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In the paper, published Friday in Science Advances, the researchers lay out the anatomical changes that took place in many reptile groups, including the forerunners of crocodiles and dinosaurs, concentrated between 260 to 230 million years ago.

The study provides a close look at how a large group of organisms evolved because of climate change, which is especially pertinent today amid rising global temperatures. In fact, the rate of carbon dioxide released into the atmosphere today is about nine times that seen in the period that culminated 252 million years ago in the biggest climate-change-driven mass extinction ever: the Permian-Triassic mass extinction.

“Major shifts in global temperature can have dramatic and varying impacts on biodiversity,” said Pierce, Thomas D. Cabot Associate Professor of Organismic and Evolutionary Biology and curator of vertebrate paleontology in the Museum of Comparative Zoology. “Here we show that rising temperatures during the Permian-Triassic led to the extinction of many animals, including many of the ancestors of mammals, but also sparked the explosive evolution of others, especially the reptiles that went on to dominate the Triassic period.”

The study involved nearly eight years of data collection along with loads of camerawork, CT scanning, and passport stamps as Simões traveled to more than 20 countries and 50 different museums to take scans and snapshots of more than 1,000 reptilian fossils.

The researchers created an expansive data set that was analyzed with state-of-the-art statistical methods to produce a diagram called an evolutionary time tree. That helped researchers see how early reptiles were related to each other, when their lineages first originated, and how fast they were evolving. They then overlaid it with global temperature data from millions of years ago.

Diversification of reptile body plans started about 30 million years before the Permian-Triassic extinction, making it clear these changes weren’t triggered by the event, as previously thought. The extinction events did help put them in gear though.

The data set also showed that rises in global temperatures, which started about 270 million years ago and lasted until at least 240 million years ago, were followed by rapid body changes in most reptile lineages. For instance, some of the larger cold-blooded animals evolved to become smaller, allowing them to cool down easier; others evolved to life in water. The latter group included some ill-fated reptiles that would eventually become extinct, such as a giant, long-necked marine reptile (like the modern conception of a Loch Ness monster); a tiny, chameleon-like creature with a bird-like skull and beak; and a gliding reptile resembling a gecko with wings. It also includes the ancestors of reptiles that still exist today, such as turtles and crocodiles.

Smaller reptiles, which gave rise to the first lizards and tuataras, traveled a different path than their larger reptile brethren. Their evolutionary rates slowed down and stabilized in response to the rising temperatures. The researchers believe it was because the small-bodied reptiles were already better adapted to rapidly rising temperatures.

The researchers say they are planning to expand on this work investigating the impact of environmental catastrophes on evolution of organisms with abundant modern diversity, such as the major groups of lizards and snakes.

Mincheol Park — an international student from South Korea who has a joint concentration in chemistry, physics, and math — is working on the theoretical side of quantum science. The rising junior is trying to produce a protocol to implement error-correcting codes for quantum processors that exist today. He’s valued the mentorship working full-time in the lab of physicist Mikhail Lukin. Park said he’s learned a lot from graduate students in the lab about how to prioritize work and what to do when something isn’t working. It also helps to hear about their career paths.

“It’s really good that I am able to learn this kind of lifestyle this early after my second year of college,” Park said.

The HQI undergraduate fellowship hosts a series of lunches for the fellows to network with other fellows and learn about each other’s work, as well as unwind and bond over their shared summer experience. There is also a poster session where the students present their work to the larger HQI community.

“It was an unexpected community this summer,” said Cassia Lee, a rising junior in Eliot House concentrating in chemistry and physics. “It’s easy to focus on your work and be in your own bubble, but it was really good to take a step back and see what everyone is doing.”

Standing at the poster session amid the different projects and diverse group of students, Doyle reflected on another of the key points of the fellowship: students pushing themselves to their limits and beyond.

“Generally, students are able to rise to whatever level of capabilities they have,” Doyle said. “In the lab, there is no upper limit. They can go as far as they want.”

WASP-39 b was already on scientists’ radar. In 2018 NASA’s Spitzer Space Telescope revealed hints of carbon dioxide in its atmosphere. Previous observations from other telescopes had revealed water vapor, sodium, and potassium.

