outstanding contribution to cosmology

Cocconi Prize, outstanding contribution to cosmology

 

Kyle Dawson (right) and eBOSS co-leadership accept the Giuseppe and Vanna Cocconi Prize. CREDIT: COURTESY OF THE EUROPEAN PHYSICAL SOCIETY

The High Energy and Particle Physics Division of the European Physical Society (EPS) held its award ceremony at their annual conference on August 21, 2023, where they honored the field’s most influential research projects. The SDSS/BOSS/eBOSS collaboration won the Giuseppe and Vanna Cocconi Prize for an outstanding contribution to particle astrophysics and cosmology in the last fifteen years. The University of Utah was a key contributor to the BOSS and eBOSS collaborations.

“I joined the BOSS experiment when moving to the University of Utah. At the time, it felt like a gamble moving into a new cosmology experiment when starting as an assistant professor. It was clearly the right gamble to make as the experience has defined my career and has set me up to help plan large cosmology experiments over the next decade and beyond,” said Kyle Dawson, principal investigator of eBOSS and professor in physics and astronomy at the U.

The SDSS/BOSS/eBOSS projects are international collaborations involving hundreds of scientists that have fundamentally changed our understanding of the universe.

Read the full story in @TheU.

Gravitational Waves

Gravitational waves thrum through the cosmos

Last June dozens of astronomy enthusiasts gathered on the University of Utah campus to watch a live stream of a mysterious announcement. For weeks prior, scientists on Twitter, TikTok and IRL were abuzz with anticipation, awaiting results from the North American Nanohertz Observatory for Gravitational Waves’ (NANOGrav) 15 years’ worth of data.

 

NANOGrav confirmed what had long been suspected—gravitational waves are thrumming throughout the universe, emitting a low-pitched symphony that distorts the fabric of space and time.

 Tanmoy Laskar, assistant professor at the U’s Department of Physics & Astronomy thought of organizing the watch party to share in the excitement and discuss the results with the U community. He spoke with @TheU to explain the announcement.

Why is the astrophysics community so excited about the announcement?

This is very exciting because our current astrophysics and cosmology theories tell us that the universe should be full of these gravitational waves and, with these new results, the evidence for the existence of such a gravitational wave background just got much, much stronger. Furthermore, multiple global teams published their own, independent data sets on the same day and each team finds strong evidence for the presence of this gravitational wave background, which means that this signal is very likely real.

An amphitheater with dozens of people face towards a pull-down screen with the NSF and NANOGrav logo on it.

PHOTO CREDIT: TANMOY LASKAR

A live stream watch party for the NANOGrav announcement at the U.

 DOWNLOAD FULL-RES IMAGE

How did the collaboration detect the gravitational waves?

Gravitational waves are essentially a small stretch and squeeze in space and time. This means that if we want to detect a gravitational wave going by, we need to measure small perturbations to the distance between free-floating masses or to the time difference between two freely falling clocks. But the gravitational wave background that was the focus of the new studies involves waves with extremely long wavelengths—dozens of light years. This means to detect them we need clocks or masses separated by similar distances.

To navigate this, NANOGrav and their sister experiments used a technique called pulsar timing. Pulsars are rapidly spinning, very dense stars packing the mass of our sun into the size of a small city. They were discovered in 1967 by Dame Jocelyn Bell-Burnell as extraterrestrial objects producing regular radio pulses. The radio pulses from pulsars tend to be extremely regular because they behave similar to lighthouses. If you look at a lighthouse from the shore, its rotating beam of light flashes towards you at regular intervals. In the same way, pulsars appear as regular radio pulses seen when their lighthouse-like radio beams periodically sweep past Earth.

Astronomers realized that an array of pulsars spread across our galaxy could be used as a network of clocks. By timing the arrival of the pulses from these pulsars, one could look out for passing gravitational waves that would disrupt the timing of radio pulses that would usually arrive like clockwork. Tracking a large number of pulsars for disruptions is much more reliable. The idea is that if a gravitational wave goes through, then not only will there will be offsets in the time of arrival of the pulses from each pulsar from their expected times, such effects will be correlated in a predictable fashion between different pulsars depending on each pulsar’s direction and distance from Earth.

