Jack Dennis, an influential MIT professor emeritus of computer science and engineering, died on March 14 at age 94. The original leader of the Computation Structures Group within the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL), he pioneered the development of dataflow models of computation, and, subsequently, many novel principles of computer architecture inspired by dataflow models.

The second child of an engineer and a textile designer, Dennis showed early interest in both engineering and music, rewriting Gilbert and Sullivan lyrics with his parents and playing piano with the Norwalk Symphony Orchestra in Connecticut as a teen, while building a canoe at home with his father. As an undergraduate at MIT, he developed his wide array of interests further, joining the VI-A Cooperative Program in Electrical Engineering; working at the Air Force Cambridge Research Laboratories on projects in speech processing and novel radar systems; participating in the model railroad club; and joining the MIT Symphony Orchestra, where he met his first wife, Jane Hodgson ’55, SM ’56, PhD ’61. (The two later separated when she went to study medicine in Florida.) 

Dennis earned his BS (1953), MS (1954), and ScD (1958) from MIT before joining the then-Department of Electrical Engineering as a faculty member. He was promoted to full professor status in 1969. His doctoral thesis, entitled, “Mathematical Programming and electrical networks,” explored analogies between electric circuit theory and quadratic programming problems. Ideas he developed in that paper further crystallized in his 1964 paper, “Distributed solution of network programming problems,” which created an important early class of digital distributed optimization solvers.

In a 2003 piece that Dennis wrote for his undergraduate class’s 50th reunion, he remembered his earliest encounters with computers at the Institute: “I prepared programs written in assembly language on punched paper tape using Frieden 'Flexowriters,' and stood aside watching the myriad lights blink and flash while operator Mike Solamita fed the tapes [...] That was 1954. Fifty years later, much has changed: A room full of vacuum tubes has become a tiny chip with millions of transistors. A phenomenon once limited to research laboratories has become an industry producing commodity products that anyone can own and use beneficially.”

Dennis’ influence in steering that change was profound. As a collaborator with the teams behind both Project MAC and Multics, the earliest attempts to allow multiple users to work with a single computer seemingly simultaneously (i.e., a time-shared operating system), Dennis helped to specify the unique segment addressing and paging mechanisms that became a fundamental part of the General Electric Model 645 computer. His insights stemmed from a tendency to pay equal attention to both hard- and software when others considered themselves specialists in one or the other. 

“I formed the Computation Structures Group [within CSAIL] and focused on architectural concepts that could narrow the acknowledged gap between programming concepts and the organization of computer hardware,” Dennis explained in his 2003 recollection. “I found myself dismayed that people would consider themselves to be either hardware or software experts, but paid little heed to how joint advances in programming and architecture could lead to a synergistic outcome that might revolutionize computing practice.”

Dennis’ emphasis on synergy did not go unnoticed. Gerald Sussman, the Panasonic Professor of Electrical Engineering, points out “the relationship of [Dennis’] dataflow architecture to single-assignment programs, and thus to pure functional programs. This coupled the virtue of referential transparency in programming to the effective use of hardware parallelism. Dennis also pioneered the use of self-timed circuits in digital systems. The ideas from that work generalize to much of the work on highly distributed systems.” 

The Computation Structures Group attracted multiple scholars interested in developing asynchronous computing and dataflow architecture, many of whom became lifelong friends and collaborators. These included Peter Denning, with whom Dennis and Joseph Qualitz co-authored the textbook “Machines, Languages, and Computation” (1978); the late Arvind, who became faculty head of computer science for the Department of Electrical Engineering and Computer Science (EECS), and the late Guang R. Gao, who became distinguished professor of electrical and computer engineering at the University of Delaware. 

In recognition of his contributions to the Multics project, Dennis was elected fellow of the Institute of Electrical and Electronics Engineers (IEEE). Many additional honors would follow: He received the Association for Computing Machinery (ACM)/IEEE Eckert-Mauchly Award in 1984; was inducted as a fellow of the ACM (1994); was named to the National Academy of Engineering (2009); was elected to the (ACM) Special Interest Group on Operating Systems (SIGOPS) Hall of Fame (2012); and was awarded the IEEE John von Neumann Medal (2013). 

