Nature Climate Change, Published online: 11 September 2025; doi:10.1038/s41558-025-02434-7

The role of climate science is changing — fast. Once positioned to inform policy, scientific assessments are increasingly being used in courtrooms to substantiate claims of harm, causation and state responsibility. Climate knowledge has now become legal evidence in the fight for climate justice.

Nature Climate Change, Published online: 11 September 2025; doi:10.1038/s41558-025-02428-5

How evapotranspiration changes with warming is not well understood. Here the authors show that when often-neglected land–atmosphere feedbacks are considered, evapotranspiration increases less than currently projected by offline models.

If the Supreme Court doesn’t reverse a lower court’s ruling, internet service providers (ISPs) could be forced to terminate people’s internet access based on nothing more than mere accusations of copyright infringement. This would threaten innocent users who rely on broadband for essential aspects of daily life. EFF—along with the American Library Association, the Association of Research Libraries, and Re:Create—filed an amicus brief urging the Court to reverse the decision.

The Stakes: Turning ISPs into Copyright Police

Among other things, the Supreme Court approving the appeals court’s findings will radically change the amount of risk your ISP takes on if a customer infringes on copyright, forcing the ISP to terminate access to the internet for those users accused of copyright infringement—and everyone else who uses that internet connection.

This issue turns on what courts call “secondary liability,” which is the legal idea that someone can be held responsible not for what they did directly, but for what someone else did using their product or service.

The case began when music companies sued Cox Communications, arguing that the ISP should be held liable for copyright infringement committed by some of its subscribers. The Court of Appeals for the Fourth Circuit agreed, adopting a “material contribution” standard for contributory copyright liability (a rule for when service providers can be held liable for the actions of users). The lower court said that providing a service that could be used for infringement is enough to create liability when a customer infringes.

In the Patent Act, where Congress has explicitly defined secondary liability, there’s a different test: contributory infringement exists only where a product is incapable of substantial non-infringing use. Internet access, of course, is overwhelmingly used for lawful purposes, making it the very definition of a “staple article of commerce” that can’t be liable under the patent framework. Yet under the Fourth Circuit’s rule, ISPs could face billion-dollar damages if they fail to terminate users on the basis of even flimsy or automated infringement claims.

Our Argument: Apply Clear Rules from the Patent Act, Not Confusing Judge-Made Tests

Our brief urges the Court to do what it has done in the past: look to patent law to define the limits of secondary liability in copyright. That means contributory infringement must require more than a “material contribution” by the service provider—it should apply only when a product or service is especially designed for infringement and lacks substantial non-infringing uses.

The Human Cost: Losing Internet Access Hurts Everyone

The Fourth Circuit’s rule threatens devastating consequences for the public. Terminating an ISP account doesn’t just affect a person accused of unauthorized file sharing—it cuts off entire households, schools, libraries, or businesses that share an internet connection.

• Public libraries, which provide internet access to millions of Americans who lack it at home, could lose essential service.
• Universities, hospitals, and local governments could see internet access for whole communities disrupted.
• Households—especially in low-income and communities of color, which disproportionately share broadband connections with other people—would face collective punishment for the alleged actions of a single user.

With more than a third of Americans having only one or no broadband provider, many users would have no way to reconnect once cut off. And given how essential internet access is for education, employment, healthcare, and civic participation, the consequences of termination are severe and disproportionate.

What’s Next

The Supreme Court has an opportunity to correct course. We’re asking the Court to reject the Fourth Circuit’s unfounded “material contribution” test, reaffirm that patent law provides the right framework for secondary liability, and make clear that the Constitution requires copyright to serve the public good. The Court should ensure that copyright enforcement doesn’t jeopardize the internet access on which participation in modern life depends.

We’ll be watching closely as the Court considers this case. In the meantime, you can read our amicus brief here.

Whether you’re an artist, advertising specialist, or just looking to spruce up your home, turning everyday objects into dynamic displays is a great way to make them more visually engaging. For example, you could turn a kids’ book into a handheld cartoon of sorts, making the reading experience more immersive and memorable for a child.

But now, thanks to MIT researchers, it’s also possible to make dynamic displays without using electronics, using barrier-grid animations (or scanimations), which use printed materials instead. This visual trick involves sliding a patterned sheet across an image to create the illusion of a moving image. The secret of barrier-grid animations lies in its name: An overlay called a barrier (or grid) often resembling a picket fence moves across, rotates around, or tilts toward an image to reveal frames in an animated sequence. That underlying picture is a combination of each still, sliced and interwoven to present a different snapshot depending on the overlay’s position.

While tools exist to help artists create barrier-grid animations, they’re typically used to create barrier patterns that have straight lines. Building off of previous work in creating images that appear to move, researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have developed a tool that allows users to explore more unconventional designs. From zigzags to circular patterns, the team’s “FabObscura” software turns unique concepts into printable scanimations, helping users add dynamic animations to things like pictures, toys, and decor.

MIT Department of Electrical Engineering and Computer Science (EECS) PhD student and CSAIL researcher Ticha Sethapakdi SM ’19, a lead author on a paper presenting FabObscura, says that the system is a one-size-fits-all tool for customizing barrier-grid animations. This versatility extends to unconventional, elaborate overlay designs, like pointed, angled lines to animate a picture you might put on your desk, or the swirling, hypnotic appearance of a radial pattern you could spin over an image placed on a coin or a Frisbee.

“Our system can turn a seemingly static, abstract image into an attention-catching animation,” says Sethapakdi. “The tool lowers the barrier to entry to creating these barrier-grid animations, while helping users express a variety of designs that would’ve been very time-consuming to explore by hand.”

Behind these novel scanimations is a key finding: Barrier patterns can be expressed as any continuous mathematical function — not just straight lines. Users can type these equations into a text box within the FabObscura program, and then see how it graphs out the shape and movement of a barrier pattern. If you wanted a traditional horizontal pattern, you’d enter in a constant function, where the output is the same no matter the input, much like drawing a straight line across a graph. For a wavy design, you’d use a sine function, which is smooth and resembles a mountain range when plotted out. The system’s interface includes helpful examples of these equations to guide users toward their preferred pattern.