Of course a lot of different effects still need to be accounted for, including the motion of the Earth and planets in the Solar System and the slowing down of each pulsar as it slowly loses energy. Not to mention the fact that these gravitational waves have wavelengths that correspond to several Earth years, meaning that the observations need to be collected for over a decade to make a discovery!

To read the full interview with Lisa Potter visit @TheU

Information Engines Pay the Piper

Physicists sometimes get a bad rap. Theoretical physicists even more so. Consider Sheldon Cooper in the TV sit-com The Big Bang Theory:


Sheldon
: I’m a physicist. I have a working knowledge of the entire universe and everything it contains.
Penny: Who’s Radiohead?
Sheldon: (after several seconds of twitching) I have a working knowledge of the important things in the universe.

Mikhael Semaan

But a working knowledge of anything is always informed and arguably improved — even transformed — by robust and analytical “thought experiments.” In fact, theoretical physics is key to advancing our understanding of the universe, from the cosmological to the particle scale, through mathematical models.

That is why Mikhael Semaan, Ph.D. and others like him spend their time in the abstract, standing on the figurative shoulders of past giants and figuring out what could happen . . . theoretically. That Semaan is also one of the celebrated postdoctoral researchers/mentors in the Science Research Initiative (SRI), is a coup for undergraduates at the University of Utah who “learn by doing” in a variety of labs and field sites.

“The SRI is awesome,” Semaan says. It’s “a dream job where I can continue advancing my own research while ‘bridging the gap’ in early undergraduate research experiences, giving them access to participation in the cutting edge alongside personalized mentoring.”

Want to learn how to bake something? Hire a baker. Better still, watch the baker bake (and maybe even lick the bowl when allowed). And now that Semaan’s second first-author paper — done with senior investigator Jim Crutchfield of UC Davis, his former PhD advisor — has just “dropped,” students get to witness in real time how things get done, incrementally adding to the trove of scientific knowledge that from past experience, we know, can change the world.

Theory’s abstraction lets us examine certain essential features of the subjects and models we study, which in Semaan and Crutchfield’s case concern the first and second laws of thermodynamics. Is it possible to run a car from the hard drive of a computer? In the parlance of this brand of physics, the short answer is, “Yes, theoretically.”

Thermodynamics of Information Processing

From that question as a jumping off point, Semaan explains further. “The primary impact of our contribution is, for now, mostly to other theorists working out the thermodynamics of information processing. … [W]e suggest a change in viewpoint that simplifies and unifies various preceding lines of inquiry, by combining familiar tools to uncover new results.”

The physicist and writer C.P. Snow said that the first three laws of thermodynamics can be pithily summarized with, “You can’t win. You can’t even break even. You can’t stay out of the game.” Semaan elaborates on the second law, “the universe must increase its entropy — its degree of ‘disorder’ — on average…[b]esides offering an excuse for a messy room, this statement has far-reaching implications and places strict limits on the efficiency of converting one form of energy to another … .”

These limits are obeyed by everything from the molecular motors in our bodies to the increasingly sophisticated computers in our pockets to the impacts of global industry on the Earth’s climate and beyond. Yet in the second law’s case, there’s a catch: it turns out that information in the abstract is itself a form of entropy. This insight is key to the much-celebrated “Landauer bound:” stated simply, learning about a system — going from uncertainty to certainty — fundamentally costs energy.

But what about the converse situation? If it costs energy to “reduce” uncertainty, can we extract energy by “gaining” it — for example, by scrambling a hard drive? If so, how much?

Ratchet Information

To answer this question, previous researchers, including Crutchfield, imagine a “ratchet” which moves in one direction along an “information tape,” interacting with one “bit” at a time. As it does so, the ratchet modifies the tape’s statistical properties. That “tape” could be the hard drive in your computer or could be a sequence of base pairs in a strand of DNA.

