As 2024 draws to a close, we look back at some of the Caltech-led discoveries and innovations from throughout the past year. This research extends our understanding of the natural world, enhances researchers' ability to probe ever further the mysteries of the universe, and advances new technologies and approaches aimed at diagnosing and treating diseases, building a more sustainable world, and harnessing technologies to benefit society.
The Earth, Our Home
This year the earth's North and South poles were the focus of research investigating how the coldest parts of our planet are reacting to a warming climate. Caltech researchers discovered that water is flowing down new paths in the Arctic as its permafrost—the thick layer of perennially frozen ground—thaws, creating risks for human communities that live downstream. Meanwhile, Institute experts showed that Antarctic ice shelves are melting from below thanks to warm seawater moving beneath them.
The earth's oceans are notoriously difficult for humans to explore, as our own bodies are not adapted to the watery deep. Fortunately, there are animals that move freely in all areas of the ocean. This year, Caltech researchers enlisted the aid of one such animal by engineering "bionic" jellyfish. The animals carry a tiny electronic payload that enhances their swimming and can gather data on the ocean's salinity, temperature, and oxygen levels.
This year also brought innovative means for detecting the nature and movement of land. Specialized seismic sensors, originally designed to detect earthquakes, are now being used to measure soil moisture in the shallow subterranean region between the surface and underground aquifers. The same instrumentation was shown to measure how seismic waves from earthquakes are reflected off the earth's mantle, located beneath the brittle crust, allowing scientists to map these deeper structures of our planet.
Farther from Earth, a study of seismicity on Saturn's moon Enceladus indicated that its surface ice sheet may cover a global ocean chemically suited to support life. Meanwhile, researchers found evidence that Jupiter's moon Io has been volcanically active for billions of years due to tidal heating from the giant planet's gravity.
Black Holes: Observing and Modeling What Cannot Be Seen
Part of the lifespan of a supermassive black hole includes the emission of giant jets that spread cosmic rays, heat, heavy atoms, and magnetic fields throughout the space between galaxies. Though these jets were already known to be quite large, the discovery this year of a pair that are 23 million light-years in length reframes astronomers' expectations regarding black hole ecology.
Other discoveries include a triple-star system made up of two stars orbiting a black hole, a collision between two massive clusters of galaxies in which dark matter accelerated more quickly than normal matter, and at least 21 binary systems in which ordinary stars like our Sun orbit around neutron stars—incredibly dense, dim husks of dead stars.
Caltech scientists provided new understanding of the dynamics of black hole formation by simulating the journey of primordial gas to a stage where it fuels supermassive black holes and reconstructing the first 3D movie of flares around a supermassive black hole.
Eyes and Ears on the Universe
Caltech researchers not only observe the universe, they design, build, and manage many of the instruments they and others train on the sky. Seventy-five years since the 200-inch Hale Telescope achieved "first light" at Palomar Observatory, Caltech's San Diego County–based facility, aided by ever-improving instrumentation, continues to play a pivotal role in researchers' quest to understand the universe. The Zwicky Transient Facility, or ZTF, which resides at Palomar's 48-inch Samuel Oschin telescope, reached a new benchmark as it led to the classification of more than 10,000 supernovae. Also in 2024, we learned that a curious brown dwarf—discovered at Palomar in 1995 and seemingly too dim for its mass—is actually a pair of brown dwarfs orbiting one another extremely quickly, every 12 days.
Astronomers have known about fast radio bursts from space since 2007, but this year, using Caltech's Deep Synoptic Array-110, or DSA-110, at the Owens Valley Radio Observatory, they have traced the bursts' source to magnetars, highly magnetized neutron stars, that tend to occur more often in massive star-forming galaxies than low-mass star-forming galaxies.
The now-retired Wide-field Infrared Survey Explorer provided the data analyzed by an amateur astronomer to identify in 2013 the remnants of a supernova that was visible from Earth with the naked eye in the year 1181. In 2024, using Caltech's Keck Cosmic Web Imager, this supernova remnant and its wispy tendrils resembling a dandelion were mapped in three dimensions for the first time.
The Caltech-led SPHEREx mission, which will create the first all-sky 3D map of hundreds of millions of galaxies, was scheduled for launch at the end of February 2025. Future cosmic discoveries are promised by a Caltech-led space mission, UVEX, approved this year and targeted to launch in 2030 to survey ultraviolet light across the sky to help reveal how galaxies and stars evolve. Meanwhile, researchers at Caltech and JPL, which Caltech manages for NASA, gained new funding opportunities for ambitious projects to build and test scientific instrumentation to study the earth and the universe through the creation of the Brinson Exploration Hub.
Sustainability, Now and for Future Generations
Caltech's efforts to secure a more sustainable future continued at a rapid pace in 2024, which marked the first year of the Space Solar Power Project's ambitious endeavor to harvest solar power from space and transmit it to Earth, and featured the opening of the Institute's newest building, the Resnick Sustainability Center (RSC). RSC provides an interdisciplinary center and houses several state-of-the-art facilities where researchers from across campus can come together to address the warming planet's most pressing problems related to energy and resource utilization.
