Institute for Gravitation and the Cosmos

2025-09-23

The violent collision and merger of two black holes emits gravitational waves — ripples in spacetime — that can cause the resulting newborn black hole to recoil and rapidly move, sometimes escaping its own galaxy. Now, an international team that includes a Penn State researcher has measured the direction of this recoil for the first time, as well as its speed. The international research team published their work in the journal Nature Astronomy. “When two black holes spiral into each other and merge, they don't just disappear quietly,” said Koustav Chandra, postdoctoral researcher in astronomy and astrophysics in the Penn State Eberly College of Science at the time of the research, currently at the Max Planck Institute for Gravitational Physics in Germany, and an author of the paper. “The violent collision emits gravitational waves that carry away energy and momentum. If the gravitational waves are emitted unevenly in different directions, it will create an imbalance that literally ‘kicks’ the newly formed black hole, sometimes at speeds of thousands of kilometers per second.” Gravitational waves were first predicted by Einstein in 1916 but remained undetected until 2015, when the two detectors of the U.S. National Science Foundation Laser Interferometer Gravitational-Wave Observatory (NSF LIGO) — designed to detect these very signals — first observed the merger of two black holes of similar sizes. Since then, nearly 300 such events have been detected. However, measuring the recoil of the remnant black hole required observations of a specific type of merger: two black holes with unequal masses. The team analyzed GW190412, the merger of two black holes with unequal masses that was detected in 2019 by both LIGO and its gravitational wave–detecting counterpart in Italy, Virgo, during their third observing run. This mass imbalance was key, because it created gravitational waves that appear significantly different depending on the observer's position relative to the recoiling black hole. “Gravitational waves from black-hole mergers can be understood as a superposition of different signals, much like an orchestra,” said Juan Calderón-Bustillo, professor in the Galician Institute for High Energy Physics at the University of Santiago de Compostela and an author of the paper. “However, this orchestra is special: audiences located in various positions will hear slightly different combinations of instruments, helping them to understand their exact location around it.” The researchers fully characterized the remnant black hole's motion for the first time by combining these directional clues with predictions based on Einstein’s theory of general relativity for recoil speed based on the black holes' masses and spins. They found that GW190412's remnant was kicked at over 31 miles per second — fast enough to eject it from the globular cluster of stars where it was originally located. For the first time, the researchers also determined the kick's direction relative to Earth and the original binary system. "This is truly awesome!” Chandra said. “We're not just detecting something — we're actually reconstructing the motion of an object billions of light-years away using only ripples in spacetime. This is a step beyond most astronomical measurements, which often only give a two-dimensional projection.” This work opens new possibilities in gravitational-wave astronomy, Chandra said, by providing a technique to measure recoil measurements for future detections of asymmetric mergers with current technology. It may also improve the ability to pair up signals from “multi-messenger” events that emit both gravitational waves and electromagnetic radiation that are observed with different detectors on Earth and in space. “Black-hole mergers in dense environments can lead to detectable electromagnetic signals — known as flares — as the remnant black hole traverses a dense environment like an active galactic nucleus,” said Samson Hin Wai Leong, doctoral student at the Chinese University of Hong Kong and an author of the article. “Because the visibility of the flare depends on the recoil’s orientation relative to Earth, measuring the recoils will allow us to distinguish between a true gravitational wave-electromagnetic signal pair that comes from a binary black hole and a just random coincidence.” Beyond recoils, the team said their methods provide a new toolkit for exploring other subtle properties of these violent astronomical events, expanding the ability to study the universe's most extreme phenomena. The Penn State contributions to this work were funded by the U.S. National Science Foundation.

