If you ever have two hours to kill in Cambridge, Massachusetts, skip the museums and take a seat looking onto the sidewalk. Listen for laughter and plans being hatched; watch for lots of texting and Google Maps-orienting. At least that’s what Carlo Ratti recommends. “It’s like you do in Paris,” he said. “Just observe the life unfolding before you”—online and in the flesh.

People-watching may have been a slightly wistful tip. On a daffodil afternoon made more spectacular by an earlier forecast of rain, Ratti was stuck inside a glass-walled conference room at MIT’s Department of Urban Studies and Planning, taking team meetings, client phone calls, and media interviews.

Then again, this was the Senseable City Lab, the MIT think-tank where Ratti, an Italian engineer, architect, educator, and inventor, is the director. It’s where some of the world’s sharpest minds come to observe and tinker with 21st-century cities.

Composed of six investigators and dozens of researchers, the lab studies human interactions within urban spaces, and how digital information and interfaces can shape and illuminate them. Across a range of subjects—trees, sewage, bikes, on-demand vehicles—Ratti and his team publish papers, test robots and artificial intelligence, and occasionally spin off their work into startups and business ideas. Ratti also leads the Carlo Ratti Associati, an international design and innovation firm whose real-world projects play with interaction via sensors and data. If there’s a thread that links this all together, it is his fascination with, and optimism about, the dynamism of urban life in an ever-more connected era. “The digital and physical worlds are converging,” Ratti told me. “What interests me is, how do we use all of this potential to create new kinds of dynamics?” It’s people-watching, plus.

Through his research, innovation, and writing, Ratti evangelizes the concept of a “real-time city,” where physical and social networks are in constant interplay, knitted together by a layer of digital sensors. In Ratti’s future metropolis, streets, buildings, and objects sense and respond to the movements of the smartphone-equipped masses using powerful algorithms. But while other “smart city” acolytes preach the social-engineering capabilities of such technologies, Ratti’s is a more playful approach: Make tweaks, and let them ripple.

Just before our interview, Ratti had met with fellow lab members to review their progress on the Roboat, one of their latest endeavors. Later this summer, in a collaboration with technologists in Amsterdam, they’ll deploy prototypes of the world’s first fleet of autonomous boats. These would not only transport goods and people on Amsterdam’s canals sans captain, but also gather remote environmental data and reassemble into bridges on command, Transformers-style. A model roughly the size of a large suitcase sat on the opposite wall, all translucent plastic and glittering motherboards.

Roboat is a typical lab project in a couple of ways, first in that it is another entry into the “internet of things,” those blinking, scanning, wifi-connected objects that increasingly blanket our homes, cars, and public spaces. And second, the Roboat isn’t designed to solve anything, per se. It’s more like a proposal, with lots of different use cases.

The same goes for another recent and high-profile Lab project, “Underworlds,” which sent robotic waste-samplers into the sewers of Cambridge. The probes (one fat, one short, nicknamed Mario and Luigi for their pipe-hopping personalities) scanned sewage samples in near real-time, which MIT microbiologists examined for signs of viruses and substance abuse. With that, they built a city-wide health map that public health officials could tap into. The proof of concept conducted in Cambridge was so successful that the project spun off into Biobot, a startup partnering with cities around the U.S. to hunt for traces of opioid abuse using similar sewage-mucking robots.

Biobot is now publicized as an innovative, tech-based response to a most pressing public health crisis. But when it started, Ratti told me, it was more open-ended. “It wasn’t supposed to solve anything. It was more like, what we can discover?” he said. “And actually, it turns out there is a lot of valuable information in sewage.”

For Ratti, urban design isn’t about directly addressing problems. The way he sees it, cities just don’t work that way. He sees architecture and civic innovation as parts of a city’s larger social and infrastructural webbing. Whether it’s a high-rise, a vehicle, or a boat-based probe, introducing new objects into the urban landscape can cause network-wide shifts that designers can’t always foresee. Design, therefore, should not seek to control. Instead, it should tap into the natural human flows you might witness from the nearest city square or riverbank.

After gathering civil engineering degrees in both Paris and Turin, Ratti earned his Ph.D. in architecture from the University of Cambridge, outside of London. A Fulbright scholarship brought him to MIT in 2001, where he has more or less stayed ever since. On the day we met, Ratti dressed the part of perpetual grad-student: wire-rimmed glasses, slightly mussed hair, jeans frayed at the bottom by thin-soled, low-top tennis shoes. He bridles at any one label to describe his work. “It’s sort of like the guy says in the film by Truffaut, Jules et Jim: Be curieux aux profession—curious by profession,” he told me.

