Enlarge / Artist's conception of a dark matter filament containing a galaxy with large jets. (Caltech noted that some details of this image were created using AI.) (credit: Martijn Oei (Caltech) / Dylan Nelson (IllustrisTNG Collaboration).)

The supermassive black holes that sit at the center of galaxies aren't just decorative. The intense radiation they emit when feeding helps drive away gas and dust that would otherwise form stars, providing feedback that limits the growth of the galaxy. But their influence may extend beyond the galaxy they inhabit. Many black holes produce jets and, in the case of supermassive versions, these jets can eject material entirely out of the galaxy.

Now, researchers are getting a clearer picture of just how far outside of the galaxy their influence can reach. A new study describes the largest-ever jets observed, extending across a total distance of 23 million light-years (seven megaparsecs). At those distances, the jets could easily send material into other galaxies and across the cosmic web of dark matter that structures the Universe.

Extreme jets

Jets are formed in the complex environment near a black hole. The intense heating of infalling material ionizes and heats it, creating electromagnetic fields that act as a natural particle accelerator. This creates jets of particles that travel at a substantial fraction of the speed of light. These will ultimately slam into nearby material, creating shockwaves that heat and accelerate that, too. Over time, this leads to large-scale, coordinated outflows of material, with the scale of the jet being proportional to a combination of the size of the black hole and the amount of material it is feeding on.

Enlarge / Many have seen a reflection of Vincent van Gogh's inner turmoil in the swirling vortices of The Starry Night. (credit: Public doman)

Vincent van Gogh's most famous painting is The Starry Night (1889), created (along with several other masterpieces) during the artist's stay at an asylum in Arles following his breakdown in December 1888. Where some have seen the swirling vortices of the night sky depicted in Starry Night as a reflection of van Gogh's own inner turmoil, physicists often see a masterful depiction of atmospheric turbulence. According to a new paper published in the journal Physics of Fluids, the illusion of movement in van Gogh's blue sky is also due to the scale of the paint strokes—a second kind of "hidden turbulence" at the microscale that diffuses throughout the entire canvas.

“It reveals a deep and intuitive understanding of natural phenomena,” said co-author Yongxiang Huang of Xiamen University in China. “Van Gogh’s precise representation of turbulence might be from studying the movement of clouds and the atmosphere or an innate sense of how to capture the dynamism of the sky.”

Physicists have long been fascinated by van Gogh's innate feel for turbulence. As previously reported, in a 2014 TED-Ed talk, Natalya St. Clair, a research associate at the Concord Consortium and coauthor of The Art of Mental Calculation, used Starry Night to illuminate the concept of turbulence in a flowing fluid. In particular, she talked about how van Gogh's technique allowed him (and other Impressionist painters) to represent the movement of light across water or in the twinkling of stars. We see this as a kind of shimmering effect, because the eye is more sensitive to changes in the intensity of light (a property called luminance) than to changes in color.

Enlarge / A young Maurice Sendak’s illustration of two possible outcomes of atomic power for the 1947 pop-sci book Atomics for the Millions. (credit: McGraw Hill/Public domain)

Beloved American children's author and illustrator Maurice Sendak probably needs no introduction. His 1963 book, Where the Wild Things Are, is an all-time classic in the picture genre that has delighted generations of kids. It has sold over 19 million copies worldwide, won countless awards, and inspired a children's opera and a critically acclaimed 2009 feature film adaptation, as well as being spoofed on an episode of The Simpsons.

But one might be surprised to learn (as we were) that a teenage Sendak published his first professional illustrations in a 1947 popular science book about nuclear physics, co-authored by his high school physics teacher: Atomics for the Millions. Science historian Ryan Dahn came across a copy in the Niels Bohr Library & Archives at the American Institute of Physics in College Park, Maryland, and wrote a short online article about the book for Physics Today, complete with scans of Sendak's most striking illustrations.

