Almost a hundred years ago, physicists theorized out what free fall should do to a quantum wave. If the solution they came up with is wrong, quantum mechanics and Einstein's theory of gravity flatly contradict each other. But testing it has been impossible because nobody has managed to build an interferometer that could perform the necessary measurement.

Now, a team led by Ron Folman, a physicist at Ben-Gurion University of the Negev, with collaborators in Germany, the UK, and the US, including Nobel laureate Roger Penrose, has done it. They built a new interferometer that gives a single atom two possible paths at once: one that involves a free fall, and another where it is held perfectly still. Both paths end at the same place at the same moment, allowing the team to measure what the fall does to a wave-like property of the atom.

Long time coming

Ever since Galileo, physicists have known how to describe a falling object—where it is, how fast it goes, or how quickly it accelerates. Quantum mechanics, though, insists that every object is also a wave. “Every particle, doesn't matter if it's a car or a spaceship or an atom, is a wave,” Folman says. “Everything that is a wave, like sea waves or sound waves, goes up and down. And if you're up or down, this is measured by something called a phase. A phase just tells you if you are at the top of the wave or at the bottom.”

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The standard explanation for why rain causes corrosion is that water carries dissolved salts and acids to a surface, constant drumming of raindrops abrades whatever protective coating is on it, and oxygen does the rest. Nearly all our tools to prevent this—paints, polymer films, or oxide layers—are built around this idea. But we’ve apparently been missing something important about the rain.

A new study led by Zhongyuan Ni, Rüdiger Berger, and Hans-Jürgen Butt at the Max Planck Institute for Polymer Research in Mainz, Germany, has shown that water drops routinely arrive at a surface carrying an electrical charge large enough to punch through an insulating coating. Not scratch it. Not slowly dissolve it. Electrically blow a hole in it, the way a spark jumps a gap.

Charged rain

The starting point of the study is a phenomenon called "slide electrification," which has only been properly quantified in the past few years. When a water drop slides across an insulating surface like a leaf, a painted wall, a windowpane, or a plastic panel, it strips charge from that surface and leaves an opposing charge behind. The voltages involved are not trivial. Drops charged this way have been measured at up to 9,000 volts.

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Every few years, El Niño or its cool counterpart, La Niña, shifts rainfall across the tropics, dries out Australia, floods parts of Peru, and rearranges the weather on most of the planet. The two are the warm and cold swings of a single system, the El Niño–Southern Oscillation, or ENSO, and that system is the largest source of year-to-year climate variation on Earth. Its swings sit atop the steadily rising temperatures driven by global warming.

But we didn't know whether global warming was making it stronger. It’s possible that the added energy in the atmosphere and oceans was causing its swings to be more dramatic.

“We've been seeing some very strong El Niño events in the late 20th and early 21st century, and what we didn't know was how unusual those are,” said Julie Cole, an environmental scientist at the University of Michigan. Because models disagree with one another and the instrumental data are too short to separate a trend, Cole’s team reconstructed a thousand-year-long ocean surface temperature record by analyzing fossilized Galápagos corals.

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Mount Toba was the biggest volcanic eruption in the last 2.6 million years, and some have suggested it nearly wiped out humanity. Around 74,000 years ago, a caldera on what is now Sumatra emptied thousands of cubic kilometers of magma in about two weeks, roughly a thousand times more than Mount Pinatubo spewed out in 1991. “People thought it might have caused massive cooling of the planet, and hence threatened the survival of our ancestors,” says Jinheum Park, a geoscientist at Johannes Gutenberg University in Mainz, Germany.

Park and his colleagues went looking for the records of that catastrophe in the mud taken from the bottom of a small crater lake on the Kenya-Tanzania border. They found instead that the effects of the Mount Toba eruption lasted under two years and amounted to perhaps half a degree of cooling.

Muddy calendars

Volcanic eruptions inject sulfur dioxide into the stratosphere, where it becomes a haze of tiny droplets that reflect sunlight back into space. Bigger eruptions eject more sulfur dioxide and, in principle, cause more cooling. But this trend stops working when the eruption exceeds a certain magnitude. “Bigger sulfate aerosols settle quickly, because they are heavier,” Park explains. This quick settling makes them less effective in scattering incoming solar radiation.

