The enduring mystery of dark matter has led some physicists to propose that it was forged in a distinct moment of cosmic creation, potentially transforming our view of the early universe.
By Stuart Clark
Category: physics – Page 73
The equations that describe physical systems often assume that measurable features of the system—temperature or chemical potential, for example—can be known exactly. But the real world is messier than that, and uncertainty is unavoidable. Temperatures fluctuate, instruments malfunction, the environment interferes, and systems evolve over time.
Through exquisite, millimeter-scale, formation flying, the dual satellites making up ESA’s Proba-3 will accomplish what was previously a space mission impossible: Cast a precisely held shadow from one platform to the other, in the process blocking out the fiery sun to observe its ghostly surrounding atmosphere on a prolonged basis.
Ahead of the Proba-3 pair launching together later this year, the scientists who will make use of Proba-3 observations were able to see the satellites with their own eyes. Members of this team will test hardware developed for the mission during an actual terrestrial solar eclipse over northern America next April.
The two satellites are currently undergoing final integration in the premises of Redwire near Antwerp in Belgium. They were paid a visit by the Proba-3 Science Working Team, a 45-strong group of solar physicists coming from all across Europe and the wider world.
Thousands of satellites have been launched into Earth orbit over the past decade or so, with tens of thousands more planned in coming years. Many of these will be in “mega-constellations” such as Starlink, which aim to cover the entire globe.
These bright, shiny satellites are putting at risk our connection to the cosmos, which has been important to humans for countless millennia and has already been greatly diminished by the growth of cities and artificial lighting. They are also posing a problem for astronomers – and hence for our understanding of the universe.
In new research accepted for publication in Astronomy and Astrophysics Letters, we discovered Starlink satellites are also “leaking” radio signals that interfere with radio astronomy. Even in a “radio quiet zone” in outback Western Australia, we found the satellite emissions were far brighter than any natural source in the sky.
In fields such as physics and engineering, partial differential equations (PDEs) are used to model complex physical processes to generate insight into how some of the most complicated physical and natural systems in the world function.
To solve these difficult equations, researchers use high-fidelity numerical solvers, which can be very time consuming and computationally expensive to run. The current simplified alternative, data-driven surrogate models, compute the goal property of a solution to PDEs rather than the whole solution. Those are trained on a set of data that has been generated by the high-fidelity solver, to predict the output of the PDEs for new inputs. This is data-intensive and expensive because complex physical systems require a large number of simulations to generate enough data.
In a new paper, “Physics-enhanced deep surrogates for partial differential equations,” published in December in Nature Machine Intelligence, a new method is proposed for developing data-driven surrogate models for complex physical systems in such fields as mechanics, optics, thermal transport, fluid dynamics, physical chemistry, and climate models.
HELSINKI — China launched its Einstein Probe early Tuesday to detect X-ray emissions from violent, fleeting cosmic phenomena using novel lobster eye-inspired optics.
A Long March 2C rocket lifted off from Xichang Satellite Launch Center in southwestern China at 2:03 a.m. (0703 UTC), Jan. 9. The China Aerospace Science and Technology Corp. (CASC) confirmed launch success within the hour.
The Einstein Probe (EP) is part of growing Chinese strategic space science efforts. The spacecraft will spend at least three years observing distant, violent interactions such as tidal disruption events—in which stars are pulled apart by supermassive black holes—supernovae, and detect and localize the high-energy, electromagnetic counterparts to gravitational wave events.
Recent theoretical work has identified the possibility of a new and fundamental form of magnetism.
Collinear magnetism, where magnetic moments of all ions are parallel or antiparallel to each other, is a century-old concept in condensed-matter physics. In the past two decades, researchers began exploring the exotic world of noncollinear magnets, which include spin spirals, skyrmions, spin ices, and more. But more recently a fundamentally new form of collinear magnetism has emerged: altermagnetism. Like ferromagnetism, it breaks time-reversal symmetry and harbors anomalous transport properties, such as the anomalous Hall effect and magneto-optics. Like antiferromagnetism, it has, by symmetry, no net magnetization. The phenomenon was identified between 2019 and 2021 by four different groups [1–4]. In 2022, Libor Šmejkal of Johannes Gutenberg University Mainz in Germany and colleagues named it altermagnetism [5]. Despite its youth, altermagnetism is already proving a fertile field for theory and for proposed applications.
Using a spectral synthesis code designed to simulate conditions in interstellar matter, astronomers have explored a faint tidal disruption event (TDE) designated iPTF16fnl. Results of the study, published Dec. 29 on the pre-print server arXiv, deliver important insights into the properties of this TDE.
TDEs are astronomical phenomena that occur when a star passes close enough to a supermassive black hole and is pulled apart by the black hole’s tidal forces, causing the process of disruption. Such tidally-disrupted stellar debris starts raining down on the black hole and radiation emerges from the innermost region of accreting debris, which is an indicator of the presence of a TDE. All in all, the debris stream-stream collision causes an energy dissipation, which may lead to the formation of an accretion disk.
Therefore, TDEs are perceived by astronomers as potentially important probes of strong gravity and accretion physics, providing answers about the formation and evolution of supermassive black holes.
A team of Chinese researchers used a novel theory to invent a new type of ultrathin optical crystal with high energy efficiency, laying the foundation for next-generation laser technology.
Prof. Wang Enge from the School of Physics, Peking University, recently told Xinhua that the Twist Boron Nitride (TBN) made by the team, with a micron-level thickness, is the thinnest optical crystal currently known in the world. Compared with traditional crystals of the same thickness, its energy efficiency is raised by 100 to 10,000 times.
Wang, also an academician of the Chinese Academy of Sciences, said this achievement is an original innovation by China in the theory of optical crystals and has created a new field of making optical crystals with two-dimensional thin-film materials of light elements.