In other sustainability news, Caltech experts found ways to mitigate environmental damage from chemical production and identified a previously underestimated producer of greenhouse gases in bacteria that can "breathe" nitrate in low-oxygen conditions to release nitrous oxide, the third-most potent greenhouse gas after carbon dioxide and methane.
Science in a Brave New AI World
In a year when emeritus professor John Hopfield was awarded the Nobel Prize in Physics for laying the groundwork for artificial neural networks, Caltech researchers leveraged artificial intelligence (AI) and machine learning to advance studies and lead discoveries across fields as diverse as health science, robotics, and climate studies.
Researchers at Caltech used AI to design a catheter tube that reduces the upstream travel of bacteria 100-fold, determine which types of lung cancer are most likely to metastasize, predict South Asian monsoon rainfall 10 to 30 days in advance, and to allow unmanned aerial vehicles to respond to changing wind conditions in real time and to continue flying when a rotor fails.
Caltech experts also emerged at the forefront of efforts to measure the public health impact of the large air pollution–generating AI data centers and the search for methods to remediate those effects.
Medical Innovations and Basic Biology
More effective measurements of the behavior of bodily systems can lead to better diagnosis and treatment of disease. In 2024, Caltech researchers developed a noninvasive method to continually measure true blood pressure; a smart mask that can track breath particulates to monitor such conditions as asthma, COPD, and post-COVID-19 infections; and a laser-based headset that measures blood flow in the brain to assess future stroke risk.
In the realm of preventative health and treatment, a Caltech team continued its development of a new vaccine candidate called mosaic-8 that can induce an immune response to a broad range of coronaviruses, including COVID-19. The vaccine has proved effective in animals that had never encountered coronaviruses and also in animals that previously mounted an immune response to these viruses.
Fundamental research into human development revealed that a 1-day-old fetus composed of only two cells, or blastomeres, develops from a single blastomere, while its placenta develops from both blastomeres. Knowing this, IVF clinics will be better able to screen embryos to find those best suited for implantation.
Other basic biology work tackled the enigma of rove beetles and their phenomenal evolutionary success, as researchers in the lab of Joe Parker, who was named a MacArthur Fellow this year, identified two cell types that form a chemical defense gland in the rove beetles' bodies. In another lab, researchers offered new insights into the evolution of the sympathetic nervous system through studies of lamprey, eel-like jawless fish that model the ancient fish ancestors from which we evolved 550 million years ago.
Inside the Brain
The brain, long thought to be a black box, is gradually yielding its secrets to neuroscientists. This year Caltech featured progress in the development of brain–machine interfaces (BMIs) that may one day allow people who cannot speak to simply think a word and have it accurately transmitted to a computer, and the creation of a new type of window into the brain, a skull prosthetic that enables researchers to directly "see" brain activity using ultrasound technology in patients with brain and skull injuries.
Research this year also demonstrated that zebra finches, which learn their unique song patterns from their fathers, can recreate these songs even after brain damage, in a similar way to human stroke patients, who can relearn abilities like walking and talking.
Quantum Technologies
As the quest to create a quantum computer continues, Caltech researchers are working to overcome fundamental challenges. Quantum computing shows great promise, but errors persist, and standard computers struggle to document and interpret these errors. A new Caltech method makes it possible for standard computers to measure quantum computing error rates without running a full simulation, which is impossibly time-consuming.
The potential of quantum computing was illustrated this year with the development of a precise timekeeper through the marriage of atomic clocks and quantum computing, while in other work, ultrafast laser pulses were able to create molecules with the quantum mechanical property of superposition, effectively turning these molecules into quantum sensors that can measure chemical phenomena in their surroundings.
Making Materials and Breaking Bonds
In a feat of materials design and bioengineering, Caltech researchers were able to "print" swarms of miniature hydrogel microrobots to use for drug delivery in mice. The biocompatible, bioresorbable, bubble-like robots can be imaged using ultrasound and directed to a target using magnets, where they will release their cargo without causing harm. Other Caltech experts engineered a metasurface patterned with miniscule tunable antennas capable of reflecting an incoming beam of optical light to create many sidebands, or channels, of different optical frequencies.
Meanwhile, other research groups on campus focused on breaking chemical bonds to facilitate the synthesis of "natural" products with potential use as pharmaceuticals or as new materials in green industry. Caltech experts engineered an enzyme that can break human-made bonds between silicon and carbon in widely used chemicals known as siloxanes, or silicones—a step toward rendering the chemicals biodegradable. Another lab designed a process to break normally nonreactive carbon–hydrogen bonds and functionalize them to build highly complex natural molecules, work that opens up a new category of possible reactions for organic chemists.
Science and Public Policy
This year, Caltech's experts also extended the Institute's long tradition of informing and educating not just future scientists and engineers but decision- and policymakers. During this year's election cycle, Caltech continued to monitor election integrity and help to prevent election misinformation through a large-scale study of "pre-bunking" myths and conspiracies to voters in advance of American elections.
Caltech experts also tackled the complex issue of how best to regulate emerging new biotechnologies with potentially profound social impact. In 2024, the Ronald and Maxine Linde Center for Science, Society, and Policy (LCSSP) entered this space with a policy paper to outline the risks associated with bioengineering—creating new microbes and releasing them into the environment—and to streamline approvals processes so that it is easier to identify real risks and opportunities more quickly and accurately.
