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Spotting signs of life in an alien planet’s atmosphere may be tougher than scientists had thought. One prominent such “biosignature” target, ozone, may get trapped near the equators of Proxima b, TRAPPIST-1d and other potentially habitable worlds that orbit close to their host stars, making the gas hard to detect from afar, a new study suggests. “Absence of traces of ozone in future observations does not have to mean there is no oxygen at all,” study lead author Ludmila Carone, of the Max Planck Institute for Astronomy in Heidelberg, Germany, said in a statement....

Cities are almost always hotter than the surrounding rural area but global warming takes that heat and makes it worse. In the future, this combination of urbanization and climate change could raise urban temperatures to levels that threaten human health, strain energy resources, and compromise economic productivity. Summers in the U.S. have been warming since 1970. But on average across the country cities are even hotter, and have been getting hotter faster than adjacent rural areas....

In a speech given at Columbia University last December, United Nations Secretary General António Guterres said, “Humanity is waging war on nature. This is suicidal. Nature always strikes back—and it is already doing so with growing force and fury.” The triple global crises of biodiversity loss, climate change and the increasing risks of emerging pandemic diseases are all interrelated, all three reflecting the appallingly destructive toll that human activity has taken on our planet over the past two centuries....

The road to self-assembling houses and shape-shifting robots could begin with something as simple as plumbing. Today when we want to build infrastructure for moving water around a city, we take rigid pipes with fixed capacities and then bury them. And the system works well enough—until we need to increase the flow of water to an area or until a pipe breaks. Then we have to dig the whole thing up and replace it....

When the world talks climate change—as is currently under way in Durban, South Africa—the main issue is carbon dioxide emissions. CO2 is emanating from the negotiators’ mouths and the power plants and cars of their home countries—and that simple molecule is responsible for the bulk of global warming to date. But CO2 isn’t the only molecule trapping heat in the atmosphere. The warm conditions of the earth get a big boost from water vapor as well as several other culprits, some of which never existed in the atmosphere prior to human influence....

Physicist Robert Kerr uses irony to describe the first hint of trouble: “Radio quiet,” he calls it. After four years as director of the Arecibo Observatory, home to the world’s largest single-dish radio telescope, he says, he was suddenly out of the loop: contacts at both the US National Science Foundation (NSF), which owns the Arecibo Observatory, and SRI International, the contractor that runs it, stopped returning his e-mails and phone calls....

Tensions between the top Republican on the House of Representatives’ science, space, and technology (HSST) committee and the US academic research community have reached fever pitch. At issue is an inquiry spearheaded by the committee’s chairman, Lamar Smith, questioning the value of scores of research grants funded by the National Science Foundation (NSF). The Association of American Universities (AAU), which represents more than 60 leading research universities, says the congressman has highlighted 60 NSF grants as being of dubious value to US taxpayers....

New research on collective intelligence demonstrates an innovative approach to combating belief polarization. The core idea of collective intelligence is that collaboration can improve both individual and group performance, depending on characteristics of group members and on conditions that facilitate (or inhibit) the exchange of information. In a recent study, researchersfrom the University of Pennsylvania’s Annenberg School for Communication set up social networks and found that they could eliminate belief polarization between liberals and conservatives on the issue of climate change....

VIRGINIA BEACH, Va.—On a hot Tuesday morning in early September two women north of 65-years-old, clad in shorts and matching Virginia Aquarium and Marine Science Center Stranding Response Program team T-shirts, are readying a massive, white truck for about 90 kilograms of dead dolphin. They are part of a fleet of about 60 volunteers who spend their spare time retrieving the remains of ailing or dead creatures along the state’s coast....

Scientists at the European Space Agency (ESA) are debating whether to change part of the Rosetta mission in what would probably be the last attempt to find lost comet-lander Philae—but the shift would mean sacrificing long-planned science. Since its batteries ran out just days after a bumpy landing on November 12, Philae has been silent, and its exact location remains a mystery. Now ESA is considering launching what would probably be a final attempt to find it, at least during the primary mission of Philae’s parent craft, Rosetta....

