Caltech is a place unlike any other, an Institute that is truly "small but mighty." Its small size and the expertise of its community enable interdisciplinary connections and collaborative projects at all scales, sometimes in rapid response to devastating need. Here, physicists and mathematicians easily and regularly interact with biologists and chemists, astronomers and engineers, and collegiality and shared interests lead to fruitful, sometimes world-changing developments. Even in a year that has brought tremendous challenges, beginning with the Los Angeles fires that affected so many in our community, Caltech has come together and pushed the expansion of knowledge and progress across disciplines.
As 2025 comes to a close, we can look back at some of the Institute's key accomplishments across a stunning diversity of fields—from the creation of technologies to enable new medical interventions, to insights into the secrets of the cosmos and what they mean for our understanding of the universe, to the identification of new ways to use artificial intelligence to fuel chemical insights and improve early warnings of earthquakes. Here are some highlights.
Science in the Public Interest
This past year brought our collective consciousness of natural disasters to new heights in many areas of the world—and particularly in Caltech's own backyard. The devastating Eaton fire in January 2025 burned over 9,000 structures, razing entire neighborhoods in Altadena, just north of Pasadena. Caltech scientists, aware of hazards both immediate and potential, provided the community with resources and information to help prevent further devastation to the area.
In the aftermath of the fire, it was discovered that the network of air sensors dotting Altadena were all but completely eradicated by the blaze. Caltech experts spearheaded the PHOENIX (Post-fire airborne Hazard Observation Environmental Network for Integrated Xposure-monitoring) project to mount commercially available, solar-powered sensors and cellular signals to collect real-time air quality data from across the burn zone and distribute it to the public.
Through a series of webinars hosted by the Caltech Science Exchange, Caltech explained the atmospheric risks posed by the fire and gave guidance on home cleaning for safe removal of particulates and contaminants affecting homes many miles away from the burn zone, and offered the public, via a Watson Lecture, information about the post-fire risk of debris flows, a concern in any mountainous area that has recently experienced the dramatic loss of vegetation that accompanies fire, and particularly in the San Gabriel mountains north of Pasadena.
Farther afield, Caltech researchers made use of unused fiber-optic cables on a remote peninsula in Iceland to deploy distributed acoustic sensing systems. The technology has previously been used in other areas for earthquake detection, and was quickly and successfully set up, even under harsh conditions in Iceland, to provide early warnings of lava eruptions.
In 2025, the Ronald and Maxine Linde Center for Science, Society, and Policy (LCSSP) launched a new biopolicy initiative to explore questions of ethics and policy raised by the rapid evolution taking place in biotechnology and related fields. In line with the LCSSP's mission of fostering meaningful connections between scientists and policymakers, the first science policy workshop, "Biotech Beyond Conventional Containment: A Workshop on Policy & Governance," took place on campus in October.
Investigating Our Earth
Caltech's longstanding expertise in seismology and earth science continued to deepen our understanding of our planet, with researchers modeling the behavior of supershear earthquakes and refining the laws of friction with interdisciplinary collaborations. As our planet's climate evolves, researchers have been quantifying climate change's impact on a crucial Atlantic ocean current, which could have major implications for regional sea level rise and weather patterns. Data-driven estimates of humanity's impact on global biomass provide fundamental data for policymakers and everyday citizens to make sustainable choices.
This year, the Brinson Exploration Hub at Caltech kicked off its first round of funded projects, with a focus on exploring the icy frontier of Antarctica and the cosmos. The work supported by the Hub will both expand our understanding of these extreme environments and serve as a testbed for instrumentation to explore icy worlds, a step toward answering questions about the origin and evolution of life in the universe. The projects, each with a co-lead at Caltech and JPL, which Caltech manages for NASA, were selected for their ability to drive scientific and societal benefit, take advantage of emerging opportunities in the broader Earth and space exploration ecosystem, and be executed with speed and risk tolerance.
Exploring our Closest Neighbors
Furthering our understanding of our closest planetary neighbors and how they have changed over time, researchers this year revealed more about the primordial origins of Jupiter and created models of the distribution of water in the giant planet's atmosphere. In collaboration with colleagues at JPL, scientists used measurements taken by the Mars rovers to conduct forensic analyses on the ancient Martian climate, finding signatures of liquid lakes on the Red Planet's surface.
Black Hole Extremes
Caltech scientists continued to inspect the exotic nature of black holes—objects so dense that not even light can escape their gravitational grasp. LIGO, the U.S. National Science Foundation (NSF)-funded Laser Interferometer Gravitational-wave Observatory, witnessed its biggest black-hole collision yet: a whopper of a smashup producing a final black hole 225 times the mass of our Sun. LIGO also found evidence of hierarchical mergers between black holes that were themselves the products of earlier collisions.