Born in Brooklyn to Polish-Jewish parents, Sendak acknowledged that his childhood had been a sad one, overshadowed by losing many extended family members during the Holocaust. That, combined with health issues that confined him to his bed, compelled the young Sendak to find solace in books. When Sendak was 12, he watched Walt Disney's Fantasia, which inspired him to become an illustrator.

Pong will always hold a special place in the history of gaming as one of the earliest arcade video games. Introduced in 1972, it was a table tennis game featuring very simple graphics and gameplay. In fact, it's simple enough that even non-living materials known as hydrogels can "learn" to play the game by "remembering" previous patterns of electrical stimulation, according to a new paper published in the journal Cell Reports Physical Science.

"Our research shows that even very simple materials can exhibit complex, adaptive behaviors typically associated with living systems or sophisticated AI," said co-author Yoshikatsu Hayashi, a biomedical engineer at the University of Reading in the UK. "This opens up exciting possibilities for developing new types of 'smart' materials that can learn and adapt to their environment."

Hydrogels are soft, flexible biphasic materials that swell but do not dissolve in water. So a hydrogel may contain a large amount of water but still maintain its shape, making it useful for a wide range of applications. Perhaps the best-known use is soft contact lenses, but various kinds of hydrogels are also used in breast implants, disposable diapers, EEG and ECG medical electrodes, glucose biosensors, encapsulating quantum dots, solar-powered water purification, cell cultures, tissue engineering scaffolds, water gel explosives, actuators for soft robotics, supersonic shock-absorbing materials, and sustained-release drug delivery systems, among other uses.

Enlarge / The Wow! signal, represented as "6EQUJ5," was discovered in 1977 by astronomer Jerry Ehman. (credit: Public domain)

An unusually bright burst of radio waves—dubbed the Wow! signal—discovered in the 1970s has baffled astronomers ever since, given the tantalizing possibility that it just might be from an alien civilization trying to communicate with us. A team of astronomers think they might have a better explanation, according to a preprint posted to the physics arXiv: clouds of atomic hydrogen that essentially act like a naturally occurring galactic maser, emitting a beam of intense microwave radiation when zapped by a flare from a passing magnetar.

As previously reported, the Wow! signal was detected on August 18, 1977, by The Ohio State University Radio Observatory, known as “Big Ear.” Astronomy professor Jerry Ehman was analyzing Big Ear data in the form of printouts that, to the untrained eye, looked like someone had simply smashed the number row of a typewriter with a preference for lower digits. Numbers and letters in the Big Ear data indicated, essentially, the intensity of the electromagnetic signal picked up by the telescope over time, starting at ones and moving up to letters in the double digits (A was 10, B was 11, and so on). Most of the page was covered in ones and twos, with a stray six or seven sprinkled in.

But that day, Ehman found an anomaly: 6EQUJ5 (sometimes misinterpreted as a message encoded in the radio signal). This signal had started out at an intensity of six—already an outlier on the page—climbed to E, then Q, peaked at U—the highest power signal Big Ear had ever seen—then decreased again. Ehman circled the sequence in red pen and wrote “Wow!” next to it. The signal appeared to be coming from the direction of the Sagittarius constellation, and the entire signal lasted for about 72 seconds. Alas, SETI researchers have never been able to detect the so-called “Wow! Signal” again, despite many tries with radio telescopes around the world.

Enlarge / The two spacecraft for NASA's ESCAPADE mission at Rocket Lab's factory in Long Beach, California. (credit: Rocket Lab)

Two NASA spacecraft built by Rocket Lab are on the road from California to Florida this weekend to begin preparations for launch on Blue Origin's first New Glenn rocket.

These two science probes must launch between late September and mid-October to take advantage of a planetary alignment between Earth and Mars that only happens once every 26 months. NASA tapped Blue Origin, Jeff Bezos' space company, to launch the Escape and Plasma Acceleration and Dynamics Explorers (ESCAPADE) mission with a $20 million contract.