2025-09-10

On September 14, 2015, a signal arrived on Earth, carrying information about a pair of remote black holes that had spiraled together and merged. The signal had traveled about 1.3 billion years to reach us at the speed of light — but it was not made of light. It was a different kind of signal: a quivering of space-time called gravitational waves first predicted by Albert Einstein 100 years prior. On that day 10 years ago, the twin detectors of the U.S. National Science Foundation Laser Interferometer Gravitational-Wave Observatory (NSF LIGO) made the first-ever direct detection of gravitational waves, whispers in the cosmos that had gone unheard until that moment. Now, a decade later, researchers on this collaboration have “heard” the clearest evidence for a theorem proposed by Stephen Hawking in 1971 that merging black holes must grow their collective surface areas, despite energy loss and other competing factors. The team, which includes scientists at Penn State, published the finding today (Sept. 10) in Physical Review Letters. It’s only the most recent finding resulting directly from the initial discovery of gravitational waves. “I have seen first-hand the transformation of knowledge brought on by gravitational wave discoveries,” said Chad Hanna, professor of physics and of astronomy and astrophysics in the Eberly College of Science at Penn State, a co-hire of the Penn State Institute for Computational and Data Sciences (ICDS) and a leader of the Penn State LIGO group. “Reflecting over the last 10 years I am reminded of a job interview which occurred years before the initial gravitational wave discovery. After delivering a lecture on searching for binary black hole mergers with a null result, one faculty member in the audience was quick to point out the flaw in my research — binary black holes detectable by LIGO don’t exist! Of course, we now know that binary black hole mergers do exist, are quite common in the universe, and are regularly detected by the LIGO-Virgo-KAGRA (LVK) collaboration, but before the gravitational wave discovery 10 years ago many scientists were skeptical that LIGO would be successful.” The first historic discovery meant that researchers could sense the universe through three different means. Light waves, such as X-rays, optical, radio and other wavelengths of light as well as high-energy particles called cosmic rays and neutrinos had been captured before, but this was the first time anyone had witnessed a cosmic event through its gravitational warping of space-time. “LIGO finally captured the unmistakable signature of a black hole,” said B.S. Sathyaprakash, Bert Elsbach Professor of Physics and professor of astronomy and astrophysics in the Eberly College of Science at Penn State and a leader of the Penn State LIGO group. “Black holes are believed to be ubiquitous, but distinguishing them from other exotic objects that might mimic their behavior has been a longstanding challenge. The decisive evidence lies in the unique spectrum of gravitational waves that only black holes can produce. For the first time, we confirmed, with high statistical confidence, that the observed signals indeed bear this unmistakable signature. After decades of pursuit, it was deeply gratifying to see LIGO, with its unmatched technology, finally capture the definitive proof of black holes.”

2025-08-18

A pair of new grants from the U.S. National Science Foundation (NSF) and the German Research Foundation (DFG) will support an international research collaboration and student exchange program between Penn State and the University of Jena in Germany. The grants will support research to produce a database of simulations of neutron stars merging with other neutron stars or black holes. This work will not only explore the physics of incredibly energetic cosmic events but also lend insight into how rare-earth elements and heavy metals are formed and provide a frame of reference to interpret future observations of merger emissions. The $392,000 NSF grant is awarded to David Radice, Knerr Early Career Professor of Physics and and associate professor astronomy and astrophysics in the Eberly College of Science at Penn State, and the DFG grant is awarded to Radice’s colleagues in Germany. The collision and merger of two neutron stars, or of a neutron star with a black hole, are some of the most energetic events in the universe. These events produce gravitational waves, or ripples in space time that can be detected on Earth with observatories like NSF’s Laser Interferometer Gravitational-Wave Observatory (LIGO). Mergers also often result in the ejection of matter into space, which produces electromagnetic radiation like gamma rays, X-rays, and visible light that can be detected with ground-based observatories like NSF’s Vera Rubin Observatory and space-based observatories like NASA’s James Webb Space Telescope.

2025-06-23

UNIVERSITY PARK, Pa. — “Deep learning is driving a revolution in physics, science, and engineering,” said Robin Tuluie, founder and chairman of PhysicsX, during the Alumni and Friends Reunion of the Penn State Institute for Gravitation and the Cosmos (IGC) on May 30. Tuluie, who was a postdoctoral scholar with the IGC from 1993 to 1995, presented a talk about the use of deep learning to push the boundaries of engineering. Deep learning is a type of artificial intelligence machine learning inspired by neural networks in the human brain, using several layers of artificial neurons to process data in different ways. Much like large language models (LLMs) — a type of deep learning model— like OpenAI’s ChatGPT and Microsoft Copilot “train” on existing texts and language to create logical sentences, Large physics models and large geometry models train on data from physics, geometry and spatial relationships in order to generate predictions for variables like air or fluid flow across arbitrary geometries. PhysicsX has created large physics models and large geometry models to address engineering challenges in optimizing structures, from aircraft wings and hydro-turbine blades to the tires of Formula 1 cars and the heat-exchangers used to keep batteries in electric vehicles cool. Traditional analysis of structural optimization, Tuluie explained, might involve running many simulations to explore, for example, how adjusting aspects of an airplane wing’s geometry might reduce drag. But even on the fastest supercomputers, the hundreds of simulations required might take hours, days or even months to run. But after a day or two of training, the deep geometry models can accomplish the same results in less than a second.

