Your fear of flying is only going to get worse once you hear what these white hat hackers figured out to do with a popular airliner.

As Wired reports, a team of security researchers from the University of California, San Diego and Oberlin College created a device the size of a coin that can take over the autopilot system of a Boeing 737 and change its flight plan, not to mention tampering with key values in its takeoff and fuel calculations. 

According to its creators, the device could also change the data on a pilot’s screen so they don’t notice anything’s amiss — or even trick a pilot into making a disastrous decision.

“If you could get 60 seconds with an airplane, what could you do?” Stefan Savage, a UCSL professor who led the project, asked Wired. “Well, it turns out there’s a port that’s externally accessible. You can get to it with no special tools in about 15 seconds. And you can shove in a piece of electronics a little bigger than a quarter that lets you basically tell the autopilot what to do and lie to the pilot about changes to the flight plan.”

The attack relies on plugging the device, which costs less than $100, into a port hidden by a hatch on the exterior of the plane, which the researchers say is easily within reach of maintenance workers and airline staff. Once the device is plugged in, it could connect to the plane’s in-flight Wi-Fi system and allow a hacker to remotely control the aircraft’s systems from terra firma.

As Savage explained to Wired, his team found this vulnerability after spending years cobbling together 737 computer parts to effectively recreate the plane’s nervous system. Inspired by credit card skimming devices that plug into ATMs to steal your information, they realized that an entire aircraft could be broken into by physically plugging a device into its internal “bus” — the system that connects different components of its computer. 

And after digging through Boeing wiring diagrams, they found their way in: a port carrying data between the plane’s Flight Manage Computer and the pilot’s display unit, accessible from an unlocked hatch on the plane’s exterior. 

It was like finding “the goddamn exhaust port on the Death Star,” Savage told Wired.

The havoc a hacker wreaks using their attack could be catastrophic. They could feed the pilot the wrong information about the air temperature outside or about the weight of its cargo and passengers and cause them to miss the speed they need for takeoff before running out of runway, Wired noted. Or they could suddenly change its navigation and crash it into a mountain.

The attacks could also be far more sneaky.

“It could be something as subtle as, you’re in the Pacific, you see blue everywhere, and this diverts you 3 degrees off course, and now you’re in the middle of nowhere,” Aaron Schulman, another UCSD professor working on the project, told the magazine.

Savage and Schulman shared their findings with Boeing six years ago and have worked closely with the company to explore the vulnerability.

But the researchers say that Boeing hasn’t told them about any fix to the vulnerabilities they found. In fact, they say it’s likely that it any fix may not have been implemented yet, since commercial airplanes are rarely redesigned.

You shouldn’t panic though, they insist.

“All of the authors of this paper routinely travel on Boeing 737 aircraft and expect to continue doing so,” they wrote in their paper.

Beau Woods, a former adviser to the Cybersecurity and Infrastructure Security Agency and the Boeing’s Industry Cyber Technical Council, was alarmed by the findings.

“It is entirely possible to have someone who is on staff go up to an airplane when it’s on the ground, going through maintenance, and put this type of thing in there,” Woods told Wired.

“This is something the aviation industry will want to plan to defend against,” Savage agreed. “I would not sleep on this one.”

More on aviation: Why Aren’t Any AI Companies Watching Their Frontier Models to Make Sure They Don’t Go on Hacking Sprees?

The post Hackers Created a Device That Can Take Over a Boeing 737 Jet’s Autopilot Without Anyone Noticing appeared first on Futurism.

A local post office owner in Liverpool says he has never seen anything like the surge in demand for solar eclipse glasses, describing the rush as “crazy” as customers race to secure a pair before the celestial event.

The specialist glasses, which are essential for safely viewing a solar eclipse without damaging the eyes, have become a hot commodity as public excitement builds. Unlike ordinary sunglasses, eclipse glasses use specially designed filters that block out nearly all visible light, as well as harmful ultraviolet and infrared radiation, allowing viewers to look directly at the sun during the event without risking permanent eye damage.

