quanta magazine – The News Desk

The Quest to Map the Inside of the Proton

14Apr

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The Quest to Map the Inside of the Proton

“How are matter and energy distributed?” asked Peter Schweitzer, a theoretical physicist at the University of Connecticut. “We don’t know.”Schweitzer has spent most of his career thinking about the gravitational side of the proton. Specifically, he’s interested in a matrix of properties of the proton called the energy-momentum tensor. “The energy-momentum tensor knows everything there is to be known about the particle,” he said.In Albert Einstein’s theory of general relativity, which casts gravitational attraction as objects following curves in space-time, the energy-momentum tensor tells space-time how to bend. It describes, for instance, the arrangement of energy (or, equivalently, mass)—the source of the lion’s share of space-time twisting. It also tracks information about how momentum...

These Rogue Worlds Upend the Theory of How Planets Form

1Jan

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These Rogue Worlds Upend the Theory of How Planets Form

“We know from direct imaging searches of young stars that very few stars have giant planets in [wide] orbits,” Bate said. “It is difficult to accept that there were many large planetary systems in Orion to disrupt.”Rogue Objects AboundAt this point, many researchers suspect there’s more than one way to make these strange in-between objects. For instance, with some fiddling, theorists might find that supernova shock waves can compress smaller gas clouds and help them to collapse into pairs of tiny stars more readily than expected. And Wang’s simulations have shown that booting giant planets in pairs is, at least in some cases, theoretically unavoidable.While many questions remain, the multitude of free-floating worlds discovered in the past two years has taught researchers two things. Firs...

The Tantalizing Mystery of the Solar System’s Hidden Oceans

25Dec

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The Tantalizing Mystery of the Solar System’s Hidden Oceans

And yet, defiantly, these alien seas remain liquid.A Mirror-Wrapped OceanScientists suspect that a handful of moons orbiting Jupiter and Saturn—and maybe even some spinning around Uranus and Neptune—harbor oceans. Hefty Ganymede and crater-scarred Callisto produce weak, Europa-like magnetic signals. Saturn’s haze-covered Titan, too, very probably has a liquid-water subsurface ocean. These “are the five that most scientists in the community feel pretty confidently about,” said Mike Sori, a planetary scientist at Purdue University.With her colleagues, Margaret Kivelson, a space physicist at UCLA, determined that a global ocean is likely hiding beneath Europa’s surface. Courtesy of Margaret KivelsonSo far, the only absolute oceanic certainty is Enceladus. “That’s a no-brainer,” said Carly Ho...

Biophysicists Uncover Powerful Symmetries in Living Tissue

10Dec

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Biophysicists Uncover Powerful Symmetries in Living Tissue

“It was pretty amazing how well the experimental data and numerical simulation matched,” Eckert said. In fact, it matched so closely that Carenza’s first response was that it must be wrong. The team jokingly worried that a peer reviewer might think they’d cheated. “It really was that beautiful,” Carenza said.The observations answer a “long-standing question about the type of order present in tissues,” said Joshua Shaevitz, a physicist at Princeton University who reviewed the paper (and did not think they’d cheated). Science often “gets murky,” he said, when data points to seemingly conflicting truths—in this case, the nested symmetries. “Then someone points out or shows that, well, those things aren’t so distinct. They’re both right.”Form, Force, and FunctionAccurately defining a liquid c...

An Invisible ‘Demon’ Lurks in an Odd Superconductor

4Dec

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An Invisible ‘Demon’ Lurks in an Odd Superconductor

A few years ago, the researchers decided to put a superconducting metal called strontium ruthenate in their crosshairs. Its structure is similar to that of a mysterious class of copper-based “cuprate” superconductors, but it can be manufactured in a more pristine way. While the team didn’t learn the secrets of the cuprates, the material responded in a way that Ali Husain, who had refined the technique as part of his doctorate, didn’t understand.Husain found that ricocheting electrons were sapped of their energy and momentum, which indicated that they were setting off energy-draining ripples in the strontium ruthenate. But the waves defied his expectations: They moved 100 times too quickly to be sound waves (which ripple through atomic nuclei) and 1,000 times too slowly to be charge waves ...