“In this situation, by scrambling an initially ordered tape, yes: we can actually extract heat from the environment, but only by increasing randomness on the tape.” While the second law still holds, it is modified. “The randomness of the information in the tape is itself a form of entropy,” explains Semaan further, “and we can reduce the entropy in our thermal environment as long as we sufficiently increase it in the tape.”

In the literature, the laws bounding this behavior are termed “information processing second laws,” in reference to their explicit accounting for information processing (via modifying the tape) in the second law of thermodynamics. In this new paper, Semaan and Crutchfield uncover an “information processing first law,” a similar modification to the first law of thermodynamics, which unifies and strengthens various second laws in the literature. It appears to do more, too: it also offers a way to tighten those second laws — to place stricter limits on the allowed behavior — for systems which have “nonequilibrium steady states.”

Non-equilibrium steady state systems — our bodies, the global climate, and our computers are all examples — need to constantly absorb and dissipate energy, and so stay out of equilibrium, even in “steady” conditions (contrast a cup of coffee left out: its “steady” state is complete equilibrium with the room).

“It turns out,” says Semaan, “that in this case we must ‘pay the piper’:  we can still scramble the tape to extract heat, but only if we do so fast enough to keep up with the non-equilibrium steady states.” To demonstrate their new bound, the authors cooked up a simple, tunable model to visualize how much tighter the new results are with concrete, if idealized, examples. “This sort of idealization is a powerful tool,” says Semaan, “because with it we can ‘zoom in’ on only those features we want to highlight and understand, in this case what having nonequilibrium steady states changes about previous results.”

This uni-directional “ratcheting” mechanism may, in fact, someday lead to engineering a device that harnesses energy from scrambling a hard drive. But first, beyond engineering difficulties, there is much left to understand about the mathematical, idealized limits of this behavior. In other words, we still have a ways to go, even “in theory.” There are plenty of remaining questions to address, the fodder for any theoretical physicist worth their salt.

Complex Systems

However, far from being “only” a theoretical exercise, says Semaan, “these continued extensions, reformulations, and corrections are necessary for us to be able to understand how real-world, highly interconnected, complex systems,” like the human body, forest ecosystems, the planetary climate, etc., “exploit (or don’t) the dynamical interplay between energy and information to function. Since so many of the intricate systems we see in nature (including ourselves) exhibit non-equilibrium steady states,” he continues, “this is a [required] step to understanding how they [do this].”

Information ratchet system: At each time step, the ratchet moves one step to the right along the tape, and interacts with one symbol at a time. As it does so, it exchanges energy in various forms with its environment — signified by the T, aux, and λ bubbles in the picture. After running for a long time, the “output tape” generated by the interactions with the ratchet has different statistical properties compared to the “input tape” it receives. The information processing first and second laws are statements about the fundamental relationship between the energy exchanged with the environment and the information processing in the tape. Credit: Semaan and Crutchfield.

This is heady stuff, and the Southern California native is positively thrilled to be sharing it with young, eager undergraduates at the U through the SRI. Semaan is keenly aware of how critical the undergraduate experience in research needs to be to turn out future physicists. A son of Lebanese immigrants who both attended college in the U.S., neither were research scientists and no one he knew had studied physics. At California State University, Long Beach, where Semaan first declared electrical engineering as his major, he was “seduced into physics” through a series of exceptional and inspirational mentors. In the SRI, he hopes to carry this experience forward, and open new doors for undergraduate students.

It was the Complexity Sciences Center at UC Davis, when he applied to graduate school, that caught his attention because of its interdisciplinary nature and concern with systems in which “the whole appears to be greater than the sum of its parts.” The study of emerging systemic behaviors, helmed by Crutchfield, the Center’s Director, ultimately inspired both his PhD and his decision to join the SRI, working with students across the entire College of Science.

Following the third law of thermodynamics, Mikhael Semaan clearly “can’t stay out of the game” (nor would he want to), but one could argue he’s more than breaking even at it.