Retailers across the region are reportedly struggling to keep pace with orders, with stock disappearing almost as soon as it arrives. The shortage highlights both the growing public interest in astronomical events and the challenges small businesses face when demand spikes unexpectedly. Experts continue to stress that looking directly at the sun without proper protection, even during a partial eclipse, can cause serious and irreversible eye damage, making certified eclipse glasses a crucial purchase for anyone hoping to witness the phenomenon safely.

As the date of the eclipse approaches, shoppers are being urged to act quickly and to verify that any glasses they purchase meet recognized international safety standards, as counterfeit or substandard products have previously circulated during periods of high demand.

The post Eclipse Glasses Fly Off Shelves as Skywatchers Scramble to Prepare first appeared on EnviroLink Network.

Skywatchers across Scotland are keeping their fingers crossed as forecasts suggest cloud cover could obscure much of the country’s view of the upcoming solar eclipse. The partial eclipse, a striking celestial event where the Moon passes between the Earth and Sun, has generated excitement among astronomy enthusiasts and casual observers alike, but weather conditions may dampen the spectacle for many.

Meteorologists note that cloud patterns can shift in the hours leading up to the eclipse, so there remains hope that breaks in the cloud cover could offer fleeting glimpses of the phenomenon in some areas. Regions with clearer skies stand the best chance of witnessing the Moon’s shadow creep across the Sun, while those under thick cloud may need to rely on live broadcasts or online streams to experience the event.

Solar eclipses offer a valuable opportunity for scientific observation and public engagement with astronomy, reminding us of the dynamic relationship between the Earth, Moon and Sun. Experts continue to remind viewers never to look directly at the Sun without proper eye protection, such as certified eclipse glasses, even when the Sun is partially obscured. Those hoping to catch the event are encouraged to check localized weather updates as the time approaches, since conditions can change quickly and vary significantly between regions of Scotland.

The post Cloudy Skies May Block Scotland’s View of Solar Eclipse first appeared on EnviroLink Network.

A significant pollution incident has devastated fish populations along a 5-kilometer stretch of the Kilkeel River in Northern Ireland’s Mourne Mountains area, with officials warning that multiple generations of fish have been effectively wiped out.

The Department of Environment confirmed the extent of the damage, describing a scene of substantial ecological harm along the waterway. Rivers like the Kilkeel serve as vital habitats for fish species, and the destruction of multiple generations suggests both breeding adults and juvenile fish have perished, a setback that could take years to reverse.

Pollution incidents of this scale typically stem from agricultural runoff, chemical spills, or wastewater discharge, though the specific cause has not been detailed. Such events often deplete oxygen levels in the water or introduce toxins directly harmful to aquatic life, leaving rivers unable to support fish populations until natural recovery processes—or active restocking efforts—take hold.

Environmental officials are expected to continue investigating the source of the contamination as part of efforts to prevent future incidents and support the river’s long-term recovery. The Mourne Mountains area is prized for its natural beauty and biodiversity, making this loss particularly concerning for local conservationists and anglers who rely on healthy river ecosystems.

The post Pollution Incident Wipes Out Generations of Fish in Kilkeel River first appeared on EnviroLink Network.

A hydrogen combustion vehicle has roared into the record books, hitting a top speed of 406 miles per hour and smashing the previous benchmark set back in 2004. The new mark is more than double the speed of that earlier record, marking a major leap forward for hydrogen-based propulsion technology in high-performance applications.

The achievement highlights growing momentum behind hydrogen as a viable alternative to fossil fuels, not just for everyday transportation but for extreme engineering feats as well. Unlike battery-electric vehicles, hydrogen combustion cars burn hydrogen fuel directly, producing power through a modified combustion process while emitting primarily water vapor rather than carbon dioxide. This makes the technology an intriguing middle ground between traditional internal combustion engines and zero-emission electric drivetrains.