Scientific American presents Nutrition Diva by Quick & Dirty Tips. Scientific American and Quick & Dirty Tips are both Macmillan companies. As I’m sure you’ve noticed, gluten-free diets have become wildly popular, even among those who do not have Celiac disease. With all the models and actresses insisting that shedding gluten keeps them thin and top tennis pros claiming that avoiding gluten improves their stamina, it’s no wonder that gluten-free has become a major diet trend....

Like many kids, Sue Smrekar dreamed that she would one day voyage into space. But instead of becoming an astronaut, she ended up as a planetary geophysicist at NASA’s Jet Propulsion Laboratory, where she worked on robotic explorers of other worlds. In some sense, her interplanetary destiny seemed preordained even before she was born: her father hails from a rural community in Pennsylvania named Venus. Fittingly, the very first mission Smrekar worked on was NASA’s Venus orbiter Magellan....

Landing is the toughest part of any trip to Mars. The planet’s atmosphere is too thin for parachutes alone to bleed off a spacecraft’s blistering entry speeds, and landing solely via retro-rockets requires more fuel than any near-future mission to Mars is likely to have. NASA uses both techniques together for most of its Mars missions, and even its high-tech Curiosity rover used a vintage 1970s parachute apparatus during its landing in 2012....

Ants: “I’m Not Dead Yet” Ants are notoriously efficient undertakers, carrying off dead nestmates before the corpses can infect the colony with their pathogens. Some researchers had hypothesized that ants detected breakdown products in decomposing bodies, but a new study undermines that theory. Entomologists from the University of California, Riverside, found that Argentine ants could detect dead nestmates before decomposition could have taken hold. More telling, the team found that living ants produce two “I’m not dead yet” chemicals, called dolichodial and iridomyrmecin....

Visual perception begins with our retinas locating the edges of objects in the world. Downstream neural mechanisms analyze those borders and use that information to fill in the insides of objects, constructing our perception of surfaces. What happens when those borders—the fundamental fabric of our visual reality—are tweaked? Our internal representation of objects fails, and our brain’s ability to accurately represent reality no longer functions. Seemingly small mistakes lead to the very distorted perceptions of an illusory world....

Indonesian dragons can breed without the benefit of masculine companionship. Last week, researchers reported in Nature that the only two sexually mature female Komodo dragons in all of Europe laid viable eggs without insemination from a male. One Komodo, named Flora, lives at the Chester Zoo in England and has never been kept with a male; yet a few months ago she laid a clutch of 11 eggs, eight of which seem to be developing normally and may hatch as soon as January....

Summer arrived early for parts of the Southwest last weekend, as a heat wave sizzled across Southern California and into neighboring states. Temperatures in downtown Los Angeles climbed into the 90s. And Phoenix broke 102 degrees Fahrenheit on Sunday, a record for daily heat on April 26. Both cities made the decision to open up cooling centers around town—air-conditioned public buildings where residents without AC can shelter from the heat. It’s a common public health service across the country during the summer....

Enamel, the tough outer covering of a tooth, is the hardest substance in the human body. It is also notoriously difficult to replicate artificially. Throughout history, dentists have repaired damaged and decayed teeth with everything from beeswax to mercury composites to modern ceramic- or resin-based materials. But they might soon have a synthetic option that is much closer to the real thing. A team of chemical and structural engineers has invented a new material that mimics enamel’s fundamental properties: It is strong and—very importantly—also slightly elastic....

Lurking deep below the surface in California and Wyoming are two hibernating volcanoes of almost unimaginable fury. Were they to go critical, they would blanket the western U.S. with many centimeters of ash in a matter of hours. Between them, they have done so at least four times in the past two million years. Similar supervolcanoes smolder underneath Indonesia and New Zealand. A supervolcano eruption packs the devastating force of a small asteroid colliding with the earth and occurs 10 times more often–making such an explosion one of the most dramatic natural catastrophes humanity should expect to undergo....

The U.S. has been roiled this year by two crises that seem on the surface to be unrelated: the coronavirus pandemic and law-enforcement killings of black Americans—the latter leading to mass protests and police violence toward protesters. Although the immediate causes of these two tragedies seem distinct, both have their roots in structural racism. The virus has killed a disproportionate number of black people (as well as other people of color), and black people are by some estimates 2....