A successful researcher, Dennis was perhaps equally influential in the development of EECS’ curriculum, developing six subjects in areas of computer theory and systems: Theoretical Models for Computation; Computation Structures; Structure of Computer Systems; Semantic Theory for Computer Systems; Semantics of Parallel Computation; and Computer System Architecture (taught in collaboration with Arvind.) Several of the courses that Dennis developed continue to be taught, in updated form, to this day.

Following his retirement from teaching in 1987, he consulted on projects relating to parallel computer hardware and software for such varied groups as NASA Research Institute for Advanced Computer Science; Boeing Aerospace; McGill University; the Architecture Group of Carlstedt Elektronik in Gothenburg, Sweden; and Acorn Networks, Inc. His fruitful relationship with former student Guang Gao continued in the form of a lecture tour through China, as well as co-authorship of a book, “Dataflow Architecture,” currently in progress at MIT Press. 

A voracious lifelong learner, Dennis was fond of repeating a friend’s observation that “a scholar is just a book’s way of making another book.” In a full and active retirement, he still made room for music, trying his hand at composing; performing at Tanglewood as a tenor in Chorus Pro Musica; playing piano at the marriage of Guang Gao’s son Nick; and joining the chorus at the First Church in Belmont, Massachusetts, where his celebration of life (with concurrent livestreaming) will be held on Monday, June 8, at 2 p.m. 

Dennis is survived by his wife Therese Smith ’75; children David Hodgson Dennis of North Miami, Florida; Randall Dennis of Connecticut; and Galen Dennis, a resident of Australia. 

Regulation is hard:

The South Pacific Regional Fisheries Management Organization (SPRFMO) oversees fishing across roughly 59 million square kilometers (22 million square miles) of the South Pacific high seas, trying to impose order on a region double the size of Africa, where distant-water fleets pursue species ranging from jack mackerel to jumbo flying squid. The latter dominated this year’s talks.

Fishing for jumbo flying squid (Dosidicus gigas) has expanded rapidly over the past two decades. The number of squid-jigging vessels operating in SPRFMO waters rose from 14 in 2000 to more than 500 last year, almost all of them flying the Chinese flag. Meanwhile, reported catches have fallen markedly, from more than 1 million metric tons in 2014 to about 600,000 metric tons in 2024. Scientists worry that fishing pressure is outpacing knowledge of the stock. ...

We go through this every couple of years: Section 702 of the Foreign Intelligence Surveillance Act (FISA), which of Americans’ communications with foreign persons overseas is up for renewal. As always, Congress can reauthorize it with or without changes, or just let it expire. We know, we know, it’s a pain to have to do this every few years–but it gives us a chance to lift the hood of this behemoth tool of government surveillance and tinker with how it works. That’s why it’s so important right now to urge your Member of Congress not to pass any bill that reauthorizes Section 702 without substantial reforms.   

Take action

TELL congress: 702 Needs Reform

Section 702 is rife with problems, loopholes, and compliance issues that need fixing. The National Security Agency (NSA) collects full conversations being conducted by surveillance targets overseas and stores them, allowing the Federal Bureau of Investigation (FBI) to operate in a “finders keepers” mode of surveillance—they reason that it's already collected, so why can’t they look at those conversations? There, the FBI can query and even read the U.S. side of that communication without a warrant. The problem is, people who have been spied on by this program won’t even know and have very few ways of finding out. EFF and other civil liberties advocates have been trying for years to know when data collected through Section 702 is used as evidence against them.  

There’s simply no excuse for any Member of Congress to support a "clean" reauthorization of Section 702. Anyone who votes to do so does not take your privacy seriously. Full stop.  

The intelligence community and its defenders in Congress, as always, seem more interested in defending their rights to read your private communications than in protecting your right to privacy. It’s not really a compromise between safety and privacy if it's always your privacy that gets sacrificed. Now, we’re drawing a line in the sand: Congress cannot pass a clean extension.  

Use this EFF tool to write to your Member of Congress and tell them not to pass a clean reauthorization of Section 702.  

Take action

TELL congress: 702 Needs Reform

Claude is actually pretty good on the issues.

