Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog – Page 13

Get the latest international news and world events from around the world.

Log in for authorized contributors

Can String Theory Be Explained with No Strings Attached?

Using a “bootstrap” approach, researchers show that a small set of assumptions may naturally lead to a string-theory description of certain high-energy processes.

String theory has been a remarkably influential conceptual framework for modern theoretical physics. While its description of nature in terms of tiny strings captures the imagination, the string framework has had profound impact in a broad range of subfields, going well beyond its lead role as a viable theory of quantum gravity. For instance, it has led to deeper understanding of black holes and their relation to entanglement and quantum information [1], and it has provided theoretical benchmarks for explaining quark–gluon plasma observations in quantum chromodynamics [2]. As a complement to direct calculations, theoretical physicists would like to understand string theory as emerging from a set of fundamental principles that any theory of nature must respect. Consistency with these bedrock conditions, so goes the idea, could perhaps make string theory inevitable.

Broken time-reversal symmetry phase in kagome metals may establish conditions for superconductivity

Physicists have long suspected that a peculiar quantum state lurks inside a class of materials known as kagome metals, but proving its existence has been elusive. Now, a team led by Yeongkwan Kim at the Korea Advanced Institute of Science and Technology has performed experiments on a kagome metal that provide the strongest evidence yet for this exotic state.

Published in Nature Physics, the team’s results could shed new light on how these materials transition into superconductivity.

Experiment upends beliefs on how electrons actually behave in warm dense matter

Researchers at European XFEL, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Rostock University and other collaborating institutions have used high-precision experiments to demonstrate that the most widely used models for the behavior of electrons in warm dense matter are inaccurate. Warm dense matter is challenging to study, but also is of key importance for a plethora of research, including the investigation of planetary interiors, materials science and laser fusion experiments. The study is published in Physical Review Letters.

In warm dense matter, electron density oscillates. The collective oscillations are called plasmons. They carry important information and can be observed using X-rays, resulting in scattering spectra—abstract images captured by a detector. In many experiments, these spectra are interpreted using simplified uniform electron gas models. However, the new measurements show that for warm dense aluminum, these models consistently overestimate the plasmon energy by up to about 25% (about 8 electronvolts) and fail to reproduce the full measured shape of the signal.

“Our measurements are precise enough to clearly distinguish between competing models,” says Dr. Thomas Preston of European XFEL. “That is important because these models are widely used to diagnose extreme states of matter. If the model is incorrect, that leads to inaccurately inferred properties.”

Room-temperature device synchronizes distant laser spots into single coherent ‘supermode’

Researchers have demonstrated a new way to make spatially separated lasers synchronize and act as a single coherent light source—without extreme conditions or complex materials.

A team of physicists from the University of Southampton (UK), University of Warsaw (PL), Military University of Technology (PL), Institut Pascal, Université Clermont Auvergne, CNRS (FR), and CNR (IT) has developed a new class of tunable photonic devices in which multiple tiny laser beams spontaneously synchronize and behave as a unified, spatially extended and coherent light source. Remarkably, this effect is achieved at room temperature using a simple system based on liquid crystals and organic dye molecules, opening new possibilities for low-cost and reconfigurable optical technologies.

The work is published in the journal Nature Communications. The study demonstrates that spatially separated laser spots inside an optical microcavity can spontaneously phase-lock—that is, align (or synchronize) their oscillations—and form a collective state known as a “supermode.” Traditionally, such behavior has been observed only in highly specialized semiconductor systems operating at cryogenic temperatures and in the so-called strong light-matter coupling regime.

Investigating quantum and molecular plumbing in nanofluidics research

Our body contains an intricate system of tiny vessels through which blood, water and other molecules flow. When the size of the pipes shrinks to the nanoscale, where only a few molecules can fit side by side, the classical laws of physics governing the behavior of water are influenced by the atomic structure of the walls. “It’s not that classical hydrodynamics breaks down, but rather that it gets mixed with the condensed matter physics of the solid walls,” says Nikita Kavokine, tenure-track assistant professor and leader of the EPFL Quantum Plumbing Lab.