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Mount Toba was the biggest volcanic eruption in the last 2.6 million years, and some have suggested it nearly wiped out humanity. Around 74,000 years ago, a caldera on what is now Sumatra emptied thousands of cubic kilometers of magma in about two weeks, roughly a thousand times more than Mount Pinatubo spewed out in 1991. “People thought it might have caused massive cooling of the planet, and hence threatened the survival of our ancestors,” says Jinheum Park, a geoscientist at Johannes Gutenberg University in Mainz, Germany.

Park and his colleagues went looking for the records of that catastrophe in the mud taken from the bottom of a small crater lake on the Kenya-Tanzania border. They found instead that the effects of the Mount Toba eruption lasted under two years and amounted to perhaps half a degree of cooling.

Muddy calendars

Volcanic eruptions inject sulfur dioxide into the stratosphere, where it becomes a haze of tiny droplets that reflect sunlight back into space. Bigger eruptions eject more sulfur dioxide and, in principle, cause more cooling. But this trend stops working when the eruption exceeds a certain magnitude. “Bigger sulfate aerosols settle quickly, because they are heavier,” Park explains. This quick settling makes them less effective in scattering incoming solar radiation.

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Wherever two fluids slide past each other at different speeds, the boundary between them buckles, then curls, then rolls up into vortexes. It’s called the Kelvin-Helmholtz instability, and the physics behind it was worked out in the late 1860s. We know this instability explains why wind causes ripples on the surface of water and clouds shear into a row of curves.

For decades scientists argued the same thing must be happening with plasma on the surface of the Sun, and yet nobody had been able to confirm it. Now, a team led by David Kuridze and Friedrich Wöger of the National Solar Observatory reports that Kelvin-Helmholtz instabilities are not just visible on the Sun, but they’re ubiquitous. Their new study proposes that this may change the way we think about how heat, mass, and magnetic energy move through the Sun's atmosphere.

Telescope’s test drive

The reason plasma whirlpools on the Sun stayed hidden for so long is rather trivial: They are very small. Their scale sits below what telescopes with mirrors smaller than 2 meters can resolve. For most of the history of solar physics, that has ruled out every telescope on Earth. This changed when the US National Science Foundation opened the Daniel K. Inouye Solar Telescope, a 4-meter instrument in Hawaii and the largest solar telescope in the world. The telescope entered its operational phase back in November 2021.

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Wherever two fluids slide past each other at different speeds, the boundary between them buckles, then curls, then rolls up into vortexes. It’s called the Kelvin-Helmholtz instability, and the physics behind it was worked out in the late 1860s. We know this instability explains why wind causes ripples on the surface of water and clouds shear into a row of curves.

For decades scientists argued the same thing must be happening with plasma on the surface of the Sun, and yet nobody had been able to confirm it. Now, a team led by David Kuridze and Friedrich Wöger of the National Solar Observatory reports that Kelvin-Helmholtz instabilities are not just visible on the Sun, but they’re ubiquitous. Their new study proposes that this may change the way we think about how heat, mass, and magnetic energy move through the Sun's atmosphere.

Telescope’s test drive

The reason plasma whirlpools on the Sun stayed hidden for so long is rather trivial: They are very small. Their scale sits below what telescopes with mirrors smaller than 2 meters can resolve. For most of the history of solar physics, that has ruled out every telescope on Earth. This changed when the US National Science Foundation opened the Daniel K. Inouye Solar Telescope, a 4-meter instrument in Hawaii and the largest solar telescope in the world. The telescope entered its operational phase back in November 2021.

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A fruit fly hunting a piece of rotting fruit or a mate navigates by smell, following plumes of odor. Out in the wild, turbulent air swirls these plumes into a chaotic, broken landscape—dense chemical filaments laced through long stretches of clean air. A fly trying to find the source gets the smell in stutters, from constantly shifting directions, with no guarantee that a next whiff is coming at all.

Scientist had little idea of how fruit flies manage this chaotic signal with a brain the size of a pinhead. For a long time, biologists stood by the “surge and cast” model, which posited that insects solved this with hardwired reflexes. The idea was that, when a fly registers the plume with olfactory neurons in its antennae, it simply flies upwind until it’s gone and then flies side to side attempting to catch it again. But now a team led by Vanessa Ruta, a neuroscientist at the Rockefeller University, has shown that fruit flies do something far more advanced.