Last November, the space agency confirmed the $79 million ESCAPADE mission will launch on the inaugural flight of Blue Origin's New Glenn rocket. With this piece of information, the opaque schedule for Blue Origin's long-delayed first New Glenn mission suddenly became more clear.

Enlarge / Some cricket bowlers favor keeping the arm horizontal during delivery, the better to trick the batsmen. (credit: Rae Allen/CC BY 2.0)

Although the sport of cricket has been around for centuries in some form, the game strategy continues to evolve in the 21st century. Among the newer strategies employed by "bowlers"—the equivalent of the pitcher in baseball—is delivering the ball with the arm horizontally positioned close to the shoulder line, which has proven remarkably effective in "tricking" batsmen in their perception of the ball's trajectory.

Scientists at Amity University Dubai in the United Arab Emirates were curious about the effectiveness of the approach, so they tested the aerodynamics of cricket balls in wind tunnel experiments. The team concluded that this style of bowling creates a high-speed spinning effect that shifts the ball's trajectory mid-flight—an effect also seen in certain baseball pitches, according to a new paper published in the journal Physics of Fluids.

“The unique and unorthodox bowling styles demonstrated by cricketers have drawn significant attention, particularly emphasizing their proficiency with a new ball in early stages of a match,” said co-author Kizhakkelan Sudhakaran Siddharth, a mechanical engineer at Amity University Dubai. “Their bowling techniques frequently deceive batsmen, rendering these bowlers effective throughout all phases of a match in almost all formats of the game.”

Enlarge / Great white sharks can reduce drag at different swimming speeds thanks to high and low ridged denticles in its skin. (credit: Terry Goss/CC BY 2.5)

The great white shark (Carcharodon carcharias) is a swift and mighty hunter, capable of reaching speeds as high as 6.7 m/s when breaching, although it prefers to swim at slower speeds for migration and while waiting for prey. A team of Japanese researchers has studied the structure of the great white's skin to learn more about how these creatures adapt so well to a wide range of speeds. Their findings could lead to more efficient aircraft and boats with greatly reduced drag, according to a recent paper published in the Journal of the Royal Society Interface.

As previously reported, anyone who has touched a shark knows the skin feels smooth if you stroke from nose to tail. Reverse the direction, however, and it feels like sandpaper. That's because of tiny translucent scales, roughly 0.2 millimeters in size, called "denticles" (because they strongly resemble teeth) all over the shark's body, especially concentrated in the animal's flanks and fins. It's like a suit of armor for sharks, and it also serves as a means of reducing drag in the water while swimming.

Pressure drag is the result of flow separation around an object, like an aircraft or the body of a mako shark as it moves through water; the magnitude of pressure drag is determined by the shape of the object. It's what happens when the fluid flow separates from the surface of an object, forming eddies and vortices that impede the object's movement. Since the shark's body is constantly undulating as it swims, it needs something to help keep the flow attached around that body to reduce that drag. Denticles serve that purpose.

Enlarge (credit: jules/CC BY 2.0)

Inertial confinement fusion is one method for generating energy through nuclear fusion, albeit one plagued by all manner of scientific challenges (although progress is being made). Researchers at Lehigh University are attempting to overcome one specific bugbear with this approach by conducting experiments with mayonnaise placed in a rotating figure-eight contraption. They described their most recent findings in a new paper published in the journal Physical Review E with an eye toward increasing energy yields from fusion.

The work builds on prior research in the Lehigh laboratory of mechanical engineer Arindam Banerjee, who focuses on investigating the dynamics of fluids and other materials in response to extremely high acceleration and centrifugal force. In this case, his team was exploring what's known as the "instability threshold" of elastic/plastic materials. Scientists have debated whether this comes about because of initial conditions, or whether it's the result of "more local catastrophic processes," according to Banerjee. The question is relevant to a variety of fields, including geophysics, astrophysics, explosive welding, and yes, inertial confinement fusion.