A simple interface for elaborate ideas

FabObscura works for all known types of barrier-grid animations, supporting a variety of user interactions. The system enables the creation of a display with an appearance that changes depending on your viewpoint. FabObscura also allows you to create displays that you can animate by sliding or rotating a barrier over an image.

To produce these designs, users can upload a folder of frames of an animation (perhaps a few stills of a horse running), or choose from a few preset sequences (like an eye blinking) and specify the angle your barrier will move. After previewing your design, you can fabricate the barrier and picture onto separate transparent sheets (or print the image on paper) using a standard 2D printer, such as an inkjet. Your image can then be placed and secured on flat, handheld items such as picture frames, phones, and books.

You can enter separate equations if you want two sequences on one surface, which the researchers call “nested animations.” Depending on how you move the barrier, you’ll see a different story being told. For example, CSAIL researchers created a car that rotates when you move its sheet vertically, but transforms into a spinning motorcycle when you slide the grid horizontally.

These customizations lead to unique household items, too. The researchers designed an interactive coaster that you can switch from displaying a “coffee” icon to symbols of a martini and a glass of water by pressing your fingers down on the edges of its surface. The team also spruced up a jar of sunflower seeds, producing a flower animation on the lid that blooms when twisted off.

Artists, including graphic designers and printmakers, could also use this tool to make dynamic pieces without needing to connect any wires. The tool saves them crucial time to explore creative, low-power designs, such as a clock with a mouse that runs along as it ticks. FabObscura could produce animated food packaging, or even reconfigurable signage for places like construction sites or stores that notify people when a particular area is closed or a machine isn’t working.

Keep it crisp

FabObscura’s barrier-grid creations do come with certain trade-offs. While nested animations are novel and more dynamic than a single-layer scanimation, their visual quality isn’t as strong. The researchers wrote design guidelines to address these challenges, recommending users upload fewer frames for nested animations to keep the interlaced image simple and stick to high-contrast images for a crisper presentation.

In the future, the researchers intend to expand what users can upload to FabObscura, like being able to drop in a video file that the program can then select the best frames from. This would lead to even more expressive barrier-grid animations.

FabObscura might also step into a new dimension: 3D. While the system is currently optimized for flat, handheld surfaces, CSAIL researchers are considering implementing their work into larger, more complex objects, possibly using 3D printers to fabricate even more elaborate illusions.

Sethapakdi wrote the paper with several CSAIL affiliates: Zhejiang University PhD student and visiting researcher Mingming Li; MIT EECS PhD student Maxine Perroni-Scharf; MIT postdoc Jiaji Li; MIT associate professors Arvind Satyanarayan and Justin Solomon; and senior author and MIT Associate Professor Stefanie Mueller, leader of the Human-Computer Interaction (HCI) Engineering Group at CSAIL. Their work will be presented at the ACM Symposium on User Interface Software and Technology (UIST) this month.

Kresge Auditorium came alive Friday as MIT entrepreneurs took center stage to share their progress in the delta v startup accelerator program.

Now in its 14th year, delta v Demo Day represents the culmination of a summer in which students work full-time on new ventures under the guidance of the Martin Trust Center for MIT Entrepreneurship.

It also doubles as a celebration, with Trust Center Managing Director (and consummate hype man) Bill Aulet setting the tone early with his patented high-five run through the audience and leap on stage for opening remarks.

“All these students have performed a miracle,” Aulet told the crowd. “One year ago, they were sitting in the audience like all of you. One year ago, they probably didn’t even have an idea or a technology. Maybe they did, but they didn’t have a team, a clear vision, customer models, or a clear path to impact. But today they’re going to blow your mind. They have products — real products — a founding team, a clear mission, customer commitments or letters of intent, legitimate business models, and a path to greatness and impact. In short, they will have achieved escape velocity.”

The two-hour event filled Kresge Auditorium, with a line out the door for good measure, and was followed by a party under a tent on the Kresge lawn. Each presentation began with a short video introducing the company before a student took the stage to expand on the problem they were solving and what their team has learned from talks with potential customers.

In total, 22 startups showcased their ventures and early business milestones in rapid-fire presentations.

Rick Locke, the new dean of the MIT Sloan School of Management, said events like Demo Day are why he came back to the Institute after serving in various roles between 1988 and 2013.

“What’s great about this event is how it crystallizes the spirit of MIT: smart people doing important work, doing it by rolling up their sleeves, doing it with a certain humility but also a vision, and really making a difference in the world,” Locke told the audience. “You can feel the positivity, the energy, and the buzz here tonight. That’s what the world needs more of.”

A program with a purpose

This year’s Demo Day featured 70 students from across MIT, with 16 startups working out of the Trust Center on campus and six working from New York City. Through the delta v program, the students were guided by mentors, received funding, and worked through an action-oriented curriculum full-time between June and September. Aulet also noted that the students presenting benefitted from entrepreneurial support resources from across the Institute.

The odds are in the startups’ favor: A 2022 study found that 69 percent of businesses from the program were still operating five years later. Alumni companies had raised roughly $1 billion in funding.

Demo Day marks the end of delta v and serves to inspire next year’s cohort of entrepreneurs.

“Turn on a screen or look anywhere around you, and you'll see issues with climate, sustainability, health care, the future of work, economic disparities, and more,” Aulet said. “It can all be overwhelming. These entrepreneurs bring light to dark times. Entrepreneurs don’t see problems. As the great Biggie Smalls from Brooklyn said, ‘Turn a negative into a positive.’ That’s what entrepreneurs do.”

Startups in action

Startups in this year’s cohort presented solutions in biotech and health care, sustainability, financial services, energy, and more.

One company, Gees, is helping women with hormonal conditions like polycystic ovary syndrome (PCOS) with a saliva-based sensor that tracks key hormones to help women get personalized insights and manage symptoms.

