Archive for the ‘physics’ category: Page 3

Nov 3, 2023

Vacuum in optical cavity can change material’s magnetic state without laser excitation

Posted by in categories: computing, engineering, physics

Researchers in Germany and the U.S. have produced the first theoretical demonstration that the magnetic state of an atomically thin material, α-RuCl3, can be controlled solely by placing it into an optical cavity. Crucially, the cavity vacuum fluctuations alone are sufficient to change the material’s magnetic order from a zigzag antiferromagnet into a ferromagnet. The team’s work has been published in npj Computational Materials.

A recent theme in material physics research has been the use of intense laser light to modify the properties of magnetic materials. By carefully engineering the laser light’s properties, researchers have been able to drastically modify the and optical properties of different materials.

However, this requires continuous stimulation by high-intensity lasers and is associated with some practical problems, mainly that it is difficult to stop the material from heating up. Researchers are therefore looking for ways to gain similar control over materials using light, but without employing intense lasers.

Nov 3, 2023

3D printers learn to paint like Jackson Pollock

Posted by in categories: 4D printing, media & arts, physics, robotics/AI

If you’ve ever drizzled honey on a piece of toast, you’ve noticed how the amber liquid folds and coils in on itself as it hits the toast. The same thing can happen with 3D and 4D printing if the print nozzle is too far from the printing substrate. Harvard scientists have taken a page from the innovative methods of abstract expressionist artist Jackson Pollock —aka the “splatter master”—to exploit the underlying physics rather than try to control it to significantly speed up the process, according to a new paper published in the journal Soft Matter. With the help of machine learning, the authors were able to decorate a cookie with chocolate syrup to demonstrate the viability of their new approach.

As reported previously, Pollock early on employed a “flying filament” or “flying catenary” technique before he perfected his dripping methods. The paint forms various viscous filaments that are thrown against a vertical canvas. The dripping technique involved laying a canvas flat on the floor and then pouring paint on top of it. Sometimes, he poured it directly from a can; sometimes he used a stick, knife, or brush; and sometimes he used a syringe. The artist usually “rhythmically” moved around the canvas as he worked. His style has long fascinated physicists, as evidenced by the controversy surrounding the question of whether or not Pollock’s paintings show evidence of fractal patterns.

Back in 2011, Harvard mathematician Lakshminarayanan Mahadevan collaborated with art historian Claude Cernuschi on an article for Physics Today examining Pollock’s use of a “coiling instability” in his paintings. The study mathematically describes how a viscous fluid folds onto itself like a coiling rope—just like pouring cold maple syrup on pancakes.

Nov 1, 2023

New telescopes to study the aftermath of the Big Bang

Posted by in categories: cosmology, physics

Astronomers are currently pushing the frontiers of astronomy. At this very moment, observatories like the James Webb Space Telescope (JWST) are visualizing the earliest stars and galaxies in the universe, which formed during a period known as the “Cosmic Dark Ages.” This period was previously inaccessible to telescopes because the universe was permeated by clouds of neutral hydrogen.

As a result, the only light is visible today as relic radiation from the Big Bang—the (CMB)—or as the 21 cm spectral line created by the reionization of hydrogen (aka the Hydrogen Line).

Now that the veil of the Dark Ages is being slowly pulled away, scientists are contemplating the next frontier in astronomy and cosmology by observing “primordial ” created by the Big Bang. In recent news, it was announced that the National Science Foundation (NSF) had awarded $3.7 million to the University of Chicago, the first part of a grant that could reach up to $21.4 million. The purpose of this grant is to fund the development of next-generation telescopes that will map the CMB and the gravitational waves created in the immediate aftermath of the Big Bang.

Oct 30, 2023

Webb Telescope sees explosion 1 million times brighter than the Milky Way

Posted by in categories: cosmology, physics

This particular burst, called GRB 230307A, was likely created when two neutron stars — the incredibly dense remnants of stars after a supernova — merged in a galaxy about one billion light-years away. In addition to releasing the gamma-ray burst, the merger created a kilonova, a rare explosion that occurs when a neutron star merges with another neutron star or a black hole, according to a study published Wednesday in the journal Nature.

The Space Telescope Science Institute in Baltimore is the mission operations center for the telescope. It launched last in 2021 from French Guiana.

“There are only a mere handful of known kilonovas, and this is the first time we have been able to look at the aftermath of a kilonova with the James Webb Space Telescope,” said lead study author Andrew Levan, astrophysics professor at Radboud University in the Netherlands. Levan was also part of the team that made the first detection of a kilonova in 2013.

