Enlarge (credit: IBM )

Large Language Models, the AI tech behind things like Chat GPT, are just what their name implies : big. They often have billions of individual computational nodes and huge numbers of connections among them. All of that means lots of trips back and forth to memory and a whole lot of power use to make that happen. And the problem is likely to get worse.

One way to potentially avoid this is to mix memory and processing. Both IBM and Intel have made chips that equip individual neurons with all the memory they need to perform their functions. An alternative is to perform operations in memory , an approach that has been demonstrated with phase-change memory.

Now, IBM has followed up on its earlier demonstration by building a phase-change chip that's much closer to a functional AI processor. In a paper released on Wednesday by Nature, the company shows that its hardware can perform speech recognition with reasonable accuracy and a much lower energy footprint.

Enlarge / H.G. Wells' The Invisible Man inspired a 1933 film. It's just one cultural example of the human fascination with invisibility. (credit: Universal Pictures)

There's a well-known story in Plato's Republic in which a humble shepherd named Gyges finds a magical gold ring that renders whoever wears it invisible. Gyges proceeds to use his newfound power to murder a king and take over the throne. Plato intended it as a cautionary tale about whether a man could act justly even if the fear of consequence was removed. (The fictional Gyges clearly failed that moral test.) The parable famously inspired J.R.R. Tolkien's Lord of the Rings trilogy, among other works. And it's one of the earliest examples of the longstanding human fascination with invisibility in both fiction and scientific pursuits.

"Invisibility represents the perfect merger of not being seen while being able to see others, which would be great if you were a primitive hunter-gatherer," Greg Gbur, a physicist at the University of North Carolina, Chapel Hill, told Ars. "But more purely, it represents power. You see that in the story of the Ring of Gyges, where the ability to make yourself unseen gives you a tremendous advantage over others. So it's fascinating as a symbol of pure power and how people might use and abuse it."

Gbur is the author of a new book from Yale University Press, Invisibility: The History and Science of How Not to Be Seen , covering the earliest discoveries in optical physics through to the present, along with how invisibility has been portrayed in science fiction (a longstanding passion for Gbur). He's also the author of 2019's fascinating Falling Felines and Fundamental Physics , which explored the surprisingly complicated physics of why cats always seem to land on their feet, ferreting out several obscure scientific papers spanning decades of research in the process. His interest in invisibility science dates back to his graduate school days when his advisor assigned him a project on the topic.

Enlarge / Blood Falls seeps from the end of the Taylor Glacier into Lake Bonney. Scientists believe a buried saltwater reservoir is partly responsible for the discoloration, which is a form of reduced iron. (credit: NSF/Peter Rejcek/Public domain)

In 1911, an Australian geologist named Thomas Griffith Taylor was exploring a valley in Antarctica when he stumbled upon a strange waterfall. The meltwater flowing from beneath the glacier that now bears Taylor's name turns a deep red upon coming into contact with the air, earning the site the moniker "Blood Falls." Various hypotheses have been proposed over the last century to explain the strange phenomenon. A team of scientists now thinks they've finally found the answer: tiny nanospheres rich in iron, silica, calcium, aluminum, and sodium, among other elements.

But why has solving this mystery taken more than a century? It seems the nanospheres are amorphous materials, meaning they lack a crystalline structure and hence eluded prior analytical methods looking for minerals because they are not, technically, minerals, according to a recent paper published in the journal Frontiers in Astronomy and Space Science. That might seem like an odd choice of journal for this study, but the Blood Falls at Taylor Glacier is a so-called "analogue" site for astrobiologists and planetary scientists keen to learn more about how life might evolve and thrive in similar inhospitable environments elsewhere in the universe.

"With the advent of the Mars Rover missions, there was an interest in trying to analyze the solids that came out of the waters of Blood Falls as if it was a Martian landing site," said co-author Ken Livi of Johns Hopkins University. "What would happen if a Mars Rover landed in Antarctica? Would it be able to determine what was causing the Blood Falls to be red? It's a fascinating question and one that several researchers were considering."

Enlarge / The world’s smallest 3D-printed wineglass in silica glass (left) and an optical resonator for fiber optic telecommunication, photographed with scanning electron microscopy. The rim of the glass is smaller than the width of a human hair. (credit: KTH Royal Institute of Technology)

A team of Swedish scientists has developed a novel 3D-printing technique for silica glass that streamlines a complicated energy-intensive process. As a proof of concept, they 3D-printed the world's smallest wineglass (made of actual glass) with a rim smaller than the width of one human hair, as well as an optical resonator for fiber optic telecommunications systems—one of several potential applications for 3D-printed silica glass components. They described their new method in a recent paper in the journal Nature Communications.

“The backbone of the Internet is based on optical fibers made of glass," said co-author Kristinn Gylfason of the KTH Royal Institute of Technology in Stockholm. "In those systems, all kinds of filters and couplers are needed that can now be 3D printed by our technique. This opens many new possibilities.”

Silica glass (i.e., amorphous silicon dioxide) is one material that remains challenging for 3D printing, particularly at the microscale, according to the authors, though several methods seek to address that challenge, including stereolithography, direct ink writing, and digital light processing. Even those have only been able to achieve feature sizes on the order of several tens of micrometers, apart from one 2021 study that reported nanoscale resolution.