“Over 200 million women live with PCOS worldwide,” said MIT postdoc and co-founder Walaa Khushaim. “If it goes unmanaged, it can lead to even more serious diseases. The good news is that 80 percent of cases can be managed with lifestyle changes. The problem is women trying to change their lifestyle are left in the dark, unsure if what they are doing is truly helping.”

Gees’ sensor is noninvasive and easier to use than current sensors that track hormones. It provides feedback in minutes from the comfort of users’ homes. The sensor connects to an app that shows results and trends to help women stay on track. The company already has more than 500 sign-ups for its wait list.

Another company, Kira, has created an electrochemical system to increase the efficiency and access of water desalination. The company is aiming to help companies manage their brine wastewater that is often dumped, pumped underground, or trucked off to be treated.

“At Kira, we’re working toward a system that produces zero liquid waste and only solid salts,” says PhD student Jonathan Bessette SM ’22.

Kira says its system increases the amount of clean water created by industrial processes, reduces the amount of brine wastewater, and optimizes the energy flows of factories. The company says next year it will deploy a system at the largest groundwater desalination plant in the U.S.

A variety of other startups presented at the event:

AutoAce builds AI agents for car dealerships, automating repetitive tasks with a 24/7 voice agent that answers inbound service calls and books appointments.

Carbion uses a thermochemical process to convert biomass into battery-grade graphite at half the temperature of traditional synthetic methods.

Clima Technologies has developed an AI building engineer that enables facilities managers to “talk” to their buildings in real-time, allowing teams to conduct 24/7 commissioning, act on fault diagnostics, minimize equipment downtime, and optimize controls.

Cognify uses AI to predict customer interactions with digital platforms, simulating customer behavior to deliver insights into which designs resonate with customers, where friction exists in user journeys, and how to build a user experience that converts.

Durability uses computer vision and AI to analyze movement, predict injury risks, and guide recovery for athletes.

EggPlan uses a simple blood test and proprietary model to assess eligibility for egg freezing with fertility clinics. If users do not have a baby, their fees are returned, making the process risk-free.

Forma Systems developed an optimization software for manufacturers to make smarter, faster decisions about things like materials use while reducing their climate impact.

Ground3d is a social impact organization building a digital tool for crowdsourcing hyperlocal environmental data, beginning with street-level documentation of flooding events in New York City. The platform could help residents with climate resilience and advocacy.

GrowthFactor helps retailers scale their footprint with a fractional real estate analyst while using an AI-powered platform to maximize their chance of commercial success.

Kyma uses AI-powered patient engagement to integrate data from wearables, smart scales, sensors, and continuous glucose monitors to track behaviors and draft physician-approved, timely reminders.

LNK Energies is solving the heavy-duty transport industry’s emissions problem with liquid organic hydrogen carriers (LOHCs): safe, room-temperature liquids compatible with existing diesel infrastructure.

Mendhai Health offers a suite of digital tools to help women improve pelvic health and rehabilitate before and after childbirth.

Nami has developed an automatic, reusable drinkware cleaning station that delivers a hot, soapy, pressurized wash in under 30 seconds.

Pancho helps restaurants improve margins with an AI-powered food procurement platform that uses real-time price comparison, dispute tracking, and smart ordering.

Qadence offers older adults a co-pilot that assesses mobility and fall risk, then delivers tailored guidance to improve balance, track progress, and extend recovery beyond the clinic.

Sensopore offers an at-home diagnostic device to help families test for everyday illnesses at home, get connected with a telehealth doctor, and have prescriptions shipped to their door, reducing clinical visits.

Spheric Bio has developed a personal occlusion device to improve a common surgical procedure used to treat strokes.

Tapestry uses conversational AI to chat with attendees before events and connect them with the right people for more meaningful conversations.

Torque automates financial analysis across private equity portfolios to help investment professionals make better strategic decisions.

Trazo helps interior designers and architects collaborate and iterate on technical drawings and 3D designs of new construction of remodeling projects.

San Francisco billionaire Chris Larsen once again has wielded his wallet to keep city residents under the eye of all-seeing police surveillance. 

The San Francisco Police Commission, the Board of Supervisors, and Mayor Daniel Lurie have signed off on Larsen’s $9.4 million gift of a new Real-Time Investigations Center. The plan involves moving the city’s existing police tech hub from the public Hall of Justice not to the city’s brand-new police headquarters but instead to a sublet in the Financial District building of Ripple Labs, Larsen’s crypto-transfer company. Although the city reportedly won’t be paying for the space, the lease reportedly cost Ripple $2.3 million and will last until December 2026. 

The deal will also include a $7.25 million gift from the San Francisco Police Community Foundation that Larsen created. Police foundations are semi-public fundraising arms of police departments that allow them to buy technology and gear that the city will not give them money for.  

In Los Angeles, the city’s police foundation got $178,000 from the company Target to pay for the services of the data analytics company Palantir to use for predictive policing. In Atlanta, the city’s police foundation funds a massive surveillance apparatus as well as the much-maligned Cop City training complex. (Despite police foundations’ insistence that they are not public entities and therefore do not need to be transparent or answer public records requests, a judge recently ordered the Atlanta Police Foundation to release documentation related to Cop City.) 

A police foundation in San Francisco brings the same concerns: that an unaccountable and untransparent fundraising arm shmoozing with corporations and billionaires would fund unpopular surveillance measures without having to reveal much to the public.  

Larsen was one of the deep pockets behind last year’s Proposition E, a ballot measure to supercharge surveillance in the city. The measure usurped the city’s 2019 surveillance transparency and accountability ordinance, which had required the SFPD to get the elected Board of Supervisors’ approval before buying and using new surveillance technology. This common-sense democratic hurdle was, apparently, a bridge too far for the SFPD and for Larsen.  

We’re no fans of real-time crime centers (RTCCs), as they’re often called elsewhere, to start with. They’re basically control rooms that pull together all feeds from a vast warrantless digital dragnet, often including automated license plate readers, fixed cameras, officers’ body-worn cameras, drones, and other sources. It’s a means of consolidating constant surveillance of the entire population, tracking everyone wherever they go and whatever they do – worrisome at any time, but especially in a time of rising authoritarianism.  