Magnetic Minerals May Have Given Life Its Molecular Asymmetry

16Oct

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Magnetic Minerals May Have Given Life Its Molecular Asymmetry

Naaman and his team discovered that chiral molecules filter electrons based on the direction of their spin. Electrons with one spin orientation will move more efficiently across a chiral molecule in one direction than the other. Electrons with the opposite spin move more freely the other way.To understand why, imagine throwing a Frisbee that glances off the wall of a hallway. If the Frisbee hits the right-hand wall, it will bounce forward only if it’s rotating clockwise; otherwise, it will bounce backward. The opposite will happen if you hit the Frisbee off the left-hand wall. Similarly, chiral molecules “scatter the electrons according to their direction of rotation,” Naaman said. He and his team named this phenomenon the chiral-induced spin selectivity (CISS) effect.Because of that scat...

How Insect Brains Melt and Rewire During Metamorphosis

1Oct

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How Insect Brains Melt and Rewire During Metamorphosis

The original version of this story appeared in Quanta Magazine.On warm summer nights, green lacewings flutter around bright lanterns in backyards and at campsites. The insects, with their veil-like wings, are easily distracted from their natural preoccupation with sipping on flower nectar, avoiding predatory bats, and reproducing. Small clutches of the eggs they lay hang from long stalks on the underside of leaves and sway like fairy lights in the wind.The dangling ensembles of eggs are beautiful but also practical: They keep the hatching larvae from immediately eating their unhatched siblings. With sickle-like jaws that pierce their prey and suck them dry, lacewing larvae are “vicious,” said James Truman, a professor emeritus of development, cell and molecular biology at the University o...

The Secret of How Cells Make ‘Dark Oxygen’ Without Light

25Sep

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The Secret of How Cells Make ‘Dark Oxygen’ Without Light

The original version of this story appeared in Quanta Magazine.Scientists have come to realize that in the soil and rocks beneath our feet there lies a vast biosphere with a global volume nearly twice that of all the world’s oceans. Little is known about these underground organisms, who represent most of the planet’s microbial mass and whose diversity may exceed that of surface-dwelling life forms. Their existence comes with a great puzzle: Researchers have often assumed that many of those subterranean realms are oxygen-deficient dead zones inhabited only by primitive microbes keeping their metabolisms at a crawl and scraping by on traces of nutrients. As those resources get depleted, it was thought, the underground environment must become lifeless with greater depth.In new research publi...

A New Proof Moves the Needle on a Sticky Geometry Problem

17Sep

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A New Proof Moves the Needle on a Sticky Geometry Problem

The original version of this story appeared in Quanta Magazine.In 1917, the Japanese mathematician Sōichi Kakeya posed what at first seemed like nothing more than a fun exercise in geometry. Lay an infinitely thin, inch-long needle on a flat surface, then rotate it so that it points in every direction in turn. What’s the smallest area the needle can sweep out?If you simply spin it around its center, you’ll get a circle. But it’s possible to move the needle in inventive ways, so that you carve out a much smaller amount of space. Mathematicians have since posed a related version of this question, called the Kakeya conjecture. In their attempts to solve it, they have uncovered surprising connections to harmonic analysis, number theory, and even physics.“Somehow, this geometry of lines pointi...

20Aug

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The Lawlessness of Large Numbers

The original version of this story appeared in Quanta Magazine.So far this year, Quanta has chronicled three major advances in Ramsey theory, the study of how to avoid creating mathematical patterns. The first result put a new cap on how big a set of integers can be without containing three evenly spaced numbers, like {2, 4, 6} or {21, 31, 41}. The second and third similarly put new bounds on the size of networks without clusters of points that are either all connected, or all isolated from each other.The proofs address what happens as the numbers involved grow infinitely large. Paradoxically, this can sometimes be easier than dealing with pesky real-world quantities.For example, consider two questions about a fraction with a really big denominator. You might ask what the decimal expansio...