Caltech: Caltech’s 84th Annual Seminar Day Looks into the Body and out to the Stars

Caltech’s annual Seminar Day gives alumni from around the world the opportunity to hear about exciting research and new discoveries from experts across various fields of science, technology, and engineering. Seminar Day 2021, presented on May 15 by the Caltech Alumni Association, marked the second time in the event’s 84-year history that it was held virtually because of the COVID-19 pandemic, with speakers and attendees joining via Zoom. The 761 people from 16 countries who participated heard Institute alumni, faculty, and other luminaries discuss topics including supermassive black holes, the power of artificial intelligence, and the hunt for life beyond Earth.

“As the miasma of the coronavirus pandemic lifts, we need to save our connections and to celebrate our accomplishments,” Caltech president Thomas F. Rosenbaum said. “Today, Seminar Day, is such an opportunity. Thank you for being part of this effort.” Rosenbaum and Los Angeles Times columnist Patt Morrison hosted the event, introducing the four presentations.

The first talk, “The Supermassive Black Hole Story,” featured Andrea Ghez (MS ’89, PhD ’92), the Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics at UCLA. Ghez was awarded the Nobel Prize in 2020 for pioneering research that helped reveal a supermassive black hole lurking at the center of the Milky Way galaxy. In her Seminar Day talk, she explained the work that led up to that finding and how it impacted the field of astrophysics.

“This has given us the best evidence today that these exotic objects exist in the universe and has provided us with a wonderful laboratory for understanding the physics of black holes,” she said. “In other words, how do black holes warp space-time or how does gravity work near a supermassive black hole … and what role do black holes play in the formation and evolution of galaxies?”

Ghez explained that the existence of black holes was theorized before it was proven experimentally. Physicists realized that a star much bigger than our sun would, at its death, collapse upon itself to create a small object in which gravity overcomes all other known forces. Later, the existence of black holes was proven thanks to experiments such as the Caltech/MIT collaboration LIGO. By contrast, she said, knowledge of supermassive black holes, like the one at the center of our galaxy, which are a million to a billion times the mass of the sun, started on the observational side before their existence was explained theoretically.

Moderator Satoshi Ohtake (BS ’00), senior director of pharmaceutical research and development at Pfizer, framed the future-facing panel discussion “Blood, Sweat, and Tears, Meet Your Best Friend: AI.” The panel included Caltech faculty members Animashree Anandkumar and David Van Valen (PhD ’11), and Christie Canaria (PhD ’08), program director of National Cancer Institute Small Business Innovation Research (SBIR) Development Center. Panelists covered the transformative power of artificial intelligence for the medical fields, particularly in its ability to look at medical images and find patterns in huge data sets that humans might miss or not have the bandwidth to take on.

“Good [AI] models that can assess whether there are tumors and what is the state of health can make a big difference because radiologists today are in short supply,” said Anandkumar, who works on this research at Nvidia. “And there’s also the time component: If we could do this quickly, maybe you can come up with more real-time insights into what’s happening [inside the body].”

Canaria pointed out another huge growth area for AI in medicine: natural language processing, or a machine’s ability to understand spoken or written language. Such an AI could be unleashed upon a clinician’s notes and medical records to unearth clues and patterns hidden therein.

In the third session, “Photoacoustic Imaging: From Organelles to Cancer Patients,” Bren Professor of Medical Engineering and Electrical Engineering Lihong Wang explained his quest to develop new tools that would allow us to peer into the body noninvasively for better medical diagnoses. Seeing the molecules deep inside the body has been a centuries-long challenge because opaque biological tissues scatter light, preventing older technologies such as microscopy and laser imaging from penetrating very far. Wang combines light and sound in clever ways to create high-resolution images inside the body.

He says this technology could be used for basic biological research and for drug discovery, where a researcher needs to repeatedly monitor what is happening inside a test subject. Importantly, Wang’s photoacoustic imaging does not carry with it the exposure to potentially damaging radiation that comes with X-ray scans, for example. He says it is also useful in trying to see into the brain.

“It’s very hard to do that with any other form of imaging, so optics has a unique role to play,” Wang says. “However, standard optical means do not allow you to see the whole brain in high resolution. Our technologies are ready for that application because we can see the entire brain.”

In the final seminar, “Is There Life Beyond Earth?” Mike Brown, Richard and Barbara Rosenberg Professor of Planetary Astronomy, framed the search for extraterrestrial life this way: scientists know the core principles of physics, chemistry, and geology that work on Earth are at work on other worlds. The same is true of aeronautics, which the Ingenuity helicopter showed again when it flew on Mars. The existence of life on other planets hinges on whether this is also true for the field of biology. “Has biology ever worked beyond the earth, or is it really just something that’s unique here.”

Heather Knutson, professor of planetary science, explained how her research, studying the atmospheres of planets that orbit other stars, could be the way not only to find faraway worlds that are potentially habitable but also to find the signatures of life that might exist there.

“The atmosphere sets the stage for life,” she says. “It determines the conditions on the surface, whether or not you actually get that liquid water [that is necessary for life]. But also the atmosphere can be a sort of repository for materials produced by life. So, if you have little bacteria covering the surface of your planet, they’re taking in gasses and they’re releasing gasses, and so they can alter the composition of the atmosphere merely by being there.”