A treadmill for flies

The trouble with the traditional surge and cast model is that it struggles to explain how an insect tracks a meandering plume across long distances. Chemical cues floating in the air in the natural environment are often sparse and unreliable. But those same features make the mechanism behind olfactory navigation notoriously difficult to test. "Odors are invisible," Ruta says, "and often they're carried along by turbulent airflow." We’ve got no way of knowing what the animal is smelling from one moment to the next.

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A fruit fly hunting a piece of rotting fruit or a mate navigates by smell, following plumes of odor. Out in the wild, turbulent air swirls these plumes into a chaotic, broken landscape—dense chemical filaments laced through long stretches of clean air. A fly trying to find the source gets the smell in stutters, from constantly shifting directions, with no guarantee that a next whiff is coming at all.

Scientist had little idea of how fruit flies manage this chaotic signal with a brain the size of a pinhead. For a long time, biologists stood by the “surge and cast” model, which posited that insects solved this with hardwired reflexes. The idea was that, when a fly registers the plume with olfactory neurons in its antennae, it simply flies upwind until it’s gone and then flies side to side attempting to catch it again. But now a team led by Vanessa Ruta, a neuroscientist at the Rockefeller University, has shown that fruit flies do something far more advanced.

A treadmill for flies

The trouble with the traditional surge and cast model is that it struggles to explain how an insect tracks a meandering plume across long distances. Chemical cues floating in the air in the natural environment are often sparse and unreliable. But those same features make the mechanism behind olfactory navigation notoriously difficult to test. "Odors are invisible," Ruta says, "and often they're carried along by turbulent airflow." We’ve got no way of knowing what the animal is smelling from one moment to the next.

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Human eyes don’t register the infrared portion of the light spectrum because infrared photons don't carry enough energy to trigger the signaling pathway inside our light-sensing cells. But we’ve been able to make devices that give us a visual representation of what’s happening in the infrared.

A team at the Beijing Institute of Technology, led by Xin Tang and Ge Mu, has now built a device that lets people see infrared in a new way. Instead of just translating it to visible shades of green as it’s done in standard night-vision goggles, it translates different infrared wavelengths into distinct parts of the visual spectrum, giving the eye something closer to natural vision.

Researchers achieved that by combining mercury telluride colloidal quantum dots, which absorb infrared light, and a dual-layer OLED, which converts that absorbed energy into visible color. Stacked together with the right internal wiring, they make incoming infrared radiation come out the other side as an ordinary-looking, full-color image.

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Human eyes don’t register the infrared portion of the light spectrum because infrared photons don't carry enough energy to trigger the signaling pathway inside our light-sensing cells. But we’ve been able to make devices that give us a visual representation of what’s happening in the infrared.

A team at the Beijing Institute of Technology, led by Xin Tang and Ge Mu, has now built a device that lets people see infrared in a new way. Instead of just translating it to visible shades of green as it’s done in standard night-vision goggles, it translates different infrared wavelengths into distinct parts of the visual spectrum, giving the eye something closer to natural vision.

Researchers achieved that by combining mercury telluride colloidal quantum dots, which absorb infrared light, and a dual-layer OLED, which converts that absorbed energy into visible color. Stacked together with the right internal wiring, they make incoming infrared radiation come out the other side as an ordinary-looking, full-color image.

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Naked mole rats are weird. They spend their lives almost entirely underground, are largely insensitive to some kinds of pain, can persist without oxygen for a long time, rarely develop cancer, and can live past 30 years, which is decades longer than similarly sized rodents. They are also eusocial, like ants, bees, or termites—in a colony that can hold more than a hundred animals, only one female, the queen, breeds.

We didn’t know how exactly naked mole-rat queens stop other females from breeding. For a long time, our leading hypothesis was bullying and violence, but that may be a bit impractical, given their kingdoms are vast networks of tunnels that can stretch for up to three kilometers. But now a team of Lewin Lab scientists at Max Delbrück Center for Molecular Medicine in Berlin discovered it’s actually just one part of a sophisticated olfactory signaling program.