Land speed record attempts have long served as proving grounds for emerging automotive technology, and this run is no exception. Engineers and clean energy advocates see the milestone as evidence that hydrogen power can compete on performance, not just sustainability credentials. As governments and manufacturers continue investing in hydrogen infrastructure, from fueling stations to industrial applications, records like this help build public confidence that clean energy vehicles don’t have to sacrifice speed or excitement.

While hydrogen combustion vehicles remain a niche category compared to battery-electric cars, breakthroughs like this one could help accelerate research and investment into hydrogen as a broader climate solution, particularly for sectors like aviation, shipping, and heavy trucking, where battery weight remains a significant hurdle.

The post Hydrogen-Powered Car Shatters Land Speed Record with 406 MPH Run first appeared on EnviroLink Network.

In October 1982, engineers in Paraguay and Brazil closed the gates along the Paraná River, setting in motion the slow flooding of a valley that would soon disappear beneath the reservoir of what became the world’s largest dam by energy output. As the waters rose, they swallowed forests, riverbanks, and islands that had teemed with life for generations, forcing one of the most urgent wildlife rescue efforts in South American history.

Conservationists and volunteers scrambled against the clock, wading into rising floodwaters to capture and relocate thousands of stranded animals—from sloths and monkeys to snakes, birds, and small mammals—before their habitat vanished entirely. The operation, born of necessity rather than long-term planning, revealed both the resilience of wildlife rescue teams and the harsh trade-offs that come with large-scale hydroelectric development.

The flooding of the Itaipu reservoir ultimately submerged hundreds of square miles of subtropical forest, reshaping the region’s ecology and displacing countless species along with local communities. While the dam has since become a cornerstone of clean energy production for both nations, supplying a significant share of their electricity, its creation stands as a stark reminder of the ecological costs embedded in even the most celebrated renewable energy projects.

Decades later, the story of the 1982 rescue continues to inform conversations about how nations balance the promise of hydropower with the irreversible loss of biodiversity, raising questions that remain urgent as new dam projects are proposed across the globe.

The post When the Itaipu Dam Rose, a Desperate Wildlife Rescue Began first appeared on EnviroLink Network.

Crowds gathered across Kent, Surrey and Sussex to witness a striking celestial event as the moon partially obscured the sun in a rare partial solar eclipse. Armed with specialised viewing glasses, telescopes fitted with solar filters, and pinhole projectors, spectators young and old turned their eyes skyward to catch a glimpse of the phenomenon.

The eclipse offered a dramatic reminder of the intricate mechanics governing our solar system, as the moon’s shadow crept across the sun’s face, temporarily dimming daylight and casting an eerie glow over the countryside. Astronomy enthusiasts and casual observers alike described the experience as awe-inspiring, with many capturing photographs to mark the occasion.

Local astronomy clubs and community groups had organised viewing events in parks, schools and public spaces, providing safe equipment and guidance to ensure onlookers could enjoy the spectacle without risking eye damage from direct sunlight exposure. Experts had urged the public in the days leading up to the event to avoid looking directly at the sun without proper protection.

Partial solar eclipses, while less dramatic than total eclipses, still offer a valuable opportunity for both amateur and professional astronomers to study solar activity and inspire public interest in space science. Such events also serve as a reminder of the delicate cosmic alignments that shape our understanding of the natural world, encouraging renewed curiosity about the skies above.

The post Skywatchers Across South East England Marvel at Rare Partial Solar Eclipse first appeared on EnviroLink Network.

Skywatchers across Yorkshire turned their eyes upward as crowds gathered in York, Leeds, and Bradford to witness the most significant solar eclipse visible from the region since 1999. The rare celestial event drew families, students, and astronomy enthusiasts alike to public squares and open spaces, many armed with specialized eclipse glasses and homemade viewing devices to safely observe the spectacle.

Onlookers described the experience as “incredible,” with many noting the eerie dimming of daylight as the moon passed between the Earth and the sun. In York, crowds packed public viewing areas, while similar scenes unfolded in Leeds and Bradford, where local astronomy groups and science centers set up telescopes and provided guidance on safe viewing practices.