The release of this paper, titled “First and second laws of information processing by nonequilibrium dynamical states” in the journal Physical Review E is proof of that.


by David Pace

APS Fellows

APS Fellows


Physics Professors Named APS Fellows

Two professors in the U’s Department of Physics & Astronomy—Christoph Boehme, Professor and Chair of the department, and Ramón Barthelemy, Assistant Professor, have been elected fellows of the American Physical Society (APS). The APS Fellowship Program was created to recognize members who may have made advances in physics through original research and publication, or made significant innovative contributions in the application of physics to science and technology. They may also have made significant contributions to the teaching of physics or service and participation in the activities of the society.

Election to the APS is considered one of the most prestigious and exclusive honors for a physicist—the number of recommended nominees in each year may not exceed one-half percent of the current membership of the Society. APS is a nonprofit membership organization working to advance the knowledge of physics through its outstanding research journals, scientific meetings, and education, outreach, advocacy, and international activities. The APS represents more than 50,000 members, including physicists in academia, national laboratories, and industry in the United States and throughout the world.

Christoph Boehme

Christoph Boehme

“I am profoundly honored by my selection as an APS Fellow. Receiving this recognition is an excellent opportunity to look back at my research career, starting with my first experiments as an undergraduate researcher more than 25 years ago. When I think about all the discoveries and inventions I have had the chance to contribute to, I realize that none of them would have happened without the collaboration, support, and collegiality of many others. These include my former research advisors, all the students and postdocs who have worked in my research labs, my colleagues at the University of Utah (both staff and faculty), and other institutions. I am very much indebted to all these wonderful people.”

Boehme was born and raised in Oppenau, a small town in southwest Germany, 20 miles east of the French city of Strasbourg. After obtaining an undergraduate degree in electrical engineering, and committing to 15 months of civil services caring for disabled people (chosen to avoid the military draft), he moved to Heidelberg, Germany in 1994 to study physics at Heidelberg University.

In 1997 Boehme won a German-American Fulbright Student Scholarship, which brought him to the United States for the first time, where he studied at North Carolina State University and met his spouse. In 2000 they moved to Berlin, Germany, where they lived for five years while he worked for the Helmholtz-Zentrum Berlin, a national laboratory. He finished his dissertation work as a graduate student of the University of Marburg in 2002 and spent an additional three years working as a postdoctoral researcher.

Boehme moved to Utah in 2006 to join the Department of Physics & Astronomy as an Assistant Professor. He was promoted to Associate Professor and awarded tenure in 2010; three years later, he became a professor. During his tenure at the U, Boehme received recognition through a CAREER Award of the National Science Foundation in 2010, the Silver Medal for Physics and Materials Science from the International EPR Society in 2016, as well as the U’s Distinguished Scholarly and Creative Research Award in 2018 for his contributions and scientific breakthroughs in electron spin physics and for his leadership in the field of spintronics.

He was appointed Chair of the department in July, 2020 after serving as interim chair. Previously, Boehme served as associate chair of the department from 2010-2015. His research is focused on the exploration of spin-dependent electronic processes in condensed matter. The goal of the Boehme Group is to develop sensitive coherent spin motion detection schemes for small spin ensembles that are needed for quantum computing and general materials research.

Ramón Barthelemy

Ramón Barthelemy

“When I started graduate school you couldn’t even ask the LGBT question in physics without ending your career,” said Barthelemy. “Although homophobia and transphobia are still rampant in physics, a few of us are lucky enough to ask the question and still continue in the field. It is amazing to get this recognition for my work considering the history of queer people in physics, from Alan Turing‘s death to the ending of Frank Kameny‘s astronomy career, and the inability of people like Sally Ride and Nikola Tesla to be public with all of their relationships. I am both humbled and full of gratitude to pursue funded work giving voice to queer people in physics and, importantly, changing policy.”

Barthelemy is an early-career physicist with a record of groundbreaking scholarship and advocacy that has advanced the field of physics education research as it pertains to gender issues and lesbian, gay, bisexual, and transgender (LGBT)+ physicists.