How exactly does inertial confinement fusion work? As Chris Lee explained for Ars back in 2016:

A collision between subatomic particles in the Large Hadron Collider's CMS detector. (credit: Research.gov)

Particle physics is poised to hit the bright lights of Broadway with the adaptation into a musical of the 2013 documentary Particle Fever, which charts the journey to detect the Higgs boson at the world's largest particle accelerator. According to Deadline Hollywood, the creators described their musical as being filled with “heart, humor, and hope,” calling it an “exploration of the very nature of exploration itself... Particle Fever proves that even the very best theories are often no match for reality.”

(Spoiler: Physicists discovered the Higgs boson in 2012.)

Johns Hopkins University's David Kaplan was a film student turned theoretical physicist when he came up with the idea for a documentary on the search for the Higgs boson—at the time, the last remaining piece of the Standard Model of Particle Physics yet to be detected. The Large Hadron Collider at CERN was designed for that purpose, although the physics community hoped (in vain thus far) to also discover exciting new physics.

Enlarge / A naked-eye sunspot group on May 11, 2024. There are typically 40,000 to 50,000 sunspots observed in ~11-year solar cycles. (credit: E. T. H. Teague)

A team of Japanese and Belgian astronomers has re-examined the sunspot drawings made by 17th century astronomer Johannes Kepler with modern analytical techniques. By doing so, they resolved a long-standing mystery about solar cycles during that period, according to a recent paper published in The Astrophysical Journal Letters.

Precisely who first observed sunspots was a matter of heated debate in the early 17th century. We now know that ancient Chinese astronomers between 364 and 28 BCE observed these features and included them in their official records. A Benedictine monk in 807 thought he'd observed Mercury passing in front of the Sun when, in reality, he had witnessed a sunspot; similar mistaken interpretations were also common in the 12th century. (An English monk made the first known drawings of sunspots in December 1128.)

English astronomer Thomas Harriot made the first telescope observations of sunspots in late 1610 and recorded them in his notebooks, as did Galileo around the same time, although the latter did not publish a scientific paper on sunspots (accompanied by sketches) until 1613. Galileo also argued that the spots were not, as some believed, solar satellites but more like clouds in the atmosphere or the surface of the Sun. But he was not the first to suggest this; that credit belongs to Dutch astronomer Johannes Fabricus, who published his scientific treatise on sunspots in 1611.

Enlarge / A jet of particles moving at nearly light-speed emerges from a massive star in this artist’s concept of the BOAT. (credit: NASA's Goddard Space Flight Center Conceptual Image Lab)

Scientists have been all aflutter since several space-based detectors picked up a powerful gamma-ray burst (GRB) in October 2022—a burst so energetic that astronomers nicknamed it the BOAT (Brightest Of All Time). Now an international team of astronomers has analyzed an unusual energy peak detected by NASA's Fermi Gamma-ray Space Telescope and concluded that it was an emission spectra, according to a new paper published in the journal Science. Per the authors, it's the first high-confidence emission line ever seen in 50 years of studying GRBs.

As reported previously, gamma-ray bursts are extremely high-energy explosions in distant galaxies lasting between mere milliseconds to several hours. There are two classes of gamma-ray bursts. Most (70 percent) are long bursts lasting more than two seconds, often with a bright afterglow. These are usually linked to galaxies with rapid star formation. Astronomers think that long bursts are tied to the deaths of massive stars collapsing to form a neutron star or black hole (or, alternatively, a newly formed magnetar). The baby black hole would produce jets of highly energetic particles moving near the speed of light, powerful enough to pierce through the remains of the progenitor star, emitting X-rays and gamma rays.

Those gamma-ray bursts lasting less than two seconds (about 30 percent) are deemed short bursts, usually emitting from regions with very little star formation. Astronomers think these gamma-ray bursts are the result of mergers between two neutron stars, or a neutron star merging with a black hole, comprising a "kilonova." That hypothesis was confirmed in 2017 when the LIGO collaboration picked up the gravitational wave signal of two neutron stars merging, accompanied by the powerful gamma-ray bursts associated with a kilonova.

