, early voting is happening at record levels. Millions of people have already cast their ballot, making the final presidential debate especially inconsequential.
“There’s something very counterintuitive about telling people that, actually, this debate probably won’t matter at all,” Van Bavel says. “The things that will matter in this election—probably more than any other—are voter turnout, voter registration and early voting.”
The search for extraterrestrial life is one of the most exciting frontiers in astronomy, and the recent detection of a potential biosignature in the atmosphere of Venus has now raised the possibility that life might exist on the nearest planet to Earth.
Absorption of light at millimeter wavelengths by phosphine molecules has been identified in the Venusian cloud deck 35 miles above ground level, where the temperature and pressure are similar to what they are in the lower atmosphere of Earth. There, microbes may reside in droplets at a density that is orders of magnitude smaller than in air on Earth; if so, they could have common ancestry to terrestrial life, given that asteroids occasionally graze the atmospheres of both planets, potentially transferring material from one to the other. Of course, conclusive evidence for Venusian life will have to await a probe that would scoop material from the Venusian clouds and search for microbes within it.
We assign special significance to finding extraterrestrial life because it would imply that we are not alone in the universe. But do our personal interests impose any obligations on the universe? In this context, my Harvard colleague Stephen Greenblatt e-mailed me recently a problem raised by Lucretius’ version of Epicureanism: “Since we are all made up out of the atoms that we share with inanimate matter, is there a particular value in life forms?” My reply as a physicist was simple: “We are complex structures of atoms, and we tend to get emotional when witnessing other complex systems. But the splendor of complex structures of LEGO does not imply that they carry anything else beyond the pieces that make them.”
The question of whether there is something beyond our physical body boils down to a straightforward line of inquiry: “Is physics a complete description of nature?” So far, based on all experimental evidence, the answer is in the affirmative.
Works of art marked by special beauty, such a Leonardo da Vinci’s Mona Lisa, which is ultimately just paint on canvas, or Michelangelo’s David, made of marble, trigger a sense of awe and an emotional reaction. But they do not imply any building blocks beyond the standard model of physics. The same is true about our most advanced creations in computer technology. We respond to artificial intelligence (AI) systems as if they had a life of their own. Our interaction with living things can be viewed as a natural extension from works of art and technology to systems with a higher level of complexity. In fact, the Turing test is all about our inability to detect the difference between an interaction with a human and a computer.
When structures are too complex for us to fully understand in detail, we assign an abstract meta-level description for their behavior that goes beyond the hardware that makes them. Software engineers at Google do not fully understand how their AI system operates but they can attribute general qualities to its response to data. What we label the “human mind” is probably a meta-level description of this sort. It has to do with the behavior of one of the most complex systems we know, a human, in response to the environment. A human is a structure of atoms, so complex that we lack the computational capacity to forecast how it will respond to particular circumstances. “Free will” is linked to the unpredictability of our crude model of humans and the limited information we have on their environment.
Our scant understanding applies to ourselves as much as it does to others. What I call “myself” is different from “someone else,” if you consider how much knowledge I have about myself and the fact that whatever happens to it matters more to me than it does to you. But just as I do not have a better understanding of my liver than I do the liver of another person, I do not understand the inner workings of my mind any better than I do the mind of others.
Given this perspective, the “mind” represents an emergent phenomenon of a complex system that we do not fully comprehend. But science is a work in progress, and it is possible that we will gain a better understanding in the future. As our knowledge improves, less of the human mind will appear mysterious, and more of its phenomenology will be associated with the physical body, in the same way that the charm of the Mona Lisa can be traced back to the specific paint marks left by da Vinci’s brush on the canvas.
Of course, this notion might be unsettling to philosophers who wish to elevate the status of what it means to be human beyond the physical reality of atoms. To that, all I can say is that reality is whatever it is, irrespective of the misconceptions that people have about it. The sun did not revolve around the Earth just because philosophers thought it did.
This perspective also carries a narrative for the end of our life. Its minimalistic interpretation of death is that it resembles the unplugging of a computer from the wall socket. The system shuts off abruptly and the hardware becomes inactive afterwards. One is left with a body that returns the atoms it borrowed for a short time from Earth. Burial resembles the disposal of the computer relic in a recycling bin, making its raw materials available for new structures to form.
