Lifeboat Foundation

Mode-locked lasers are advanced lasers that produce very short pulses of light, with durations ranging from femtoseconds to picoseconds. These lasers are widely used to study ultrafast and nonlinear optical phenomena, but they have also proved useful for various technological applications.

Researchers at California Institute of Technology have recently been exploring the potential of mode-locked lasers as platforms to study topological phenomena. Their paper, published in Nature Physics, outlines the potential of these lasers for studying and realizing new non-Hermitian topological physics, with various potential applications.

“The idea of utilizing topological robustness and topological protection for photonic devices has attracted substantial attention in the past decade, yet whether such behaviors can provide substantial practical benefits remains unclear,” Alireza Marandi, lead author of the paper, told Phys.org.

In March 2024, the CMS collaboration announced the observation of two photons creating two tau leptons in proton–proton collisions. It is the first time that this process has been seen in proton–proton collisions, which was made possible by using the precise tracking capabilities of the CMS detector. It is also the most precise measurement of the tau’s anomalous magnetic moment and offers a new way to constrain the existence of new physics.

Swiss physicists have achieved a groundbreaking breakthrough in lightning control using laser beams, which could lead to advanced lightning protection systems for critical infrastructure such as airports and rocket launch sites, Science reports.

The study, led by scientists at the École Polytechnique and the University of Geneva, successfully demonstrated the ability to steer lightning using high-powered lasers. This expensive breakthrough could offer enhanced protection against lightning strikes, which can cause significant damage and pose risks to human safety.

In the 1920s, Edwin Hubble and Georges Lemaitre made a startling discovery that forever changed our perception of the Universe. Upon observing galaxies beyond the Milky Way and measuring their spectra, they determined that the Universe was expanding. By the 1990s, with the help of the Hubble Space Telescope, scientists took the deepest images of the Universe to date and made another startling discovery: the rate of expansion is speeding up! This parameter, denoted by Lambda, is integral to the accepted model of cosmology, known as the Lambda Cold Dark Matter (LCDM) model.

Since then, attempts to measure distances have produced a discrepancy known as the “Hubble Tension.” While it was hoped that the James Webb Space Telescope (JWST) would resolve this “crisis in cosmology,” its observations have only deepened the mystery. This has led to several proposed resolutions, including the idea that there was an “Early Dark Energy” shortly after the Big Bang. In a recent paper, an international team of astrophysicists proposed a new solution based on an alternate theory of gravity that states that our galaxy is in the center of an “under-density.”

Continue reading “If Our Part of the Universe is Less Dense, Would That Explain the Hubble Tension?” »

A century ago, Emmy Noether published a theorem that would change mathematics and physics. Here’s an all-ages guided tour through this groundbreaking idea.

New research from Australian scientists shows strong evidence even mid-life stable stars like our sun have engulfed entire planets.

Open any astronomy textbook to the section on white dwarf stars and you’ll likely learn that they are “dead stars” that continuously cool down over time. New research published in Nature is challenging this theory, with the University of Victoria (UVic) and its partners using data from the European Space Agency’s Gaia satellite to reveal why a population of white dwarf stars stopped cooling for more than eight billion years.

“We discovered the classical picture of all white dwarfs being dead stars is incomplete,” says Simon Blouin, co-principal investigator and Canadian Institute of Theoretical Astrophysics National Fellow at UVic.

“For these white dwarfs to stop cooling, they must have some way of generating extra energy. We weren’t sure how this was happening, but now we have an explanation for the phenomenon.”

Understanding how a thermonuclear flame spreads across the surface of a neutron star—and what that spreading can tell us about the relationship between the neutron star’s mass and its radius—can also reveal a lot about the star’s composition.

In Verlinde’s picture of emergent gravity, as soon as you enter low-density regions — basically, anything outside the solar system — gravity behaves differently than we would expect from Einstein’s theory of general relativity. At large scales, there is a natural inward pull to space itself, which forces matter to clump up more tightly than it otherwise would.

This idea was exciting because it allowed astronomers to find a way to test this new theory. Observers could take this new theory of gravity and put it in models of galaxy structure and evolution to find differences between it and models of dark matter.

Over the years, however, the experimental results have been mixed. Some early tests favored emergent gravity over dark matter when it came to the rotation rates of stars. But more recent observations haven’t found an advantage. And dark matter can also explain much more than galaxy rotation rates; tests within galaxy clusters have found emergent gravity coming up short.