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Demon hunting: Physicists confirm 67-year-old prediction of massless, neutral composite particle

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Credit: The Grainger College of Engineering at the University of Illinois Urbana-Champaign
Researchers have discovered Pines’ demon, a collection of electrons in a metal that behaves like a massless wave.

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.

Journal Link: Nature

Source: University Of Illinois Grainger College Of Engineering

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Unlocking the Next Frontier: Odysseus Lunar Lander’s Historic Mission

“Odysseus lunar lander aims to make history with first U.S. spacecraft touchdown on moon in 50 years. A testament to human ambition and innovation.”

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In the vast expanse of space, where dreams of exploration meet the harsh realities of technology and finance, Thursday marks a potential landmark moment in the annals of space exploration. The Odysseus lunar lander, a testament to human ingenuity and perseverance, stands on the precipice of making history as it aims to achieve what no U.S.-made spacecraft has done in five decades: a controlled touchdown on the lunar surface.

Intuitive Machines-1 Lunar Landing (Official NASA Broadcast)

After a breathtaking lift-off from Florida, Odysseus embarked on its journey towards the moon, capturing awe-inspiring images of our planet Earth along the way. Now, as it hurtles closer to its destination, the anticipation mounts for what could be the most perilous test yet – a soft landing on the moon’s surface.

Intuitive Machines, the pioneering force behind Odysseus, dares to tread where no private company has ventured before. If successful, this endeavor would mark the resurgence of American-made spacecraft landing on the moon since the final Apollo mission in 1972.

However, the road to lunar exploration is fraught with challenges, both technical and financial. While the Apollo program once commanded a budget exceeding 4% of all U.S. government spending, today’s NASA operates on a fraction of that, a mere 0.4%. To stretch resources further, NASA has turned to outsourcing robotic lunar landings to commercial entities like Intuitive Machines, aiming to achieve ambitious goals like the Artemis program’s lunar return with reduced costs.

But cost isn’t the only hurdle. The technical feat of landing a spacecraft precisely on a celestial body a quarter of a million miles away is akin to hitting a golf ball from New York to Los Angeles and landing it in a specific hole – a daunting task even with today’s advanced technology. Compounding the challenge is the time delay of roughly three seconds for signals to travel between Earth and the moon, leaving little room for error during critical maneuvers.

Moreover, the legacy of Apollo-era expertise has waned over the decades, leaving a gap that new technology alone cannot bridge. As Dr. Scott Pace of George Washington University’s Space Policy Institute aptly notes, “These are people doing it for the first time, and there’s no substitute for that experience.”

Yet, amidst these challenges, there’s an undeniable sense of optimism and determination. As Lisa Altemus of Intuitive Machines emphasizes, success in lunar exploration requires collective resilience, collaboration, and a willingness to learn from failures. It heralds not just a scientific achievement but the dawn of a new era – an emerging lunar economy where the moon’s resources could unlock boundless opportunities for humanity.

If Odysseus achieves its mission, it will not only mark the first U.S. spacecraft landing on the moon in half a century but also pave the way for future lunar endeavors, including the exploration of the moon’s south pole, a region rich in potential resources like ice and water.

As we stand on the brink of this historic moment, let us marvel at the audacity of human ambition, the tenacity of scientific endeavor, and the boundless possibilities that lie beyond Earth’s confines. The journey to the moon may be fraught with challenges, but with each step, we inch closer to unlocking the mysteries of our celestial neighbor and forging a new chapter in the saga of space exploration.

https://www.azfamily.com/app/2024/02/22/us-company-attempts-first-moon-landing-thursday-since-1972/

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NASA Astronaut Available for Interviews Prior to Space Station Mission

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NASA astronaut Tracy Dyson poses for a portrait at NASA’s Johnson Space Center in Houston.
Credits: NASA

NASA astronaut Tracy C. Dyson is available in limited opportunities to discuss her mission beginning at 8 a.m. EST on Monday, Feb. 26. The interviews will take place ahead of Dyson launching to the International Space Station in March.

The virtual interviews will stream live on NASA+, NASA Television, and the agency’s website. Learn how to stream NASA TV through a variety of platforms including social media.

Interested media must submit a request to speak with Dyson no later than 12 p.m. Friday, Feb. 23, to the NASA Johnson Space Center in Houston newsroom at 281-483-5111 or jsccommu@mail.nasa.gov.