Thus the exoplanet was the ideal candidate for a follow-up using the new and improved JWST, said López-Morales.

Another factor: WASP-39 b is a transiting planet. During a transit, some of the starlight is eclipsed by the planet completely, causing overall dimming, and some is transmitted through the atmosphere. The atmosphere filters out some colors more than others depending on what it is made of, how thick it is, and whether there are clouds. Because different gases absorb different combinations of colors, researchers can analyze small differences in brightness of the transmitted light across a spectrum of wavelengths to determine the exact make-up of an atmosphere.

In this case, the resulting spectrum scientists obtained was significant: the first clear, detailed, indisputable evidence for carbon dioxide ever detected in a planet outside our solar system.

“The remarkably strong signal is a testament to [JWST’s] exquisite precision and revolutionary wavelength range, and demonstrates how much we stand to learn from this awesome observatory,” Kirk said.

In early 2016, a team led by Capasso, with key contributions by Khorasaninejad, graduate student Rob Devlin, and postdoc Wei Ting Chen, showed that it indeed could be done and done well enough that commercial devices were possible. Capasso filed a report of invention with the Harvard Office of Technology Development and, soon after, the discovery made Science’s cover. Gordon, OTD’s director of business development for physical sciences, stepped in to manage the avalanche of interest.

“I’ve been doing this for far longer than I like to admit but that paper, the invention, and the patent we filed generated far more commercial interest — from companies, entrepreneurs, investors — than any other hard-tech invention I can remember,” said Gordon. “It was exciting and a bit shocking. We met and talked with a lot of people about this work.”

Those people understood then what Capasso had seen more than a decade earlier. Lenses are essential components in a host of devices, focusing and detecting light — both visible and invisible — for applications well beyond imaging, including facial recognition in smartphones and laptops, proximity and gesture detection to enhance responsive functions in automated devices, depth-sensing cameras, environmental awareness in drones and robots, and collision avoidance in self-driving cars.

In many of those devices, space is tight. The stacked elements of plastic or glass in traditional lenses have resisted the true miniaturization that most other components have undergone. They remain among the bulkier components, and a bottleneck in device design.

“I hold up my cellphone and pull out a credit card,” Gordon said, describing how he introduces the technology to potential investors. “There are only two reasons the phone is not as slim as the credit card. One is the camera and the other is the battery. The metalens will help enable the phone to be as slim as a credit card.”

While traditional lenses use curved glass or plastic to bend light and focus an image, a metalens uses a series of tiny pillars on a millimeter-thin wafer. The pillars are smaller than the wavelength of light and transparent to the desired wavelength. The pillars’ shape, the distances between them, and their arrangement on the wafer are varied to bend light as desired.

Not long after that Science cover, OTD licensed the technology to a startup, Boston-based Metalenz, founded by Capasso, Devlin, and Bart Riley, a tech entrepreneur with whom that office had previously worked. Now Metalenz’s chief executive, Devlin made a key materials advance in the Capasso lab that greatly improved the lenses’ efficiency. Earlier this year, Metalenz logged its first major sale, with manufacturer STMicroelectronics. STMicro will use metalenses in the company’s “time of flight” modules, which provide 3D sensing in an array of devices and which have previously sold 1.7 billion units. Those units appear in everything from drones to robots to smartphones. Metalenz said in June that it expects its optical components to be in millions of consumer devices this year.

Khorasaninejad, who today is CEO and cofounder of San Francisco-based Leadoptik, called the deal “a very, very strong endorsement from industry,” while Capasso said that the metalens can be made in the same factories as computer chips is potentially “game-changing,” as it unifies two industries: semiconductor manufacturing and lens-making.

“The same planar technology, known as deep ultraviolet lithography, to mass-produce integrated circuits — chips — can be used by the same foundry to make flat optics such as metalenses,” Capasso said. “It means that the entire camera module of a cellphone or laptop will eventually be manufactured in one sweep, including the metalens and the sensor.”

‘Can you get rid of the lens?’

