Around 1.3 billion years ago, two orbiting black holes smashed into one another and set loose ripples in the fabric of space-time. These gravitational waves raced through the universe at the speed of light. Eventually, those rippling waves would set off a tiny shift in the distance between two pairs of mirrors monitored with laser beams at the heart of the underground Laser Interferometer Gravitational-Wave Observatory (LIGO). This triggered the 2015 announcement of the first observation of Albert Einstein’s predicted gravitational waves. 

It was the moment Emanuele Berti, a professor in the William H. Miller III Department of Physics and Astronomy, had been waiting for. Berti had been researching gravitational waves and working to merge that research with modern-day astronomy since his time as a physics student at the Sapienza University of Rome in the late 1990s. He was in a field where scientists had been trying unsuccessfully to detect gravitational waves since the 1950s. 

“It was life changing,” he says simply. “It’s the best feeling you could have— you know, my life was not in vain. And now let’s get as much science as we can out of this.” 

Like the Plucking of a Guitar

Berti was recently awarded the 2023 American Physical Society’s Richard A. Isaacson Award in Gravitational-Wave Science for his work on black holes and gravitational waves. In addition to pioneering connections between physicists and astronomers who were working on gravitational-wave studies, Berti was one of the first people to explore in depth how to test the theory of general relativity using gravitational waves. He published a foundational paper for using LIGO to analyze black holes via spectroscopy. He also explored how to use gravitational waves to study the history of how stars evolve, form binary systems, turn into compact objects (such as neutron stars or black holes), and eventually merge. 

Gravitational waves occur when massive, accelerating bodies—such as black holes or neutron stars—orbit each other. Berti likens the waves they give off to the plucking of a guitar. But instead of hearing the oscillation of a string, you’re experiencing the oscillation of space time. 

And just as a musician can tell the shape and material of a drum from the sound of it being played, a scientist can determine the properties of an object from its gravitational waves. All black holes should give off identical gravitational waves because they are simple objects characterized only by their mass and rotation. Because black holes devour light and can only be observed by the behavior of the material swirling around them, gravitational-wave observations allow scientists to discover, for instance, whether a suspected black hole truly is a black hole—or some other type of astronomical object. 

“All black holes play the same music, and once we know the mass and the spin, all the tones each black hole plays have to be the same,” Berti says. 

All black holes play the same music, and once we know the mass and the spin, all the tones each black hole plays have to be the same.”

—Emanuele Berti

A New Understanding

Knowledge about the role of gravitational waves in physics and astronomy will only increase as the future detectors and observatories come online. Berti is a member of the U.S. NASA study team contributing to the European Space Agency’s upcoming Laser Interferometer Space Antenna. It’s a trio of satellites that will detect gravitational waves from space, and he is working on the science case for the next generation of ground-based detectors. 

So far, LIGO evidence points to the black holes observed as being black holes—as Einstein thought. But gravitational waves aren’t just important because they tell us Einstein was right. They’re important because someday they might tell us Einstein was wrong. 

Einstein’s theory of general relativity has governed humanity’s understanding of gravity for decades. But mysteries like the presence of invisible dark matter and now dark energy—an unknown force speeding up the expansion of the universe—hint at possible flaws that could eventually pave the way to a new theory. If that happens, gravitational wave studies could be at the forefront. 

“The dream would be to break general relativity and maybe find clues to a new theory that will explain all these things,” Berti says. 

Art history professor Stephen J. Campbell has been teaching about Leonardo da Vinci for 20 years at the Krieger School of Arts and Sciences. Throughout his academic career, he’s seen interest in the Italian Renaissance artist and inventor explode with the growing value of Leonardo’s work at auction houses, the fervor created by Dan Brown’s The Da Vinci Code, and the boom in biographies that followed. 

At the same time, Campbell has observed with some trepidation how biographers have increasingly veered from verifiable fact into presumption. Sometimes, transforming the historic figure into an almost fictitious one. 

“With these invented Leonardos that have come down since the 1500s to the present time, writers liberally fill in the gaps with conjecture, and conjectures that build on conjecture,” says Campbell. The lack of historical rigor has troubled the historian, and he’s found it difficult to locate texts on Leonardo’s life suitable for sharing with his students. 

Pop Culture Problem

That’s why he decided to write Da Vinci Worlds: Towards an Anti-biography of Leonardo. The book explores the different ways Leonardo has been handled in 21st-century popular culture. It looks at how biographers make speculative psychological leaps to make him fit the mold of a 21st-century “genius”—an outsider figure, a bit obsessive, a social non-conformist. 