2025-06-23

UNIVERSITY PARK, Pa. — “Deep learning is driving a revolution in physics, science, and engineering,” said Robin Tuluie, founder and chairman of PhysicsX, during the Alumni and Friends Reunion of the Penn State Institute for Gravitation and the Cosmos (IGC) on May 30. Tuluie, who was a postdoctoral scholar with the IGC from 1993 to 1995, presented a talk about the use of deep learning to push the boundaries of engineering. Deep learning is a type of artificial intelligence machine learning inspired by neural networks in the human brain, using several layers of artificial neurons to process data in different ways. Much like large language models (LLMs) — a type of deep learning model— like OpenAI’s ChatGPT and Microsoft Copilot “train” on existing texts and language to create logical sentences, Large physics models and large geometry models train on data from physics, geometry and spatial relationships in order to generate predictions for variables like air or fluid flow across arbitrary geometries. PhysicsX has created large physics models and large geometry models to address engineering challenges in optimizing structures, from aircraft wings and hydro-turbine blades to the tires of Formula 1 cars and the heat-exchangers used to keep batteries in electric vehicles cool. Traditional analysis of structural optimization, Tuluie explained, might involve running many simulations to explore, for example, how adjusting aspects of an airplane wing’s geometry might reduce drag. But even on the fastest supercomputers, the hundreds of simulations required might take hours, days or even months to run. But after a day or two of training, the deep geometry models can accomplish the same results in less than a second.

2025-06-16

Several years ago, a cosmic particle detector in Antarctica observed a series of unusual radio signals, according to an international research group that includes scientists from Penn State. The strange radio pulses were detected between 2016 and 2018 by NASA’s Antarctic Impulsive Transient Antenna (ANITA), a range of instruments flown on balloons high above Antarctica that are designed to detect radio waves from cosmic rays hitting the atmosphere, and a new study provides additional context to the nearly decade-old results. The goal of the ANITA experiment was to gain insight into distant cosmic events by analyzing signals that reach the Earth. Rather than reflecting off the ice, the signals — a form of radio waves — appeared to be coming from below the horizon, an orientation that could not be explained by the current understanding of particle physics and may have hinted at new types of particles or interactions previously unknown to science, the team said at the time. A new study using the Pierre Auger Observatory in Argentina analyzed 15 years of cosmic data to try to make sense of those signals. The team of international scientists, including Penn State researchers, recently published their results in the journal Physical Review Letters. “The radio waves that we detected nearly a decade ago were at really steep angles, like 30 degrees below the surface of the ice,” said Stephanie Wissel, associate professor of physics, astronomy and astrophysics who worked on the ANITA team searching for signals from elusive particles called neutrinos. "While the origin of these events is still unclear, our new study indicates that such events have not been seen by an experiment with a long exposure like the Pierre Auger Observatory. So, it does not indicate that there is new physics, but rather more information to add to the story." She explained that by their calculations, the anomalous signal had to pass through and interact with thousands of kilometers of rock before reaching the detector, which should have left the radio signal undetectable because it would have been absorbed into the rock. “It’s an interesting problem because we still don't actually have an explanation for what those anomalies are, but what we do know is that they're most likely not representing neutrinos,” Wissel said. Neutrinos, a type of particle with no charge and the smallest mass of all subatomic particles, are abundant in the universe. Usually emitted by high-energy sources like the sun or major cosmic events like supernovas or even the Big Bang, there are neutrino signals everywhere. The problem with these particles, though, is that they are notoriously difficult to detect, Wissel explained.

