Scientists at EPFL and IBM have developed a new type of laser that could have a significant impact on optical ranging technology. The laser is based on a material called lithium niobate, often used in the field of optical modulators, which controls the frequency or intensity of light that is transmitted through a device.
1. The mind, brain, and body are inextricably linked
The idea that the mind and brain are separate is usually attributed to the 17th-century French mathematician and philosopher René Descartes, who was what philosophers now call a substance dualist. Descartes believed that the mind and body are made of different substances: the body of a physical substance, and the mind of some mysterious, nonphysical material.
Today, most neuroscientists reject this idea. Modern brain research suggests that the mind is made of matter and emerges from brain activity. Even so, most still study the brain in isolation, without taking the body into consideration.
The novel substance is detailed in a research paper, Evidence of near-ambient superconductivity in a N-doped lutetium hydride, which is published in the scientific journal Nature.
“It is very difficult to change the properties of a medium quick enough, uniformly, and with enough contrast to time reflect electromagnetic signals because they oscillate very fast,” Gengyu Xu, a co-author and post-doc student at CUNY ASRC, said in a press statement. “Our idea was to avoid changing the properties of the host material, and instead create a metamaterial in which additional elements can be abruptly added or subtracted through fast switches.”
This time reflection also behaves differently than spatial reflections. Because this time echo reflects that last part of the signal first, the researchers say that if you looked in a time mirror, you would see your back instead of your face. To translate the experience acoustically, it’d be like listening to a tape on rewind—which is to say fast and high-pitched.
Called a Wolf-Rayet, these stars expel most of their outer layers into their surroundings before exploding as supernovae.
NASA’s James Webb Space Telescope has released a phenomenal image of a supernova waiting to happen. Called a Wolf-Rayet, these stars are among the most massive, luminous, and “briefly detectable” stars known. They’re at an advanced stage of stellar evolution and expel most of their outer layers into their surroundings before exploding as supernovae.
Webb had a rare sighting of a Wolf-Rayet star in June 2022. In the latest image, the telescope shows the star, WR 124, in unprecedented detail, thanks to its infrared instruments.
NASA, ESA, CSA, stsci, webb ERO production team.
Not all stars go through a brief Wolf-Rayet phase before evolving into a supernova, which is why astronomers think Webb has captured a rare phase. This particular star is 30 times the mass of the Sun and has shed 10 Suns’ worth of material – so far. According to a release, as the ejected gas moves away from the star and cools, cosmic dust forms and glows in the infrared light detectable by Webb.
A breakthrough regarding dendrites made by MIT researchers may finally open the way to the building of a new type of rechargeable lithium battery that is safer, lighter, and more compact than existing models, a concept that has been pursued by labs all over the world for years.
The replacement of the liquid electrolyte between the positive and negative electrodes with a considerably thinner, lighter layer of solid ceramic material and the replacement of one electrode with solid lithium metal are the two essential components of this prospective advancement in battery technology. By making these changes, the battery’s overall size and weight would be significantly reduced, and the flammable liquid electrolytes that provide a safety risk would be eliminated. Dendrites, however, have proven to be a significant obstacle in that pursuit.
Dendrites are metal growths that can accumulate on the lithium surface, pierce through the solid electrolyte, and finally cross from one electrode to the other, shorting out the battery cell. Their name is from the Latin word for branches. There hasn’t been much advancement in the understanding of what causes these metal filaments or how to stop them from occurring, making lightweight solid-state batteries a problematic alternative.
Hydrides are created by combining rare earth metals with hydrogen, then adding nitrogen or carbon. In recent years, they offered scientists a tantalizing “working recipe” for creating superconducting materials.
Technically speaking, rare earth metal hydrides take the form of cage-like structures called clathrates, where the rare earth metal ions serve as carrier donors and supply enough electrons to promote the dissociation of the H2 molecules. Carbon and nitrogen aid in material stabilization. The bottom line is that superconductivity can occur at lower pressures.
Scientists have also employed additional rare earth metals besides yttrium. Yet, the resultant compounds turn superconductive at pressures or temperatures that are still impractical for applications.