Ripples in space-time called gravitational waves are normally associated with massive objects like black holes, but we could make our own using lasers – and perhaps even use them to communicate.
By Alex Wilkins
Imagine a juggler tossing balls into the air. The art of juggling is a dance between motion and pause, where the ball’s speed slows as it ascends, and then quickens on the way down. This dance reveals one of the core tenets of physics: conservation laws.
Simply put, these laws tell us that certain features of our world, like energy, don’t just vanish; they transform from one form to another. In our juggling example, the energy of motion (kinetic energy) morphs into the energy of position (potential energy) and back again.
Conservation laws aren’t just limited to juggling, or even Earth for that matter. They’re universal principles, true across various fields of physics. Yet, they aren’t always straightforward.
The results of the Chi-Nu physics experiment at Los Alamos National Laboratory have contributed essential, never-before-observed data for enhancing nuclear security applications, understanding criticality safety and designing fast-neutron energy reactors. The Chi-Nu project, a years-long experiment measuring the energy spectrum of neutrons emitted from neutron-induced fission, recently concluded the most detailed and extensive uncertainty analysis of the three major actinide elements—uranium-238, uranium-235 and plutonium-239.
“Nuclear fission and related nuclear chain reactions were only discovered a little more than 80 years ago, and experimenters are still working to provide the full picture of fission processes for the major actinides,” said Keegan Kelly, a physicist at Los Alamos National Laboratory. “Throughout the course of this project, we have observed clear signatures of fission processes that in many cases were never observed in any previous experiment.”
The Los Alamos team’s final Chi-Nu study, on the isotope uranium-238, was recently published in Physical Review C. The experiment measured uranium-238’s prompt fission neutron spectrum: the energy of the neutron inducing the fission—the neutron that crashes into a nucleus and splits it—and the potentially wide-ranging energy distribution (the spectrum) of the neutrons released as a result. Chi-Nu focuses on “fast-neutron-induced” fission, with incident neutron energies in millions of electron volts, where there have typically been very few measurements.
In this episode, we explore how a triple-lens supernova observed by the James Webb Space Telescope could help solve the mystery of the Hubble tension, which is the discrepancy between different measurements of the expansion rate of the Universe. We also learn about the details of the supernova and the galaxy cluster that caused the gravitational lensing effect, and how JWST and other telescopes can use this supernova to test various cosmological models and parameters.
Paper Link:
https://arxiv.org/abs/2309.
Continue reading “James Webb just Found a Supernova That Could Break the Laws of Physics” »
It lets researchers extract pixel-by-pixel information from nanoscale.
The nanoscale refers to a length scale that is extremely small, typically on the order of nanometers (nm), which is one billionth of a meter. At this scale, materials and systems exhibit unique properties and behaviors that are different from those observed at larger length scales. The prefix “nano-” is derived from the Greek word “nanos,” which means “dwarf” or “very small.” Nanoscale phenomena are relevant to many fields, including materials science, chemistry, biology, and physics.
Black holes are regions in space characterized by extremely strong gravity, which prevents all matter and electromagnetic waves from escaping it. These fascinating cosmic bodies have been the focus of countless research studies, yet their intricate physical nuances are yet to be fully uncovered.
Researchers at University of California–Santa Barbara, University of Warsaw and University of Cambridge recently carried out a theoretical study focusing on a class of black holes known as extremal Kerr black holes, which are uncharged stationary black holes with a coinciding inner and outer horizon. Their paper, published in Physical Review Letters, shows that these black holes’ unique characteristics could make them ideal “amplifiers” of new, unknown physics.
“This research has its origin in a previous project started during my visit to UC Santa Barbara,” Maciej Kolanowski, one of the researchers who carried out the study, told Phys.org. “I started discussing very cold (so called, extremal) black holes with Gary Horowitz (UCSB) and Jorge Santos (at Cambridge). Soon we realized that in fact, generic extremal black holes look very different than it was previously believed.”
Knowing black holes’ speed after being kicked by gravitational waves can reveal how much energy converging black holes can release.
Grandfathers, take heart. You’ll survive the paradox that’s been gunning for you since the 1930s.
With up to a million X-ray flashes a second, the laser will help study mechanisms in physics, chemistry, and biology.
The US Department of Energy’s (DOE) SLAC National Accelerator Laboratory has fired the first X-rays using the upgraded Linac Coherent Light Source (LCLS) X-ray free-electron laser (XFEL), a press release said. The upgraded version, dubbed LCLS-II, was built for $1.1 billion.
Continue reading “World’s most powerful X-ray laser fired for the first time” »
