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Category: physics – Page 5

Dipole toroidal modes are a unique set of excitations that are predicted to occur in various physical systems, ranging from atomic nuclei to metamaterials. What characterizes these excitations, or modes, is a toroidal distribution of currents, which results in the formation of vortex-like structures.

A classic example is smoke rings, the characteristic “rings” of smoke produced when puffs of smoke are released into the air through a narrow opening. Physics theories have also predicted the existence of toroidal dipole excitations in atomic nuclei, yet observing these modes has so far proved challenging.

Researchers at Technische Universitat Darmstadt, the Joint Institute for Nuclear Research, and other institutes recently identified candidates for toroidal dipole excitations in the nucleus 58 Ni for the very first time. Their paper, published in Physical Review Letters, opens new possibilities for the experimental observations of these elusive modes in .

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Physicists have proposed a solution to a long-standing puzzle surrounding the GD-1 stellar stream, one of the most well-studied streams within the galactic halo of the Milky Way, known for its long, thin structure, and unusual spur and gap features.

The team of researchers, led by Hai-Bo Yu at the University of California, Riverside, proposed that a core-collapsing self-interacting (SIDM) “subhalo” — a smaller, satellite halo within the galactic halo — is responsible for the peculiar spur and gap features observed in the GD-1 stellar stream.

Study results appear in The Astrophysical Journal Letters in a paper titled “The GD-1 Stellar Stream Perturber as a Core-collapsed Self-interacting Dark Matter Halo.” The research could have significant implications for understanding the properties of dark matter in the universe.

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Jacob Bernoulli returned to Switzerland and taught mechanics at the University in Basel from 1,683, giving a series of important lectures on the mechanics of solids and liquids. Since his degree was in theology it would have been natural for him to turn to the Church, but although he was offered an appointment in the Church he turned it down. Bernoulli’s real love was for mathematics and theoretical physics and it was in these topics that he taught and researched. During this period he studied the leading mathematical works of his time including Descartes’ Géométrie and van Schooten’s additional material in the Latin edition. Jacob Bernoulli also studied the work of Wallis and Barrow and through these he became interested in infinitesimal geometry. Jacob began publishing in the journal Acta Eruditorum which was established in Leipzig in 1682.

In 1,684 Jacob Bernoulli married Judith Stupanus. They were to have two children, a son who was given his grandfather’s name of Nicolaus and a daughter. These children, unlike many members of the Bernoulli family, did not go on to become mathematicians or physicists.

You can see the Bernoulli family tree at THIS LINK.

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Shooting a laser pulse at a porous silver target generates more intense x rays than previous targets, which will help studies of matter in extreme conditions.

Physicists rely on intense bursts of high-energy x rays to observe the progress of fusion experiments and to probe the dynamics of matter under conditions of extreme temperature and pressure. Current techniques for generating such bursts involve firing a laser pulse at a material target but typically turn only a small fraction of the laser energy into usable x rays, thereby limiting the burst energy and intensity. Now researchers have demonstrated a doubling of the efficiency by using a target made of a low-density metallic foam [1]. They expect that the new targets will lead to much brighter x-ray bursts capable of illuminating extreme physical processes under conditions that were previously inaccessible to x-ray observations.

When a powerful laser pulse strikes a foil of material such as silver, the laser strips away the electrons, leaving exposed the highly charged nuclei. Surrounding electrons then fall back into the lowest energy levels, creating high-energy x rays. However, most of the laser energy can be lost in the process, and the overall efficiency is very sensitive to the nature of the material target. Researchers have found, for example, that solid targets generally yield low efficiencies, as x rays emerge from only a small volume near the surface, while laser energy is otherwise consumed by stirring up plasma waves in the material. This low efficiency limits the x-ray intensity.

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Scientists are diving deep into the origins of supermassive black holes, using recent gravitational wave detections as a key tool.

By leveraging signals from smaller black holes, researchers hope to detect the harder-to-catch waves from supermassive pairs, potentially unlocking the secrets of their formation and growth.

Unveiling the mystery of supermassive black holes.

