Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: materials

‘Ghost tunnels’ guide sound waves in one direction while staying invisible to others

Acoustic metamaterials are a fast-evolving family of materials which manipulate sound waves in ever more advanced ways. Now, a team led by Changqing Xu at Nanjing Normal University in China has engineered an acoustic metamaterial, a “ghost tunnel”: a structure which acts as a near-perfect waveguide for sound entering through its ends, while being essentially invisible to waves incident on its sides. The results, published in Physical Review Letters, could open new avenues for manipulating sound waves in complex signal environments.

Acoustic waveguides work by confining sound within a channel, using boundaries that reflect waves back inward to keep them on track. While this can be achieved with a structure as simple as a hollow pipe, the problem is that those same reflective boundaries inevitably interact with any sound waves approaching from outside the channel.

Rather than passing through undisturbed, external waves scatter off the rigid walls: a significant drawback in technologies where multiple signal channels must coexist in close proximity without interfering with one another.

Scientists May Have Found the Key to Jupiter and Saturn’s Moon Mystery

Jupiter and Saturn, the two largest planets in our Solar System, also host the most extensive systems of moons. Jupiter is currently known to have more than 100 moons, while Saturn, along with its prominent ring system, has more than 280.

Despite these large numbers, their moon systems are very different. Jupiter has four major moons, including Ganymede, the largest moon in the Solar System. Saturn, on the other hand, is dominated by a single standout moon, Titan, which ranks as the second largest.

Because both planets are gas giants, scientists have long tried to understand why their satellite systems developed so differently. Existing theories of moon formation offer some explanations, but recent research on stellar magnetic fields suggests those ideas may need revision. One key question involves magnetic accretion and whether an inner cavity can form in Jupiter’s circumplanetary disk, the accumulation of material orbiting a planet from which satellites may form.

A Macroscopic Magnet Precesses

An isolated magnet’s intrinsic angular momentum induces gyroscopic motion, an observation that could lead to ultrasensitive magnetometers.

In 1861, physicist James Clerk Maxwell proposed that a magnet behaves to some extent like a spinning gyroscope [1], but his experiments never managed to demonstrate the effect. Since then, researchers have observed various manifestations of so-called gyromagnetism, mostly in specialized magnetic materials or with spinning magnets, but now a research team has detected signatures of gyroscopic motion corresponding to Maxwell’s original ideas [2]. The team used a microscopic magnetic sphere in a technique that, with improvements, could be employed for ultrasensitive magnetic-field detection, which could be useful for research on biological magnetism.

If you try to tilt a gyroscope spinning around a vertical axis, it will respond by tilting at 90° from the push direction, an effect that leads to precession in response to gravity—such as the slow loop executed by the axis of a spinning top. An electron in a magnetic field behaves like a gyroscope in a gravitational field because the electron has a magnetic moment, which is associated with intrinsic angular momentum, or spin. So you might expect that a material whose microscopic spins align—such as an ordinary ferromagnet—would have a macroscopic angular momentum and behave like a gyroscope.

Underwater architects: Nest-building in cichlids reveals more than hardwired instinct

We associate nests with shelter, warmth, and a safe retreat—and usually picture a bird’s nest made out of twigs, grass and feathers. Yet many other animals take advantage of such refuges, with nests being built by a diversity of species ranging from termites to great apes, which impress with their hugely varied forms and the wide array of materials used to construct them.

For fish, nest-building comes with an added challenge as they must put together their underwater nests equipped with “only” their fins. Yet fish too have developed a remarkable variety of nest-building innovations, burrowing into sandy lake beds, creating masses of floating bubbles on the water’s surface, or setting up camp in abandoned snail shells repurposed as nests—as is the case with the shell-dwelling cichlid Lamprologus ocellatus.

Endemic to Lake Tanganyika in Africa, these cichlids use empty snail shells for shelter and to raise their young. To do so, the snail shell is positioned and covered in sand in a very specific way, leaving just the opening exposed—only then does it become the perfect home.

Search for dark matter intensifies as leading detector reaches milestone

Deep underground in a Canadian mine, a refrigerator nearly 1,000 times colder than outer space has just reached its target temperature—a milestone that brings scientists one step closer to potentially detecting dark matter, the invisible material thought to make up most of the mass in the universe.