The field of physics struggles to support students and faculty from historically excluded groups. Barthelemy has long worked to make the field more inclusive—he has served on the American Association of Physics Teachers (AAPT) Committee on Women in Physics and on the Committee on Diversity—and was an early advocate for LGBT+ voices in the AAPT. He co-authored LGBT Climate in Physics: Building an Inclusive Community, an influential report for the American Physical Society, and the first edition of the LGBT+ Inclusivity in Physics and Astronomy Best Practices Guide, which offers actionable strategies for physicists to improve their departments and workplaces for LGBT+ colleagues and students. He also recently published the first peer reviewed quantitative study on LGBT+ physicists which received national attention.

In 2019, Barthelemy joined the U’s College of Science as its first tenure-track faculty member focusing on physics education research (PER), a field that studies how people learn physics and culture of the community. Since arriving, he has built a program that gives students rigorous training in physics concepts and in education research, qualities that prepare students for jobs in academia, education policy, or general science policy. He founded the Physics Education Research Group at the University of Utah (PERU), where he and a team of postdoctoral scholars and graduate and undergraduate students explore how graduate program policies impact students’ experiences; conduct long-term studies of the experience of women in physics and astronomy and of Students of Color in STEM programs; and seek to understand the professional network development and navigation of women and LGBT+ PhD physicists.

In discussing Barthelemy’s election as a fellow to the APS, two of his mentors, Geraldine L. Cochran and Tim Atherton, commented on his work: “Barthelemy has provided an excellent example for how research on the educational experiences of people from marginalized groups can center the voices of the research participants,” said Cochran, Associate Professor at Rutgers University. “Indeed, Dr. Barthelemy was among the first—if not the first—in physics education research to use Feminist Standpoint Theory in his research.”

“Fellowship is one of the highest honors that that American Physical Society can bestow and is normally reserved for scientists much further along in their careers,” said Atherton, Associate Professor of Physics at Tufts University. “Ramón’s election is a signature of the incredible esteem in which his fellow physicists hold him and points to the significance of his work. This kind of work is necessary to transform the culture of physics to fully include LGBTQ+ people. As one of these people myself, and as someone who has not always been included by the academic community, I’m thrilled that Ramón has been given this incredible honor.”

Barthelemy earned his Bachelor of Science degree in astrophysics at Michigan State University and received his Master of Science and doctorate degrees in PER at Western Michigan University. “Originally, I went to graduate school for nuclear physics, but I discovered I was more interested in diversity, equity, and inclusion in physics and astronomy. Unfortunately, there were very few women, People of Color, LGBT or first-generation physicists in my program,” said Barthelemy, who looked outside of physics to understand why.

Other awards:
In 2022, Earlier he received the 2022 WEPAN (Women in Engineering ProActive Network) Betty Vetter Research Award for notable achievement in research related to women in engineering.

In 2021, Barthelemy received the Doc Brown Futures Award, an honor that recognizes early career members who demonstrate excellence in their contributions to physics education and exhibit excellent leadership.

He received the 2020 Fulbright Finland award but wasn’t able to travel to Finland to give his lectures until 2022.

In 2020, he and his U colleagues Jordan Gerton and Pearl Sandick were awarded $200,000 from the National Science Foundation to complete a case study exploring the graduate program changes in the U’s Department of Physics & Astronomy. In the same year, Barthelemy received a $350,000 Building Capacity in Science Education Research award to continue his longitudinal study on women in physics and astronomy and created a new study on People of Color in U.S. graduate STEM programs. Later, he received a $120,000 supplement to continue the work.

He also co-received a $500,000 grant with external colleagues Dr. Charles Henderson and Dr. Adrienne Traxler to study the professional network development and career pathways of women and LGBT+ PhD physicists in academia, the government, and private sectors. Lastly, Barthelemy was selected to conduct a literature review on LGBT+ scientists as a virtual visiting scholar by the ARC Network, an organization dedicated to improving STEM equity in academia.

In 2014, Barthelemy completed a Fulbright Fellowship at the University of Jyväskylä, in Finland where he conducted research looking at student motivations to study physics in Finland. In 2015, he received a fellowship from the American Association for the Advancement of Science Policy in the United States Department of Education and worked on science education initiatives in the Obama administration. After acting as a consultant for university administrations and research offices, he began to miss doing his own research and was offered a job as an assistant professor at the University of Utah.

first published @ physics.utah.edu

 

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