Month: March 2025

The promise of fusion energy is cheap and abundant power for the entire planet. Scientists have made startling advances towards achieving it at scale, but there are still many problems holding it back. One of them is the production of fuel, which requires vast amounts of enriched lithium. Enriching lithium has been an environmental catastrophe, but researchers in Texas believe they’ve found a way to do it cheaply and at scale without poisoning the world.

A team of researchers at Texas A&M University discovered the new process by accident while working on a method for cleaning groundwater contaminated during oil and gas extraction. The research has just been published in the scientific journal Chem under the title “Electrochemical 6-Lithium Isotope Enrichment Based on Selective Insertion in 1D Tunnel-Structured V2O5.”

The effect the research has on nuclear fusion might be enormous. “Nuclear fusion is the primary source of energy emitted by stars such as the Sun,” Sarbajit Banerjee, a professor and researcher at ETH Zürich and Texas A&M and one of the authors of the paper, told Gizmodo. The simplest method of doing fusion on Earth instead of space involves tritium and deuterium isotopes. Tritium is rare and radioactive so reactors currently “breed” it on demand to generate energy.

They breed the tritium by bombarding lithium isotopes with neutrons. Most lithium on the planet, more than 90% of it, is lithium-7. Breeding tritium works way more efficiently with the ultra-rare lithium-6. “When 7Li, the most commonly occurring lithium isotope, is used, tritium production is much less efficient as compared to 6Li,” Banerjee said. “As such, modern reactor designs are based on breeding blankets with enriched 6Li isotope that has to be specifically extracted from natural lithium.”

You can turn naturally abundant mixtures of lithium isotopes into Lithium-6, “enriching” it, but the process is a toxic nightmare. “From 1955 to 1963, the United States produced 6Li at the Y12 plant at Oak Ridge National Laboratory in Tennessee for thermonuclear weapons applications, taking advantage of the slight difference in solubility of 6Li and 7Li isotopes in liquid mercury,” Banerjee said. “This did not go so well.”

“About 330 tons of mercury were released to waterways and the process was shut down in 1963 because of environmental concerns,” he said. Mercury is a toxic nightmare substance that’s difficult to clean up. After 60 years, heavy metals from the process of extracting Lithium-6 from naturally abundant mixtures are still poisoning Tennessee today. Cleaning up the remnants of the environmental disaster is a major project for Oak Ridge National Lab’s current residents.

During a different project, the team at Texas A&M developed a compound called zeta-V2O5 that it used to clean groundwater. As it ran water through this membrane it noticed something strange: it was really good at isolating Lithium-6. The team decided to see if it could harvest Lithium-6 from mixtures of Lithium isotopes without mercury.

It worked.

“Our approach uses the essential working principles of lithium-ion batteries and desalination technologies,” Banerjee said. “We insert Li-ions from flowing water streams within the one-dimensional tunnels of zeta-V2O5…our selective Li sponge has a subtle but important preference for 6Li over 7Li that affords a much safer process to extract lithium from water with isotopic selectivity.”

Banerjee this could lead to a massive change in how fuel is developed for fusion generators. It also doesn’t require a massive re-design of the existing reactors. “Our work outlines a path to overcoming a key supply chain issue for fusion. However, to be clear we are not redesigning the actual reactors—tokamaks or stellarators—although there is tremendous recent excitement about new innovations and designs in plasma physics,” he said.

A lot of people are banking on fusion being the path towards cheap and abundant energy. My entire life I’ve heard that the breakthrough that will make it real is “just around the corner.” It’s been a constant refrain that’s become a bit of a joke. Just last year the Bulletin of the Atomic Scientists asked if fusion might be “forever the energy of tomorrow.”

But Banerjee was hopeful. “Despite the incredible challenges, fusion is too big of a prize to give up on,” he said. “The transformative potential has been clear but there have been critical gaps in engineering designs, materials science for extreme environments, and understanding of the complexity of plasma processes to enumerate just a few gaps. There is an intensifying global competition and billions of dollars in private and public investments—while still not imminent, there are promising signs of realistic fusion energy in about two or three decades.”

What if you could listen to music or a podcast without headphones or earbuds and without disturbing anyone around you? Or have a private conversation in public without other people hearing you?

Our newly published research introduces a way to create audible enclaves – localized pockets of sound that are isolated from their surroundings. In other words, we’ve developed a technology that could create sound exactly where it needs to be.

The ability to send sound that becomes audible only at a specific location could transform entertainment, communication and spatial audio experiences.

What is sound?

Sound is a vibration that travels through air as a wave. These waves are created when an object moves back and forth, compressing and decompressing air molecules.

The frequency of these vibrations is what determines pitch. Low frequencies correspond to deep sounds, like a bass drum; high frequencies correspond to sharp sounds, like a whistle.

Controlling where sound goes is difficult because of a phenomenon called diffraction – the tendency of sound waves to spread out as they travel. This effect is particularly strong for low-frequency sounds because of their longer wavelengths, making it nearly impossible to keep sound confined to a specific area.

Certain audio technologies, such as parametric array loudspeakers, can create focused sound beams aimed in a specific direction. However, these technologies will still emit sound that is audible along its entire path as it travels through space.

The science of audible enclaves

We found a new way to send sound to one specific listener: through self-bending ultrasound beams and a concept called nonlinear acoustics.

Ultrasound refers to sound waves with frequencies above the human hearing range, or above 20 kHz. These waves travel through the air like normal sound waves but are inaudible to people. Because ultrasound can penetrate through many materials and interact with objects in unique ways, it’s widely used for medical imaging and many industrial applications.

In our work, we used ultrasound as a carrier for audible sound. It can transport sound through space silently – becoming audible only when desired. How did we do this?