It is a problematic endeavor, says Campbell. As with most artists of the Renaissance, not much is known about the private life of Leonardo da Vinci, despite his numerous notebooks. “In them, Leonardo doesn’t tell us anything about himself. He doesn’t write about his own life,” says Campbell. “There’s very little biographical information. It doesn’t resolve into the holistic celebrity some of us want him to be.” 

With these invented Leonardos that have come down since the 1500s to the present time, writers liberally fill in the gaps with conjecture, and conjectures that build on conjecture.” 

—Stephen J. Campbell

Leonardo’s writings were a critical component of Campbell’s research process. He finds himself constantly reminded of their power for the reader. “Every time you return to them, it’s extraordinary in the sense that you get multiple voices and multiple selves talking to each other,” says Campbell. “Leonardo is an intersection of maker, problem solver, engineer, painter, and someone who lays claim to the role of philosopher. Many of his academic contemporaries would not have agreed with that description.” 

That’s made more powerful because the texts were often written in the second person, as if speaking to the reader. Campbell thinks therein lies part of the reason many feel compelled to flesh out the missing details of his life. “People think something has been whispered to them, some kind of mystery has been divulged,” he says. 

Ethics of the Past

Campbell says we tend to view Leonardo through a modern lens and risk turning him into something he’s not. “Our models of biography right now didn’t exist in Leonardo’s time,” he says. We invent “da Vincis” to fit the mold of contemporary celebrity—to be the equivalent of a tech visionary like Steve Jobs, to be an isolated and persecuted gay man, to suffer from attention deficit disorder, or to precociously be a vegan. 

By highlighting these tendencies in his book—which is expected to go into production this fall—Campbell hopes readers will realize how Leonardo has been repurposed to fit current interests. 

“There’s a whole ethics of approaching the past that I want people to confront while reading this book,” says Campbell. He also hopes his book serves as a caution to future biographers. “Be aware of when you are projecting and know how to signal that in your writing. Be very self-conscious about when you are doing that and why you need to do it.” 

Anyone who follows the news—and cares about the health of our planet —can understand Ying Chen’s focus. 

The associate professor in the Department of Economics couldn’t help but notice that environmental regulations enacted under one U.S. presidential administration were often reversed by the subsequent one. That made progress difficult, to say the least. 

“Just in the last two terms, [President Donald] Trump reversed a lot of environmental regulation when he was in power,” she says. “And then when [President Joseph] Biden came to power, he reversed the reverses.” 

Chen chose to investigate the challenges of an elected official who is committed to long-term goals and aware of policymaker turnover. She applied her expertise in game theory to identify a sensible long-term strategy that acknowledged the political realities. Her efforts, to date, suggest that leaders can improve their effectiveness—even against intense political opposition—by focusing on investments in innovations. 

“If you innovate and lower the cost of green options, the newfound incentives to go green will persist even if you are subsequently out of power,” she says. 

Games for a Complex System

Chen came to the United States from China to earn a PhD in economics from Yale University. While there, she developed an interest in game theory. Game theory is the idea of creating mathematical models of strategic interactions between rational agents. 

The economy, she says, “is such a complex system, with so many different interdependent components. I liked the challenge of coming up with a relatively rigorous way of thinking about the interactions.” 

[The economy] is such a complex system, with so many different interdependent components. I liked the challenge of coming up with a relatively rigorous way of thinking about the interactions.” 

—Ying Chen

After an appointment at Arizona State University, she joined the Johns Hopkins faculty in 2014. Some of her previous research has focused on the nuances of strategic communication and budget negotiations. 

She plans to submit the paper, titled “Irreversible Investment in Technology and the Dynamics of Public Good Provision,” for publication this summer. Though it uses environmental policies as an example, her idea applies to many other public goods, she says. 

Seeing Payoffs

Stepping back from mathematical modeling, Ying sees support for her theory in both the substantial gains in government-supported green innovations, and in the growth of public support, once the general public came to appreciate the payoffs of such efforts. Case in point: Wind and solar tax credits have persisted through several changes in power in Washington. 