Think of what this data could do if it got into federal hands; imagine how vulnerable city residents would be subject to harassment if every move they made was centralized and recorded downtown. But you don’t have to imagine, because SFPD already has been caught sharing automated license plate reader data with out-of-state law enforcement agencies assisting in federal immigration investigations. 

We’re especially opposed to RTCCs using live feeds from non-city surveillance cameras to push that panopticon’s boundaries even wider, as San Francisco’s does. Those semi-private networks of some 15,000 cameras, already abused by SFPD to surveil lawful protests against police violence, were funded in part by – you guessed it – Chris Larsen. 

These technologies could potentially endanger San Franciscans by directing armed police at them due to reliance on a faulty algorithm or by putting already-marginalized communities at further risk of overpolicing and surveillance. But studies find that these technologies just don’t work. If the goal is to stop crime before it happens, to spare someone the hardship and the trauma of getting robbed or hurt, cameras clearly do not accomplish this. There’s plenty of footage of crime occurring that belies the idea that surveillance is an effective deterrent, and although police often look to technology as a silver bullet to fight crime, evidence suggests that it does little to alter the historic ebbs and flows of criminal activity. 

Yet now this unelected billionaire – who already helped gut police accountability and transparency rules and helped fund sketchy surveillance of people exercising their First Amendment rights – wants to bankroll, expand, and host the police’s tech nerve center. 

Policing must be a public function so that residents can control - and demand accountability and transparency from - those who serve and protect but also surveil and track us all. Being financially beholden to private interests erodes the community’s trust and control and can leave the public high and dry if a billionaire’s whims change or conflict with the will of the people. Chris Larsen could have tried to address the root causes of crime that affect our community; instead, he exercises his bank account's muscle to decide that surveillance is best for San Franciscans with less in their wallets. 

Elected officials should have said “thanks but no thanks” to Larsen and ensured that the San Francisco Police Department remained under the complete control and financial auspices of nobody except the people of San Francisco. Rich people should not be allowed to fund the further degradation of our privacy as we go about our lives in our city’s public places. Residents should carefully watch what comes next to decide for themselves whether a false sense of security is worth living under constant, all-seeing, billionaire-bankrolled surveillance. 

A little over a year ago we released Rayhunter, our open source tool designed to detect cell-site simulators. We’ve been blown away by the level of community engagement on this project. It has been installed on thousands of devices (or so we estimate, we don’t actually know since Rayhunter doesn’t have any telemetry!). We have received dozens of packet captures, hundreds of improvements, both minor and major, documentation fixes, and bug reports from our open source community. This project is a testament to the power and impact of open source and community driven counter-surveillance.  

If this is your first time hearing about Rayhunter, you can read our announcement blog post here. Or if you prefer, you can watch our DEF CON talk. In short, Rayhunter is an open source Linux program that runs on a variety of mobile hotspots (dedicated devices that use a cellular connection to give you Wi-Fi). Rayhunter’s job is to look for cell-site simulators (CSS), a tool police use to locate or identify people's cell phones, also known as IMSI catchers or Stingrays. Rayhunter analyzes the “handshakes” between your Rayhunter device and the cell towers it is connected to for behaviors consistent with that of a CSS. When it finds potential evidence of a CSS it alerts the user with an indicator on the screen and potentially a push notification to their phone.  

Understanding if CSS are being used to spy on protests is one of the main goals of the Rayhunter project. Thanks to members of our community bringing Rayhunter to dozens of protests, we are starting to get a picture of how CSS are currently being used in the US. So far Rayhunter has not turned up any evidence of cell-site simulators being used to spy on protests in the US — though we have found them in use elsewhere.  

So far Rayhunter has not turned up any evidence of cell-site simulators being used to spy on protests in the US.  

There are a couple of caveats here. First, it’s often impossible to prove a negative. Maybe Rayhunter just hasn’t been at protests where CSS have been present. Maybe our detection signatures aren’t picking up the techniques used by US law enforcement. But we’ve received reports from a lot of protests, including pro-Palestine protests, protests in Washington DC and Los Angeles, as well as the ‘No Kings’ and ‘50501’ protests all over the country. So far, we haven’t seen evidence of CSS use at any of them.  

A big part of the reason for the lack of CSS at protests could be that some courts have required a warrant for their use, and even law enforcement agencies not bound by these rulings have policies that require police to get a warrant. CSS are also costly to buy and use, requiring trained personnel to use nearly one million dollars worth of equipment.  

The fact is police also have potentially easier to use tools available. If the goal of using a CSS at a protest is to find out who was at the protest, police could use tools such as:  

• License plate readers to track the vehicles arriving and leaving at the protest. 
• Location data brokers, such as Locate X and Fog Data Science, to track the phones of protestors by their mobile advertising IDs (MAID).
• Cellebrite and other forensic extraction tools to download all the data from phones of arrested protestors if they are able to unlock those phones.  
• Geofence warrants, which require internet companies like Google to disclose the identifiers of devices within a given location at a given time.
• Facial recognition such as Clearview AI to identify all present via public or private databases of peoples faces.
• Tower dumps from phone companies, which, similar to geofence warrants, require phone companies to turn over a list of all the phones connected to a certain tower at a certain time.  

We think, due to the lack of evidence of CSS being used, protestors can worry less about CSS and more about these other techniques. Luckily, the actions one should take to protect themselves are largely the same: 

• To protect yourself against Locate X and Fog you can turn off location services on your phone (iPhone and Android). 
• To protect yourself from Cellebrite you can use a strong password, turn off biometric unlocks, and keep your phone up to date. 
• To protect against facial recognition, you can wear a mask. 
• To protect against tower dumps put your phone into airplane mode (though especially high risk individuals may want to use a Faraday bag instead). 

We feel pretty good about Rayhunter’s detection engine, though there could still be things we are missing. Some of our confidence in Rayhunter’s detection engine comes from the research we have done into how CSS work. But the majority of our confidence comes from testing Rayhunter against a commercial cell-site simulator thanks to our friends at Cape. Rayhunter detected every attack run by the commercial CSS.  