For researchers at Texas A&M University, the moment is especially meaningful. Their custom-designed detectors sit at the heart of the Super Cryogenic Dark Matter Search (SuperCDMS), and they only become sensitive enough to detect possible dark-matter interactions at these extreme temperatures. SuperCDMS is in SNOLAB, an underground research facility in a nickel mine near Sudbury, Ontario.

Scientists there are targeting “light dark matter,” a much lower-mass form of dark matter that’s even harder to detect.

Scientists turn ‘mess’ into breakthrough: Chaotic design unlocks next-generation optical devices

Researchers from the Monash University School of Physics and Astronomy have flipped a long-held assumption in optics, showing that deliberately introducing controlled disorder into ultra-thin optical devices can dramatically increase their power and versatility, without making them bigger or more complex.

Published in Nature Communications, the study reveals a new class of “disordered mosaic metasurfaces” nanostructured materials that manipulate light, capable of performing multiple optical functions simultaneously within a single device.

At the center of the breakthrough is a counterintuitive idea: instead of carefully arranging structures in perfect order, the team scattered them in a controlled, mosaic-like pattern, and found that performance didn’t degrade. In fact, it improved.

Webb Telescope spots “impossible” atmosphere on ancient super-Earth

A scorching “lava world” once thought barren may actually be wrapped in a thick, mysterious atmosphere. Astronomers have uncovered surprising evidence of a thick atmosphere surrounding TOI-561 b, a scorching, fast-orbiting rocky planet once thought too extreme to hold onto any gas. Using NASA’s James Webb Space Telescope, researchers found the planet is far cooler than expected for a bare rock, hinting at a heat-distributing atmosphere above a churning magma ocean. This strange world—where a year lasts just over 10 hours and one side is locked in eternal daylight—may even be rich in volatile materials, behaving like a “wet lava ball.”

A team of astronomers led by Carnegie has uncovered the clearest evidence yet that a rocky planet outside our Solar System has an atmosphere. Using NASA’s James Webb Space Telescope (JWST), the researchers identified signs of gas surrounding an unusual target: an ancient, extremely hot super Earth that likely has a surface covered by molten rock. The findings were published in The Astrophysical Journal Letters.

The planet, known as TOI-561 b, has about twice the mass of Earth but is dramatically different in almost every other way. It orbits extremely close to its star, at a distance just one fortieth that of Mercury from the Sun. Even though its star is slightly smaller and cooler than our Sun, the planet’s tight orbit means it completes a full year in only 10.56 hours. One side constantly faces the star, leaving it locked in permanent daylight.

Plant-inspired water membrane filters CO₂ with constant selectivity and adjustable permeance

Gas separation membranes are vital for carbon capture, biogas upgrading, and hydrogen purification, all of which require the separation of carbon dioxide from gases like nitrogen, methane and hydrogen. However, the membranes currently in use for these applications suffer from limitations like low throughput or performance under high pressure and humidity, low gas flow, instability, and reaction rate limits.

Plants may have inspired a solution to many of these issues with the way their leaves absorb CO2. In a new study, published in Nature Communications, a team of researchers tests out a plant-inspired, water-based membrane that offers highly selective and permeable gas separation that outperforms many other materials, while also providing a greener, safer, and potentially cheaper way to capture CO2 and purify gases.

Carbon nanotube fiber sensors achieve record measurement error below 0.1%

Skoltech scientists, in collaboration with colleagues from China and Iran, have taken a major step toward creating highly precise carbon nanotube fiber (CNTF)-based sensors. In a paper published in the iScience journal, the authors, for the first time, quantitatively assessed the accuracy of CNTF sensors for dual-stage, i.e., manufacturing and post-manufacturing monitoring of epoxy-based polymer nanocomposites with dispersed CNTs.

The researchers emphasize that this development paves the way for creating a cutting-edge carbon-based material for high-precision and real-time sensing applications.

Existing monitoring sensors, such as fiber optics or piezoelectric sensors, are not suitable for the dual-stage monitoring of polymer composite materials. Additionally, embedding them into the composite structure often leads to deterioration in the mechanical properties of ready-made materials, making it more vulnerable to failure.

/* */