The eclipse offered a rare opportunity for the public to engage directly with a dramatic astronomical phenomenon, sparking widespread interest in solar science and inspiring curiosity about future celestial events. Local schools and community organizations used the occasion to educate the public about the mechanics of eclipses and the importance of protecting eyesight when observing the sun.

Events like this eclipse serve as reminders of the dynamic relationship between Earth and the wider solar system, offering moments of collective wonder that transcend everyday life. As skies cleared over Yorkshire, the shared experience underscored how such natural phenomena continue to captivate public imagination, uniting communities in a shared moment of awe beneath the same sky.

The post Yorkshire Crowds Marvel at Most Significant Solar Eclipse Since 1999 first appeared on EnviroLink Network.

For the first time in my life, I have a proper garden, and I was determined to make the most of it. Back in spring, I went all in: seeds, trays, pots, grow bags, soil, and a shiny new watering can. My vision was modest but hopeful: a small patch of fruit and vegetables, flowers to attract pollinators, and a chance to teach my eldest child how things grow, and how to handle it when they don’t.

We started with tomatoes, a household favorite. The seedlings sprouted with promise, only to shrivel and die in the season’s first heatwave. It felt like a bad sign. The dahlias, ranunculus, and freesias I’d planted refused to bloom at all. Slowly, my gardening enthusiasm began to fade.

What started as a cozy parent-child project in patience and resilience is beginning to feel like something else entirely: a small, personal front line in the climate crisis. As heatwaves become more frequent and intense across Britain, pushing more regions into drought, the simple act of growing your own food is no longer just a hobby. It’s a test of adaptability, and increasingly, a luxury that requires more water, more vigilance, and more heartbreak than it once did.

My family’s failed harvest is a tiny story, but it echoes a much bigger one, as gardeners, allotment holders, and small-scale growers across the country grapple with unpredictable weather patterns that are reshaping how, and whether, we can grow our own food at all.

The post My Garden Dreams Wilted in the Heat, and Now I Wonder If Home Gardening Is a Climate-Era Luxury first appeared on EnviroLink Network.

A stunning drone video capturing dozens of stingrays swimming together off the coast of New York has drawn widespread attention from beachgoers and marine life enthusiasts alike. The footage offers an unusual bird’s-eye perspective on cownose rays, a species known for its seasonal visits to Long Island’s waters.

Captured last Friday off Southampton, the video was filmed by Joanna Steidle, a Hamptons-based drone pilot recognized for her striking aerial ocean photography. The clip shows a large group of cownose rays gliding gracefully just beneath the water’s surface, their distinctive wing-shaped bodies visible in remarkable detail.

Cownose rays, which can grow wing spans of up to three feet, are known for traveling in large schools and typically arrive in the region during the warmer summer months. Despite their somewhat intimidating appearance, marine scientists describe the species as shy and generally harmless to humans, posing little threat to swimmers or beachgoers who might encounter them.

While the sight of so many rays moving together may seem unusual to casual observers, experts note that this behavior is a normal part of their seasonal pattern and that these creatures have likely been visiting Long Island’s coastal waters for decades. The viral footage has offered a rare glimpse into a natural phenomenon that typically goes unnoticed by those on shore, highlighting the rich marine biodiversity present just off New York’s beaches during summer.

The post Drone Captures Rare Aerial View of Stingray Migration Off Long Island first appeared on EnviroLink Network.

At sunrise, the yacht Boaventura II departs Rio de Janeiro carrying a boatload of eager whale watchers. Just past the Cagarras Islands, a rocky archipelago three miles from Ipanema beach, passengers crowd the bow, eyes fixed on the horizon.

Their patience is quickly rewarded. A pod of bottlenose dolphins surfaces first, leaping and diving playfully near the boat. Moments later, two plumes of mist rise into the air—the telltale sign of humpback whales. The massive creatures breathe rhythmically at the surface before diving, their distinctive tail flukes briefly visible above the waves.