Where Rayhunter Has Detected Likely Surveillance

Rayhunter users have found potential evidence of CSS being used in the wild, though not at protests. One of the most interesting examples that triggered multiple detections and even inspired us to write some new detection rules was at a cruise port in the Turks and Caicos Islands. The person who captured this data put the packet captures online for other researchers to review. 

Rayhunter users have detected likely CSS use in the US as well. We have received reports from Chicago and New York where our “IMSI Sent without authentication” signature was triggered multiple times over the course of a couple hours and then stopped. Neither report was in the vicinity of a protest. We feel fairly confident that these reports are indicative of a CSS being present, though we don’t have any secondary evidence to back them up. 

We have received other reports that have triggered our CSS detection signatures, but the above examples are the ones we feel most confident about.  

We encourage people to keep using Rayhunter and continue bringing it to protests. Law enforcement trends can change over time and it is possible that some cities are using them more often than others (for example Fontana, California reportedly used their CSS over 300 times in two years). We also know that ICE still uses CSS and has recently renewed their contracts. Interestingly, in January, the FBI requested a warrant from the Foreign Intelligence Surveillance Court to use what was likely a CSS and was rejected. This was the first time the FBI has sought a warrant to use a CSS using the Foreign Intelligence Surveillance Act since 2015, when the Justice Department began requiring a warrant for their use. If police start using CSS to spy on protests we want to know.

There is still a lot we want to accomplish with Rayhunter, we have some future plans for the project that we are very excited to share with you in the near future, but the biggest thing we need right now is more testing outside of the United States.  

Taking Rayhunter International  

We are interested in getting Rayhunter data from every country to help us understand the global use of CSS and to refine our signatures. Just because CSS don't appear to be used to spy on protests in the US right now doesn't mean that is true everywhere. We have also seen that some signatures that work in the US are prone to false positives elsewhere (such as our 2G signature in countries that still have active 2G networks). The first device supported by Rayhunter, the Orbic hotspot, was US only, so we have very little international data. But we now have support for multiple devices! If you are interested in Rayhunter, but can’t find a device that works in your country, let us know. We recommend you consult with an attorney in your country to determine whether running Rayhunter is likely to be legally risky or outlawed in your jurisdiction.

Related Cases: Carpenter v. United States

The U.S. Department of Energy’s National Nuclear Security Administration (DOE/NNSA) recently announced that it has selected MIT to establish a new research center dedicated to advancing the predictive simulation of extreme environments, such as those encountered in hypersonic flight and atmospheric re-entry. The center will be part of the fourth phase of NNSA's Predictive Science Academic Alliance Program (PSAAP-IV), which supports frontier research advancing the predictive capabilities of high-performance computing for open science and engineering applications relevant to national security mission spaces.

The Center for the Exascale Simulation of Coupled High-Enthalpy Fluid–Solid Interactions (CHEFSI) — a joint effort of the MIT Center for Computational Science and Engineering, the MIT Schwarzman College of Computing, and the MIT Institute for Soldier Nanotechnologies (ISN) — plans to harness cutting-edge exascale supercomputers and next-generation algorithms to simulate with unprecedented detail how extremely hot, fast-moving gaseous and solid materials interact. The understanding of these extreme environments — characterized by temperatures of more than 1,500 degrees Celsius and speeds as high as Mach 25 — and their effect on vehicles is central to national security, space exploration, and the development of advanced thermal protection systems.

“CHEFSI will capitalize on MIT’s deep strengths in predictive modeling, high-performance computing, and STEM education to help ensure the United States remains at the forefront of scientific and technological innovation,” says Ian A. Waitz, MIT’s vice president for research. “The center’s particular relevance to national security and advanced technologies exemplifies MIT’s commitment to advancing research with broad societal benefit.”

CHEFSI is one of five new Predictive Simulation Centers announced by the NNSA as part of a program expected to provide up to $17.5 million to each center over five years.

CHEFSI’s research aims to couple detailed simulations of high-enthalpy gas flows with models of the chemical, thermal, and mechanical behavior of solid materials, capturing phenomena such as oxidation, nitridation, ablation, and fracture. Advanced computational models — validated by carefully designed experiments — can address the limitations of flight testing by providing critical insights into material performance and failure.

“By integrating high-fidelity physics models with artificial intelligence-based surrogate models, experimental validation, and state-of-the-art exascale computational tools, CHEFSI will help us understand and predict how thermal protection systems perform under some of the harshest conditions encountered in engineering systems,” says Raúl Radovitzky, the Jerome C. Hunsaker Professor of Aeronautics and Astronautics, associate director of the ISN, and director of CHEFSI. “This knowledge will help in the design of resilient systems for applications ranging from reusable spacecraft to hypersonic vehicles.”

Radovitzky will be joined on the center’s leadership team by Youssef Marzouk, the Breene M. Kerr (1951) Professor of Aeronautics and Astronautics, co-director of the MIT Center for Computational Science and Engineering (CCSE), and recently named the associate dean of the MIT Schwarzman College of Computing; and Nicolas Hadjiconstantinou, the Quentin Berg (1937) Professor of Mechanical Engineering and co-director of CCSE, who will serve as associate directors. The center co-principal investigators include MIT faculty members across the departments of Aeronautics and Astronautics, Electrical Engineering and Computer Science, Materials Science and Engineering, Mathematics, and Mechanical Engineering. Franklin Hadley will lead center operations, with administration and finance under the purview of Joshua Freedman. Hadley and Freedman are both members of the ISN headquarters team. 

CHEFSI expects to collaborate extensively with the DoE/NNSA national laboratories — Lawrence Livermore National Laboratory, Los Alamos National Laboratory, and Sandia National Laboratories — and, in doing so, offer graduate students and postdocs immersive research experiences and internships at these facilities.

The following article is adapted from a press release issued by the Laser Interferometer Gravitational-wave Observatory (LIGO) Laboratory. LIGO is funded by the National Science Foundation and operated by Caltech and MIT, which conceived and built the project.

