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Category: physics

Gleaning Information from Noise

Researchers derive a universal limit linking noise and response to perturbations in systems far from equilibrium.

Noise comes in many forms. A microscopic bead twitches in an optical trap; voltage fluctuations flicker through a circuit. But it’s not only a nuisance. Since 1966, physicists have understood that for systems in thermal equilibrium, such randomness also gives valuable information: Spontaneous fluctuations and the system’s response to external perturbations are locked together, frequency by frequency, according to the so-called fluctuation–dissipation theorem (FDT) [1]. That link is the basis of noise-based thermometry, microrheology, and many calibration methods. But thermal equilibrium is rare in the real world. Rather, most physical and biological systems are driven by an external force, fed, or alive, with energy continually flowing through them.

Dark lunar craters could host ultrastable lasers for moon navigation

They rank among the darkest and coldest places in the solar system: Hundreds of lunar craters, many of them at the moon’s south pole, never receive direct sunlight and lie in permanent shadow. That’s exactly why physicist Jun Ye and his colleagues suggest that these craters are the perfect place to build a critical component for an ultrastable laser.

On the moon, a highly stable laser—a source of coherent light that has a nearly unwavering frequency, or color—could provide a master time signal and offer GPS-like lunar navigation, said Ye, who is affiliated with both the National Institute of Standards and Technology (NIST) and JILA, a joint institute of NIST and the University of Colorado Boulder. Multiple copies of these lunar lasers could precisely measure the distances between objects and potentially detect exotic physics phenomena such as ripples in spacetime.

To construct a lunar laser, astronauts would first install a key component known as an optical silicon cavity —a block of silicon that permits only certain frequencies of light to bounce back and forth between mirrors on each end of the block. The distance between the two mirrors determines the frequencies that are allowed to resonate; for a highly stable optical cavity, that distance, and therefore those frequencies, does not vary.

Learning physics can derail some students: New research shows the best way to keep them on track

For many undergraduate students, exploring the complexities of physics for the first time, from wading through advanced mathematics, to absorbing information in a large lecture format, can be a daunting endeavor—one that dissuades many students from continuing their studies.

Educators have known for some time that students tend to learn these subjects better in hands-on, or “active learning,” environments—but some are more effective than others.

AI shapes the design of the electron-ion collider

Artificial intelligence and machine learning are shaping major design and research decisions for the planned Electron-Ion Collider (EIC), a next-generation nuclear physics research facility that will collide electrons with protons or nuclei to probe matter’s structure.

The EIC—being built at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory in partnership with DOE’s Thomas Jefferson National Accelerator Facility (Jefferson Lab)—will reveal the inner structure of matter in unprecedented detail. It is the world’s first collider designed with AI and machine learning integrated into both its accelerator and detector systems.

“EIC is a new facility that can take advantage of AI and machine learning from the start,” said Tanja Horn, a professor of physics at The Catholic University of America, and co-chair of AI4EIC, a working group devoted to developing AI for the EIC. “A wide array of AI tools is now available—perfectly timed for the EIC.”

Surrounded by stardust: Antarctic ice cores confirm Earth is accumulating iron-60 from local interstellar cloud

Our solar system is currently passing through the Local Interstellar Cloud, a region of highly diluted gas and dust between the stars. On its path, Earth continuously accumulates iron-60, a rare radioactive isotope of iron produced in stellar explosions. This has now been confirmed by an international research team led by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) through the analysis of Antarctic ice tens of thousands of years old. From the steady but time-varying influx, the researchers conclude that the radioactive isotope has been stored within the cloud since a long-past stellar explosion. The results have been published in the journal Physical Review Letters.

Iron-60 is formed in the interiors of massive stars and is ejected into space when they explode. Geological archives show that our solar system was hit twice by iron-60 from supernovae millions of years ago. In more recent times, however, there have been no nearby stellar explosions—and thus no direct supply of iron-60. When scientists discovered iron-60 in Antarctic surface snow less than twenty years old a few years ago, the question of its origin arose.

“Our idea was that the Local Interstellar Cloud contains iron-60 and can store it over long time periods. As the solar system moves through the cloud, Earth could collect this material. However, we couldn’t prove this at the time,” explains Dr. Dominik Koll from the Institute of Ion Beam Physics and Materials Research at HZDR.

Science beyond the physical

For centuries, we’ve assumed that science has banished the transcendent and established that reality is entirely physical. But critics argue there are signs that a rigorous materialism might be holding science back. Increasingly, “emergence” is used to account for everything from consciousness to spacetime – a convenient placeholder for what materialist science may be unable to explain. Physicists like Heisenberg and Hawking concluded that science gives us models of reality, rather than final descriptions of its true nature, while there are scientists working in everything from biology to computer science who suggest that dualism is a productive metaphysical framework for their research. Materialism may have enabled science to reach beyond the dogmas of religion, but there are now those who are restlessly probing the limits of materialism itself.

Astrophysicists use ‘space archaeology’ to trace the history of a spiral galaxy

Billions of years ago, a young spiral galaxy began to grow in a crowded part of the universe. It pulled in gas and small companion galaxies, slowly building up the bright central region and sweeping spiral arms we see today.

In a new study published in March 2026, my colleagues and I used this galaxy’s chemical fingerprints to reconstruct its life story in detail.

Astronomers want to know how spiral galaxies like our own Milky Way came to be, as these galaxies can give us hints about how the elements we rely on, such as oxygen, were created and spread through space over time.

A hidden threshold enables tunable control of liquid crystal helices for energy-efficient technologies

Liquid crystals are an integral part of modern technology, ranging from displays to advanced sensory systems. In a study published in Scientific Reports, researchers from the Institute of Experimental Physics of the Slovak Academy of Sciences (IEP SAS) in Košice, in collaboration with international partners, have demonstrated how minute changes in material composition can achieve precise control over behavior in electric and magnetic fields.

The research focused on cholesteric liquid crystals, which naturally form spiral (helical) structures. These structures provide unique optical properties used in displays, smart windows, and virtual reality devices.

The team investigated how the addition of a specific substance, a chiral dopant, affects the “unwinding” process of this helix.

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