It’s his horizontal, more participatory vision of the future of cities—not to mention his glitzy, media-friendly projects—that have made Ratti influential as an urban innovator and theorist. Over the past ten years, his work has landed him on “best and brightest” lists from Fast Company, Wired, Esquire, Forbes, and numerous architectural magazines. He has delivered multiple TED talks, and has authored more more than 500 scientific publications. Recent books, including Open-Source Architecture and The City of Tomorrow: Sensors, Networks, Hackers, and the Future of Urban Life, are manifestos that call for and lay out a vision of how digital interfaces can make cities more open, engaging, and democratic places to live. The latter book imagines the metropolises of the coming centuries as fully sensory and responsive, with digital and physical networks and interfaces “overlapping with, and including, its inhabitants,” wrote the critic and scholar of visual culture Richard J. Williams in his review of the book.

The work of Carlo Ratti Associati speaks to that future: For design expos around the world, the group has built a climate-controlled “garden pavilion” in which all four seasons can be experienced, a “supermarket of the future” where products come digitally labeled, and a gazebo with motion-detecting cascades of water for walls. A yet-unbuilt project: a proposal for the future of Italian highways, featuring a network of telephone poles outfitted with nesting drones that communicate with driverless vehicles. Another project is manufacturing a drone capable of drawing any preprogrammed design, pattern, or image onto wall surfaces, called Scribit. What excites him most about these works, Ratti told me, is that he more often gets a chance to see how the public will react.

Already, smartphones, connected vehicles, and “smart” energy systems churn out an unprecedented amount of data about how we live, move, and consume resources; Ratti foresees a future where that data is open and accessible to all, so that all may participate in building “smarter” cities. He dispenses with the notion that one planner or starchitect could possibly hold the answer to a more efficient, liveable environment—the “great man” theory of 19th and 20th-century urban planning. “People would come up a solution, and they thought it was just going to be implemented and that was that,” Ratti told me. Block by block, byte by byte, digital networks can restore urbanism to its more iterative roots, where residents help build the cities they live in, he believes.

At least in theory. In old interviews from the early 2010s, Ratti praised the Obama campaign’s savvy use of Facebook and Twitter to engage and energize voters. Now, in the era of Trump, in the wake of the Cambridge Analytica Facebook data scandal, I asked him if widespread access to big data across social networks doesn’t look a little more nefarious. He responded that both can be true: that the same technology, and the same types of data, can be used to have opposite results: empowerment or manipulation. “The difference is our response in society—policies, taxation, and so on—and how we make sure we end up on one side or another,” Ratti said. “We have to be vigilant.” Not just regulators, he added, but the citizens themselves. The new data privacy standards introduced this month in the E.U. should bring a stronger measure of egalitarianism to data control, he said.

But in the American context, at least right now, it feels simplistic to expect that “citizens” will organize themselves around technology to build a more desirable social order. Political polarization is increasing, as is economic segregation and inequality, gaping issues that Ratti’s research is not designed to address. “I don’t think that the answer lies in any of the smart devices or computers or networks we currently have,” said Michael Batty, an emeritus professor of planning at University College London’s Centre for Advanced Spatial Analysis. “The issues are behavioral, not technological; they involve social networks primarily. This is not the major preoccupation of Carlos’s group.” And since the Senseable City Lab mostly develops one-off projects and research questions, it’s hard to point to long-term, lasting results or evolutions in human/urban interactions.

Ratti likes to talk about civic engagement implications of his work, but he becomes a little less convincing when he does. Writing about the book Open Source Architecture, Flora Samuel, a professor of architecture at the University of Sheffield, took issue with Ratti and his co-author Matthew Claudel’s lack of detail about how the world might, for example, scale up the concept of a WikiHouse”—i.e., blueprints for a reproducible structure that anyone can “edit” and build—so that it’s accessible to all tiers of society. “How this is to be achieved without a private income I do not know,” she wrote.

Yet Ratti insists that the gaps are closing, not widening, for people trying to access these digital interfaces. He told me how, when he first came to MIT in the early 2000s, some of the older professors were ruffled by his use of cell-phone data to study urban activity. “Some of them said, ‘not everyone has a cell-phone, so why don’t you do something that tries to close that divide instead?’” he recalled. Soon, there will be more cellphones than humans on the planet.

It’s the long-term impacts that count, Ratti told me. “I like to see our work as something that contributes to the production of mutations, accelerating the transformation of the present into how it ‘ought to be’,” he told me later via email. “You could say that designers are like the mutagens,” he said, using the term for the agents that cause mutations in DNA, evolving life over time. There is no one finite outcome.

If he had to do it all over again, Ratti told me he’d go into biology, to study how the convergence of technology will shape human life at the cellular level. As it is, he views cities as akin to living, breathing, circulating organisms—even and especially as computers are integrated into them. He harkened back to Mesopotamia, some 8,000 years ago, where archaeologists peg the first emergence of urban life. “Even then, cities emerged to bring us together, to allow us to exchange goods, ideas, and chromosomes,” he said. That’s the magic of the city. To Ratti the optimist, the machines of the digital era—big data, remote sensing, artificial intelligence—are beginning to unlock its codes.

The story also appears in London ideas, a journal on urban innovation by Centre for London.