On Sept. 14, 2015, a signal arrived on Earth, carrying information about a pair of remote black holes that had spiraled together and merged. The signal had traveled about 1.3 billion years to reach us at the speed of light — but it was not made of light. It was a different kind of signal: a quivering of space-time called gravitational waves first predicted by Albert Einstein 100 years prior. On that day 10 years ago, the twin detectors of the U.S. National Science Foundation Laser Interferometer Gravitational-wave Observatory (NSF LIGO) made the first-ever direct detection of gravitational waves, whispers in the cosmos that had gone unheard until that moment.

The historic discovery meant that researchers could now sense the universe through three different means. Light waves, such as X-rays, optical, radio, and other wavelengths of light, as well as high-energy particles called cosmic rays and neutrinos, had been captured before, but this was the first time anyone had witnessed a cosmic event through the gravitational warping of space-time. For this achievement, first dreamed up more than 40 years prior, three of the team’s founders won the 2017 Nobel Prize in Physics: MIT’s Rainer Weiss, professor emeritus of physics (who recently passed away at age 92); Caltech’s Barry Barish, the Ronald and Maxine Linde Professor of Physics, Emeritus; and Caltech’s Kip Thorne, the Richard P. Feynman Professor of Theoretical Physics, Emeritus.

Today, LIGO, which consists of detectors in both Hanford, Washington, and Livingston, Louisiana, routinely observes roughly one black hole merger every three days. LIGO now operates in coordination with two international partners, the Virgo gravitational-wave detector in Italy and KAGRA in Japan. Together, the gravitational-wave-hunting network, known as the LVK (LIGO, Virgo, KAGRA), has captured a total of about 300 black hole mergers, some of which are confirmed while others await further analysis. During the network’s current science run, the fourth since the first run in 2015, the LVK has discovered more than 200 candidate black hole mergers, more than double the number caught in the first three runs.

The dramatic rise in the number of LVK discoveries over the past decade is owed to several improvements to their detectors — some of which involve cutting-edge quantum precision engineering. The LVK detectors remain by far the most precise rulers for making measurements ever created by humans. The space-time distortions induced by gravitational waves are incredibly miniscule. For instance, LIGO detects changes in space-time smaller than 1/10,000 the width of a proton. That’s 1/700 trillionth the width of a human hair.

“Rai Weiss proposed the concept of LIGO in 1972, and I thought, ‘This doesn’t have much chance at all of working,’” recalls Thorne, an expert on the theory of black holes. “It took me three years of thinking about it on and off and discussing ideas with Rai and Vladimir Braginsky [a Russian physicist], to be convinced this had a significant possibility of success. The technical difficulty of reducing the unwanted noise that interferes with the desired signal was enormous. We had to invent a whole new technology. NSF was just superb at shepherding this project through technical reviews and hurdles.”

Nergis Mavalvala, the Curtis and Kathleen Marble Professor of Astrophysics at MIT and dean of the MIT School of Science, says that the challenges the team overcame to make the first discovery are still very much at play. “From the exquisite precision of the LIGO detectors to the astrophysical theories of gravitational-wave sources, to the complex data analyses, all these hurdles had to be overcome, and we continue to improve in all of these areas,” Mavalvala says. “As the detectors get better, we hunger for farther, fainter sources. LIGO continues to be a technological marvel.”

The clearest signal yet

LIGO’s improved sensitivity is exemplified in a recent discovery of a black hole merger referred to as GW250114. (The numbers denote the date the gravitational-wave signal arrived at Earth: January 14, 2025.) The event was not that different from LIGO’s first-ever detection (called GW150914) — both involve colliding black holes about 1.3 billion light-years away with masses between 30 to 40 times that of our sun. But thanks to 10 years of technological advances reducing instrumental noise, the GW250114 signal is dramatically clearer.

“We can hear it loud and clear, and that lets us test the fundamental laws of physics,” says LIGO team member Katerina Chatziioannou, Caltech assistant professor of physics and William H. Hurt Scholar, and one of the authors of a new study on GW250114 published in the Physical Review Letters.

By analyzing the frequencies of gravitational waves emitted by the merger, the LVK team provided the best observational evidence captured to date for what is known as the black hole area theorem, an idea put forth by Stephen Hawking in 1971 that says the total surface areas of black holes cannot decrease. When black holes merge, their masses combine, increasing the surface area. But they also lose energy in the form of gravitational waves. Additionally, the merger can cause the combined black hole to increase its spin, which leads to it having a smaller area. The black hole area theorem states that despite these competing factors, the total surface area must grow in size.

Later, Hawking and physicist Jacob Bekenstein concluded that a black hole’s area is proportional to its entropy, or degree of disorder. The findings paved the way for later groundbreaking work in the field of quantum gravity, which attempts to unite two pillars of modern physics: general relativity and quantum physics.

In essence, the LIGO detection allowed the team to “hear” two black holes growing as they merged into one, verifying Hawking’s theorem. (Virgo and KAGRA were offline during this particular observation.) The initial black holes had a total surface area of 240,000 square kilometers (roughly the size of Oregon), while the final area was about 400,000 square kilometers (roughly the size of California) — a clear increase. This is the second test of the black hole area theorem; an initial test was performed in 2021 using data from the first GW150914 signal, but because that data were not as clean, the results had a confidence level of 95 percent compared to 99.999 percent for the new data.

Thorne recalls Hawking phoning him to ask whether LIGO might be able to test his theorem immediately after he learned of the 2015 gravitational-wave detection. Hawking died in 2018 and sadly did not live to see his theory observationally verified. “If Hawking were alive, he would have reveled in seeing the area of the merged black holes increase,” Thorne says.

The trickiest part of this type of analysis had to do with determining the final surface area of the merged black hole. The surface areas of pre-merger black holes can be more readily gleaned as the pair spiral together, roiling space-time and producing gravitational waves. But after the black holes coalesce, the signal is not as clear-cut. During this so-called ringdown phase, the final black hole vibrates like a struck bell.