Normally, sound waves combine linearly, meaning they just proportionally add up into a bigger wave. However, when sound waves are intense enough, they can interact nonlinearly, generating new frequencies that were not present before.

This is the key to our technique: We use two ultrasound beams at different frequencies that are completely silent on their own. But when they intersect in space, nonlinear effects cause them to generate a new sound wave at an audible frequency that would be heard only in that specific region.

Crucially, we designed ultrasonic beams that can bend on their own. Normally, sound waves travel in straight lines unless something blocks or reflects them. However, by using acoustic metasurfaces – specialized materials that manipulate sound waves – we can shape ultrasound beams to bend as they travel. Similar to how an optical lens bends light, acoustic metasurfaces change the shape of the path of sound waves. By precisely controlling the phase of the ultrasound waves, we create curved sound paths that can navigate around obstacles and meet at a specific target location.

The key phenomenon at play is what’s called difference frequency generation. When two ultrasonic beams of slightly different frequencies, such as 40 kHz and 39.5 kHz, overlap, they create a new sound wave at the difference between their frequencies – in this case 0.5 kHz, or 500 Hz, which is well within the human hearing range. Sound can be heard only where the beams cross. Outside of that intersection, the ultrasound waves remain silent.

This means you can deliver audio to a specific location or person without disturbing other people as the sound travels.

Advancing sound control

The ability to create audio enclaves has many potential applications.

Audio enclaves could enable personalized audio in public spaces. For example, museums could provide different audio guides to visitors without headphones, and libraries could allow students to study with audio lessons without disturbing others.

In a car, passengers could listen to music without distracting the driver from hearing navigation instructions. Offices and military settings could also benefit from localized speech zones for confidential conversations. Audio enclaves could also be adapted to cancel out noise in designated areas, creating quiet zones to improve focus in workplaces or reduce noise pollution in cities.

This isn’t something that’s going to be on the shelf in the immediate future. For instance, challenges remain for our technology. Nonlinear distortion can affect sound quality. And power efficiency is another issue – converting ultrasound to audible sound requires high-intensity fields that can be energy intensive to generate.

Despite these hurdles, audio enclaves present a fundamental shift in sound control. By redefining how sound interacts with space, we open up new possibilities for immersive, efficient and personalized audio experiences.

Jiaxin Zhong, Postdoctoral Researcher in Acoustics, Penn State and Yun Jing, Professor of Acoustics, Penn State. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Amazon’s AI-enhanced Alexa assistant is going to need all your voice recordings, and there’s nothing you can do about it. An email sent to Alexa users notes the online retail giant is ending one of its few privacy provisions about recorded voice data in the lead up to Alexa+. The only way to make sure Amazon doesn’t get a hold of any of your vocals may be to quit using Alexa entirely. Gizmodo reached out to Amazon for confirmation, though we did not immediately hear back.

You can find the full email on Reddit (as first reported by Ars Technica), which plainly states the “Do Not Send Voice Recordings” setting on Alexa is being discontinued on March 28. Anybody who has the setting enabled will have it automatically revoked, and Amazon will then be able to process your voice recordings. Amazon claims it will delete the recordings once it’s done processing your request.

“As we continue to expand Alexa’s capabilities with generative AI features that rely on the processing power of Amazon’s secure cloud, we have decided to no longer support this feature,” the email reads. “If you do not take action, your Alexa Settings will automatically be updated to ‘Don’t save recordings.’ This means that, starting on March 28, your voice recording will be sent to and processed in the cloud, and they will be deleted after Alexa processes your requests. any previously saved voice recordings will also be deleted.”

Alexa+, Amazon’s upcoming AI version of its normally inconsistent voice assistant, is supposed to allow for far more utility than it had in the past. The new assistant should be able to order groceries via multiple apps including Amazon Fresh and Instacart for you based on broad requests like “get me all the ingredients I need to make a pizza at home.” It’s supposed to set smart home routines, access your security footage, and look for Prime Video content in a conversational manner. The other big headline feature is Voice ID, where Amazon claims Alexa can identify who is speaking to it. The AI theoretically should  learn users’ habits over time and tailor its responses to each individual.

Alexa+ is supposed to come to all current Echo Show devices and will supposedly make its way to future Echo products as well. If you have an Amazon Prime account, you’ll get immediate access to Alexa+. Without the subscription, you’ll need to cough up another $20 a month for the sake of talking to AI-infused Alexa. The tradeoff is now you will have to offer your vocals to the online retail giant for it to do as it pleases.

There are more than a few reasons you don’t want Amazon anywhere near your voice data. For years, Amazon’s default setting gave workers access to user data, even offering some the ability to listen to users’ Alexa recordings. In 2023, the company paid out $25 million to the Federal Trade Commission over allegations it gave employees access to children’ s voice data and Ring camera footage. For its part, Amazon said it had changed its data practices to comply with the Children’s Online Privacy Protection Act, aka COPPA. Amazon’s privacy track record is spotty, at best. The company has long been obsessed with users’ voice data. In 2023, Amazon revealed it was using Alexa voice recordings to help train its AI. Gizmodo reached out to Amazon to confirm whether Alexa+ voice recordings will also be used to train the company’s AI models. We will update this story once we hear back.

Unlike Apple, which made big claims about data protections with its “private cloud compute” system for processing cloud-based AI requests anonymously, Amazon has made far fewer overtures to keeping user data safe. Smaller AI models can run on-device, but those few examples we have of on-device capabilities from the likes of Windows Copilot+ laptops or Gemini on Samsung Galaxy S25 phones are—in their current iteration—little more than gimmicks. Alexa+ wants to be the first instance of true assistant AI with cross-app capabilities, but it may also prove a privacy nightmare from a company that has  routinely failed to protect users’ data.