Enlarge / Deployment of LSPM junction box 1. (credit: IN2P3/CNRS)

In 1962, one of the world's first underwater research laboratories and human habitats was established off the coast of Marseilles, France, at a depth of 10 meters. The Conshelf 1 project consisted of a steel structure that hosted two men for a week.

Now, more than 60 years later, another underwater laboratory is being set up not far from Marseilles, this time to study both the sea and sky. Unlike the Conshelf habitat, the Laboratoire Sous-marin Provence Méditerranée (LSPM) won't be manned by humans. Located 40 km off the coast of Toulon at a depth of 2,450 meters, it is Europe’s first remotely operated underwater laboratory.

Physics under the sea

Currently, three junction boxes capable of powering several instruments and retrieving data are at the heart of LSPM. The boxes, each measuring 6 meters long and 2 meters high, are connected to a power system on land via a 42-kilometer-long electro-optical cable. The optical portion of this cable is used to collect data from the junction boxes.

On the morning of October 9, 2022, multiple space-based detectors picked up a powerful gamma-ray burst (GRB) passing through our Solar System, sending astronomers around the world scrambling to train their telescopes on that part of the sky to collect vital data on the event and its aftermath. Dubbed GRB 221009A and deemed likely to be the "birth cry" of a new black hole, the gamma-ray burst is the most powerful yet recorded. That's why astronomers nicknamed it the BOAT , or Brightest Of All Time.

The event was promptly published in the Astronomer's Telegram, and we now have new data from follow-up observations in several new papers published in a special focus issue of the Astrophysical Journal Letters. The findings confirmed that GRB 221009A was indeed the BOAT, appearing especially bright because its narrow jet was pointing directly at Earth. “It’s probably the brightest event to hit Earth since human civilization began,” Eric Burns, an astronomer at Louisiana State University, told New Scientist . “The energy of this thing is so extreme that if you took the entire sun and you converted all of it into pure energy, it still wouldn’t match this event. There’s just nothing comparable.”

But the various analyses also yielded several surprising results that puzzle astronomers and may lead to a significant overhaul of our current models of gamma ray bursts. For instance, a supernova should have occurred a few weeks after the initial burst, but astronomers have yet to detect one. Radio data from observations of the afterglow didn't match predictions of existing models, and astronomers detected rare extended rings of X-ray light echoes from the initial blast in distant dust clouds.

Enlarge / Certain squid have the ability to camouflage themselves by making themselves transparent and/or changing their coloration. (credit: YouTube/KQED Deep Look )

Certain cephalopods like cuttlefish, octopuses, and squid have the ability to camouflage themselves by making themselves transparent and/or changing their coloration. Scientists would like to learn more about the precise mechanisms underlying this unique ability, but it's not possible to culture squid skin cells in the lab. Researchers at the University of California, Irvine, have discovered a viable solution: replicating the properties of squid skin cells in mammalian (human) cells in the lab. They presented their research at a meeting of the American Chemical Society being held this week in Indianapolis.

"In general, there's two ways you can achieve transparency," UC Irvine's Alon Gorodetsky, who has been fascinated by squid camouflage for the last decade or so, said during a media briefing at the ACS meeting. "One way is by reducing how much light is absorbed—pigment-based coloration, typically. Another way is by changing how light is scattered, typically by modifying differences in the refractive index." The latter is the focus of his lab's research.

Squid skin is translucent and features an outer layer of pigment cells called chromatophores that control light absorption. Each chromatophore is attached to muscle fibers that line the skin's surface, and those fibers, in turn, are connected to a nerve fiber. It's a simple matter to stimulate those nerves with electrical pulses, causing the muscles to contract. And because the muscles pull in different directions, the cell expands, along with the pigmented areas, which changes the color. When the cell shrinks, so do the pigmented areas.

Enlarge / Event display of a W-boson candidate decaying into a muon and a muon neutrino inside the ATLAS experiment. The blue line shows the reconstructed track of the muon, and the red arrow denotes the energy of the undetected muon neutrino. (credit: ATLAS Collaboration/CERN)

It's often said in science that extraordinary claims require extraordinary evidence. Recent measurements of the mass of the elementary particle known as the W boson provide a useful case study as to why. Last year , Fermilab physicists caused a stir when they reported a W boson mass measurement that deviated rather significantly from theoretical predictions of the so-called Standard Model of Particle Physics —a tantalizing hint of new physics. Others advised caution, since the measurement contradicted prior measurements.

That caution appears to have been warranted. The ATLAS collaboration at CERN's Large Hadron Collider (LHC) has announced a new, improved analysis of their own W boson data and found the measured value for its mass was still consistent with Standard Model. Caveat: It's a preliminary result. But it lessens the likelihood of Fermilab's 2022 measurement being correct.

"The W mass measurement is among the most challenging precision measurements performed at hadron colliders," said ATLAS spokesperson Andreas Hoecker . "It requires extremely accurate calibration of the measured particle energies and momenta, and a careful assessment and excellent control of modeling uncertainties. This updated result from ATLAS provides a stringent test, and confirms the consistency of our theoretical understanding of electroweak interactions.”

Enlarge / Artist's depiction of the interstellar comet 'Oumuamua, as it warmed up in its approach to the Sun and outgassed hydrogen. (credit: NASA/ESA/STScI)

In late 2017, our Solar System received its very first known interstellar visitor: a bizarre cigar-shaped object hurtling past at 44 kilometers per second, dubbed 'Oumuamua (Hawaiian for "messenger from afar arriving first"). Was it a comet? An asteroid? A piece of alien technology? Scientists have been puzzling over the origin and unusual characteristics of 'Oumuamua ever since, most notably its strange orbit, and suggesting various models to account for them.