2025-06-04

The Eberly College of Science has a long history of research and teaching excellence in physics, including notable achievements in atomic-scale research and quantum science. In 1955, the late Erwin Müller, Evan Pugh Research Professor of Physics, became the first person to “see” the atom, using a field ion microscope that he invented, in Osmond Laboratory on the Penn State University Park campus. Prior to this landmark advance in scientific instrumentation, there was no direct proof of the existence of atoms. Müller’s research group, which included then–graduate student John Panitz, went on to invent the atom-probe field ion microscope, an atomic-resolution microscope that can reveal the chemical identity of individual atoms, in 1967. Panitz has generously donated a variety of equipment and Müller’s research materials to the Eberly College of Science, which are now on display in Müller’s former office and the lobby of Osmond Laboratory. In 1986, Abhay Ashtekar, Atherton Professor of Physics, developed the theory of loop quantum gravity, which uses quantum mechanics to extend gravitational physics beyond Einstein’s theory of general relativity and opened up a new paradigm in modern physics. As part of this effort, he discovered a new set of variables, now known as Ashtekar variables, that provide a powerful representation of canonical general relativity. Ashtekar founded the Institute for Gravitation and the Cosmos at Penn State, which investigates the fundamental forces of the universe, including gravity, as a way to explain the origin and evolution of the universe. He also founded and later endowed the popular Ashtekar Frontiers of Science lecture series, which celebrated its 31st season this spring. In 1988, Jainendra Jain, Evan Pugh University Professor and Erwin W. Müller Professor of Physics and holder of the Eberly Family Chair in Physics, made theoretical advances that reshaped understanding of quantum mechanics. For these “groundbreaking contributions to quantum matter and its topological potential,” he was recognized with the prestigious 2025 Wolf Prize in Physics. In his early theory research, Jain introduced a class of exotic particles called composite fermions, which helped explain nuances around a phenomenon known as the quantum Hall effect. The quantum Hall effect occurs when electrons in two dimensions are subjected to a strong magnetic field, which results in unique electrical properties. His theory included the intricate sequence of fractional quantum Hall states, now known as Jain states. Jain’s theoretical advances have led to many theoretical and experimental advances, which may ultimately support applications like quantum computing. To further support world-class research and education at Penn State, Osmond Laboratory will undergo critical renovations, including a 48,000-square-foot addition. The renovation will feature new, cutting-edge research lab spaces and a high-bay research facility to accommodate large-scale experiments; spaces to facilitate collaboration and connection; and improvements to teaching spaces. According to physics department head Mauricio Terrones, “These updates to the physics department facilities, specifically those for condensed-matter physics and particle astrophysics, will help us continue to attract and retain the best faculty in support of our highly ranked program.”

2025-05-07

Two months after Jainendra K. Jain, Evan Pugh University Professor and Erwin W. Müller Professor of Physics and holder of the Eberly Family Chair in the Penn State Eberly College of Science, received the 2025 Wolf Prize in Physics, he has been featured on the front page of the Hindustan Times. Earlier this year, Microsoft announced a potential breakthrough in quantum computing based, in part, on the early work of Jain and others in this space. "He discovered a new state of matter — years ago," wrote journalist Kanika Sharma in the Hindustan Times. "There are new formulas named after him. His particles could lead to the discovery of even weirder ones. And Jain recently won the Wolf Prize, considered second only to the Nobel." The full article and May 4 edition of the paper can be read on the Hindustan Times and for those with a Penn State account through Penn State's University Libraries press reader.

2025-05-02

The Institute for Gravitation and the Cosmos is hosting an Alumni and Friends Reunion on May 30-31 at the Hyatt meeting room in State College, Pennsylvania. This event will feature presentations by several postdoctoral scholar alumni, networking opportunities, panel discussions, and a showcase of new developments and initiatives at the IGC. “We are thrilled to welcome back alums and friends of the Institute for Gravitation and the Cosmos, including six people whose time at Penn State collectively spanned the last three decades,” said Sarah Shandera, director of the IGC and professor of physics. “All of them were here as postdoctoral researchers—a career stage when people have the expertise and time to develop new ideas, and when they also serve as the glue in a research group, connecting busy faculty and mentoring graduate students.” Speakers include: Robin Tuluie (IGC postdoc, 1993-1995), previous head of R&D at Renault F1 (engine design); founder PhysicsX Tristan McLoughlin (IGC postdoc, 2005-2007), professor of pure and applied mathematics, Trinity College Dublin Darren Grant (IGC postdoc, 2007-2009), Canada Excellence Research Chair, Simon Fraser University (to be confirmed) Gordana Tešic (IGC postdoc, 2012-2017), data scientist at Meta, Ottawa Jonathan Trump (IGC postdoc, 2013-2016), associate professor of physics, U. Connecticut Surabhi Sachdev (IGC postdoc, 2018-2020), assistant professor of physics, Georgia Tech “We are delighted to showcase their roles as key drivers in our research ecosystem as well as their accomplishments,” Shandera said. “Each of our keynote speakers went on to do really interesting and impactful things in industry or academia, and we are excited to hear their stories! Their talks will anchor the reunion’s program of networking and discussion, including updates on how the Institute is adapting to better serve its members.” Please sign up to attend by May 10. A virtual option will be available for portions of the program. More information about event is available on the IGC website, with an updated program coming soon. Questions can be directed to Courtney Shaffer as cls6664@psu.edu.

