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Category: physics – Page 223

An international research team analyzed a database of more than 1000 supernova explosions and found that models for the expansion of the Universe best match the data when a new time dependent variation is introduced. If proven correct with future, higher-quality data from the Subaru Telescope and other observatories, these results could indicate still unknown physics working on the cosmic scale.

Edwin Hubble’s observations over 90 years ago showing the expansion of the Universe remain a cornerstone of modern astrophysics. But when you get into the details of calculating how fast the Universe was expanding at different times in its history, scientists have difficulty getting theoretical models to match observations.

To solve this problem, a team led by Maria Dainotti (Assistant Professor at the National Astronomical Observatory of Japan and the Graduate University for Advanced Studies, SOKENDAI in Japan and an affiliated scientist at the Space Science Institute in the U.S.A.) analyzed a catalog of 1048 supernovae which exploded at different times in the history of the Universe. The team found that the theoretical models can be made to match the observations if one of the constants used in the equations, appropriately called the Hubble constant, is allowed to vary with time.

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A University of California San Diego engineering professor has solved one of the biggest mysteries in geophysics: What causes deep-focus earthquakes?

These mysterious earthquakes originate between 400 and 700 kilometers below the surface of the Earth and have been recorded with magnitudes up to 8.3 on the Richter scale.

Xanthippi Markenscoff, a distinguished professor in the Department of Mechanical and Aerospace Engineering at the UC San Diego Jacobs School of Engineering, is the person who solved this mystery. Her paper “Volume collapse instabilities in deep earthquakes: a shear source nucleated and driven by pressure” appears in the Journal of the Mechanics and Physics of Solids.

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The findings could lead to faster, more secure memory storage, in the form of antiferromagnetic bits.

When you save an image to your smartphone, those data are written onto tiny transistors that are electrically switched on or off in a pattern of “bits” to represent and encode that image. Most transistors today are made from silicon, an element that scientists have managed to switch at ever-smaller scales, enabling billions of bits, and therefore large libraries of images and other files, to be packed onto a single memory chip.

But growing demand for data, and the means to store them, is driving scientists to search beyond silicon for materials that can push memory devices to higher densities, speeds, and security.

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If you are a space enthusiast, there is some good news for you. In a new research, that could possibly open doors to many unknown aspects of the Universe, researchers have detected a resonant “hum” produced by the gravitational waves in the Universe. Experts say this can be imagined as a gravitational wave background of the Universe.

This hum of the Universe was reportedly detected by the North American Nanohetz Observatory for Gravitational Waves (NANOGrav), and the findings of the research was published in The Astrophysical Journal Letters.

In a report, ScienceAlert said this gravitational wave background can be imagined as “something like the ringing left behind by massive events throughout our Universe’s history”.

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Using neural networks, Flatiron Institute research fellow Yin Li and his colleagues simulated vast, complex universes in a fraction of the time it takes with conventional methods.

Using a bit of machine learning magic, astrophysicists can now simulate vast, complex universes in a thousandth of the time it takes with conventional methods. The new approach will help usher in a new era in high-resolution cosmological simulations, its creators report in a study published online on May 4, 2021, in Proceedings of the National Academy of Sciences.

“At the moment, constraints on computation time usually mean we cannot simulate the universe at both high resolution and large volume,” says study lead author Yin Li, an astrophysicist at the Flatiron Institute in New York City. “With our new technique, it’s possible to have both efficiently. In the future, these AI-based methods will become the norm for certain applications.”

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For millennia, humans in the high latitudes have been enthralled by auroras—the northern and southern lights. Yet even after all that time, it appears the ethereal, dancing ribbons of light above Earth still hold some secrets.

In a new study, physicists led by the University of Iowa report a new feature to Earth’s atmospheric light show. Examining video taken nearly two decades ago, the researchers describe multiple instances where a section of the diffuse —the faint, background-like glow accompanying the more vivid light commonly associated with auroras—goes dark, as if scrubbed by a giant blotter. Then, after a short period of time, the blacked-out section suddenly reappears.

The researchers say the behavior, which they call “diffuse auroral erasers,” has never been mentioned in the . The findings appear in the Journal of Geophysical Research Space Physics.

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A team of researchers from Zhejiang University, Xi’an Jiaotong University and Monash University has developed a way to bind multiple strands of graphene oxide into a thick cable. In their paper published in the journal Science, the group describes their process and possible uses for it. Rodolfo Cruz-Silva and Ana Laura Elías with Shinshu University and Binghamton University have published a Perspectives piece in the same issue outlining the work by the researchers and explaining why they believe the technique could prove useful in manufacturing efforts.

In recent years, have been exploring the possibility of making products using total or partial self-assembly as a way to produce them faster or at less cost. In where two materials self-assemble into a third material, scientists describe this as a fusion process, borrowing terminology from physics. So when a single material spontaneously separates into two or more other materials, they refer to it as a fission process. In this new effort, the researchers have developed a technique for creating graphene-oxide-based yarn that exploits both processes.

The work by the team is very basic. They created multiple strands of graphene oxide and then dunked them into a solvent for 10 minutes. When the strands were pulled from the solution, they banded together forming a cord, or single strand of yarn. They also developed a means for reversing the process—dunking the strand of yarn in a different solvent solution.

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Past physics theories introduced several fundamental constants, including Newton’s constant G, which quantifies the strength of the gravitational interaction between two massive objects. Combined, these fundamental constants allow physicists to describe the universe in ways that are straightforward and easier to understand.

In the past, some researchers wondered whether the value of changed over cosmic time. Moreover, some alternative theories of gravity (i.e., adaptations or substitutes of Einstein’s theory of general relativity), predict that the constant G varies in time.

Researchers at the International Centre for Theoretical Sciences of the Tata Institute for Fundamental Research in India recently proposed a method that can be used to place constraints on the variation of G over cosmic time. This method, outlined in a paper published in Physical Review Letters, is based on observations of merging binary neutron stars.

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A team of international scientists, led by the Galician Institute of High Energy Physics (IGFAE) and the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), has proposed a simple and novel method to bring the accuracy of the Hubble constant measurements down to 2% using a single observation of a pair of merging neutron stars.

The universe is in continuous expansion. Because of this, distant objects such as galaxies are moving away from us. In fact, the further away they are, the faster they move. Scientists describe this expansion through a famous number known as the Hubble constant, which tells us how fast objects in the universe recede from us depending on their distance to us. By measuring the Hubble constant in a precise way, we can also determine some of the most fundamental properties of the universe, including its age.

For decades, scientists have measured Hubble’s constant with increasing accuracy, collecting electromagnetic signals emitted throughout the universe but arriving at a challenging result: the two current best measurements give inconsistent results. Since 2015, scientists have tried to tackle this challenge with the science of gravitational waves, ripples in the fabric of space-time that travel at the speed of light. Gravitational waves are generated in the most violent cosmic events and provide a new channel of information about the universe. They’re emitted during the collision of two —the dense cores of collapsed —and can help scientists dig deeper into the Hubble constant mystery.

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