NANOGrav’s recent work in gravitational waves may give way to a paradigm shift in the way astronomy and astrophysics research are conducted.
Category: physics – Page 13
Scientists provide clear observation of spin and density modes in a two-component fluid of light
Recent physics studies have found that light can sometimes flow in unexpected ways, behaving like a so-called “superfluid.” Superfluids, such as ultracold atomic gases or helium-4 below specific temperatures, are phases of matter characterized by flowing behavior with zero viscosity (i.e., with no resistance).
Physicists observe image rotation in plasma
Light sometimes appears to be “dragged” by the motion of the medium through which it is traveling. This phenomenon, referred to as “light dragging,” is typically imperceptible when light is traveling in most widely available materials, as the movement is significantly slower than the speed of light. So far, it has thus proved difficult to observe in experimental settings.
Researchers at the University of Toulouse, University of California-Los Angeles (UCLA), University of Paris-Saclay and Princeton University recently observed a specific type of light dragging known as image rotation in a plasma-based system.
Their observation, outlined in a paper published in Physical Review Letters, was made using magnetohydrodynamic (MHD) waves that propagate in a magnetized plasma, known as Alfvén waves.
Rethinking the Anomalous Hall Effect: A Symmetry Revolution
A new symmetry-breaking scenario provides a comprehensive description of magnetic behavior associated with the anomalous Hall effect.
In 1879 Edwin Hall discovered that a flat conductor carrying current, when placed in a magnetic field, will develop a transverse voltage caused by the deflection of charge carriers. Two years later he discovered that the same effect arises in ferromagnets even without an applied magnetic field. Dubbed the anomalous Hall effect (AHE), that phenomenon, alongside the ordinary Hall effect, not only catalyzed the rise of semiconductor physics and solid-state electronics but also laid the groundwork for a revolutionary convergence of topology and condensed-matter physics a century after Hall’s discoveries. Recent experiments, however, have uncovered behavior that cannot be explained with current theories for the AHE.
Physicists Uncover Forgotten 1938 Fusion Breakthrough That Could Power the Future
Physicists confirm DT fusion insights from a 1938 experiment. The findings connect past theory with current fusion efforts. A team at Los Alamos National Laboratory has successfully recreated a significant yet largely overlooked physics experiment: the first recorded observation of deuterium-trit
Dark dwarfs lurking at the center of our galaxy might hint at the nature of dark matter
Celestial objects known as dark dwarfs may be hiding at the center of our galaxy and could offer key clues to uncover the nature of one of the most mysterious and fundamental phenomena in contemporary cosmology: dark matter.
A paper published in the Journal of Cosmology and Astroparticle Physics by a team of researchers based in the UK and Hawaii describes these objects for the first time and proposes how to verify their existence using current observational tools such as the James Webb Space Telescope. The paper is titled “Dark Dwarfs: Dark Matter-Powered Sub-Stellar Objects Awaiting Discovery at the Galactic Center.”
The Anglo-U.S. team behind the study named them dark dwarfs. Not because they are dark bodies—on the contrary—but because of their special link with dark matter, one of the most central topics in current cosmology and astrophysics research.
Machine learning outpaces supercomputers for simulating galaxy evolution coupled with supernova explosion
Researchers have used machine learning to dramatically speed up the processing time when simulating galaxy evolution coupled with supernova explosion. This approach could help us understand the origins of our own galaxy, particularly the elements essential for life in the Milky Way.
The findings are published in The Astrophysical Journal.
The team was led by Keiya Hirashima at the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) in Japan, along with colleagues from the Max Planck Institute for Astrophysics (MPA) and the Flatiron Institute.
Record-breaking material emits infrared light better than it absorbs it, without violating the laws of physics
New results published in the journal Physical Review Letters detail how a specially designed metamaterial was able to tip the normally equal balance between thermal absorption and emission, enabling the material to better emit infrared light than absorb it.
At first glance, these findings appear to violate Kirchhoff’s law of thermal radiation, which states that—under specific conditions—an object will absorb infrared light (absorptivity) in one direction and emit it (emissivity) with equal intensity in another, a phenomenon known as reciprocity.
Over the past decade, however, scientists have begun exploring theoretical designs that, under the right conditions, could allow materials to break reciprocity. Understanding how a material absorbs and emits infrared light (heat) is central to many fields of science and engineering. Controlling how a material absorbs and emits infrared light could pave the way for advances in solar energy harvesting, thermal cloaking devices, and other technologies.
Hans Bethe — Biographical
Hans Albrecht Bethe was born in Strasbourg, Alsace-Lorraine, on July 2 1906. He attended the Gymnasium in Frankfurt from 1915 to 1924. He then studied at the University of Frankfurt for two years, and at Munich for two and one half years, taking his Ph. D. in theoretical physics with Professor Arnold Sommerfeld in July 1928.
He then was an Instructor in physics at Frankfurt and at Stuttgart for one semester each. From fall 1929 to fall 1933 his headquarters were the University of Munich where he became Privatdozent in May 1930. During this time he had a travel fellowship of the International Education Board to go to Cambridge, England, in the fall of 1930, and to Rome in the spring terms of 1931 and 1932. In the winter semester of 1932–1933,he held a position as Acting Assistant Professor at the University of Tubingen which he lost due to the advent of the Nazi regime in Germany.
Bethe emigrated to England in October 1933 where he held a temporary position as Lecturer at the University of Manchester for the year 1933–1934, and a fellowship at the University of Bristol in the fall of 1934. In February 1935 he was appointed Assistant Professor at Cornell University, Ithaca, N. Y. U.S.A., then promoted to Professor in the summer of 1937. He has stayed there ever since, except for sabbatical leaves and for an absence during World War II. His war work took him first to the Radiation Laboratory at the Massachusetts Institute of Technology, working on microwave radar, and then to the Los Alamos Scientific Laboratory which was engaged in assembling the first atomic bomb. He returned to Los Alamos for half a year in 1952. Two of his sabbatical leaves were spent at Columbia University, one at the University of Cambridge, and one at CERN and Copenhagen.