Archive for the ‘physics’ category: Page 10

Oct 11, 2019

Physicists look to navigational ‘rhumb lines’ to study polymer’s unique spindle structure

Posted by in categories: biological, physics

From the intricate patterns of pollen grains to the logarithmic spirals of nautilus shells, biology is full of complex patterns, shapes, and geometries. Many of these intricate structures play important roles in biological function, but can be difficult to create in a lab without state-of-the-art equipment or expensive and energy-consuming processes and materials.

A new study describes how spheres can be transformed into twisted spindles thanks to insights from 16th century navigational tools. Researchers show how polymers can contract into spiral structures, known as loxodromes, that have complex patterning ten times smaller than the width of a human hair. Published in Physical Review Letters, the research was conducted by University of Pennsylvania graduate student Helen Ansell, postdoc Daeseok Kim, and professors Randall Kamien and Eleni Katifori in the School of Arts and Sciences, in collaboration with Teresa Lopez-Leon of the École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI).

Kim, who worked on this project at ESPCI before coming to Penn, was inspired by other studies showing that a mixture of polymer and liquid crystal took on a new shape when placed in a different solvent. It was a change that was also reversible and reproducible, with little to no energy required to cause the change in shape.

Oct 10, 2019

Accidental Discovery of an Unbreakable “Molecular Pinball Machine”

Posted by in categories: cyborgs, physics

An organic material that can repeatedly change shape without breaking would have many useful applications, such as artificial muscles, pumps or as a switch. Physicists at Radboud University accidentally discovered a material with that property. Their findings were published in the scientific journal Nature Communications today October 8, 2019.

“I tend to call it the ‘molecular pinball machine,’” says Theo Rasing, professor of Spectroscopy of Solids and Interfaces at Radboud University. Together with colleagues from Nijmegen and China, he demonstrates the shape-changing abilities of the material by having it fling a glass bead at high speed. In that process, the organic crystal material called 4-DBpFO delivers a force corresponding to ten thousand times its own weight.

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Oct 10, 2019

CERN congratulates 2019 physics Nobel Prize winners

Posted by in categories: cosmology, evolution, physics

CERN congratulates James Peebles, Michel Mayor and Didier Queloz on the award of the Nobel Prize in physics “for contributions to our understanding of the evolution of the universe and Earth’s place in the cosmos”. Peebles receives the prize “for theoretical discoveries in physical cosmology” and Mayor and Queloz are recognised “for the discovery of an exoplanet orbiting a solar-type star”.

Cosmology studies the universe’s origin, structure and ultimate fate. Peebles’ theoretical framework of cosmology, developed since the mid-1960s, is the foundation of our knowledge of the cosmos today. Thanks to his seminal theoretical work, physicists now have a model that can describe the universe from its earliest moments to the present day, and into the distant future.

Meanwhile, Mayor and Queloz have explored our cosmic neighbourhood and announced in 1995 the first discovery of an exoplanet – a planet outside our Solar System – orbiting a solar-type star in the Milky Way. The discovery of this exoplanet, dubbed 51 Pegasi b, was a milestone in astronomy and has since led to the discovery of more than 4000 exoplanets in our galaxy.

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Oct 8, 2019

From ‘weirdo’ PhD stargazer to Nobel Physics laureate

Posted by in categories: physics, space

As a student astronomer scanning the skies with homemade instruments a quarter of a century ago, Didier Queloz spent months doubting the data that led him to an inescapable conclusion: he’d just discovered the first planet outside Earth’s solar system.

The Swiss scientist had spent much of his PhD research refining techniques to detect so-called exoplanets, which until one fateful night in October 1995 had previously only existed in the realm of science fiction.

Queloz and his colleague Michel Mayor, who on Tuesday were awarded the Nobel Prize for Physics for their pioneering work, had already overcome a number of obstacles in their galaxy-wide search.

Oct 8, 2019

Are Black Holes Made of Dark Energy? Error Made When Applying Einstein’s Equations to Model Growth of the Universe?