This scene, once unimaginable, has become increasingly common off Rio’s coast. Humpback whales, hunted to near extinction during the 20th century whaling era, have made a remarkable comeback in Brazilian waters. Their resurgence has sparked a booming whale-watching tourism industry, drawing visitors eager to witness these ocean giants up close.

Yet the very success story that brings tourists to the water is now raising concerns among marine biologists. As boat traffic increases to meet demand, researchers are questioning whether unchecked tourism growth could threaten the fragile recovery of the species. The challenge now facing Rio: how to celebrate and share this conservation triumph without loving the whales back toward danger.

The post Humpback Whales Return to Rio De Janeiro’s Waters, but Can Tourism and Conservation Coexist? first appeared on EnviroLink Network.

At the quantum scale, tiny particles behave in bizarre ways. One reason for this is the uncertainty principle, which says that the more you know about where a quantum particle is, the less you can know about how fast it’s moving, and vice versa. Recently, this rule got a rare upgrade. The new uncertainty principle relates to fractals, shapes that remain equally complex no matter how much you…

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For several months, I had been on the hunt for new T-shirts. I vaguely had a vision of what they should look like: not so different from my current T-shirts, except in some way elevated and, more urgent, free of stains or holes. Perhaps they could come in interesting colors? Ideally, they would not be made in sweatshops. There were many, many shirts that seemed to meet these criteria—and with a few clicks, they could be delivered to my doorstep, maybe even by tomorrow. And still, I had purchased none of them.

The problem is the overabundance of options. The problem is too much information, or too little information. The problem is inflation, which has eroded any sense I had of what a T-shirt is supposed to cost. Yet none of them alone can explain why shopping is sucking up more of my time—and maybe yours too. “I don’t think people are actually enjoying the shopping process,” Jaehee Jung, a University of Delaware professor who studies the psychology of fashion, told me. “People spend more time contemplating, and the pre-decision process seems to be taking longer.”

Everywhere, someone is selling something: on Instagram and TikTok, over email and via text. At this point, the boundary between “shopping” and “not shopping” has all but collapsed. There is now a third state: “a little bit shopping.” Shopping is visiting a store or website on purpose, examining the wares, and either buying or not buying them. A little bit shopping is the constant thrum of consumer opportunities that lead mostly to more consumer opportunities. It is looking at a pair of shoes, which leads to looking at another pair of shoes, and another, and then you’re $15 short of the minimum for free shipping and is there anything else you need? It is the feeling of being haunted by the targeted ads that populate your social-media feeds. Even if you never click on them, their very presence contributes to the overwhelming sense that the retail landscape is infinite—so infinite that perfection must exist, and if you look long enough and hard enough, somewhere in the universe, it is probably on sale.

[Read: There is too much stuff]

In small doses, a little bit shopping can be fun, a private thrill. It is both a genuine attempt at making a purchase, and a hobby that is infinitely expandable to fill any length of time. Who among us has not scrolled through sweater sales while trapped on a work call? It does not require spending money, nor does it apply to urgent and essential purchases: You don’t a little bit shop for baby Tylenol. “No matter what you’re doing on the computer,” Wendy Woloson, a material historian at Rutgers University at Camden, told me, “it seems like there’s a really easy drift into the shopping mode.”

Unlike brick-and-mortar stores, the internet never closes. You can a little bit shop forever, until you are also a little bit miserable. Shopping in person, then, ought to solve the problem, but it often doesn’t. A survey of 30 retailers by the consulting firm AlixPartners found that, on average, they carried only 9 percent of their online offerings in store. The shoes are out of stock in your size, but have you checked the website? You could stand in line to buy lesser, uglier shoes and be done with it, but why? Online, beautiful shoes are infinite and, in theory, instant.

The more mindful you are about various concerns—overconsumption, worker exploitation, microplastics—the higher the bar climbs: I need not only black pants, but ethical black pants that I can wear to the beach, but also to the opera, and that will be flattering from now until my death. No such pants exist, which is why I don’t have any, but as long as you’re a little bit shopping, the possibility exists.