In the new study, the researchers precisely measured the details of the ringdown phase, which allowed them to calculate the mass and spin of the black hole and, subsequently, determine its surface area. More specifically, they were able, for the first time, to confidently pick out two distinct gravitational-wave modes in the ringdown phase. The modes are like characteristic sounds a bell would make when struck; they have somewhat similar frequencies but die out at different rates, which makes them hard to identify. The improved data for GW250114 meant that the team could extract the modes, demonstrating that the black hole’s ringdown occurred exactly as predicted by math models based on the Teukolsky formalism — devised in 1972 by Saul Teukolsky, now a professor at Caltech and Cornell University.

Another study from the LVK, submitted to Physical Review Letters today, places limits on a predicted third, higher-pitched tone in the GW250114 signal, and performs some of the most stringent tests yet of general relativity’s accuracy in describing merging black holes.

“A decade of improvements allowed us to make this exquisite measurement,” Chatziioannou says. “It took both of our detectors, in Washington and Louisiana, to do this. I don’t know what will happen in 10 more years, but in the first 10 years, we have made tremendous improvements to LIGO’s sensitivity. This not only means we are accelerating the rate at which we discover new black holes, but we are also capturing detailed data that expand the scope of what we know about the fundamental properties of black holes.”

Jenne Driggers, detection lead senior scientist at LIGO Hanford, adds, “It takes a global village to achieve our scientific goals. From our exquisite instruments, to calibrating the data very precisely, vetting and providing assurances about the fidelity of the data quality, searching the data for astrophysical signals, and packaging all that into something that telescopes can read and act upon quickly, there are a lot of specialized tasks that come together to make LIGO the great success that it is.”

Pushing the limits

LIGO and Virgo have also unveiled neutron stars over the past decade. Like black holes, neutron stars form from the explosive deaths of massive stars, but they weigh less and glow with light. Of note, in August 2017, LIGO and Virgo witnessed an epic collision between a pair of neutron stars — a kilonova — that sent gold and other heavy elements flying into space and drew the gaze of dozens of telescopes around the world, which captured light ranging from high-energy gamma rays to low-energy radio waves. The “multi-messenger” astronomy event marked the first time that both light and gravitational waves had been captured in a single cosmic event. Today, the LVK continues to alert the astronomical community to potential neutron star collisions, who then use telescopes to search the skies for signs of kilonovae.

“The LVK has made big strides in recent years to make sure we’re getting high-quality data and alerts out to the public in under a minute, so that astronomers can look for multi-messenger signatures from our gravitational-wave candidates,” Driggers says.

“The global LVK network is essential to gravitational-wave astronomy,” says Gianluca Gemme, Virgo spokesperson and director of research at the National Institute of Nuclear Physics in Italy. “With three or more detectors operating in unison, we can pinpoint cosmic events with greater accuracy, extract richer astrophysical information, and enable rapid alerts for multi-messenger follow-up. Virgo is proud to contribute to this worldwide scientific endeavor.”

Other LVK scientific discoveries include the first detection of collisions between one neutron star and one black hole; asymmetrical mergers, in which one black hole is significantly more massive than its partner black hole; the discovery of the lightest black holes known, challenging the idea that there is a “mass gap” between neutron stars and black holes; and the most massive black hole merger seen yet with a merged mass of 225 solar masses. For reference, the previous record holder for the most massive merger had a combined mass of 140 solar masses.

Even in the decades before LIGO began taking data, scientists were building foundations that made the field of gravitational-wave science possible. Breakthroughs in computer simulations of black hole mergers, for example, allow the team to extract and analyze the feeble gravitational-wave signals generated across the universe.

LIGO’s technological achievements, beginning as far back as the 1980s, include several far-reaching innovations, such as a new way to stabilize lasers using the so-called Pound–Drever–Hall technique. Invented in 1983 and named for contributing physicists Robert Vivian Pound, the late Ronald Drever of Caltech (a founder of LIGO), and John Lewis Hall, this technique is widely used today in other fields, such as the development of atomic clocks and quantum computers. Other innovations include cutting-edge mirror coatings that almost perfectly reflect laser light; “quantum squeezing” tools that enable LIGO to surpass sensitivity limits imposed by quantum physics; and new artificial intelligence methods that could further hush certain types of unwanted noise.

“What we are ultimately doing inside LIGO is protecting quantum information and making sure it doesn’t get destroyed by external factors,” Mavalvala says. “The techniques we are developing are pillars of quantum engineering and have applications across a broad range of devices, such as quantum computers and quantum sensors.”

In the coming years, the scientists and engineers of LVK hope to further fine-tune their machines, expanding their reach deeper and deeper into space. They also plan to use the knowledge they have gained to build another gravitational-wave detector, LIGO India. Having a third LIGO observatory would greatly improve the precision with which the LVK network can localize gravitational-wave sources.

Looking farther into the future, the team is working on a concept for an even larger detector, called Cosmic Explorer, which would have arms 40 kilometers long. (The twin LIGO observatories have 4-kilometer arms.) A European project, called Einstein Telescope, also has plans to build one or two huge underground interferometers with arms more than 10 kilometers long. Observatories on this scale would allow scientists to hear the earliest black hole mergers in the universe.

“Just 10 short years ago, LIGO opened our eyes for the first time to gravitational waves and changed the way humanity sees the cosmos,” says Aamir Ali, a program director in the NSF Division of Physics, which has supported LIGO since its inception. “There’s a whole universe to explore through this completely new lens and these latest discoveries show LIGO is just getting started.”

The LIGO-Virgo-KAGRA Collaboration

LIGO is funded by the U.S. National Science Foundation and operated by Caltech and MIT, which together conceived and built the project. Financial support for the Advanced LIGO project was led by NSF with Germany (Max Planck Society), the United Kingdom (Science and Technology Facilities Council), and Australia (Australian Research Council) making significant commitments and contributions to the project. More than 1,600 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. Additional partners are listed at my.ligo.org/census.php.

The Virgo Collaboration is currently composed of approximately 1,000 members from 175 institutions in 20 different (mainly European) countries. The European Gravitational Observatory (EGO) hosts the Virgo detector near Pisa, Italy, and is funded by the French National Center for Scientific Research, the National Institute of Nuclear Physics in Italy, the National Institute of Subatomic Physics in the Netherlands, The Research Foundation – Flanders, and the Belgian Fund for Scientific Research. A list of the Virgo Collaboration groups can be found on the project website.