How liquids, and water in particular, behave at scales of a few nanometers is one of the big gaps in modern physics. For example, in some experiments, it has been observed that water flows through carbon nanotubes orders of magnitude faster than expected. Scientists are trying to understand phenomena that biology has mastered after millions of years of evolution.

“At the nanometer scale, our body leverages specific properties of water to filter molecules with high energy efficiency,” explains Kavokine. Aquaporins, for example, are protein channels embedded in cell membranes that use these molecular-scale interactions to let water pass while blocking ions and other molecules.

Electron-Ion Collider’s radiofrequency controls system passes first real-world test

The U.S. Department of Energy’s (DOE) Brookhaven National Laboratory has reached a key early milestone in developing radiofrequency control systems for the Electron-Ion Collider (EIC)—a next-generation research facility that will collide electrons with ions to reveal how the building blocks of matter are held together.

At the heart of any particle accelerator are radiofrequency (RF) systems, which use electromagnetic waves to accelerate particle beams to near-light speed and keep them tightly controlled. The system tested here—known as low-level radiofrequency (LLRF)—acts as the “brain,” precisely controlling those RF fields to ensure stable and accurate operation.

This milestone marks the first successful test of the newly built EIC common platform-based LLRF electronics on a real accelerator cavity. The common platform is a shared hardware and control system for accelerator operations, allowing teams to use the same technology rather than create separate electronics for each system.

Quantum gravity research links continuous parameters to local operators within the theory itself

A researcher at Kyushu University and his collaborators have shown that continuous parameters in quantum gravity may not be freely adjustable “dials” from outside the theory, but rather arise from operators within the theory itself, supporting the century-old claim by Albert Einstein about the fundamental laws of nature.

Einstein argued that the fundamental equations of physics contain no freely adjustable parameters. In other words, he believed that the laws of nature should not include arbitrary numbers chosen from outside a theory. Instead, such quantities should emerge naturally from physical processes.

This idea has become especially important in the search for quantum gravity, a theory that aims to combine gravity with quantum mechanics. Physicists expect that the equations governing quantum gravity should not contain freely adjustable quantities. Rather, all parameters should arise from physical fields.

How oxygen sneaks into a corked wine bottle long before the first pour

The main reason for sealing wine bottles with a cork is to protect the liquid from oxygen. However, it is not an impermeable barrier, and a small amount of air leaks in, which is not always entirely bad news. The gas helps the wine mature and develop a more complex flavor.

In a paper published in the journal Science Advances, researchers highlight several mechanisms that control how oxygen enters and behaves inside the bottle.

Oxygen is, in fact, a crucial consideration. Too much, and the wine can oxidize and spoil, while too little can stunt its development and lead to unpleasant aromas. So winemakers have a delicate balancing act to get it right.

How languages recycle parts of words to avoid confusion

Many languages recycle words, giving them different meanings. For example, in English, “run” can mean to move quickly but also to manage something, like “run a company.” In Spanish, “lengua” is both the word for tongue and language, as in “la lengua española.” This type of word reuse is known as colexification.

But there is another type of recycling, and that is partial colexification, where languages reuse only parts of words. A good example is the word “grand,” which is shared in “grandfather” and “grandmother.” Until now, very little was known about the rules, patterns and how widespread this type of recycling is across different languages.

A new study published in the journal Nature Human Behaviour explores how different languages systematically reuse these smaller word parts while balancing efficiency with the need to keep meanings distinct. Barend Beekhuizen at the Department of Language Studies at the University of Toronto Mississauga in Canada has published a News & Views piece on the research in the same journal.

Scientists design a clay that can prevent fruits and vegetables from rotting too quickly

Avocados from Chile, bananas from Costa Rica, tomatoes from southern Spain, mangoes from Brazil. A large share of the fruit and vegetables we eat have traveled across the globe before they reach store shelves here at home. But many millions of tons are lost every year before they get that far.

One of the main reasons is ethylene—a natural gas that many fruits and vegetables produce and that controls their ripening. When fruits and vegetables are confined in closed packaging or containers during transport and storage, the concentration of ethylene in the air increases, accelerating the ripening process. As a result, a large share of the cargo ends up rotting before it reaches its final destination.

/* */