This state of perpetual shopping has been building for ages. People were a little bit shopping on Amazon and eBay in 2005. But the feeling has become even more acute in recent years as e-commerce has taken over and affiliate marketing has boomed. In addition to sites such as Wirecutter and The Strategist, and every media property with a gift guide, all kinds of influencers have opinions about what you should buy (and may receive a commission if you do).

[Read: What happened to Wirecutter?]

My own digital social life is a mix of people I know, people I don’t know, brands that post like people, and people launching brands. Here is my high-school lab partner’s baby. Here is a plate of pasta. Here is a picture of an antique lamp for sale from an estate-sale company in Texas. “Everyone is trying to either make money or gain recognition”—and thereby make money—“for their taste,” Isabel Slone, who writes about fashion on the Substack Freak Palace, told me. An influencer can help move $1 million worth of swimsuits in three hours. For a solitary activity, a little bit shopping is perversely social. It is pleasantly intimate, knowing how an opinionated stranger feels about their chef’s knife, or their microwave, or the life-changing sweater that got them through their divorce and is available right now if you click the link in the bio. Whether it is helpful consumer education is a separate question: “I do think that the affiliate-link economy,” Slone said, “contributes to this constant feeling of not knowing exactly what is good.”

There is, of course, a way out. You could stop caring. You could embrace the good-enough and the suboptimal, understanding that a little bit shopping is a trap that keeps you shopping all the time. Eventually, I bought a T-shirt, which is in all ways absolutely adequate, and in no sense exceptional. And then, the next day, I saw a post about a T-shirt, which was better. I clicked.

The event horizons of black holes that are far from equilibrium can now be described by the first and second laws of thermodynamics thanks to new work by theoretical physicists at Pennsylvania State University in the US. The result augments the work of the late Stephen Hawking and others who showed in the 1970s that these classical concepts have applications in idealized, static black holes.

Black holes are objects so dense that their gravitational pull prevents anything – even light – from escaping them. The “point of no return” of any object falling into a black hole is called the event horizon, and it represents the black hole’s mathematically defined “edge”.

Although black holes can be described using concepts from quantum mechanics and Einstein’s general theory of relativity, some 50 years ago physicists like Hawking and Jacob Bekenstein showed that the equations governing them are also astonishingly similar to the fundamental laws of thermodynamics. “This seminal observation sparked a rethinking of black holes in thermodynamics terms,” explains Abhay Ashtekar, a physicist at Penn State’s Eberly College who led the new study. In particular, Ashtekar says it meant that black holes could be assigned an entropy that is equal to the area of their event horizon.

The problem, he continues, is that technically, these relationships are only valid for black holes in equilibrium – that is, those that are stable and do not change over time. In contrast, real astrophysical black holes are constantly changing: they form, merge and eventually evaporate because of quantum effects.

“In these dynamical objects, event horizons are ‘teleological’, meaning that we need to know how a black hole will behave for all of eternity to be able to define its entropy today,” Ashtekar explains. “This notion of black hole entropy is therefore physically untenable. Indeed, this limitation was already recognized in the 1990s and it has been the elephant in the room since then.”

Extending the laws of thermodynamics

In their new work, Ashtekar and colleagues sought to overcome this limitation by replacing static event horizons with an alternative concept known as dynamical horizon segments. These segments are characterized by the physical properties of a black hole at a given moment in time, and other researchers have employed them in numerical simulations of black hole mergers and gravitational collapse. Indeed, Ashtekar and various colleagues had previously shown that dynamical horizons were a physically admissible replacement for event horizons.

However, Ashtekar says that these earlier studies had not addressed two central questions. These involved defining intensive parameters – analogues of pressure and temperature in ordinary thermodynamics systems such as gases – and defining the energy of a black hole by itself in a highly curved region of space-time at a given instant.

