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Circa 2018

Higgs and Goldstone modes are possible collective modes of an order parameter on spontaneously breaking a continuous symmetry. Whereas the low-energy Goldstone (phase) mode is always stable, additional symmetries are required to prevent the Higgs (amplitude) mode from rapidly decaying into low-energy excitations. In high-energy physics, where the Higgs boson¹ has been found after a decades-long search, the stability is ensured by Lorentz invariance. In the realm of condensed-matter physics, particle–hole symmetry can play this role² and a Higgs mode has been observed in weakly interacting superconductors^3,4,5. However, whether the Higgs mode is also stable for strongly correlated superconductors in which particle–hole symmetry is not precisely fulfilled or whether this mode becomes overdamped has been the subject of numerous discussions^{6,7,8,9,10,11}. Experimental evidence is still lacking, in particular owing to the difficulty of exciting the Higgs mode directly. Here, we observe the Higgs mode in a strongly interacting superfluid Fermi gas. By inducing a periodic modulation of the amplitude of the superconducting order parameter Δ, we observe an excitation resonance at the frequency 2Δ/h. For strong coupling, the peak width broadens and eventually the mode disappears when the Cooper pairs turn into tightly bound dimers signalling the eventual instability of the Higgs mode.

Two entrepreneurs from Mexico have created vegan leather out of cactus leaves. The cruelty-free leather is called Desserto.

Adrián López Velarde and Marte Cázarez are said to be the first to create organic leather out of only nopal (prickly-pear) cactus. They don’t use toxic chemicals, phthalates, or PVC in their design.

The vegan leather is partially biodegradable. It’s flexible, breathable, and lasts for at least 10 years. The material feels like animal-based leather. Companies can use it in furniture, cars, leather accessories, and clothing.

Spraying this material on desert sand will turn it into green, fertile land.

Artificial flesh is growing ever closer to the real thing. Scientists in Australia have now created a new jelly-like material which they claim has the strength and durability of actual skin, ligaments, or even bone.

“With the special chemistry we’ve engineered in the hydrogel, it can repair itself after it has been broken like human skin can,” explains chemist Luke Connal from the Australian National University.

“Hydrogels are usually weak, but our material is so strong it could easily lift very heavy objects and can change its shape like human muscles do.”

High-entropy alloys, which are made from nearly equal parts of several primary metals, could hold great potential for creating materials with superior mechanical properties.

But with a practically unlimited number of possible combinations, one challenge for metallurgists is figuring out where to focus their research efforts in a vast, unexplored world of metallic mixtures.

A team of researchers at the Georgia Institute of Technology has developed a new process that could help guide such efforts. Their approach involves building an atomic resolution chemical map to help gain new insights into individual high-entropy alloys and help characterize their properties.

California’s drought is spawning a slew of proposed desalination plants to create potable water from seawater, including one coming up in Santa Barbara. Just how clean are these facilities and what is their impact on ocean life?

The term “Isotonic” originates from the Greek root words “iso” and “tonos.” The root “iso” isn’t just a file format, it actually means equal. “Tonos,” on the other hand, means to stretch. The word Isotonic can mean a multitude of things stretching from material and physical sciences to liberal arts.

Equal Stretch Regression (Isotonic Regression) is a really cool model for statistical inference. My obsession with isotonic regression has long been expanding, because the model is just so interesting, and cool.

Supermassive black holes exist at the center of most galaxies, and our Milky Way is no exception. But many other galaxies have highly active black holes, meaning a lot of material is falling into them, emitting high-energy radiation in this “feeding” process. The Milky Way’s central black hole, on the other hand, is relatively quiet. New observations from NASA’s Stratospheric Observatory for Infrared Astronomy, SOFIA, are helping scientists understand the differences between active and quiet black holes.