Capasso came to Harvard in 2003 after a career at Bell Labs, where, in 1994, he and colleagues invented and developed the quantum cascade laser, currently being commercialized in devices for chemical sensing and spectroscopy.

Capasso traced the development of the metalens to a conversation he had more than a decade ago with Jim Anderson, the Philip S. Weld Professor of Atmospheric Chemistry. The two had been discussing putting a quantum cascade laser on a drone that Anderson wanted to use to detect certain chemicals in the atmosphere, but there wasn’t enough room. That was in part because of the bulky optical elements needed for focusing. Anderson got to the heart of the problem.

“He said, ‘Can you get rid of the lens?’” Capasso recalled. “My first reaction was, ‘What the hell is he talking about?’ But then I said, ‘No, wait a moment.’”

Capasso started to brainstorm the idea with a couple of students in his group. Starting in 2007 or 2008, they began to focus on the scientific question of whether it was possible to bend light in an entirely flat device.

Early work used what they termed “plasmonic antennas” that eventually evolved into metasurfaces — millimeter-thick, two-dimensional surfaces studded with tiny nanostructures smaller than the wavelength of light. Those arrays, Capasso said, can alter the path of light flowing through it in a kind of “artificial refraction.”

That work progressed incrementally, producing several scientific papers that led to a 2011 breakthrough, published in Science and now cited more than 5,400 times. Capasso and members of his lab demonstrated they could tune the nanostructures and bend light to a roughly focused “hotspot.”

While the results were of scientific interest, the efficiency was so low that most of the light was lost, a result that skeptics said meant it would never become useful.

Bringing fresh eyes, new skills

In 2012, Devlin joined the lab. With no optics background, Devlin instead worked in an area Capasso thought would be key: materials science and nanofabrication. Devlin himself believed that the lab had mostly figured out the science, and that choosing the right materials and fabrication processes would be critical to improved results.

“The metasurface was a great proof of concept, but the devices themselves were really inefficient,” Devlin said. “There were problems in how it was fabricated, in materials, and design.”

Devlin set about considering materials and processes that not only worked in the lab, but that would also work, if a successful device needed to be scaled up. Ultimately, he settled on titanium dioxide, a compound widely used in paint pigment, sunscreen, food coloring, and as a reflective surface in dielectric mirrors. More importantly to Devlin, it had low light-absorption properties.

By late 2015, there were eight to 10 people in the lab working on different aspects of metasurfaces. As each turned their focus to lens performance, they brought perspectives and insights gleaned from their diverse prior efforts.

Devlin knew they had things right when the efficiency — the amount of the available light the device could focus — abruptly began to climb, rising from 10 percent to 85 percent in a few weeks. The rapid improvement and clarity of the resulting images stunned Devlin, Khorasaninejad, and Chen.

Those results spurred the 2016 Science paper, which not only generated a buzz in the lens industry, but also became a runner-up for Science’s breakthrough of the year. Despite the accolades and new belief in the promise of a metalens, it still focused just single wavelengths of light. And, while there were certainly uses for single-wavelength light — facial recognition, for example, is done by bouncing a single wavelength outside the visible spectrum off a person’s face and analyzing the light that returns — the next challenge was to produce the first “achromatic” metalens, one that focuses light across the visible spectrum.

“I locked myself in my office with Wei Ting Chen for the weekend, and I said, ‘Now we need to understand what we have done,’” Capasso said. “Our design ensured that all the colors, irrespective of where they take off, arrive at the same time in the same spot.”

It took two years, but in 2018, they became the first to report success, with high resolution.

In the meantime, though, Gordon was fielding calls from industry and advising Capasso and Devlin as to the next step of the metalenses’ commercial development. He counseled them that founding a startup around a new technology tends to be more successful than licensing it to a large corporation, where it can get lost. They listened and founded Metalenz to commercialize the invention and look for additional applications.

Devlin, meanwhile, had a decision to make. He had entered his graduate studies thinking he would pursue an academic track when he left Capasso’s lab. But he had the opportunity to be among the founders of Metalenz and shepherd the device’s development himself.

