Newswise — In 1956, theoretical physicist David Pines predicted that electrons in a solid can do something strange. While they normally have a mass and an electric charge, Pines asserted that they can combine to form a composite particle that is massless, neutral, and does not interact with light. He called this particle a “demon.” Since then, it has been speculated to play an important role in the behaviors of a wide variety of metals. Unfortunately, the same properties that make it interesting have allowed it to elude detection since its prediction.
Now, a team of researchers led by Peter Abbamonte, a professor of physics at the University of Illinois Urbana-Champaign, have finally found Pines’ demon 67 years after it was predicted. As the researchers report in the journal Nature, they used a nonstandard experimental technique that directly excites a material’s electronic modes, allowing them to see the demon’s signature in the metal strontium ruthenate.
“Demons have been theoretically conjectured for a long time, but experimentalists never studied them,” Abbamonte said. “In fact, we weren’t even looking for it. But it turned out we were doing exactly the right thing, and we found it.”
The elusive demon
One of the most important discoveries of condensed matter physics is that electrons lose their individuality in solids. Electric interactions make the electrons combine to form collective units. With enough energy, the electrons can even form composite particles called plasmons with a new charge and mass determined by the underlying electric interactions. However, the mass is usually so large that plasmons cannot form with the energies available at room temperature.
Pines found an exception. If a solid has electrons in more than one energy band, as many metals do, he argued that their respective plasmons can combine in an out-of-phase pattern to form a new plasmon that is massless and neutral: a demon. Since demons are massless, they can form with any energy, so they may exist at all temperatures. This has led to speculation that they have important effects on the behavior of multi-band metals.
Demons’ neutrality means that they do not leave a signature in standard condensed matter experiments. “The vast majority of experiments are done with light and measure optical properties, but being electrically neutral means that demons don’t interact with light,” Abbamonte said. “A completely different kind of experiment was needed.”
A serendipitous discovery
Abbamonte recalls that he and his collaborators were studying strontium ruthenate for an unrelated reason—the metal is similar to high-temperature superconductors without being one. Hoping to find clues to why the phenomenon occurs in other systems, they were conducting the first survey of the metal’s electronic properties.
The research group of Yoshi Maeno, a professor of physics at Kyoto University, synthesized high-quality samples of the metal which Abbamonte and former graduate student Ali Husain examined with momentum-resolved electron energy-loss spectroscopy. A nonstandard technique, it uses energy from electrons shot into the metal to directly observe the metal’s features, including plasmons that form. As the researchers were looking through the data, though, they found something unusual: an electronic mode with no mass.
Husain, now a research scientist at Quantinuum, recalled, “At first, we had no idea what it was. Demons are not in the mainstream. The possibility came up early on, and we basically laughed it off. But, as we started ruling things out, we started to suspect that we had really found the demon.”
Edwin Huang, a Moore Postdoctoral Scholar at UIUC and condensed matter theorist, was eventually asked to calculate the features of strontium ruthenate’s electronic structure. “Pines’ prediction of demons necessitates rather specific conditions, and it was not clear to anyone whether strontium ruthenate should have a demon at all,” he said. “We had to perform a microscopic calculation to clarify what was going on. When we did this, we found a particle consisting of two electron bands oscillating out-of-phase with nearly equal magnitude, just like Pines described.”
The importance of just measuring stuff
According to Abbamonte, it was no accident that his group discovered the demon “serendipitously.” He emphasized that he and his group were using a technique that is not widely employed on a substance that has not been well studied. That they found something unexpected and significant is a consequence of simply trying something different, he believes.
“It speaks to the importance of just measuring stuff,” he said. “Most big discoveries are not planned. You go look somewhere new and see what’s there.”
Support was provided by the U.S. Department of Energy, the Japan Society for the Promotion of Science, the National Science Foundation, and the Gordon and Betty Moore Foundation.
Record-Setting NASA Astronaut, Crewmates Return from Space Mission
After spending an American record-breaking 371 days in space, NASA astronaut Frank Rubio safely landed on Earth with his crewmates Wednesday.
Rubio departed the International Space Station, along with Roscosmos cosmonauts Sergey Prokopyev and Dmitri Petelin, at 3:54 a.m. EDT, and made a safe, parachute-assisted landing at 7:17 a.m. (5:17 p.m. Kazakhstan time), southeast of the remote town of Dzhezkazgan, Kazakhstan.
“Frank’s record-breaking time in space is not just a milestone; it’s a major contribution to our understanding of long-duration space missions,” said NASA Administrator Bill Nelson. “Our astronauts make extraordinary sacrifices away from their homes and loved ones to further discovery. NASA is immensely grateful for Frank’s dedicated service to our nation and the invaluable scientific contributions he made on the International Space Station. He embodies the true pioneer spirit that will pave the way for future exploration to the Moon, Mars, and beyond.”