By attacking Iran, President Donald Trump has indirectly boosted an industry he has done his best to weaken in the U.S.

Energy Secretary Chris Wright said the retiring plants were needed to potentially save lives. None of them have generated power.

Approval of aid for Hawaii came one day after the new Homeland Security secretary vowed to address a backlog of requests.

The West Coast federal appeals court found the group of young people couldn't tie their alleged climate injuries to the agency's policies.

Prisoners and nonprofit advocates await a decision from a federal judge after asking him to declare state prison conditions unconstitutional.

Clean energy advocates are now the majority on the board of an Arizona utility giant, after the far-right group boosted voter turnout to record-smashing levels.

Bipartisan lawmakers warn a tighter emissions cap could drive up costs and industrial flight.

The Oregon Court of Appeals sent a class-action case against PacifiCorp back to a lower trial court over concerns about a jury instruction given during a 2023 trial.

Oil and gas firms complain the rules, designed to limit global warming, could jeopardize EU energy supplies.

Opposition lawmakers have labeled the legislation unconstitutional, contending that it rolls back essential environmental protections.

Nature Climate Change, Published online: 10 April 2026; doi:10.1038/s41558-026-02610-3

Since Nature Climate Change was launched, not only has the journal itself changed but so have the subjects of the studies we publish on the Earth system and how societies interact with it. In this Infographic, we highlight a few examples of how the world differed when we started in 2011 compared with today.

Nature Climate Change, Published online: 10 April 2026; doi:10.1038/s41558-026-02623-y

This month marks 15 years since the first publication of Nature Climate Change. Here, we reflect on how both the world and research have changed, and discuss the impacts of memorable climate change science published in our pages.

Nature Climate Change, Published online: 10 April 2026; doi:10.1038/s41558-026-02608-x

The North Atlantic is exceptional in cooling during the twentieth century while the world warmed. Here we look back on an influential 2015 study that linked this cooling to a weakening of the Atlantic Meridional Overturning Circulation and consider the wider implications that this may have for climate, ecosystems and society.

Nature Climate Change, Published online: 10 April 2026; doi:10.1038/s41558-026-02605-0

As Nature Climate Change celebrates its 15 year anniversary, we look back at some of the journal’s published works. In this Viewpoint, seven early-career researchers discuss how these papers influenced their research and careers.

Google moved up its estimated deadline for quantum preparedness in cryptography to 2029—only 33 months from now. That’s earlier than previous deadlines, and they proposed the new post-quantum migration deadline because of two new papers that comprise a big jump in the state of the technology. It’s ahead of schedule, but not altogether unexpected. Cryptographers and engineers have been working on this for years, and as the deadline gets closer, it’s not surprising to see more precise timeline estimates come up.

The preparation for the Y2K bug is not a perfect analogy. Like Y2K, if systems are not updated in time, anyone with a powerful enough quantum computer will be able to more easily insert malware into the core systems of a computer and fake authentication to allow impersonation merely by observing network traffic. These are the threats whose mitigation timelines have been moved up.

But unlike Y2K, there’s a second sort of attack that we already need to be prepared for: quantum computers will be able to decrypt years of captured messages sent over encrypted messaging platforms shared any time before those platforms updated to quantum-proof encryption. That type of attack has been the main focus of engineering efforts so far and mitigation is well on its way, since anything before the upgrade might eventually be compromised.

Fortunately, not all cryptography is broken by quantum computers. Notably, symmetric encryption is quantum resistant. That means that if you have disk encryption turned on, you shouldn’t have to worry about quantum computers breaking into your phone, as long as your system’s keys are long enough. The problem is how you get the keys to do that encryption, and how you authenticate software on your device and in the cloud.

Engineers: Time to Lock In

For those whose work touches on any sort of cryptographic deployment, you’re hopefully already working on the post-quantum transition. If not, you really should be; there are quite a few relevant posts and updates with more information about what this news means for you. Your key agreement systems should be upgraded soon if they’re not already because of store-now-decrypt-later attacks. Now it’s time to prepare for authentication attacks on forged signatures as well.

