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Category: physics – Page 10

SPHEREx space telescope begins capturing entire sky

Launched on March 11, NASA’s SPHEREx space observatory has spent the last six weeks undergoing checkouts, calibrations, and other activities to ensure it is working as it should. Now it’s mapping the entire sky—not just a large part of it—to chart the positions of hundreds of millions of galaxies in 3D to answer some big questions about the universe.

On May 1, the spacecraft began regular science operations, which consist of taking about 3,600 images per day for the next two years to provide new insights about the origins of the universe, galaxies, and the ingredients for life in the Milky Way.

“Thanks to the hard work of teams across NASA, industry, and academia that built this mission, SPHEREx is operating just as we’d expected and will produce maps of the full sky unlike any we’ve had before,” said Shawn Domagal-Goldman, acting director of the Astrophysics Division at NASA Headquarters in Washington.

Physicists determine how to cut onions with fewer tears

A team of physicists, biologists and engineers at Cornell University, in the U.S., has discovered some of the factors that lead to more or less spray when cutting onions and found a couple of ways to reduce the amount of eye irritation. The group has published a paper describing their study on the arXiv preprint server.

Prior research has shown that eye irritation when cutting is caused by the release of syn-propanethial-S-oxide into the air along with other juices in the onion. For this new study, the team in New York wanted to know what factors led to more or less of the juices being spewed into the air during slicing.

To find out, the research team outfitted a special guillotine that could be fitted with different types of blades. They also coated onion chunks with paint to allow for better viewing of the cutting process. They used the guillotine to cut samples, each of which was recorded. Trials varied knife size, sharpness and cutting speed. They even used an to accurately measure the knives before use.

A Lunar Telescope that Could Explore the Cosmic Dark Ages

Multiple space agencies will send missions to the Moon this decade and the next, with plans to establish infrastructure that will allow for many returns. This includes NASA’s Lunar Gateway and Artemis Base Camp, the Chinese-Roscosmos International Lunar Research Station (ILRS), and the ESA’s Moon Village. With so many space agencies and commercial space companies focused on lunar exploration, there are also multiple plans for establishing research facilities and scientific experiments.

In particular, NASA, China, and the ESA have proposed creating radio astronomy experiments that would operate on the far side of the Moon. In a recent paper, an international team of European astronomers proposed an ultra-long wavelength radio interferometer that could examine the cosmological periods known as the Cosmic Dark Ages and Cosmic Dawn. Known as the Dark Ages Explorer (DEX), this telescope could provide fresh insights into one of the least understood periods in the history of the Universe.

The study was led by Christiaan Brinkerink, a Scientific Engineer with the Radboud Radio Lab (RRL) at Radboud University Nijmegen. He was joined by researchers from the Netherlands Institute for Radio Astronomy (ASTRON), the Eindhoven University of Technology, the Delft University of Technology (TU Delft), the Laboratory for Instrumentation and Research in Astrophysics (LIRA), the Kapteyn Astronomical Institute, the Leiden Observatory, the Cambrige Institute of Astronomy, the Kavli Institute for Cosmology, the European Research Infrastructure Consortium (ERIC), and the ESA’s European Space Research and Technology Center (ESTEC).

Black hole dance illuminates hidden math of the universe

In the new study, however, these shapes appeared in calculations describing the energy radiated as gravitational waves when two black holes cruised past one another. This marks the first time they’ve appeared in a context that could, in principle, be tested through real-world experiments.

Mogull likens their emergence to switching from a magnifying glass to a microscope, revealing features and patterns previously undetectable. “The appearance of such structures sheds new light on the sorts of mathematical objects that nature is built from,” he said.

These findings are expected to significantly enhance future theoretical models that aim to predict gravitational wave signatures. Such improvements will be crucial as next-generation gravitational wave detectors — including the planned Laser Interferometer Space Antenna (LISA) and the Einstein Telescope in Europe — come online in the years ahead.

DeepMind’s AlphaEvolve AI: History In The Making!

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Or this is the orig. Nature Physics link with clickable citations:
https://www.nature.com/articles/s41567-022-01788-5

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‘Manu jumping’: The physics behind making humongous splashes in the pool

Whether diving off docks, cannonballing into lakes or leaping off the high board, there’s nothing quite like the joy of jumping into water.