To Capasso, though, Devlin’s first priority was finishing the degree. He didn’t let up on the younger scientist, requiring he continue research and complete another scientific paper. Then Capasso ran interference with investors and companies wanting a piece of Devlin’s time.

“Federico made sure I was not abandoning the completion of my Ph.D.,” Devlin said. “He said, ‘No one is to contact Rob until he completes his dissertation.’”

Devlin defended his dissertation in 2017 and graduated in June 2018. When OTD and Metalenz announced the startup to the world in 2021, Devlin was its chief executive.

“The Ph.D. student is not always a CEO type, but some are, and Rob has shown he has the personality for it,” Gordon said.

The last several years have seen Devlin taking the company through several startup milestones, securing funds, developing relationships with manufacturers, and the recent announcement that the company’s metalenses will go into mass production.

Though Metalenz has licensed more than 20 Capasso lab patents from Harvard, Capasso and his students and postdocs are busily working on new discoveries. A current focus is on ultracompact, polarization-sensitive cameras — based on flat optics — that can detect the direction in which light vibrates after it’s transmitted or reflected, revealing otherwise invisible details of a scene. His group is involved with two collaborations with NASA on these cameras, related to Earth sciences and solar physics. He and his students are also toying with the idea of a “universal camera” that can see all properties of light at the same time, including ones that can’t be seen by existing cameras. Capasso described that challenge as “very ambitious.”

“We are here to learn, starting with me,” Capasso said. “I always tell students, ‘If you have something good, you have to give it away. Don’t keep it to yourself.’”

GAZETTE: There are a lot of incentives aimed at consumers in the legislation, with tax credits for energy efficiency and electric cars. Does it take largely a bottom-up approach or is it more balanced than that?

HOLDREN: I think it’s more balanced. It’s both bottom-up and top-down. I’ve always thought that comprehensive programs on almost anything significant — and difficult — need to be a combination of bottom-up and top-down. This looks to me like a pretty good balance. There are important things missing that were in the other measures the Biden administration was trying to get through, but there were also some not-so-good elements in there that have been dropped. I don’t argue that this is an ideal piece of legislation, but it is so much more than we thought we were going to get.

GAZETTE: Are there specifics in there that you like in particular? That may have multiplier effects?

HOLDREN: The energy and climate total, $385 billion, is terrific. The clean-manufacturing tax credits represent a very productive approach. The tax credits to consumers for buying electric vehicles and energy-efficiency improvements, too. We know that those work. The real name of the game in getting emissions under control is making the clean options more attractive economically than the dirty options. It’s that simple. So any measure that can contribute to creating or expanding the economic advantage of going with clean and efficient technologies is a smart thing to do, and there’s a lot of that in here.

There are also some specifics, like very substantial incentives to companies for reducing methane emissions, that are a big deal. Some of the measures focused on offsetting the economic costs are also very good. There is always an emphasis on how much it’s going to cost to have cleaner options faster, but there is almost never a discussion of how much money those measures will ultimately save the economy through reduced damages from climate change. I wish there was more attention paid to the economic benefits of taking these steps. Our late, great economics Professor Dale Jorgenson, who died recently, was a great exponent of the proposition that doing what we need to do to address climate change would ultimately be an economic benefit, not a cost.

GAZETTE: Looking at cost, will we eventually reach a tipping point after which renewables will be cheap enough that they’ll spread on their own, like natural gas did when it undercut coal? Is it possible that this legislation can get us to that tipping point?

HOLDREN: In some respects, we’ve gotten to that point already. Electricity generation from solar photovoltaics and from wind power in many places is now cheaper than electricity generation with coal. And in some places, it’s cheaper than electricity generation with natural gas. That’s a very important driver. One of the challenges is that some technologies that we need to embrace if we’re going to get emissions reductions down as much as we need to are more obstinate economically. I’m thinking of carbon capture, sequestration, and utilization, for example.