Posted by in categories: cosmology, information science, physics

Two University of Hawaiʻi at Mānoa researchers have identified and corrected a subtle error that was made when applying Einstein’s equations to model the growth of the universe.

Physicists usually assume that a cosmologically large system, such as the universe, is insensitive to details of the small systems contained within it. Kevin Croker, a postdoctoral research fellow in the Department of Physics and Astronomy, and Joel Weiner, a faculty member in the Department of Mathematics, have shown that this assumption can fail for the compact objects that remain after the collapse and explosion of very large stars.

“For 80 years, we’ve generally operated under the assumption that the universe, in broad strokes, was not affected by the particular details of any small region,” said Croker. “It is now clear that general relativity can observably connect collapsed stars—regions the size of Honolulu—to the behavior of the universe as a whole, over a thousand billion billion times larger.”

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Oct 6, 2019

NASA stunned: Scientist asks ‘was Einstein wrong?’ after object breaks laws of physics

Posted by in categories: physics, space travel

Michio Kaku declared that he found Einsteins theory breaks down at a certain point and was attacked by science. Here NASA has proof that Einsteins theory of nothing traveling faster than the speed of light is wrong, and again old school wants Einstein to still be followed. That is what I have explained to Physiologists about yes, Physiolgy.

A NASA scientist has questioned whether Albert Einstein’s theories over space were inaccurate after the Hubble telescope recorded an object travelling five times the speed of light.

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Oct 5, 2019

The Nobel Prize in Physics: The papers

Posted by in category: physics

[p] Physics Today takes the spotlight off the laureates and instead focuses on the papers that prompted Nobel glory.[/p].

Oct 4, 2019

Underground Detector in Japan to Join Search for Gravitational Waves

Posted by in category: physics

A fourth gravitational wave detector, this one in Gifu Prefecture, Japan, will join the global search for cosmic events that cause ripples in spacetime, beginning this December.

The Kamioka Gravitational-Wave Detector (KAGRA) is in its commissioning phase, according to a press release, and will join the two LIGO detectors in the United States well as the Virgo detector in Italy. The three facilities will share data, serving as independent verifiers of each other’s results.

Oct 4, 2019

Molecular hydrogen becomes semimetallic at pressures above 350 GPa

Posted by in category: physics

According to condensed matter physics predictions, at a high enough pressure, hydrogen should dissociate and transform into an atomic metal. However, the exact pressure range at which this occurs has not yet been ascertained, and the process through which hydrogen becomes a metal is still somewhat unclear.

In a recent study, researchers at the Max Planck Institute of Chemistry demonstrated that at a pressure of 350–360 GPa and at temperatures below 200K, molecular starts to conduct and becomes semimetallic. Their paper, published in Nature Physics, provides interesting new insight about the transition of hydrogen at high pressures, unveiling some of the properties it acquires.

“Typically, metallic hydrogen is considered to be atomic hydrogen—a crystal built from protons after dissociation of the molecules,” Mikhail Eremets, one of the researchers who carried out the study, told Phys.org. “However, hydrogen can also transform into a metal in the molecular state—in this case, electronic bands of molecular hydrogen crystal broaden and eventually overlap so that the band gap closes, free electrons and holes appear—this is metallic state.”

Oct 2, 2019

Squid-inspired robots might have environmental, propulsion applications

Posted by in categories: military, physics, robotics/AI

Inspired by the unique and efficient swimming strategy of cephalopods, scientists developed an aquatic robot that mimics their form of propulsion.

These , squidlike robots are made of , which make them hard to detect—an advantage that has potential military reconnaissance and scientific applications—while maintaining a low environmental footprint.

Physicists Xiaobo Bi and Qiang Zhu used to illustrate the physical mechanisms and fluid mechanics of a squid’s swimming method, which uses intermittent bursts through pulsed jet propulsion. By using this form of locomotion, the new can achieve impressive speeds, just like its animal inspiration. Bi and Zhu discuss their work in this week’s Physics of Fluids.

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