Stephen replied with an insight from his brilliant book and essay on the subject. He argued: “Atomism for Lucretius was meant to be therapeutic; it was intended as a form of consolation. This notion of therapy was already in question in Lucretius’ time—Cicero asked what on earth was consoling about the prospect of returning to one’s constituent atoms—and there is something bleak, it seems to me, in your version as well. One looks for consolation elsewhere, I think […] in the wonder aroused by art; in the sheer joy of existing.”
I endorse Stephen’s bottom line. After decades of studying the physical world, I am coming around to appreciate the value of the art as consolation. With it, greater pleasure can be drawn from the way things are organized than from understanding their building blocks, especially at a time when we are stuck in advancing fundamental physics.
The 1930s and early 1940s were a good time to fish for sardines off California. Catches soared in a boom that was centered on Monterey Bay and supported the state’s flourishing economy. But the tides began to turn in 1946, and sardine catches eventually fell from an average of 234,000 tons to just 24,000 tons. The industry went belly-up.
Scientists have speculated for decades about what factors drove this infamous boom and bust, but they lacked data to test their theories. Now researchers have finally found one apparent culprit: cycles of ocean upwelling, a defining feature of the West Coast marine environment in which deep, nutrient-rich water rises to the nutrient-poor surface and replenishes the food supply there. The key that unlocked this mystery turned out to be old seaweed specimens gathered from herbaria around the U.S.
“Plants are just sitting there, recording data about the state of the ocean,” says Kyle Van Houtan, chief scientist at the Monterey Bay Aquarium and senior author of the new study, published in June in the Proceedings of the Royal Society B. “If we can access physical specimens from museums and natural history repositories, we can get information about historical ecosystems embedded in those tissues.”
Van Houtan and others had suspected upwelling played a role in sardine population trends, but scientists only started measuring the process in Monterey Bay in 1946. Historic seaweed specimens, Van Houtan realized, might fill in the blanks for earlier years—similar to the way
Not all planets orbit stars. Some are instead “free-floating” rogues adrift in interstellar space after being ejected from their home systems. For decades astronomers have sought to study such elusive outcasts, hoping to find patterns in their size and number that could reveal otherwise hidden details of how planetary systems emerge and evolve.
Of the handful known so far, most free floaters have been massive gas giants, but now researchers may have found one small enough to be rocky—smaller even than Earth. If its rogue status is confirmed, the roughly Mars-to-Earth-mass object would be the most diminutive free-floating planet ever seen. Yet finding such small worlds could soon become routine, thanks to NASA’s upcoming Nancy Grace Roman Space Telescope, set to launch in the mid-2020s.
Most planet-hunting methods rely on observing subtle changes in a star’s light to discern any orbiting companions. But free-floating worlds, of course, have no star. Instead astronomers use a quirk of Einstein’s general theory of relativity to locate these lost planets: All massive objects warp spacetime around themselves, similar to how a bowling ball stretches a rubber sheet, and can act as lenses to magnify far-distant sources. When a “lensing” foreground planet is properly aligned with a background star, it amplifies that star’s light, causing a slight brightening. This technique is known as microlensing, and astronomers first pioneered it to find black holes.
Of the approximately 100 worlds found to date by microlensing, only four have been identified as free-floating. All the rest are planets that spin around their stars on orbits that are stretched out so long that they typically elude detection through other standard planet-hunting techniques. It is possible that the newfound wee world, known as OGLE-2016-BLG-1928, could be attached to a star. But if so, its orbit would place it at least eight times as far from its stellar host as the Earth is from the sun. Confirming the planet’s likely free-floating status will require a few more years—time enough for any potential parent star, should it exist, to shift its position so that its light can be separated from that of the background star.
“It’s really a very exciting result,” says Andrew Gould, an astronomer at the Ohio State University and an author of the preprint paper describing the result. That study, which was led by Przemek Mróz of the California Institute of Technology, has been submitted to Astrophysical Journal Letters, where it is currently under review. “It’s a huge milestone to get this planet,” Gould adds.