In 2012, President Obama wanted to extend the credits, first enacted in 1992. Many members of the Republican-controlled Congress were opposed. They did not want to give Obama a win, and they did not support a market intervention that favored clean energy. Despite these political obstacles, the credit extension won approval. A few years later, during negotiations of the Republican tax reform in 2017, a rollback of the credits was brought up, but they were largely preserved in the end. 

Chen’s research offers an explanation: Those tax credits, combined with new technologies, were starting to deliver real cost savings. Reversing those advances is just about impossible, no matter which way the political winds blow. 

When you go to the beach and look out on the ocean, the sensations are of a serene vista that stretches to the horizon and beyond. But that’s not the case for David Guggenheim, because he knows what’s under those waters. 

Guggenheim, who puts on scuba gear the way most slip into a jacket, has spent decades watching the devastation and destruction that has gone on beneath the waves. He has seen species disappear both from overfishing and mysterious environmental causes; he has seen canyon-like scars along delicate reefs gouged by the weights of huge trawling nets; he has seen a surfeit of nutrients from the runoff of fertilizer and excrement—animal and human— feed algae that blots out the sun; he has seen waters warmed by climate change bring about myriad shifts in the undersea world; most of all, he has seen the spectacularly beautiful coral reefs that he first encountered as a teenager virtually disappear in his lifetime. 

And he has written a book about it. What’s surprising is that the message Guggenheim wants to deliver is one of hope. “It’s not too late” is what this adjunct professor in Johns Hopkins’ Advanced Academic Programs tells readers in The Remarkable Reefs of Cuba: Hopeful Stories From the Ocean Doctor. 

How the Reefs of Cuba are Different

The title of the book is a bit misleading. Certainly, it does tell a remarkable story about coral reefs off Cuba. But that is really only one part of a book that is everything from an autobiography of a life spent in service to the world’s oceans—he’s former vice president of the Ocean Conservancy and founded the nonprofit Ocean Doctor—to a very accessible explanation of the delicate balance required to maintain undersea ecosystems, to a history of post-Castro Cuba’s politics and agriculture, to an at times hilarious explication of the Kafka-like bureaucracies one encounters as a U.S. citizen trying to work in Cuba. 

Those frustrations were worth it because of what Guggenheim found off Cuba’s coast, he says. It was coral of the type that he first saw as a teenager at a marine education center in the Florida Keys called Seacamp that spawned a number of marine scientists like Guggenheim, who went on to get a PhD from George Mason University. One of the common experiences there was painful: stepping on the spines of a black sea urchin called a Diadema. They were ubiquitous on coral reefs in the Caribbean and then, mysteriously, they disappeared, taking with them their ability to clean those reefs of algae.

That was only one of many indignities suffered by these reefs in recent decades, their decline not only robbing divers and snorkelers of an incomparable aesthetic experience, but also fish of breeding grounds, coastlines of protection from storms, and oceans of a key component of their ecosystem. Which is why it was stunning when Guggenheim found seemingly pristine coral off the coast of Cuba, where he has traveled over 100 times in the last two decades, spending a total of more than two years there. 

We’ve helped the Cubans be proud of their healthy reefs, with good reason to show them off to the rest of the world, something important for a nation very conscious of their magnified presence on the international stage.” 

—David Guggenheim

How to Build on Success

The reason those reefs survive is a complicated story involving international politics, in particular the dissolution of the Soviet Union, which supported Cuba’s economy for three decades after Fidel Castro took over in 1959. The simple version: without that support, Cuba’s farmers could not afford fertilizer, instead growing beautiful organic crops. With no fertilizer running off into the Caribbean, the reefs were not choked with algae and flourished as in days of old. On his dives—one with Anderson Cooper for a story on 60 Minutes—Guggenheim has seen reefs flourishing even in warming waters that have bleached them in other parts of the world. 

Bottom line: Cuba has shown us what is possible. That’s the hopeful message of The Remarkable Reefs of Cuba. Guggenheim knows the situation is fragile. The loss of Soviet support led to what’s called the Special Period in Cuba, an underreported time of incredible deprivation. An improving economy could bring back industrial-style agriculture that would be bad news for the reefs. But Guggenheim has come across many Cubans who don’t want to spoil what they have. 

“The key is to help them build on all the successes they’ve had so they don’t follow our example and destroy those reefs,” he says, noting the potentially huge economic impact of tourism that a pristine ecology can bring. “I think we’ve helped the Cubans be proud of their healthy reefs, with good reason to show them off to the rest of the world, something important for a nation very conscious of their magnified presence on the international stage.”