This year, LIGO celebrated the 10th anniversary of its 2015 detection of gravitational waves. Improvements to the facility's twin detectors in Louisiana and Washington have resulted in ever-increasing rates of black hole discoveries (about 300 black hole mergers have been detected to date by LIGO and its partners).
Outside of LIGO, Caltech researchers helped discover the biggest black hole flare ever recorded, which shines with the light of 10 trillion suns. The brilliant flare—first observed by NSF-funded Zwicky Transient Facility (ZTF), based at Caltech's Palomar Observatory, and the Caltech-led Catalina Real-Time Transient Survey—may have been triggered when a supermassive black hole gobbled up a star at least 30 times the mass of our Sun.
Meanwhile, in theoretical work, Caltech researchers used supercomputers to simulate the grisly demise of a neutron star right before a collision with a black hole, uncovering details about the violent quakes that rupture its surface.
The Universe at Large
From near to far, our universe is populated with cosmic denizens that continue to enchant and surprise scientists. This year, ZTF helped nab a comet passing through our solar system named 3I/ATLAS, only the third known interstellar comet found to date, while other astronomers used NASA's James Webb Space Telescope (JWST) to find strong evidence for a planet orbiting in the habitable zone of our nearest star system to Earth. Beyond our Milky Way galaxy, observations from JWST revealed a dinosaur in the distant universe, an unexpectedly large galaxy that existed when the universe was only 2 billion years old.
Astronomers also discovered a new formation channel for cataclysmic variables—pairs of dead stars called white dwarfs in which one member steals mass from its companion and explodes—finding that in some cases, a "third wheel" of a star situated farther out helps bring the two stellar corpses together. Institute astronomers also used Caltech's Deep Synoptic Array-110, located at the Owens Valley Radio Observatory, to detect and account for so-called missing matter located between galaxies.
Continuing the Institute's long tradition of developing cutting-edge new instrumentation to interrogate and reveal the secrets of our world, NASA's Caltech-led SPHEREx mission launched this year. Built with the help of Caltech scientists, including students, its ongoing mission is to study the birth of our universe, the evolution of galaxies, and interstellar ices vital to star and planet formation.
In the realm of ground-based telescopes, the Caltech-built Next Generation Palomar Spectrograph (NGPS), based at Palomar's Hale Telescope, began operations—an effort seven years in the making. The instrument will be used to study asteroids, comets, stars, galaxies, and more in exquisite detail.
Meanwhile, Caltech particle physicists set their sights on pressing questions about the nature of matter in our universe. Working with an international collaboration representing two neutrino experiments—NOvA in the United States and T2K in Japan—the scientists presented some of the most precise measurements ever made of these ghostly particles.
Moving Toward a Sustainable World
Caltech scientists and engineers drive innovative solutions and technologies that improve efficiencies, lower costs, and leverage natural, abundant, and sustainable resources to power the planet. This year, Caltech engineers developed a solar-thermal heating system with the potential to drive the chemical reactions needed to produce jet fuel without carbon emissions, and chemists devised a new way to convert abundant carbon dioxide into desirable industrial chemicals. Meanwhile, new faculty members investigated how to use genomic techniques and approaches to more precisely engineer crops and worked to give plants superpowers so they are better suited for a warming planet.
In other work aimed at better understanding the processes that affect the amount of greenhouse gases in the atmosphere and their effect, Caltech experts quantified atmospheric levels of ammonium nitrate, a notoriously difficult to measure component of smog, finding that it is present at higher levels in Los Angeles's air than previously calculated. And in a surprising result, Caltech researchers found that the majority of carbon emissions drawn back down to Earth are stored not in trees and plants but in nonliving reservoirs, where they stay sequestered far longer than in plants.
AI
In the flourishing and expanding field of artificial intelligence, Caltech continued to lead in the application of AI and machine learning to advance scientific discovery. In November, the Institute hosted the Caltech and University of Chicago Conference on AI+Science, bringing leading AI and domain experts together to discuss the future of science as enabled by such AI.
This year, a Caltech team found that its painless breast-imaging technique, which uses machine learning to help detect suspicious tissue, performed as well as or better than other breast-imaging techniques in patients. Other researchers at Caltech and their colleagues teamed up with Google DeepMind to develop a new AI method to quiet unwanted noise in LIGO's gravitational wave detectors. Elsewhere, Caltech mathematicians developed a new type of machine-learning algorithm that can solve math problems that require thinking many steps ahead, as other Caltech researchers, in collaboration with Cedars-Sinai, developed an AI framework that can accurately, quickly, and efficiently create virtual models of brain neurons.