Dyson is scheduled to launch aboard the Soyuz MS-25 spacecraft Thursday, March 21, and will spend approximately six months aboard the space station. She will travel to the station with Roscosmos cosmonaut Oleg Novitskiy and spaceflight participant Marina Vasilevskaya of Belarus, both of whom will spend approximately 12 days aboard the orbital complex.

During her expedition, Dyson will conduct scientific investigations and technology demonstrations that help prepare humans for future space missions and benefit people on Earth. Among some of the hundreds of experiments ongoing during her mission, Dyson will continue to study how fire spreads and behaves in space with the Combustion Integrated Rack, as well as contribute to the long-running Crew Earth Observations study by photographing Earth to better understand how our planet is changing over time.

After completing her expedition, Dyson will return to Earth this fall with Roscosmos cosmonauts Oleg Kononenko and Nikolai Chub on the Soyuz MS-25 spacecraft.

Learn more about International Space Station research and operations at:

https://www.nasa.gov/station

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New NASA Mission will Study Ultraviolet Sky, Stars, Stellar Explosions

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WASHINGTON /PRNewswire/ — As NASA explores the unknown in air and space, a new mission to survey ultraviolet light across the entire sky will provide the agency with more insight into how galaxies and stars evolve. The space telescope, called UVEX (UltraViolet EXplorer), is targeted to launch in 2030 as NASA’s next Astrophysics Medium-Class Explorer mission.

This image shows the heart of the barred spiral galaxy NGC 1097, as seen by NASA’s Hubble Space Telescope. Credit: ESA/Hubble & NASA, D. Sand, K. Sheth

In addition to conducting a highly sensitive all-sky survey, UVEX will be able to quickly point toward sources of ultraviolet light in the universe. This will enable it to capture the explosions that follow bursts of gravitational waves caused by merging neutron stars. The telescope also will carry an ultraviolet spectrograph to study stellar explosions and massive stars.

“NASA’s UVEX will help us better understand the nature of both nearby and distant galaxies, as well as follow up on dynamic events in our changing universe,” said Nicola Fox, associate administrator, Science Mission Directorate at NASA Headquarters in Washington. “This mission will bring key capabilities in near-and far-ultraviolet light to our fleet of space telescopes, delivering a wealth of survey data that will open new avenues in exploring the secrets of the cosmos.”

The telescope’s ultraviolet survey will complement data from other missions conducting wide surveys in this decade, including the Euclid mission led by ESA (European Space Agency) with NASA contributions, and NASA’s Nancy Grace Roman Space Telescope, set to launch by May 2027. Together, these missions will help create a modern, multi-wavelength map of our universe.

“With the innovative new UVEX mission joining our portfolio, we will gain an important legacy archive of data that will be of lasting value to the science community,” said Mark Clampin, director of the Astrophysics Division at NASA Headquarters. “This new telescope will contribute to our understanding of the universe across multiple wavelengths and address one of the major priorities in Astrophysics today: studying fleeting changes in the cosmos.”

NASA selected the UVEX Medium-Class Explorer concept to continue into development after detailed review of two Medium-Class Explorer and two Mission of Opportunity concept proposals by a panel of scientists and engineers, and after evaluation based on NASA’s current astrophysics portfolio coupled with available resources. The UVEX mission was selected for a two-year mission and will cost approximately $300 million, not including launch costs.

The mission’s principal investigator is Fiona Harrison at Caltech in Pasadena, California. Other institutions involved in the mission include University of California at Berkeley, Northrop Grumman, and Space Dynamics Laboratory.

The Explorers Program is the oldest continuous NASA program. The program is designed to provide frequent, low-cost access to space using principal investigator-led space science investigations relevant to the agency’s astrophysics and heliophysics programs.

Since the launch of Explorer 1 in 1958, which discovered the Earth’s radiation belts, the Explorers Program has launched more than 90 missions, including the Uhuru and Cosmic Background Explorer missions that led to Nobel prizes for their investigators.

The program is managed by NASA’s Goddard Space Flight Center for the Science Mission Directorate, which conducts a wide variety of research and scientific exploration programs for Earth studies, space weather, the solar system, and the universe.

For more information about the Explorers Program, visit:

https://explorers.gsfc.nasa.gov

SOURCE NASA

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