2025-04-21

Three graduate students in the Penn State Eberly College of Science have been selected by the J. Jeffery and Ann Marie Fox Graduate School to receive awards for their research and excellence. Ish Gupta has been selected along with twelve other graduate students to receive the Alumni Association Dissertation Award; Garrett Wendel has been selected along with one other graduate student to receive the Penn State Alumni Association Scholarship; and Nate Carey has been selected along with three other graduate students to receive the Professional Master’s Excellence Award. These awards are among some of the most prestigious awards given to graduate students at Penn State. The Alumni Association Dissertation Award was made possible through a gift from the Penn State Alumni Association and provides funding and recognition to outstanding full-time doctor of philosophy students whose dissertations will have the greatest impact. These students have also demonstrated outstanding academic and personal potential in the areas of extracurricular and professional activities. The award, comprised of a certificate and a medal, is considered to be among the most prestigious available to Penn State graduate students and recognizes outstanding professional accomplishment and achievement in scholarly research in any of the disciplinary areas. The Penn State Alumni Association Scholarship for Penn State Alumni in the Fox Graduate School supports students who have been admitted to the Fox Graduate School at Penn State as candidates for a graduate degree who received their undergraduate degree from the University. The Professional Master’s Excellence Award recognizes individual student excellence in a professional master’s degree program. These students demonstrate outstanding breadth of experience, performance, and professional projects or work.

2025-03-10

Jainendra K. Jain, Evan Pugh University Professor and Erwin W. Müller Professor of Physics and holder of the Eberly Family Chair in the Penn State Eberly College of Science, has been awarded, along with two others, the 2025 Wolf Prize in Physics for “groundbreaking contributions to quantum matter and its topological potential” that revolutionized “our understanding of two-dimensional electron systems in strong magnetic fields.” The Wolf Prize acknowledges scientists and artists worldwide for their outstanding achievements in advancing science and the arts for the betterment of humanity. "The Wolf Prize is one of the highest honors in the world of science, and this well-deserved recognition of Dr. Jain’s extraordinary contributions is a proud moment for Penn State," said Penn State President Neeli Bendapudi. "For over 30 years, his groundbreaking work in theoretical physics has deepened our understanding of quantum matter, paving the way for real-world innovations in high-performance electronics and quantum computing. His research exemplifies the power of university-driven discovery, and we celebrate this prestigious recognition of his remarkable achievements." In his early theory research, Jain introduced a class of exotic particles called composite fermions, explaining a new state of matter consisting of the intricate sequence of fractional quantum Hall states, now known as Jain states. Jain described the composite fermion as an electron trapped inside a quantum vortex in this strange liquid, sometimes thought of as an electron bound to a quantized magnetic field. “I am immensely grateful to the Wolf Foundation for welcoming me into this truly esteemed community of scientists for my introduction of composite fermions. The honor truly belongs to my students, collaborators, and numerous other researchers whose brilliant work transformed composite fermions from an idea to reality,” Jain said. “Looking back, it is hard to believe how incredibly fortunate I have been. Growing up in a poor village in India, traumatized by an accident that left me on crutches with a lifelong disability, I did not think I would ever walk again or attend college, let alone pursue my dream of becoming a physicist. I don’t have words to express my profound gratitude to my family, friends, colleagues, and even strangers who have helped and supported me throughout my journey to make this possible. “When the idea of composite fermions first struck me during the Christmas break of 1988, I did not know that these particles would occupy my mind every day for the next 37 years. My hope is that this prize will motivate a few more to experience the beauty of nature through composite fermions.” Under certain conditions, composite fermions form a superconductor — or a material that can conduct electricity without losing any energy at low temperatures — that theorists predicted would contain an even stranger particle, called a Majorana, which is its own antiparticle (a particle with the same mass but different charge). “These discoveries advance high performance electronics, enabling ultra-low resistance materials and topological quantum computing,” the Wolf Foundation shared in its award presentation on March 10. “They reveal complex quantum behaviors, guiding novel materials with revolutionary properties.” Just last month, Microsoft announced a potential breakthrough in quantum computing based, in part, on the early work of Jain and others in this space. “I am on the theoretical understanding side of this spectrum, but I work closely with scientists who test whether the theories correspond to reality,” Jain said in a recent Penn State News article. “The news from Microsoft is an example of how basic research at universities could lead to real-world applications that drive innovation — like quantum computers.” The Wolf Prize is awarded annually and honors exceptional individuals who transcend barriers of religion, gender, race, geography, and political stance, according to the organization’s website. In the scientific domain, the awards are conferred in medicine, agriculture, mathematics, chemistry, and physics. In the arts, the awards recognize excellence in painting and sculpture, music, and architecture.