Running on smell

"It's very clear that mole rats actually have quite big noses and smell a lot," says Gary Lewin, a neurobiologist at the Max Delbrück Center for Molecular Medicine and senior author of the study. Naked mole rats have around 1200 olfactory receptor genes, more than mice (which have roughly 1,000 of them) and way more than the few hundred in humans. They're also blind. "They have to be able to navigate and move around without vision, so smell is one of those things that’s enhanced," Lewin said.

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WD 1856 b is the only confirmed case of a planet that survived the death of a Sun-like star. It’s a Jupiter-size world orbiting a white dwarf—the burned-out remnant of a Sun-like star. Now, a team of astronomers has used the James Webb Space Telescope to take a closer look at this planet for the first time, and what they found makes an already strange system even stranger.

A feeding frenzy

WD 1856 b was an accidental discovery. Astronomers pointed the TESS observatory at a sample of roughly 2,000 white dwarfs in 2020. These stars are the remains of a Sun-like star that have already gone through a red-giant phase, leaving behind an Earth-size body that’s primarily composed of elements like carbon and oxygen. The TESS team was searching for small objects like comets or asteroids that might transit across the face of these dead stars.

What they found in the WD 1856 system was a gas giant. “As soon as they looked at it, they said, okay, that’s weird,” said Christopher O’Connor, a theoretical astrophysicist at Cornell University and co-author of the recent Nature study on WD 1856 b.

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Albert Einstein’s general theory of relativity predicts that a rotating mass like the Earth pulls the fabric of space and time around with it in a perpetual swirl. This phenomenon is known as frame dragging or the Lense-Thirring effect, after the two physicists who modeled it back in 1918. Frame dragging becomes more significant with larger masses and faster rotation, so we’ve mainly observed it around huge black holes.

Measuring how much the Earth twists spacetime as it rotates has been much more challenging because our pale blue dot of a planet is millions of times lighter than a typical black hole and rotates rather slowly.

But now, a team of astronomers led by Ignazio Ciufolini, a physicist at the Wuhan Institute of Physics and Mathematics in China, reports the most accurate measurement of the terrestrial Lense-Thirring effect to date. Their work brings our uncertainty down from a few percentage points to just 0.2 percent. And they did it with a satellite that looks like a cross between a golf ball and a disco globe.

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For decades, biologists thought that early tetrapods, ancient vertebrates that started conquering the land over 300 million years ago, developed like modern amphibians—beginning their lives as purely aquatic tadpoles and then metamorphosing into terrestrial adults. “A lot of that comes from this old ‘scala naturae’ idea that you had fish that evolved into the next stage up, which were amphibians, and then amphibians evolved into the next stage up, which were reptiles that evolved into birds and mammals,” said Jason Pardo, a research associate at the Field Museum.

We’ve never had evidence that early tetrapods had an amphibian lifestyle; we have assumed it because it made intuitive sense. “It’s easier to make the transition from water to land if you’re already making that transition as part of your life cycle,” Pardo said. But now, a new Science study that Pardo co-authored with Arjan Mann (the Field Museum's assistant curator of early tetrapods) shows our most basic assumptions about the first tetrapods that started living on land might be wrong.

Baby monsters

The researchers' study focused mainly on embolomers, an extinct group of large predators that lived roughly 300 million years ago. Embolomers looked like a cross between a crocodile and an eel, with large skulls full of sharp teeth, followed by long, eel-like bodies. It had short, stocky limbs adapted mainly for paddling in water, but also capable of powering brief, clumsy excursions on land. They are thought to be one of the first vertebrates that made a partial transition from an aquatic to a terrestrial lifestyle. These animals could reach over three meters in length, but to understand the very beginning of their life cycle, scientists focused on examining some of their centimeter-scale babies.

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For decades, biologists thought that early tetrapods, ancient vertebrates that started conquering the land over 300 million years ago, developed like modern amphibians—beginning their lives as purely aquatic tadpoles and then metamorphosing into terrestrial adults. “A lot of that comes from this old ‘scala naturae’ idea that you had fish that evolved into the next stage up, which were amphibians, and then amphibians evolved into the next stage up, which were reptiles that evolved into birds and mammals,” said Jason Pardo, a research associate at the Field Museum.

We’ve never had evidence that early tetrapods had an amphibian lifestyle; we have assumed it because it made intuitive sense. “It’s easier to make the transition from water to land if you’re already making that transition as part of your life cycle,” Pardo said. But now, a new Science study that Pardo co-authored with Arjan Mann (the Field Museum's assistant curator of early tetrapods) shows our most basic assumptions about the first tetrapods that started living on land might be wrong.