In some cases, you may need to wait on others to finish their work first. If you’re using NGINX to host websites on Ubuntu, for example, the security settings you need to upgrade key agreement were just released in version 26.04. Updates are rolling out, so keep checking in and upgrade your systems as soon as you’re able to.

Users: Stay Updated, Check on Your Chats

But if you’re not in any position to be updating software or hardware, there may be some additional steps you can take to make sure you're as protected as possible. You’ll want to get the latest post-quantum protections as soon as they're available, so if you don't already have a habit of applying software updates in a timely manner, now’s a good time to start.

If you want to know if the website you’re using or the encrypted messaging app you’re chatting over will leak its data in a few years to anyone storing traffic now, you can search for its name with the word "quantum." The engineers are usually pretty proud of their work and have announced their post-quantum support (like what we’ve seen from Signal and iMessage). If you can’t find that information, you may want to have extra consideration for what you say over the internet, or switch the tools you're using. Those are the big areas to worry about now, before quantum computers are actually here, because they could result in the mass leakage of old messages.

The new deadline means that some technologies are simply not going to make it in time and will have to be left by the wayside, like trusted execution environments (TEEs), due to the slower speed of hardware deployments. TEEs are how companies do private processing on user data in the cloud, and they’re particularly relevant to AI offerings. 

Even now, though they offer more protection than processing data in the clear, TEEs are not as secure as homomorphic encryption or doing the processing on device. Post-quantum, the security level gets much closer to computation on cleartext, and even with strong user controls, that makes it way too easy to accidentally backdoor your own encrypted chats. If you’re worried about the contents of messages in an encrypted chat being exposed, you’ll probably want to completely avoid using AI features that might leak that content, such as summarization of recent chat history and notifications, and reply composition assistance. 

How’s the Transition Going So Far?

The work to update the world to post-quantum is well on its way. NIST finalized the standards for post-quantum cryptographic algorithms back in 2024. The larger platforms, websites, and hosting providers have already updated their algorithms, so even now, you’re probably already using post-quantum algorithms to access some of the internet. Measurements vary pretty widely, but up to about 4 in 10 websites currently support a post-quantum key exchange.

There’s still some work to be done in figuring out how to make the needed changes—for example, the way you find out a website’s private key to make HTTPS possible is being reworked to make room for larger signatures. Some technologies are just coming to market, like the post-quantum root of trust available now in some Chromebooks. In practice, this means that as you think about replacing your current devices in the next few years, you may want to check if you’re picking up hardware that has post-quantum support, if those specific protections are required for your threat model.

For the areas that still need updating, how much can we expect to actually get ready by the new deadline? It’s likely that not every cryptographically-capable device and deployment will be ready in time, and hardware with hard-coded certificates will probably be the last to update. We saw that happen when SHA-1 was deprecated; Point of Sale systems in particular were late adopters. While governments and large companies with quantum computers may not be interested in stealing money from cash registers, they will be interested in accessing secrets about people’s private lives. That’s why it’s so important that everyone does their part to upgrade, to protect the details of private communications and browsing. 

And there’s a good chance that older devices that won’t receive quantum-resistant updates were probably vulnerable to some other attack already. Quantum computation is just one type of attack on cryptography that’s notable for the scale of migration required, and how every public-key cryptosystem and authentication scheme has to do the work to prepare. That’s not a difference in kind, it’s a difference in scale, and some systems will inevitably be left behind.

Quantum preparedness hits different industries and services in different ways, but services that handle communications and financial information are particularly susceptible to risk, and need to act quickly to protect the privacy and security of billions of people.

Millions of students nationwide use text-supplemented audiobooks, learning tools that are thought to help those who struggle with reading keep up in the classroom. A new study from scientists at MIT’s McGovern Institute for Brain Research finds that many students do benefit from the audiobooks, gaining new vocabulary through the stories they hear. But study participants learned significantly more when audiobooks were paired with explicit one-on-one instruction — and this was especially true for students who were poor readers. The group’s findings were reported on March 17 in the journal Developmental Science.