“This is a very robust result and almost certainly a low-mass planet,” says astronomer Scott Gaudi of Ohio State, who is leading the science team working to determine the best observing strategy for NASA’s Roman telescope and was not part of the group that found the new world. “This gives us the first little peek at the likely distribution of a population of Earth-mass planets in the galaxy,” he says.
At the “Hairy Edge”
Most planets form from the gas and dust left over after a star is born. Under the leading planetary formation model, called core accretion, the gas and dust gradually and incrementally combine to form larger and larger pieces that eventually coalesce into planets. A competing theory, disk instability, instead proposes that small segments of the disk rapidly collapse to form planets, and it favors the creation of larger worlds over smaller rocky ones.
Not all planets in a family get along. Gas giants can act as bullies, flinging their smaller siblings into elongated orbits or tossing them out of their system completely. These ejected worlds may continue to fly through space on their own as free-floating planets.
The Optical Gravitational Lensing Experiment (OGLE) has been scanning the skies since 1992 for the faint stellar flickers caused by microlensing events. But the new world was not spotted until Mróz and his colleagues reviewed some of OGLE’s archival data. By combining OGLE’s results with contemporaneous observations from the Korea Microlensing Telescope Network, as well as data from the European Space Agency’s Milky Way–mapping Gaia satellite, the team was able to better estimate properties useful for gauging the putative free-floating planet’s mass, such as the distance between the world and the background star. Mróz and his colleagues ultimately pegged the world’s mass at somewhere between that of Mars and Earth—making it one of the smallest objects ever found by microlensing.
“It’s really at the hairy edge of what we can do,” Gaudi says.
Probing Planetary Formation
This discovery hints that rocky worlds are common in the space between stars. Detecting something like this at the limits of astronomers’ current capabilities suggests OGLE was either incredibly lucky or that small free-floating planets wander the Milky Way in astronomical abundance.
The discovery of a single free-floating terrestrial planet demonstrates that such objects do, in fact, exist, whereas before they were only theorized. And as more low-mass drifters are found, they can help scientists narrow down how worlds are born. Core accretion models suggest planets should form in bunches, while a star might form a single world under disk instability. Because of their isolation, single-world systems would have no planets to eject. If astronomers find very few free-floating worlds as technology improves, disk instability might gain stronger support as the dominant mode of planet formation. At the same time, finding terrestrial worlds drifting through deep space provides more support for the core accretion model. “It’s very difficult to form such low-mass planets” under disk instability says Wei Zhu, a research associate at the Canadian Institute for Theoretical Astrophysics, who was not part of the new discovery. The newfound drifter instead provides strong support for the core accretion model. “That’s a good sign,” he says.
But ejection caused by planetary interactions is not the only way to wind up with worlds flying through stars, which theorists will have to take into account in their studies. Most stars form in clusters, surrounded by their own stellar siblings, and they might be much better at sharing than planets are. Worlds in the outskirts of their system could be pulled away completely by the gravity of a passing star, either joining that other star’s collection of planets or being tossed aside into space. Some castaway worlds may even find themselves bouncing from star to star, attaching to and being stripped from one sun after another. “They’re basically Ping-Pong planets,” says Susanne Pfalzner, an astronomer at the Jülich Research Center in Germany, who was not part of Mróz’s team.
Beyond its potential implications for planet-formation models, the newfound rogue planet is already having an effect on astronomers’ plans for future missions. According to Gaudi, it strengthens the case for changing Roman’s survey strategy. The OGLE observations only utilized a single light filter, but two different filters can help to disentangle the source star more easily, making stronger measurements of the stellar properties that help determine the mass of the free-floating planet. Roman originally planned to focus most of its observations on a single filter, only occasionally switching to a second, but Gaudi says the new study is making the planning team reinvestigate whether more two-filter observations would be worth the reduction in data quality that would occur.
Regardless, current best-guess projections suggest Roman should reveal more than 200 free-floating Mars-sized planets—enough to potentially determine whether most are products of planetary interactions or of stellar encounters in clusters, Zhu says. In contrast, Gould is skeptical that Roman will detect sufficient numbers of small worlds to robustly discern between these two possibilities, but he remains sanguine about the future observatory’s transformative effects.
“Roman will find more free-floating planets at a higher rate than we are finding today,” he says. “It’s going to be a huge leap.”