“Our study now shows that Einstein’s equations imply that these dynamical horizons also satisfy equations very similar to the first and second laws of thermodynamics,” Ashtekar tells Physics World. “What is more, the change in thermodynamical quantities of these horizons at any given moment in time are caused directly by fluxes of energy and changes in the angular momentum of the black hole at that instant.”

The researchers’ new calculations show that even when black holes are very far from equilibrium, their evolution defines specific trajectories in the space of different equilibrium states. “This allows us to transport observables from these states to instantaneous non-equilibrium ones,” explains Ashtekar. “Such a procedure cannot be applied to conventional thermodynamics systems; black holes are very special in this regard.”

Event horizons “entirely absent” when quantum effects are included

According to team member Daniel Paraizo, the new work treats the event horizon as a dynamical horizon segment that forms in a gravitational collapse and then evaporates because of quantum effects. Intriguingly, Paraizo says that within this framework, event horizons vanish entirely when quantum effects are included – a fact which, he says, “removes a great deal of confusion currently surrounding the issue of information loss from a black hole, for example”. This same finding, he notes, also supports an idea that Hawking advocated shortly before his death in 2018: the possibility that a “true” event horizon never actually forms.

The Penn State researchers now plan to build on their present work with theories involving both classical and quantum gravity. Team member Jonathan Shu says that such theories may provide a thermodynamic explanation of several puzzling features that have been observed in numerical simulations of black hole mergers. “We have also already extended our results to theories of gravity beyond general relativity,” he reveals. “For quantum gravity, dynamical horizon segments have been successfully deployed in the so-called semi-classical phase of black hole evaporation and work is underway to address still unanswered questions about the final stages of the process using a theory known as loop quantum gravity.”

The researchers report their work in Physical Review Letters. Ashtekar will also be speaking on this subject at Penrose Fest@95, which is due to be held in Oxford, UK in September.

The post Physicists extend Hawking’s black hole laws to dynamical objects appeared first on Physics World.

A system will generally move towards equilibrium when a change is made to it in a process called relaxation. To predict the state of the system after some period of time, we only need to know its current state and the external conditions. However, some polymers have memory behaviours where the evolution of the system is not only dependent on the current state, but also on previous states. This is known as the Kovacs effect.

In this work, the researchers investigated the Kovacs effect in a system consisting of suspensions of rod-like nanoparticles. By applying an electric field to these nanoparticles they align, therefore the particles change the liquid’s optical anisotropy, which can be measured as birefringence, which is how the liquid changes light polarization. More birefringence means the particles are more aligned. Importantly, there are faster- and slower-relaxing nanoparticles because of their polydispersity and different sizes, meaning they align at different rates. By changing the strength of the electric field, the faster and slower nanoparticles become out of sync with each other. The future behaviour will then depend on the system’s previous history that is overall hidden by the global birefringence measurement; this is the Kovacs effect.

The researchers modelled the orientational dynamics using the Smoluchowski equation, which describes rotational diffusion of particles. They found that relaxation is not determined by a single timescale or relaxation mode. When some of the modes are fast and some are slow, memory effects will occur. The Kovacs effect is important because it shows that a simple strategy of applying a strong electric field before switching to the target field does not necessarily speed up relaxation. Due to memory effects arising from particles relaxing at different rates, the system overshoots the target state, reducing the expected gain in speed.

To overcome this, the researchers designed improved two- and three-step protocols that suppress the slowest relaxation modes rather than simply matching the average birefringence. These protocols reduce the memory effect, produce a smoother approach to equilibrium, and achieve faster relaxation, although the benefit of additional switching steps becomes progressively smaller. This research improves our understanding of memory effects in complex systems and provides a practical strategy for controlling nanoparticle dynamics more quickly and efficiently.

Do you want to learn more about this topic?

Scientific developments of liquid crystal-based optical memory: a review by Jai Prakash, Achu Chandran and Ashok M Biradar (2016)

The post Memory effects in nanoparticle suspensions appeared first on Physics World.