But perhaps the answer is much simpler than previously thought. That's the conclusion of a new paper published in the journal Nature. The authors suggest that 'Oumuamua's odd behavior is the result of the outgassing of hydrogen as the icy body warmed in the vicinity of the Sun—a simple mechanism common among icy comets.

As we reported previously , 'Oumuamua was first discovered by the University of Hawaii's Pan-STARRS1 telescope, part of NASA's Near-Earth Object Observations program to track asteroids and comets that come into Earth's vicinity. Other telescopes around the world soon kicked into action, measuring the object's various characteristics.

Enlarge / Artist’s illustration shows the ejection of a cloud of debris after NASA’s DART spacecraft collided with the asteroid Dimorphos. (credit: ESO/M. Kornmesser)

Last September, the Double Asteroid Redirect Test, or DART, smashed a spacecraft into a small binary asteroid called Dimorphos, successfully altering its orbit around a larger companion. We're now learning more about the aftermath of that collision, thanks to two new papers reporting on data collected by the European Southern Observatory's Very Large Telescope . The first, published in the journal Astronomy and Astrophysics, examined the debris from the collision to learn more about the asteroid's composition. The second, published in the Astrophysical Journal Letters, reported on how the impact changed the asteroid's surface.

As we've reported previously , Dimorphos is less than 200 meters across and cannot be resolved from Earth. Instead, the binary asteroid looks like a single object from here, with most of the light reflecting off the far larger Didymos. What we can see, however, is that the Didymos system sporadically darkens. Most of the time, the two asteroids are arranged so that Earth receives light reflected off both. But Dimorphos' orbit sporadically takes it behind Didymos from Earth's perspective, meaning that we only receive light reflected off one of the two bodies—this causes the darkening. By measuring the darkening's time periods, we can work out how long it takes Dimorphos to orbit and thus how far apart the two asteroids are.

Before DART, Dimorphos' orbit took 11 hours and 55 minutes; post-impact, it's down to 11 hours and 23 minutes. For those averse to math, that's 32 minutes shorter (about 4 percent). NASA estimates that the orbit is now "tens of meters" closer to Didymos. This orbital shift was confirmed by radar imaging. Earlier this month , Nature published five papers that collectively reconstructed the impact and its aftermath to explain how DART's collision had an outsize effect. Those results indicated that impactors like DART could be a viable means of protecting the planet from small asteroids.

Enlarge / Brown University scientists used two 3D-printed plastic disks to explore the Cheerios effect. (credit: A. Hooshanginejad et al., 2023)

Scientific research often produces striking visuals, and this year's winners of the Gallery of Soft Matter Physics are no exception. Selected during the American Physical Society March Meeting last week in Las Vegas, Nevada, the winning video entries featured the Cheerios effect, the physics of clogs, and exploiting the physics behind wine tears to make bubbles last longer. Submissions were judged on the basis of both striking visual qualities and scientific interest. The gallery contest was first established last year, inspired in part by the society's hugely successful annual Gallery of Fluid Motion . All five of this year's winners will have the chance to present their work at next year's March meeting in Minneapolis, Minnesota.

Mermaid Cereal

As we've previously reported , the " Cheerios effect " describes the physics behind why those last few tasty little "O"s of cereal tend to clump together in the bowl: either drifting to the center or to the outer edge. The effect can also be found in grains of pollen (or mosquito eggs) floating on top of a pond or small coins floating in a bowl of water. The culprit is a combination of buoyancy, surface tension, and the so-called " meniscus effect." It all adds up to a type of capillary action . Basically, the mass of the Cheerios is insufficient to break the milk's surface tension. But it's enough to put a tiny dent in the surface of the milk in the bowl, such that if two Cheerios are sufficiently close, they will naturally drift toward each other. The "dents" merge and the "O"s clump together. Add another Cheerio into the mix, and it, too, will follow the curvature in the milk to drift toward its fellow "O"s.

Measuring the actual forces at play on such a small scale is daunting, since they're on about the same scale as the weight of a mosquito. Typically, this is done by placing sensors on objects and setting them afloat in a container, using the sensors to deflect the natural motion. But Cheerios are small enough that this was not a feasible approach. So Brown University postdoc Alireza Hooshanginejad and cohorts used two 3D-printed plastic disks , roughly the size of a Cheerio, and placed a small magnet in one of them. Then they set the disks afloat in a small tub of water, surrounded by electric coils, and let them drift together (attraction). The coils in turn produced magnetic fields, pulling the magnetized disk away from its non-magnetized partner (repulsion).

Yellowstone National Park is most famous for Old Faithful , a geyser with fairly predictable periodic eruptions that delight visiting tourists. But it's also home to many other geothermal features like Doublet Pool , a pair of hot springs connected by a small neck with the geothermic equivalent of a pulse. The pool "thumps" every 20-30 minutes, causing the water to vibrate and the ground to shake. Researchers at the University of Utah have measured those thumping cycles with seismometers to learn more about how they change over time. Among other findings, they discovered that the intervals of silence between thumps correlate with how much heat is flowing into the pool, according to a new paper published in the journal Geophysical Research Letters.

“We knew Doublet Pool thumps every 20-30 minutes,” said co-author Fan-Chi Lin , a geophysicist at the University of Utah. “But there was not much previous knowledge on what controls the variation. In fact, I don’t think many people actually realize the thumping interval varies. People pay more attention to geysers.”

Yellowstone's elaborate hydrothermal system is the result of shallow groundwater interacting with heat from a hot magma chamber. The system boasts some 10,000 geothermal features, including steam vents (fumaroles), mud pots, and travertine terraces (chalky white rock), as well as geysers and hot springs.