Some environmentalists hate those options, saying it’s just a further lease on life for fossil fuels. But in a world that is still almost 80 percent dependent for its primary energy on coal, oil, and natural gas, we have to recognize that there is going to be quite a lot of fossil fuel burned in the years ahead. What we need to do, given the urgency of the climate change challenge, is make it possible to burn some of that fossil fuel in ways that do not release the resulting carbon dioxide into the atmosphere. But carbon capture and sequestration of that carbon in geologic formations is intrinsically expensive, and we will do it only if it is made more economical with subsidies from the government or regulations. So that is another good characteristic of this new legislation: It would provide a boost to the subsidies for carbon capture and sequestration.

GAZETTE: Might supporting carbon capture and sequestration tell oil companies that they have a place in a future carbon-free economy and bring them on board, or is there little chance of them doing anything other than fighting this tooth and nail?

HOLDREN: The situation with the big oil and gas companies has been changing. Some of them are now very progressive in their approach to this problem. BP, for example, has completely restructured its business plan and is aiming for major reductions in the emissions of their operations, and ultimately the emissions for which they’re responsible. I’m quite sure they’re serious about it. A number of the other big oil and gas companies are moving in that direction. I’ve been saying for decades that we’re not going to solve climate change over the dead bodies of private sector companies. We’re going to solve the problem by finding ways to bring those companies on board in a pathway toward a much more sustainable energy system. Those folks can also do arithmetic — in fact they’re very good at it. They can read the data, and the data on climate change make clear that it’s real, it’s deadly, it’s here. And if we are to at least minimize the worst consequences of climate change, there’s going to have to be a much bigger transition than oil and gas companies until recently were willing to acknowledge. They’re acknowledging it now and trying to figure out how to do it. We should push them along.

GAZETTE: There are tax credits to encourage energy production, including large plants of solar and wind power. Does the legislation do anything to encourage the transmission lines needed to get the power from the places where the wind blows and the sun shines to the big cities?

HOLDREN: The biggest problem with transmission is the permitting. It’s incredibly complex to build a transmission line anywhere because of the number of permits required and the ability of any one of those permit grantors to refuse and to block the project. There is language in this legislation about accelerating and streamlining the permitting processes, and that’s going to be important if it can succeed. But this is a very difficult nut to crack because of people’s affection for due process and for review at various levels. That makes it very difficult to solve the transmission problem. It’s clear that a key to a higher proportion of renewable energy in our national mix is being able to build expanded transmission networks to get the energy from where it’s most economically generated to the places where the largest consumption is taking place. We really do have to master the transmission siting challenges in this country, or we’re cooked.

GAZETTE: What’s left out? How do we get the extra 10 percent emissions reduction that Biden wants?

HOLDREN:  The single most important thing that’s left out — under current political circumstances, there was just no way it was going to get done — is putting a price on carbon emissions across the board. That could be done either with a carbon tax or with a cap-and-trade approach, as was tried initially in the Waxman-Markey bill that failed in the beginning of the Obama administration. Economists of every political stripe, conservatives as well as progressives, will tell you that the single most important and efficient thing we could do to reduce greenhouse gas emissions is to put a price on carbon emissions and let the market figure out the cheapest way to get it done.

In the Obama administration, we did calculations that said if we could have imposed a mere $30 a ton tax on carbon dioxide emissions in 2015, that the reductions by 2025 could have been 32 to 34 percent instead of the 26 to 28 percent target we embraced based on measures that didn’t include a carbon tax or its equivalent. That’s a big difference from a very low carbon tax. If we had a carbon tax of a $75 a ton or $100 a ton, it would be transformative. You could rebate the money to poor and middle-class families. You could spend some of the money to reduce other taxes. The late Dale Jorgenson showed that if you had a carbon tax and if you offset its economic impact by reducing capital gains taxes and income taxes, the economy would be better off after 20 years of having a carbon tax than without it. It’s a very old economic principle that it is more efficient in the societal sense to tax “bads” than to tax “goods.” Capital gains and income are goods and emissions are bad. If we taxed emissions instead of income and made it revenue-neutral overall, as Jorgensen pointed out a couple of decades ago or more, the economy comes out better.

GAZETTE: It seems that the power of that versus the targeted approach is that the tax is economy-wide, so it’s gaining efficiencies in every nook and cranny.

HOLDREN:  And it brings out ingenuity in every nook and cranny. That’s the beauty of it.