Enlarge (credit: audioundwerbung )

In most industrialized countries, solar panels account for only a quarter to a third of the overall cost of building a solar farm. All the other expenses—additional hardware, financing, installation, permitting, etc—make up the bulk of the cost. To make the most of all these other costs, it makes sense to pay a bit more to install efficient panels that convert more of the incoming light into electricity.

Unfortunately, the cutting edge of silicon panels is already at about 25 percent efficiency, and there's no way to push the material past 29 percent. And there's an immense jump in price between those and the sorts of specialized, hyper-efficient photovoltaic hardware we use in space.

Those pricey panels have three layers of photovoltaic materials, each tuned to a different wavelength of light. So to hit something in between on the cost/efficiency scale, it makes sense to develop a two-layer device. This week saw some progress in that regard, with two separate reports of two-layer perovskite/silicon solar cells with efficiencies of well above 30 percent. Right now, they don't last long enough to be useful, but they may point the way toward developing better materials.

Enlarge (credit: LEONELLO CALVETTI/SCIENCE PHOTO LIBRARY )

While paper isn’t exactly a smart material, it someday could be if it is covered in a new type of liquid metal. This liquid alloy has the potential to turn paper and other materials into gadgets that can do some things on their own.

Liquid metal is already used in smart objects like circuits and wearable sensors—but not as a coating. Inspired by origami , a team of scientists led by Bo Yuan of Tsinghua University in China has figured out a way to formulate liquid metal and apply it with a stamp so it sticks to paper without an adhesive, which has never been possible before. In a study recently published in Cell Reports Physical Science , the scientists showed that paper coated in the metal can be crafted into origami shapes and re-fold itself. The metal coating also conducts heat and electricity. It’s almost magic. Almost.

A sticky alloy

Because the particles in liquid metal tend to stay so close together, it is difficult to get it to adhere to any surface without something that acts as glue. But these adhesives usually have a negative effect on the metal’s properties, such as its conductivity . Yuan and his team wanted a liquid metal that could stick to paper without an adhesive. They used an alloy of bismuth, indium, and tin oxide (BiInSn) and tested how well it performed next to an indium/gallium alloy (eGaIn).

Enlarge (credit: Halamka / GETTY IMAGES )

As Homo sapiens , we often consider ourselves to be the most intelligent hominins. But that doesn’t mean our species was the first to discover everything; it appears that Neanderthals found a way to manufacture synthetics long before we ever did.

Neanderthal tools might look relatively simple, but new research shows that Homo neanderthalensis devised a method of generating a glue derived from birch tar to hold them together about  200,000 years ago—and it was tough. This ancient superglue made bone and stone adhere to wood, was waterproof, and didn’t decompose. The tar was also used a hundred thousand years before modern humans came up with anything synthetic.

A transformation

After studying ancient tools that carry residue from this glue, a team of researchers from the Eberhard Karls University of Tübingen and other institutions in Germany found evidence that this glue wasn’t just the original tar; it had been transformed in some way. This raises the question of what was involved in that transformation.

Enlarge / Because particles that astronauts breathe out can drift for a while before settling, most surfaces in the International Space Station eventually get microbial contamination. (credit: NASA )

On June 5, a SpaceX Falcon 9 rocket blasted off to the International Space Station with new supplies, including equipment for scientific research. Among the new scientific gear that has arrived at the ISS are four tablets covered with extremely thin films that could play a crucial role in the development of materials for future human space flights.

Testing these innovative films, which were developed by the French commission for atomic and renewable energy (CEA), is part of an ongoing project aimed at developing antibacterial materials for space habitats.

“MATISS (Microbial Aerosol Tethering on Innovative Surfaces in the International Space Station) consists of exposing these tablets in the ISS environments for a long time in order to collect the bacteria that gets deposited on them. These tablets are then returned to our laboratories for measuring the level of biocontamination,” says project manager Sebastien Rouquette of the French space agency CNES.

Enlarge (credit: mikroman6 / Getty Images )

Those gummy bears from last Halloween might be hard as rocks, but a new study has used physics and chemistry to find out what factors put gummies at risk of becoming almost impossible to chew—and how to keep them gummy for as long as possible.

Keeping a gooey consistency

Gummies are all about texture. They shouldn’t be too hard, soft, or sticky, but they can become any of those things depending on ingredient content or storage (often both). Keeping them fresh means preventing changes to their internal chemistry that would otherwise occur over time. The ingredients that go into gummy candy, and how much of each is used, will inevitably affect the chemical reactions that occur, as will the temperature they are stored at and how long they stay in storage. So a team of researchers experimented with different formulas and storage methods to come up with the ultimate gummy.

The main ingredients of a gummy are glucose syrup, sucrose, starch, gelatin, and water. Led by Suzan Tireki of Ozyegin University in Turkey, the research team mixed eight batches with varying amounts of those main ingredients (flavor and color were low priorities for this work). The ratio of glucose syrup to sucrose turned out to be especially important because it has the most influence on gummy texture. Glucose is also responsible for sweetness and acts as a preservative by absorbing excess water that could otherwise attract microbes. Gelatin and starch are polymers and gelling agents that help give gummies their iconic texture.