Rubio launched on his first spaceflight on Sept. 21, 2022, alongside Prokopyev and Petelin. Rubio’s spaceflight is the longest single spaceflight by a U.S. astronaut, breaking the record previously held at 355 days by NASA astronaut Mark Vande Hei.
During his mission, Rubio completed approximately 5,936 orbits and a journey of more than 157 million miles, roughly the equivalent of 328 trips to the Moon and back. He witnessed the arrival of 15 visiting spacecraft and the departure of 14 visiting spacecraft representing crewed and uncrewed cargo missions.
Rubio’s extended mission provides researchers the opportunity to observe the effects of long-duration spaceflight on humans as the agency plans to return to the Moon through the Artemis missions and prepare for exploration of Mars.
Rubio, Prokopyev, and Petelin launched aboard the Soyuz MS-22 spacecraft but, due to a coolant leak, returned to Earth aboard the Soyuz MS-23. The affected Soyuz MS-22 capsule returned without its crew after the Soyuz MS-23 capsule launched as a replacement on Feb. 23, 2023.
Following post-landing medical checks, the crew will return to Karaganda, Kazakhstan. Rubio will then board a NASA plane bound for his return to Houston.
During his record-breaking mission, Rubio spent many hours on scientific activities aboard the space station, conducting a variety of tasks ranging from plant research to physical sciences studies.
With the undocking of the Soyuz MS-23 spacecraft, Expedition 70 officially began aboard the station. NASA astronauts Loral O’Hara and Jasmin Moghbeli remain aboard the orbital outpost alongside ESA (European Space Agency) astronaut Andreas Mogensen, who became station commander Sept. 26, JAXA (Japan Aerospace Exploration Agency) astronaut Satoshi Furukawa, and Roscosmos cosmonauts Konstantin Borisov, Oleg Kononenko, and Nikolai Chub.
Mogensen, Moghbeli, Furukawa, and Borisov will return to Earth in February 2024, after a short handover with the crew of NASA’s SpaceX Crew-8 mission. O’Hara is scheduled to return to Earth in March 2024, while Kononenko and Chub will spend a year aboard the station, returning in September 2024.
NASA Names New Head of Technology, Policy, Strategy
NASA Administrator Bill Nelson announced Monday Charity Weeden will serve as associate administrator for the agency’s Office of Technology, Policy, and Strategy (OTPS), effective immediately. Weeden succeeds Bhavya Lal, who left the agency in July, and Ellen Gertsen, who had been serving as the office’s acting leader since then.
Charity Weeden poses for a portrait after being sworn in as associate administrator for NASA’s Office of Technology, Policy, and Strategy by NASA Administrator Bill Nelson, Sunday, Aug. 27, 2023, at the Mary W. Jackson NASA Headquarters building in Washington.Credits: NASA/Joel Kowsky
The Office of Technology, Policy, and Strategy, located at NASA Headquarters in Washington, provides agency leadership with high-quality, evidence-driven advice that guides strategic planning and investments. The office works across NASA’s mission directorates, as well as with the broader space community. Its researchers focus on key areas aligned with agency-level activities and develop options aimed at informing and shaping policy.
“When we established the Office of Technology, Policy, and Strategy, the goal was to address a need for strategic advice that cuts across our mission directorates, centers, and other organizations to guide NASA’s success. I am confident Charity and the OTPS team will help us continue that crucial work,” said Nelson. “I want to thank former OTPS Associate Administrator Bhava Lal and Ellen Gersten, who stepped in after Bhavya’s departure, for their leadership and guidance.”
Prior to joining NASA, Weeden served as vice president for global space policy and government relations at Astroscale U.S., leading its spaceflight safety and long-term space sustainability efforts. Before Astroscale, she was senior director of policy at the Satellite Industry Association. She is a 23-year veteran of the Royal Canadian Air Force, with more than 2,000 flight crew hours on the CP-140 long-range patrol aircraft and assignments that included deputy sensor manager for the U.S. Space Surveillance Network at U.S. Air Force Space Command, policy officer at North American Aerospace Defense Command and U.S. Northern Command, and a secondment to CSA (Canadian Space Agency) as flight support readiness manager, supporting the installation of Canadian robotics aboard the International Space Station.
Weeden earned her undergraduate degree in mechanical engineering from the Royal Military College of Canada and a master’s degree in Space Science from the University of North Dakota. She is also an alumnus of the International Space University Summer Session Program, where her team project focused on in-space servicing.
Learn more about the Office of Technology, Policy, and Strategy at:
NASA’s First Asteroid Sample Has Landed, Now Secure in Clean Room
After years of anticipation and hard work by NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification and Security – Regolith Explorer) team, a capsule of rocks and dust collected from asteroid Bennu finally is on Earth. It landed at 8:52 a.m. MDT (10:52 a.m. EDT) on Sunday, in a targeted area of the Department of Defense’s Utah Test and Training Range near Salt Lake City.