2025-02-27

More than 30 years ago, Penn State physicist Jainendra Jain pioneered the theory of a new state of matter called the fractional quantum Hall effect, whose discoverers were awarded the Nobel Prize in Physics in 1998. Jain described it as a liquid of certain strange particles that he called composite fermions. Under certain conditions, composite fermions form a superconductor — or a material that can conduct electricity without losing any energy at low temperatures — that theorists predicted would contain an even stranger particle, called a Majorana, which is its own antiparticle — a particle with the same mass but different charge. Theorists envisioned that the Majorana particles, which mirror themselves as their own antiparticles, could be used to perform fault-tolerant quantum computation. This ability to run calculations while simultaneously correcting errors is essential for advancing quantum computing for real-world, industrial scale applications. Last week (Feb. 19), Microsoft announced a potential breakthrough in quantum computing based on these long-theorized but experimentally unconfirmed Majorana particles. They also published a paper in the journal Nature on some of the work described in their announcement. In the following Q&A, Jain, an Evan Pugh University Professor and Erwin W. Müller Professor in Physics, spoke about his work on the theory of composite fermions, how it relates to Microsoft’s announcement and why skepticism is a valuable element of scientific discovery. Q: How does theoretical physics support real-world design? Jain: Quantum physics is the science of how tiny particles — like photons, particles of light, and electrons — behave in ways that seem counter to our everyday experience. Unlike objects we encounter in our daily lives, these tiny particles can pass through barriers and can seemingly exist in multiple places at once, until they are observed. It turns out that physicists can create new particles in the laboratory, which are unlike any particles nature has given us. And, sometimes, they have incredibly strange properties and do things which the old, familiar particles couldn’t. Such particles are called emergent particles. If we can understand them, then maybe we can use them to develop new materials and technologies for the benefit of humanity. I am on the theoretical understanding side of this spectrum, but I work closely with scientists who test whether the theories correspond to reality. The news from Microsoft is an example of how basic research at universities could lead to real-world applications that drive innovation — like quantum computers. Q: What is a quantum computer and how would the Majorana particle help? Jain: A normal computer works with “bits,” which are binary digits and comprise the smallest data unit. It can code either one or zero, on or off, and many of them together in a certain order convey larger messages. A quantum bit, or qubit, offers additional possibilities: it can be on, off or in any superpositions of the two, including on and off at the same time — just like the famous thought experiment “Schrodinger’s cat” in which a cat in a box is both alive and dead at the same time, until someone opens the box to check, at which time a definitive state of dead or alive is achieved. When you link many qubits together, the possibilities grow exponentially. This allows a quantum computer to do certain types of calculations, at least theoretically, much faster than a classical computer. One can come up with examples where all the world’s current computers operating together for decades would not be able to perform the calculations of one quantum computer in a day. One of the biggest hurdles in quantum computing is that information degrades because of interaction with noise, or interference from the environment or elsewhere in the system. This can lead qubits to collapse into a definite state, introducing errors. This is where the rather strange Majorana particles come in. Two Majorana particles can produce either nothing or a whole fermion, which make the on and off states of a single qubit. Unlike many other qubits, the information here can be stored non-locally in a topological fashion — meaning the two Majorana particles forming a qubit could be far apart. Then, since neither Majorana contains the full information, any local noise cannot switch off to on or on to off. This enables the qubits to hold information without information loss. Q: Tell me more about your work. What are composite fermions and how do they relate to applications like quantum computing? Jain: My work had a role in the unlikely sequence of events that led to the idea of Majorana-based quantum computation. I think this is an example of how ideas evolve and mutate and move into unexpected directions.