“It is an exciting moment in this ed-tech space,” says Grover Hermann Professor of Health Sciences and Technology John Gabrieli, noting a rapid expansion of online resources meant to support students and educators. “The admirable goal in all this is: Can we use technology to help kids progress, especially kids who are behind for one reason or another?” His team’s study — one of few randomized, controlled trials to evaluate educational technology — suggests a nuanced approach is needed as these tools are deployed in the classroom. “What you can get out of a software package will be great for some people, but not so great for other people,” Gabrieli says. “Different people need different levels of support.” Gabrieli is also a professor of brain and cognitive sciences and an investigator at the McGovern Institute. 

Ola Ozernov-Palchik and Halie Olson, scientists in Gabrieli’s lab, launched the audiobook study in 2020, when most schools in the United States had closed to slow the spread of Covid-19. The pandemic meant the researchers would not be able to ask families to visit an MIT lab to participate in the study — but it also underscored the urgency of understanding which educational technologies are effective, and for whom.

“What we were really concerned about as the pandemic hit is that the types of gaps that we see widen through the summers — the summer slide that affects poor readers and disadvantaged children to a greater extent — would be amplified by the pandemic,” says Ozernov-Palchik. Many educational technologies purport to ameliorate these gaps. But, Ozernov-Palchik says, “fewer than 10 percent of educational technology tools have undergone any type of research. And we know that when we use unproven methods in education, the students who are most vulnerable are the ones who are left further and further behind.”

So the team designed a study that could be done remotely, involving hundreds of third- and fourth-graders around the country. They focused on evaluating the impact of audiobooks on children’s vocabularies, because vocabulary knowledge is so important for educational success. Ozernov-Palchik explains that books are important for exposing children to new words, and when children miss out on that experience because they struggle to read, they can fall further behind in school.

Audiobooks allow students to access similar content in a different way. For their study, the researchers partnered with Learning Ally, an organization that produces audiobooks synchronized with highlighted text on a computer screen, so students can follow along as they listen.

“The idea is, they’re going to learn vocabulary implicitly through accessing those linguistically rich materials,” Ozernov-Palchik says. But that idea was untested. In contrast, she says, “we know that really what works in education, especially for the most vulnerable students, is explicit instruction.”

Before beginning their study, Ozernov-Palchik and Olson trained a team of online tutors to provide that explicit instruction. The tutors — college students with no educational expertise — learned how to apply proven educational methods to support students’ learning and understanding of challenging new words they encountered in their audiobooks.

Students in the study were randomly assigned to an eight-week intervention. Some were asked to listen to Learning Ally audiobooks for about 90 minutes a week. Another group received one-on-one tutoring twice a week, in addition to listening to audiobooks. A third group, in which students participated in mindfulness practice without using audiobooks or receiving tutoring, served as a control.

A diverse group of students participated, spanning different reading abilities and socioeconomic backgrounds. The study’s remote design — with flexibly scheduled testing and tutoring sessions conducted over Zoom — helped make that possible. “I think the pandemic pushed researchers to rethink how we might use these technologies to make our research more accessible and better represent the people that we’re actually trying to learn about,” says Olson, a postdoc who was a graduate student in Gabrieli’s lab.

Testing before and after the intervention showed that overall, students in the audiobooks-only group gained vocabulary. But on their own, the books did not benefit everyone. Children who were poor readers showed no improvement from audiobooks alone, but did make significant gains in vocabulary when the audiobooks were paired with one-on-one instruction. Even good readers learned more vocabulary when they received tutoring, although the differences for this group were less dramatic.

Individualized, one-on-one instruction can be time-consuming, and may not be routinely paired with audiobooks in the classroom. But the researchers say their study shows that effective instruction can be provided remotely, and you don’t need highly trained professionals to do it.

For students from households with lower socioeconomic status, the researchers found no evidence of significant gains, even when audiobooks were paired with explicit instruction — further emphasizing that different students have different needs. “I think this carefully done study is a note of caution about who benefits from what,” Gabrieli says.

The researchers say their study highlights the value and feasibility of objectively evaluating educational technologies — and that effort will continue. At Boston University, where she is a research assistant professor, Ozernov-Palchik has launched a new initiative to evaluate artificial intelligence-based educational tools’ impacts on student learning.