Olympic divers turned this natural act into a sophisticated science, with the goal of making a as small as possible. But another sport looks for just the opposite: the extreme maximum splash, one as high, wide and loud as possible.

Welcome to the world of “manu jumping.” Although not a familiar term in the United States, manu jumping is beloved throughout New Zealand. The sport originated in the Māori community, where popping a manu is a way of life. There, manu jumpers leap from bridges, wharves and diving platforms to make the giant splashes.

Optical technique detects ultra-weak atomic motion in crystals with high precision

A team of researchers from TU Dortmund University, the University of Paderborn, and the University of Nottingham has developed a new optical method to detect ultra-weak atomic motion. Their experiment performed in Dortmund has demonstrated unprecedented sensitivity of the detection of atomic motion in crystals by exploiting light interference.

The findings, recently published in Nature Materials, open new ways for studying ultrafast processes in materials.

Precise optical measurements rely on interferometers, where the beam probing a distance of interest interferes with a reference beam traveling a fixed path. This allows for assessing the path length difference of the two beams with high precision. A striking example is gravitational interferometers, which detect induced by a distant event in the universe, such as the collision of black holes.

Roses Offer Mechanical Clues for Shape-Shifting Materials

To validate these simulated results, PhD student Omri Cohen fabricated a series of disks from two polymer layers. The lower layer was patterned with a regular matrix and the upper one consisted of thin lines radiating out from the center. When the disks were heated and then cooled again, the matrix layer remained the same, while the upper layer contracted by a varying amount along the radial direction. This difference induced a curvature in the disk, and the team was able to replicate the simulated series of shape transitions by varying the curvature and thickness of the disks.

Further analysis shows that the formation of each cusp acts as a focal point for the stresses that accumulate in the petal. In older petals this localized concentration of stress inhibits growth around the cusps, producing a concave distortion on the rounded edge of the petal. “This completes a nice feedback cycle,” explains Sharon. “Simple growth first generates Mainardi-Codazzi-Peterson incompatibility, leading to a mechanical instability that forms cusps. These cusps then focus the stress, which affects the further growth of the tissue.”

Understanding the mechanical mechanisms that alter the shape of rose petals as they grow could inform the design of self-shaping materials and structures for applications like soft robotics and deployable spacecraft. “The idea is to program internal forces to enable the material to shape itself, and this work offers a new strategy for creating more localized shaping,” explains Benoît Roman of ESPCI ParisTech, an expert in shape-changing materials. “But the real value of this study is that it provides a perfect example of using physics to uncover and describe a deep and general phenomenon.”

Harnessing gradient doping boosts end-pumped Nd: YAG laser performance

In recent research published in Optics & Laser Technology and Infrared Physics & Technology, a research team led by Prof. Cheng Tingqing at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has introduced a novel low-thermal-effect gradient-doped crystal to tame thermal effects and improve the brightness of high-power end-pumped Nd: YAG lasers.

Traditional end-pumped solid-state lasers rely on uniformly doped crystals, which develop significant temperature gradients and thermal stresses under high pump power due to the axial absorption decay of pump power. These effects not only limit maximum pump power, but also degrade beam quality and conversion efficiency.

In this study, the researchers devised a numerical model for crystals whose neodymium concentration gradually increases along the rod, providing a theoretical basis for optimizing the concentration distribution and growth of novel gradient-doped crystals.

Photonic chip design offers simpler solution for one-way light flow in optical circuits

To improve photonic and electronic circuitry used in semiconductor chips and fiber optic systems, researchers at the McKelvey School of Engineering at Washington University in St. Louis tinkered with the rules of physics that govern the movement of light over time and space. They have introduced a new way to manipulate light transmission, opening possibilities for advanced optical devices.

Their method causes a “mirror-flip of the system,” said Lan Yang, the Edwin H. & Florence G. Skinner Professor of electrical and and senior author of the research, now published in Science Advances.

Using parity-time (PT) symmetric photonic waveguides, they can manipulate the light waves to “reverse time” so the system behaves the same as before, Yang added.