2025-02-20

Jacob Bourjaily, associate professor of physics, was honored with the Lars Kann-Rasmussen Prize for 2025 by the Niels Bohr International Academy (NBIA), in Copenhagen, Denmark. The prize is awarded annually to an exceptionally talented young individual who has had very high impact in research and has or has had close connections to the Niels Bohr Institute. Bourjaily was presented the prize by Lars Kann-Rasmussen, former chairman of the board of VKR Holding and the Villum Foundation, at an award ceremony on February 24 that was attended by the head of the Niels Bohr Institute Joachim Mathiesen, Deputy Dean of Research Lise Arleth, and NBIA Director Poul Henrik Damgaard. “I am extremely grateful for the generosity and support I was given during the nearly ten years I spent at the Niels Bohr Institute and International Academy,” Bourjaily said. “Through the generosity and support of the Danish people and the Niels Bohr Institute, I was able to build and lead the world’s largest team of postdoctoral scholars studying exciting new developments in quantum field theory. It is a great honor to be awarded this prize for the work that was started there.” Bourjaily was awarded the prize "for his fundamental and original contributions to quantum field theory, guided by an on-going quest for both simplifications and deeper understanding." Bourjaily is a theoretical physicist whose research revolves around quantum field theory — the basic theoretical and mathematical framework that combines quantum mechanics with relativity. He works to revolutionize how quantum field theory is used to make predictions for experiments. Among the most important of these predictions are scattering amplitudes, which encode the predicted relative likelihoods of all possible outcomes of any experiment. Bourjaily’s research has led to great advances in the ability to make such predictions and in understanding the mathematical form that these predictions take.

Astrostatistics is the study of how to use astronomical observations, with their associated uncertainties, to constrain models of astrophysics and cosmology. Measurements are made with imperfect instruments and the way in which many objects are observed can be biased by something in their local environment, like dust, that reduces or enhances the emitted signal. Accurately inferring the model from the data requires a careful accounting for all those effects. Visit Penn State's Center for Astrostatistics website to find out more about. [Image Credit: NASA/Ames/JPL-Caltech]

Black holes are regions of spacetime so dense that nothing can escape their gravitational pull - not even light. Researchers at Penn State study black holes theoretically in the context of general relativity and candidate theories for quantum gravity as well as observationally through electromagnetic and gravitational wave surveys.

Cosmic Rays are elementary particles and nuclei, detected on or near the Earth, that originate in energetic processes in the universe. Physicists work to characterize the cosmic ray spectrum: the abundance of different types of particles and their energies. Observations of the primary particles are made in space (e.g., the Alpha Magnetic Spectrometer, AMS, on the International Space Station) and with high-altitude balloons (e.g., the High Energy Light Isotope eXperiment, HELIX). When cosmic rays interact with the Earth's atmosphere, they generate showers of other particles, called secondary cosmic rays, that are detected by instruments on the ground (e.g., the Pierre Auger surface water tanks and fluorescence detectors), and under the ground (e.g., the AMIGA, Auger Muons and Infill for the Ground Array extension for Pierre Auger). Cosmic ray data is used to constrain models for sources that can produce high-energy particles, either extremely energetic astrophysical environments like those around Active Galactic Nuclei (AGN) or extreme events like gamma ray bursts (GRBs).

Cosmological surveys map out the distribution of matter in the universe. Some surveys may target a particular type of object by looking for a very particular spectral signal. For example, the HETDEX survey is designed to find a class of galaxies, Lyman-$\alpha$ emitters, at a time when the universe was about 10-11 billion years younger than it is today. By precisely measuring how those galaxies are receding from us, HETDEX will provide a new constraint on the expansion rate of the universe and the role of dark energy in the past. Other surveys collect light across a wider range of frequencies. For example, the Rubin Observatory Legacy Survey of Space and Time (LSST) will take optical images of a large fraction of the sky, nearly every night. LSST will detect nearly 4 billion galaxies that can be measured so precisely that distortions in galaxy shapes due to gravity can be used, statistically, to map out how both dark and luminous matter are distributed in the Universe. Because LSST will image the same part of the sky so often, it will also capture the variations of light emitted by objects that are changing rapidly, allowing studies of the dynamic universe.

Matter can be detected by its gravitational pull. Many different observations together indicate that about 84% of the gravitating matter in the universe emits no detectable photons. This is the dark matter, and the quest to understand what it is drives the work of large communities in cosmology and particle physics. Experiments like the Large Underground Xenon experiment, LUX, are designed to search for possible interactions between dark matter particles and the particles of the Standard Model. Surveys like the Rubin Observatory Legacy Survey of Space and Time, LSST, will carefully map out the distribution of dark matter, probing for signs that some particle physics interactions was at work along with gravity and affected the evolution of structure. Gravitational wave observations may also reveal something about the nature of dark matter if, for example, the population of detected black holes is inconsistent with the expected astrophysical population.