Enlarge / Rembrandt's The Night Watch underwent many chemical and mechanical alterations over the last 400 years. (credit: Public domain)

Since 2019, researchers have been analyzing the chemical composition of the materials used to create Rembrandt's masterpiece, The Night Watch, as part of the Rijksmuseum's ongoing Operation Night Watch, devoted to its long-term preservation. Chemists at the Rijksmuseum and the University of Amsterdam have now detected unusual arsenic-based yellow and orange/red pigments used to paint the duff coat of one of the central figures in the painting, according to a recent paper in the journal Heritage Science. It's a new addition to Rembrandt's known pigment palette that further adds to our growing body of knowledge about the materials he used.

As previously reported, past analyses of Rembrandt's paintings identified many pigments the Dutch master used in his work, including lead white, multiple ochres, bone black, vermilion, madder lake, azurite, ultramarine, yellow lake, and lead-tin yellow, among others. The artist rarely used pure blue or green pigments, with Belshazzar's Feast being a notable exception. (The Rembrandt Database is the best resource for a comprehensive chronicling of the many different investigative reports.)

Early last year, the researchers at Operation Night Watch found rare traces of a compound called lead formate in the painting—surprising in itself, but the team also identified those formates in areas where there was no lead pigment, white or yellow. It's possible that lead formates disappear fairly quickly, which could explain why they have not been detected in paintings by the Dutch Masters until now. But if that is the case, why didn't the lead formate disappear in The Night Watch? And where did it come from in the first place?

During our second Ars Live event earlier this month, screenwriter/producer Ed Solomon (Bill & Ted franchise) joined physicists Sean Carroll (Johns Hopkins University) and Jim Kakalios (University of Minnesota) and Ars Senior Reporter Jennifer Ouellette for a rousing discussion on the science and logic of time-travel movies. The discussion was inspired by last fall's Ars Guide to Time Travel in the Movies, written with the objective of helping us all make better, more informed decisions when it comes to choosing our time-travel movie fare—and having a bit of fun while doing so. You'll find the entire discussion in the video above, complete with a transcript.

Not all time-travel movies are created equal. Some make for fantastic entertainment, but the time travel makes no scientific or logical sense, while others might err in the opposite direction, sacrificing good storytelling in the interest of technical accuracy. The best strike a good balance between those two extremes.

We started off by letting Carroll recap his fundamental rules for time travel in the movies: (1) You can't go back earlier than whenever the time machine you're using was built; (2) it's easy to travel to the future, and special and general relativity give us ways to get to the future faster; (3) it may or may not be possible to travel to the past BUT.... (4) if you do, you can't change the past. Whatever happened, happened.

Enlarge / The CoulombFly doing its thing. (credit: Nature)

On Wednesday, researchers reported that they had developed a drone they're calling the CoulombFly, which is capable of self-powered hovering for as long as the Sun is shining. The drone, which is shaped like no aerial vehicle you've ever seen before, combines solar cells, a voltage converter, and an electrostatic motor to drive a helicopter-like propeller—with all components having been optimized for a balance of efficiency and light weight.

Before people get excited about buying one, the list of caveats is extensive. There's no onboard control hardware, and the drone isn't capable of directed flight anyway, meaning it would drift on the breeze if ever set loose outdoors. Lots of the components appear quite fragile, as well. However, the design can be miniaturized, and the researchers built a version that weighs only 9 milligrams.

Built around a motor

One key to this development was the researchers' recognition that most drones use electromagnetic motors, which involve lots of metal coils that add significant weight to any system. So, the team behind the work decided to focus on developing a lightweight electrostatic motor. These rely on charge attraction and repulsion to power the motor, as opposed to magnetic interactions.

Enlarge (credit: Fernando Trabanco Fotografía via Getty Images)

Isaac Newton would never have discovered the laws of motion had he studied only cats.