Within an hour and a half, the capsule was transported by helicopter to a temporary clean room set up in a hangar on the training range, where it now is connected to a continuous flow of nitrogen.
Getting the sample under a “nitrogen purge,” as scientists call it, was one of the OSIRIS-REx team’s most critical tasks today. Nitrogen is a gas that doesn’t interact with most other chemicals, and a continuous flow of it into the sample container inside the capsule will keep out earthly contaminants to leave the sample pure for scientific analyses.
The returned samples collected from Bennu will help scientists worldwide make discoveries to better understand planet formation and the origin of organics and water that led to life on Earth, as well as benefit all of humanity by learning more about potentially hazardous asteroids.
“Congratulations to the OSIRIS-REx team on a picture-perfect mission – the first American asteroid sample return in history – which will deepen our understanding of the origin of our solar system and its formation. Not to mention, Bennu is a potentially hazardous asteroid, and what we learn from the sample will help us better understand the types of asteroids that could come our way,” said NASA Administrator Bill Nelson. “With OSIRIS-REx, Psyche launch in a couple of weeks, DART’s one year anniversary, and Lucy’s first asteroid approach in November, Asteroid Autumn is in full swing. These missions prove once again that NASA does big things. Things that inspire us and unite us. Things that show nothing is beyond our reach when we work together.”
The Bennu sample – an estimated 8.8 ounces, or 250 grams – will be transported in its unopened canister by aircraft to NASA’s Johnson Space Center in Houston on Monday, Sept. 25. Curation scientists there will disassemble the canister, extract and weigh the sample, create an inventory of the rocks and dust, and, over time, distribute pieces of Bennu to scientists worldwide.
Today’s delivery of an asteroid sample – a first for the U.S. – went according to plan thanks to the massive effort of hundreds of people who remotely directed the spacecraft’s journey since it launched on Sept. 8, 2016. The team then guided it to arrival at Bennu on Dec. 3, 2018, through the search for a safe sample-collection site between 2019 and 2020, sample collection on Oct. 20, 2020, and during the return trip home starting on May 10, 2021.
“Today marks an extraordinary milestone not just for the OSIRIS-REx team but for science as a whole,” said Dante Lauretta, principal investigator for OSIRIS-REx at the University of Arizona, Tucson. “Successfully delivering samples from Bennu to Earth is a triumph of collaborative ingenuity and a testament to what we can accomplish when we unite with a common purpose. But let’s not forget – while this may feel like the end of an incredible chapter, it’s truly just the beginning of another. We now have the unprecedented opportunity to analyze these samples and delve deeper into the secrets of our solar system.”
After traveling billions of miles to Bennu and back, the OSIRIS-REx spacecraft released its sample capsule toward Earth’s atmosphere at 6:42 a.m. EDT (4:42 a.m. MDT). The spacecraft was 63,000 miles (102,000 kilometers) from Earth’s surface at the time – about one-third the distance from Earth to the Moon.
Traveling at 27,650 mph (44,500 kph), the capsule pierced the atmosphere at 10:42 a.m. EDT (8:42 a.m. MDT), off the coast of California at an altitude of about 83 miles (133 kilometers). Within 10 minutes, it landed on the military range. Along the way, two parachutes successfully deployed to stabilize and slow the capsule down to a gentle 11 mph (18 kph) at touchdown.
“The whole team had butterflies today, but that’s the focused anticipation of a critical event by a well-prepared team,” said Rich Burns, project manager for OSIRIS-REx at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “For us, this was the World Series, ninth inning, bases-loaded moment, and this team knocked it out of the park.”
Radar, infrared, and optical instruments in the air and on the ground tracked the capsule to its landing coordinates inside a 36-mile by 8.5-mile (58-kilometer by 14-kilometer) area on the range. Within several minutes, the recovery team was dispatched to the capsule’s location to inspect and retrieve it. The team found the capsule in good shape at 9:07 a.m. MDT (11:07 a.m. EDT) and then determined it was safe to approach. Within 70 minutes, they wrapped it up for safe transport to a temporary clean room on the range, where it remains under continuous supervision and a nitrogen purge.
NASA Goddard provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. The University of Arizona, Tucson leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Littleton, Colorado, built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. Curation for OSIRIS-REx, including processing the sample when it arrives on Earth, will take place at NASA Johnson. International partnerships on this mission include the OSIRIS-REx Laser Altimeter instrument from CSA (the Canadian Space Agency) and asteroid sample science collaboration with JAXA’s (the Japan Aerospace Exploration Agency) Hayabusa2 mission. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washingt on.
To learn more about the asteroid sample recovery mission visit:
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