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The Firefly Sparkle was previously imaged by Hubble Space Telescope and Keck Observatory, but was followed-up using the power of both gravitational lensing and multi-wavelength data from JWST’s CAnadian NIRISS Unbiased Cluster Survey (CANUCS). The role of the lens was played by the massive galaxy cluster called MACS J1423.8 + 2,404, which lies between us and the Firefly Sparkle.

“Without the benefit of this gravitational lens, we would not be able to resolve this galaxy,” said Kartheik Iyer, a co-lead author of the paper, in a press release. “We knew to expect it based on current physics, but it’s surprising that we actually saw it.”

In the team’s paper, published in Nature on Dec. 11, they created a model to “undo” the visual distortions of the lensing. It turns out that the Firefly Sparkle’s original form appears like a stretched raindrop; its stars have not yet settled into either the central bulge or a thin disk. In other words, the galaxy is still very much in the process of forming.

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ABSTRACT. We reanalyse the Pantheon+ supernova catalogue to compare a cosmology with non-FLRW evolution, the timescape cosmology, with the standard Lambda cold dark matter (⁠|Lambda$|CDM) cosmology. To this end, we analyse the Pantheon+ for a geometric comparison between the two models. We construct a covariance matrix to be as independent of cosmology as possible, including independence from the FLRW geometry and peculiar velocity with respect to FLRW average evolution. This framework goes far beyond most other definitions of model independence. We introduce new statistics to refine Type Ia supernova (SNe Ia) light-curve analysis. In addition to conventional galaxy correlation functions used to define the scale of statistical homogeneity we introduce empirical statistics that enables refined analysis of the distribution biases of SNe Ia light-curve parameters |beta c$| and |alpha x_1$|⁠. For lower redshifts, the Bayesian analysis highlights important features attributable to the increased number of low-redshift supernovae, the artefacts of model-dependent light-curve fitting, and the cosmic structure through which we observe supernovae. This indicates the need for cosmology-independent data reduction to conduct a stronger investigation of the emergence of statistical homogeneity and to compare alternative cosmologies in light of recent challenges to the standard model. Dark energy is generally invoked as a place-holder for new physics. For the first time, we find evidence that the timescape cosmology may provide a better overall fit than |Lambda$|CDM and that its phenomenology may help disentangle other astrophysical puzzles. Our from-first-principles reanalysis of Pantheon|$+$| supports future deeper studies between the interplay of matter and non-linear spacetime geometry in a data-driven setting.

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A team of materials scientists, physicists, mechanical engineers, and molecular physiologists at Stanford University have developed a nanoparticle technique that can be used to measure force dynamics inside a living creature, such as Caenorhabditis elegans worms biting their food.

In their paper published in the journal Nature, the group describes how they used to excite luminescent nanocrystals in a way that allowed the energy levels of cells inside a C. elegans worm to be measured.

Andries Meijerink, with Utrecht University, has published a News & Views piece in the same journal issue, outlining the work done by the team in California.

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Hula hooping is so commonplace that we may overlook some interesting questions it raises: “What keeps a hula hoop up against gravity?” and “Are some body types better for hula hooping than others?” A team of mathematicians explored and answered these questions with findings that also point to new ways to better harness energy and improve robotic positioners.

The results are the first to explain the physics and mathematics of hula hooping.

“We were specifically interested in what kinds of body motions and shapes could successfully hold the hoop up and what physical requirements and restrictions are involved,” explains Leif Ristroph, an associate professor at New York University’s Courant Institute of Mathematical Sciences and the senior author of the paper, which appears in the Proceedings of the National Academy of Sciences.

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“The Universe Expands Beyond All Bounds”

The universe expands beyond all bounds, Black holes gain mass, where wonders surround. Curvature shifts like moonlight’s gleam, Adding new mass, no matter redeemed.

A new year dawns with lessons to share, Physics reveals a truth so rare. The cosmos vast, profound, and wide, Marks 2025 with knowledge as our guide.

The first endeavor of this brand-new year, Explains black hole growth without drawing near. Expanding space, a force untamed, Curvature energy, its role proclaimed.

Based on observed and verified research: arxiv.org/abs/2302.

Through our novel gravitational field theory: dx.doi.org/10.1016/j.astropartphys.2024.

Continue reading “Observational evidence for cosmological coupling of black holes and its implications for an astrophysical source of dark energy” | >