KAGRA is the laser interferometer with 3-kilometer arm length in Kamioka, Gifu, Japan. The host institute is the Institute for Cosmic Ray Research of the University of Tokyo, and the project is co-hosted by the National Astronomical Observatory of Japan and the High Energy Accelerator Research Organization. The KAGRA collaboration is composed of more than 400 members from 128 institutes in 17 countries/regions. KAGRA’s information for general audiences is at the website gwcenter.icrr.u-tokyo.ac.jp/en/. Resources for researchers are accessible at gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/KAGRA. 

A new study from MIT neuroscientists reveals how rare variants of a gene called ABCA7 may contribute to the development of Alzheimer’s in some of the people who carry it.

Dysfunctional versions of the ABCA7 gene, which are found in a very small proportion of the population, contribute strongly to Alzheimer’s risk. In the new study, the researchers discovered that these mutations can disrupt the metabolism of lipids that play an important role in cell membranes.

This disruption makes neurons hyperexcitable and leads them into a stressed state that can damage DNA and other cellular components. These effects, the researchers found, could be reversed by treating neurons with choline, an important building block precursor needed to make cell membranes.

“We found pretty strikingly that when we treated these cells with choline, a lot of the transcriptional defects were reversed. We also found that the hyperexcitability phenotype and elevated amyloid beta peptides that we observed in neurons that lost ABCA7 was reduced after treatment,” says Djuna von Maydell, an MIT graduate student and the lead author of the study.

Li-Huei Tsai, director of MIT’s Picower Institute for Learning and Memory and the Picower Professor in the MIT Department of Brain and Cognitive Sciences, is the senior author of the paper, which appears today in Nature.

Membrane dysfunction

Genomic studies of Alzheimer’s patients have found that people who carry variants of ABCA7 that generate reduced levels of functional ABCA7 protein have about double the odds of developing Alzheimer’s as people who don’t have those variants.

ABCA7 encodes a protein that transports lipids across cell membranes. Lipid metabolism is also the primary target of a more common Alzheimer’s risk factor known as APOE4. In previous work, Tsai’s lab has shown that APOE4, which is found in about half of all Alzheimer’s patients, disrupts brain cells’ ability to metabolize lipids and respond to stress.

To explore how ABCA7 variants might contribute to Alzheimer’s risk, the researchers obtained tissue samples from the Religious Orders Study/Memory and Aging Project (ROSMAP), a longitudinal study that has tracked memory, motor, and other age-related changes in older people since 1994. Of about 1,200 samples in the dataset that had genetic information available, the researchers obtained 12 from people who carried a rare variant of ABCA7.

The researchers performed single-cell RNA sequencing of neurons from these ABCA7 carriers, allowing them to determine which other genes are affected when ABCA7 is missing. They found that the most significantly affected genes fell into three clusters related to lipid metabolism, DNA damage, and oxidative phosphorylation (the metabolic process that cells use to capture energy as ATP).

To investigate how those alterations could affect neuron function, the researchers introduced ABCA7 variants into neurons derived from induced pluripotent stem cells.

These cells showed many of the same gene expression changes as the cells from the patient samples, especially among genes linked to oxidative phosphorylation. Further experiments showed that the “safety valve” that normally lets mitochondria limit excess build-up of electrical charge was less active. This can lead to oxidative stress, a state that occurs when too many cell-damaging free radicals build up in tissues.

Using these engineered cells, the researchers also analyzed the effects of ABCA7 variants on lipid metabolism. Cells with the variants altered metabolism of a molecule called phosphatidylcholine, which could lead to membrane stiffness and may explain why the mitochondrial membranes of the cells were unable to function normally.

A boost in choline

Those findings raised the possibility that intervening in phosphatidylcholine metabolism might reverse some of the cellular effects of ABCA7 loss. To test that idea, the researchers treated neurons with ABCA7 mutations with a molecule called CDP-choline, a precursor of phosphatidylcholine.

As these cells began producing new phosphatidylcholine (both saturated and unsaturated forms), their mitochondrial membrane potentials also returned to normal, and their oxidative stress levels went down.

The researchers then used induced pluripotent stem cells to generate 3D tissue organoids made of neurons with the ABCA7 variant. These organoids developed higher levels of amyloid beta proteins, which form the plaques seen in the brains of Alzheimer’s patients. However, those levels returned to normal when the organoids were treated with CDP-choline. The treatment also reduced neurons’ hyperexcitability.

In a 2021 paper, Tsai’s lab found that CDP-choline treatment could also reverse many of the effects of another Alzheimer’s-linked gene variant, APOE4, in mice. She is now working with researchers at the University of Texas and MD Anderson Cancer Center on a clinical trial exploring how choline supplements affect people who carry the APOE4 gene.

Choline is naturally found in foods such as eggs, meat, fish, and some beans and nuts. Boosting choline intake with supplements may offer a way for many people to reduce their risk of Alzheimer’s disease, Tsai says.

“From APOE4 to ABCA7 loss of function, my lab demonstrates that disruption of lipid homeostasis leads to the development of Alzheimer’s-related pathology, and that restoring lipid homeostasis, such as through choline supplementation, can ameliorate these pathological phenotypes,” she says.

In addition to the rare variants of ABCA7 that the researchers studied in this paper, there is also a more common variant that is found at a frequency of about 18 percent in the population. This variant was thought to be harmless, but the MIT team showed that cells with this variant exhibited many of the same gene alterations in lipid metabolism that they found in cells with the rare ABCA7 variants.

“There’s more work to be done in this direction, but this suggests that ABCA7 dysfunction might play an important role in a much larger part of the population than just people who carry the rare variants,” von Maydell says.

The research was funded, in part, by the Cure Alzheimer’s Fund, the Freedom Together Foundation, the Carol and Gene Ludwig Family Foundation, James D. Cook, and the National Institutes of Health.

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