Baby monsters

The researchers' study focused mainly on embolomers, an extinct group of large predators that lived roughly 300 million years ago. Embolomers looked like a cross between a crocodile and an eel, with large skulls full of sharp teeth, followed by long, eel-like bodies. It had short, stocky limbs adapted mainly for paddling in water, but also capable of powering brief, clumsy excursions on land. They are thought to be one of the first vertebrates that made a partial transition from an aquatic to a terrestrial lifestyle. These animals could reach over three meters in length, but to understand the very beginning of their life cycle, scientists focused on examining some of their centimeter-scale babies.

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For decades, scientists have understood that plants can release volatile organic compounds—essentially airborne chemical signals—to attract the natural enemies of the things that eat them, like caterpillars. What we didn’t know was exactly how a plant translates the physical act of being eaten into a specific, predator-summoning distress signal.

“[One] thing we didn’t know is how the plant detects the caterpillar in the first place,” says Adam Steinbrenner, a biologist at the University of Washington. Now, after years of experimenting with common bean plants in the lab and in the agricultural fields of Oaxaca, Mexico, Steinbrenner’s team pinpointed a single immune receptor that orchestrates its anti-caterpillar defense system.

Drooling caterpillars

When an herbivorous insect like a caterpillar feeds on a plant, it introduces its saliva straight into the plant's damaged tissues. This saliva contains biological clues called HAMPs: herbivore-associated molecular patterns. One of the HAMPs molecules is a peptide called inceptin, and there’s an 11-amino acid fragment of inceptin named In11, as well. Both of them turn out to be a fragment of the ATP synthase found in chloroplasts—basically a piece of one of the plant’s own proteins. As the caterpillar ingests the leaf, its gut enzymes chop up the plant's cellular engines and their pieces, including In11, are regurgitated back onto the leaf’s surface, albeit at extremely small concentrations.

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Organs, arms, appendages, and other complex tissues usually decay rapidly when they’re separated from their host. Over the years, biologists have seen some success with keeping them alive outside of the body—organ transplants depend on it—but it has always required germ-free environments and nutrient-rich mediums filled with growth factors. Now, though, scientists have discovered bits of tissue removed from a species of sea cucumber called Psolus fabricii can keep on living indefinitely if they’re left in ordinary seawater.

“This is naturally occurring tissue immortality,” said Sara Jobson, a researcher at Memorial University of Newfoundland and lead author of the study. “Having tissues that survive that easily is unheard of. We’ve never seen anything like this.”

The beginning of LiPfe

Psolus fabricii is a species of sea cucumber that lives in the cold waters of the Atlantic and Arctic oceans. Its bottom side, known as a sole, is soft and ringed by a band of tube feet that it uses to grip rocks. Once on a rock, it extends soft, branching tentacles into the water to feed on suspended particles. Because these sea cucumbers inhabit harsh environments, their feet and tentacles experience high rates of injury and loss. Evolution has therefore endowed these sites with an incredibly high capacity for regeneration.

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WASP-94A b is a hot, tidally locked gas giant orbiting close to one of the stars in a binary system roughly 690 light-years away from Earth. In a new Science study, scientists led by Sagnick Mukherjee, an astrophysicist at Johns Hopkins University, used the James Webb Space Telescope to learn what the weather looks like out there.

Tidal locking means that you no longer have day- and night-side temperature differences sweeping across the planet. “We wanted to understand the atmospheres of such planets,” Mukherjee says. “Are they static or dynamic? Do they have winds? Do they have clouds?” His team found that, on WASP-94A b, it’s cloudy in the morning, but the skies are clear in the evening. The fact that we didn’t know this already means we might have gotten the chemistry of this and many other exoplanets surprisingly wrong.

Averaged atmospheres

WASP-94A b has a mass slightly below half of Jupiter but has a diameter that’s over 70 percent wider. “This means the planet has low density, and its atmosphere extends further out into space, which makes it easier to observe,” Mukherjee explains. When astronomers study atmospheres like this, they usually rely on transmission spectroscopy. By analyzing the spectrum of light filtering through the planet’s atmosphere as it crosses in front of its star, they can figure out its chemical composition.

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