Many dynamic phenomena in the universe occur over a period of seconds to years. Events with quickly evolving signals include the explosions of Type 1a supernovae, the destruction of stars passing too close to a black hole, and the merger of neutron stars. Some transient phenomena, like Type Ia supernovae, release light in such a reliable way that they can be used as standard reference events to study the evolution of the universe. Other events provide information about matter in extreme environments and at very high energies. These phenomena may be observed not just through their electromagnetic emission, but also through the generation of particles or gravitational waves. For example, a merger of two neutron stars first detected as a gravitational wave event, GW170817, was subsequently observed across the electromagnetic spectrum. Fluctuations in the energetic matter streaming out from the vicinity of a black hole in the center of a galaxy, the flaring blazar TXS 0506+056, produced both neutrinos detected by IceCube and high-energy gamma rays. Several new instruments promise to bring an explosion of data for the study of transient phenomena in the universe. [Image Credit: Illustration: CXC/M. Weiss; X-ray: NASA/CXC/UNH/D. Lin et al, Optical: CFHT. ]

Gravitational waves are tiny ripples in space created by accelerating masses such as the orbit of neutron stars and black holes. As a gravitational wave passes through space it changes the distance between two points. Researchers at Penn State study gravitational waves theoretically as well as observationally through the LIGO and Virgo observatories.

Loop Quantum Gravity is a theory of quantum gravity based on a geometric formulation that predict discrete geometrical phenomena above some minimum length scale (the Planck length).

Physics often advances when crisp mathematical structures are uncovered in a framework developed to describe observed phenomena. For example, in quantum field theory there is a vast discrepancy between the current calculational difficulty in making predictions for experiments and the simple, mathematical form of the end result. The Amplitudes program seeks to explain and exploit this surprising simplicity by reformulating the basic mathematical tools used to make predictions.

Many astrophysical phenomena release not just light (electromagnetic radiation), but also gravitational waves and/or elementary particles including neutrinos and cosmic rays. Each of those signals carries different information about the physics of the source, so collecting more than one enables us to have a deeper understanding of the event that produced them. However, it is an enormous challenge for different types of instruments to coordinate simultaneous observations, and to verify that signals have a common source. Projects like AMON and SciMMA help alert the community to potential multi-messenger events so that an observing program can be coordinated as quickly and efficiently as possible.

Neutrinos are light, electrically-neutral elementary particles that make up the least-understood part of the Standard Model of particle physics. Facilities like DUNE (the Deep Underground Neutrino Experiment) study neutrinos produced in the Fermilab collider as well as neutrinos arriving from cosmic events. Project 8 will measure neutrino mass by looking at neutrinos emitted when tritium decays. The CMB Stage 4 telescopes will use cosmological data to constrain the number of neutrinos and their mass. Many other neutrino facilities focus on detecting neutrinos produced in astrophysical processes, including ANITA, ARA, BEACON, GRAND, IceCube, PUEO, and RNO-G. These cosmic neutrinos can carry key information, along with electromagnetic radiation and gravitational waves, in "multi-messenger" detections of dynamic events in the universe.

Physical mathematics is concerned with mathematics motivated by physics. Prime example of physical mathematics is the pioneering work of Eugene Wigner on the unitary representations of Poincare group which was motivated by his results proving that symmetries of quantum systems must be realized unitarily on their Hilbert spaces. His work opened up the huge field studying the unitary duals of noncompact Lie groups which is still an unfinished chapter of mathematics. In a similar vein, the discovery of supersymmetry by physicists led to the development of the theory of unitary representations of Lie superalgebras. Remarkably, though algebraically more complicated the theory of unitary representations of noncompact Lie superalgebras turned out to be simpler than those of noncompact Lie groups. Furthermore, some of the earliest results on AdS/CFT dualities were obtained, in a true Wignerian sense, within the framework of work on fitting the spectra of Kaluza-Klein supergravities into unitary supermultiplets of their underlying supersymmetry algebras.

All physical systems obey the laws of quantum mechanics, but we have not yet achieved a full understanding of the relationship between quantum mechanics, general relativity, and cosmology. The primordial universe and black holes are two arenas to study these questions in ways that are complementary to research on laboratory quantum systems and quantum information.

Accreting supermassive black holes at the centers of galaxies

The strong force out-competes the electromagnetic force on short distances to hold protons together in atomic nuclei. Nuclear matter can be studied in particle colliders and astrophysical objects like neutron stars. The quantum effects of particles that feel the strong force are important for many measurements in particle physics, including the recently measured anomalous magnetic moment of the muon. Many theoretical predictions of the effects of the strong force rely on the numerically-intensive work that requires supercomputers.