Suppose you hold a cat, stomach up, and drop it from a second-story window. If a cat is simply a mechanical system that obeys Newton’s rules of matter in motion, it should land on its back. (OK, there are some technicalities—like this should be done in a vacuum, but ignore that for now.) Instead, most cats usually avoid injury by twisting themselves on the way down to land on their feet.

Most people are not mystified by this trick—everybody has seen videos attesting to cats’ acrobatic prowess. But for more than a century, scientists have wondered about the physics of how cats do it. Clearly, the mathematical theorem analyzing the falling cat as a mechanical system fails for live cats, as Nobel laureate Frank Wilczek points out in a recent paper.

Enlarge / From left to right, zooming in from the globular cluster to the site of its black hole. (credit: ESA/Hubble & NASA, M. Häberle)

Supermassive black holes appear to reside at the center of every galaxy and to have done so since galaxies formed early in the history of the Universe. Currently, however, we can't entirely explain their existence, since it's difficult to understand how they could grow quickly enough to reach the cutoff for supermassive as quickly as they did.

A possible bit of evidence was recently found by using about 20 years of data from the Hubble Space Telescope. The data comes from a globular cluster of stars that's thought to be the remains of a dwarf galaxy and shows that a group of stars near the cluster's core are moving so fast that they should have been ejected from it entirely. That implies that something massive is keeping them there, which the researchers argue is a rare intermediate-mass black hole, weighing in at over 8,000 times the mass of the Sun.

Moving fast

The fast-moving stars reside in Omega Centauri, the largest globular cluster in the Milky Way. With an estimated 10 million stars, it's a crowded environment, but observations are aided by its relative proximity, at "only" 17,000 light-years away. Those observations have been hinting that there might be a central black hole within the globular cluster, but the evidence has not been decisive.

Enlarge / One of the components of the reactor during leak testing. (credit: ITER)

On Tuesday, the people managing the ITER experimental fusion reactor announced that a combination of delays and altered priorities meant that its first-of-its-kind hardware wouldn't see plasma until 2036, with the full-energy deuterium-tritium fusion pushed back to 2039. The latter represents a four-year delay relative to the previous roadmap. While the former is also a delay, it's due in part to changing priorities.

COVID and construction delays

ITER is an attempt to build a fusion reactor that's capable of sustaining plasmas that allow it to operate well beyond the break-even point, where the energy released by fusion reactions significantly exceeds the energy required to create the conditions that enable those reactions. It's meant to hit that milestone by scaling up a well-understood design called a tokamak.

But the problem has been plagued by delays and cost overruns nearly from its start. At early stages, many of these stemmed from changes in designs necessitated by a better and improved understanding of plasmas held at extreme pressures and temperatures due to better modeling capabilities and a better understanding of the behavior of plasmas in smaller reactions.

Enlarge / The Milky Way's central black hole is in a very crowded neighborhood. (credit: UMass/D.Wang/NASA/STScI)

Supermassive black holes are ravenous. Clumps of dust and gas are prone to being disrupted by the turbulence and radiation when they are pulled too close. So why are some of them orbiting on the edge of the Milky Way’s own supermassive monster, Sgr A*? Maybe these mystery blobs are hiding something.

After analyzing observations of the dusty objects, an international team of researchers, led by astrophysicist Florian Peißker of the University of Cologne, have identified these clumps as potentially harboring young stellar objects (YSOs) shrouded by a haze of gas and dust. Even stranger is that these infant stars are younger than an unusually young and bright cluster of stars that are already known to orbit Sgr A*, known as the S-stars.

Finding both of these groups orbiting so close is unusual because stars that orbit supermassive black holes are expected to be dim and much more ancient. Peißker and his colleagues “discard the en vogue idea to classify [these] objects as coreless clouds in the high energetic radiation field of the supermassive black hole Sgr A*,” as they said in a study recently published in Astronomy & Astrophysics.