Oct 27, 2023

350-Year-Old Theorem Reveals ‘Profound’ Connection Between Properties of Light

Posted by in category: physics

Dutch-born Christiaan Huygens is probably one of the most famous physicists you’ve never heard of. His work in the late 17th century straddled both the intangible and tangible realms of our Universe: the nature of light, and the mechanics of moving objects.

Among his many contributions, Huygens proposed a wave theory of light that would give rise to physical optics, which deals with the interference, diffraction, and polarization of light. He also invented the first pendulum clock; the most accurate timekeeper for almost 300 years, right through the Industrial Revolution.

Little has been made of the connections between these two seemingly disparate fields of optics and classical mechanics – until now.

Oct 27, 2023

New research sheds light on early galaxy formation

Posted by in categories: computing, physics, space

Researchers have developed a new computer simulation of the early universe that closely aligns with observations made by the James Webb Space Telescope (JWST).

Initial JWST observations hinted that something may be amiss in our understanding of early galaxy formation. The first galaxies studied by JWST appeared to be brighter and more massive than theoretical expectations.

The findings, published in The Open Journal of Astrophysics, by researchers at Maynooth University, Ireland, with collaborators from US-based Georgia Institute of Technology, show that observations made by JWST do not contradict theoretical expectations. The so-called “Renaissance simulations” used by the team are a series of highly sophisticated computer simulations of galaxy formation in the early universe.

Oct 25, 2023

Astrophysicists scan the galaxy for signs of life

Posted by in categories: alien life, physics

The astrophysicists, from Trinity and the Breakthrough Listen team and Onsala Space Observatory in Sweden, are scanning the universe for “technosignatures” emanating from distant planets that would provide support for the existence of intelligent, alien life.

Using the Irish LOFAR telescope and its counterpart in Onsala, Sweden, the team—led by Professor Evan Keane, Associate Professor of Radio Astronomy in Trinity’s School of Physics, and Head of the Irish LOFAR Telescope—plans to monitor millions of star systems.

Scientists have been searching for extraterrestrial radio signals for well over 60 years. Many of these have been carried out using single observatories which limits the ability to identify signals from the haze of terrestrial interference on Earth. Much of the effort has focused on frequencies above 1 GHz because the single-dish telescopes employed operate at these frequencies.

Oct 23, 2023

Adaptive optical neural network connects thousands of artificial neurons

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

Modern computer models—for example for complex, potent AI applications—push traditional digital computer processes to their limits. New types of computing architecture, which emulate the working principles of biological neural networks, hold the promise of faster, more energy-efficient data processing.

A team of researchers has now developed a so-called event-based architecture, using photonic processors with which data are transported and processed by means of light. In a similar way to the brain, this makes possible the continuous adaptation of the connections within the neural network. This changeable connections are the basis for learning processes.

For the purposes of the study, a team working at Collaborative Research Center 1,459 (Intelligent Matter)—headed by physicists Prof. Wolfram Pernice and Prof. Martin Salinga and computer specialist Prof. Benjamin Risse, all from the University of Münster—joined forces with researchers from the Universities of Exeter and Oxford in the UK. The study has been published in the journal Science Advances.

Oct 22, 2023

Do we live in a computer simulation like in The Matrix? Proposed new law of physics backs up the idea

Posted by in categories: alien life, computing, information science, physics

The simulated universe theory implies that our universe, with all its galaxies, planets and life forms, is a meticulously programmed computer simulation. In this scenario, the physical laws governing our reality are simply algorithms. The experiences we have are generated by the computational processes of an immensely advanced system.

While inherently speculative, the simulated theory has gained attention from scientists and philosophers due to its intriguing implications. The idea has made its mark in popular culture, across movies, TV shows and books—including the 1999 film “The Matrix.”

The earliest records of the concept that reality is an illusion are from ancient Greece. There, the question “What is the nature of our reality?” posed by Plato (427 BC) and others, gave birth to idealism. Idealist ancient thinkers such as Plato considered mind and spirit as the abiding reality. Matter, they argued, was just a manifestation or illusion.

Oct 22, 2023

Black holes could come in ‘perfect pairs’ in an ever expanding universe

Posted by in categories: cosmology, physics

Researchers from the University of Southampton, together with colleagues from the universities of Cambridge and Barcelona, have shown it’s theoretically possible for black holes to exist in perfectly balanced pairs—held in equilibrium by a cosmological force—mimicking a single black hole.

Black holes are massive astronomical objects that have such a strong gravitational pull that nothing, not even light, can escape. They are incredibly dense. A black hole could pack the mass of the Earth into a space the size of a pea.

Conventional theories about , based on Einstein’s theory of General Relativity, typically explain how static or spinning black holes can exist on their own, isolated in space. Black holes in pairs would eventually be thwarted by gravity attracting and colliding them together.

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