Innovating to Improve Human Health and Beyond
Caltech is known for its interdisciplinarity, especially in innovations to study living organisms, from viruses to humans. Combining tools from machine learning and computer science, researchers developed a new software algorithm to easily detect new viruses in sequence data and a new "programming language" to control active matter with light.
Advances in biomedical technology are both improving human health outcomes and enabling precise studies of the human body to answer fundamental science questions. This year, engineers developed a biosensor to study the health of the gastrointestinal tract, a 3D-printing technique that can construct bioadhesive polymers in vivo for sealing internal wounds, and, inspired by DNA origami, a method for making reusable biomarker sensors. Researchers also began a new project to protect the inner ear against hearing loss and developed biological tools for discovery, such as a new technique to study the formation of biofilms, which are sticky masses of millions of cells that are often responsible for antibiotic-tolerant infections. Scientists also developed a new method for creating embryo-like structures from stem cells that could transform how we study fertility.
Fundamental biology research is a backbone of discovery at Caltech, often leading to translational applications in medicine. This year, scientists illuminated mechanisms of protein delivery in mitochondria (the "powerhouses" of cells) and the growth of bacteria in polymers, work that could be important to the study and treatment of diseases such as cystic fibrosis. Model organisms continue to provide insights: Studies on lamprey—a primitive type of vertebrate—can illustrate the evolution of the thyroid, and work with zebrafish gives clues to the future of regenerative medicine by illuminating the mechanisms through which these fish repair their own internal organs after damage.
Human Behavior
Caltech social scientists are always interested in better understanding human behavior—what drives individuals and groups in their actions and decision-making. This year, Caltech researchers offered new insights into why humans over-persist toward goals, even when it makes more sense to switch strategies. Researchers also developed a game to document how emotions affect the decisions of buyers and sellers. Other work, based on real-world data about competition between terrorist groups, yielded insight into what factors lead groups to be more violent—in this case Fatah (the secular Palestinian National Liberation Movement) and Hamas (the Islamic Resistance Movement). The work revealed a complex situation in which one group's violence could either encourage or discourage violence by the other group based on factors such as their respective popularity.
Harnessing the Power of Quantum
Caltech scientists made several advances in quantum sciences, accelerating the pace at which quantum computers of the future may become viable machines. In a landmark study, researchers developed an array of 6,100 qubits, the most ever assembled, by trapping neutral atoms in a grid of lasers. The finding is an important step toward scaling up quantum computers.
Quantum computers promise to solve hard problems that classical computers alone cannot, but identifying these problems has remained a challenge. Toward this end, a theoretical study proved that quantum machines will have the advantage over their classical counterparts in solving a physics problem that involves simulating how materials cool down to their lowest-energy states. Other researchers married quantum and classical approaches to create a hybrid platform that succeeded in solving chemistry problems.
Caltech researchers at the AWS Center for Quantum Computing on campus also made strides in building accurate quantum computers with their new Ocelot quantum chip. Other discoveries include a novel sound-based approach for storing quantum memories, and a new method for distributing quantum information in a parallel manner, or multiplexing.
Quantum technologies are useful in many other fields as well, including particle physics. Researchers have designed and tested a new system of quantum sensors called superconducting microwire single-photon detectors (SMSPDs), and shown that they could boost the performance of powerful particle colliders in the future.
Engineering Novel Devices
In 2025, Caltech researchers pushed to create devices that interact with the world in novel and exciting ways. A new collaboration with Meta Platforms, Inc. brought Meta scientists on campus to work with Institute researchers first on the science of smart wearable technologies such as virtual and augmented reality devices. A team of engineers developed a platform for characterizing the ultrathin membranes that could one day be used carry spacecraft at ultrafast speeds through space. Meanwhile, another team devised a method to power DNA circuits and nanoscale machines made from synthetic DNA with heat.
Caltech researchers also continued to lead the way in developing innovative robotic and autonomous systems. Engineers developed a robot with a control system that enables it to morph in midair before rolling away. Researchers from the Center for Autonomous Systems and Technologies (CAST) and Caltech students debuted and raced the Caltech Racer, a fully autonomous race car that made its debut and quickly came up to speed in the Indy Autonomous Challenge. CAST engineers also collaborated with the Technology Innovation Institute of Abu Dhabi to integrate and demonstrate a humanoid robot with a transforming drone that launches from the humanoid's back and, later, drives away. Such advances in autonomous systems will pave the way to safer, more seamless interactions with robots and devices in the future.