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No one has ever probed a particle more stringently than this.

In a new experiment, scientists measured a magnetic property of the electron more carefully than ever before, making the most precise measurement of any property of an elementary particle, ever. Known as the electron magnetic moment, it’s a measure of the strength of the magnetic field carried by the particle.

That property is predicted by the standard model of particle physics, the theory that describes particles and forces on a subatomic level. In fact, it’s the most precise prediction made by that theory.

Superconductivity can be switched on and off in “magic-angle” graphene using a short electrical pulse, according to new work by researchers at Massachusetts Institute of Technology (MIT). Until now, such switching could only be achieved by sweeping a continuous electric field across the material. The new finding could help in the development of novel superconducting electronics such as memory elements for use in two-dimensional (2D) materials-based circuits.

Graphene is a 2D crystal of carbon atoms arranged in a honeycomb pattern. Even on its own, this so-called “wonder material” boasts many exceptional properties, including high electrical conductivity as charge carriers (electrons and holes) zoom through the carbon lattice at very high speeds.

In 2018, researchers led by Pablo Jarillo-Herrero of MIT found that when two such sheets are placed on top of each other with a small angle misalignment, things become even more fascinating. In this twisted bilayer configuration, the sheets form a structure known as a moiré superlattice, and when the twist angle between them reaches the (theoretically predicted) “magic angle” of 1.08°, the material begins to show properties such as superconductivity at low temperatures – that is, it conducts electricity without any resistance.

Researchers at Harvard University, the Lawrence Berkeley National Laboratory, Arizona State University, and other institutes in the United States have recently observed an antiferromagnetic metal phase in electron-doped NdNiO₃ a material known to be a non-collinear antiferromagnet (i.e., exhibiting an onset of antiferromagnetic ordering that is concomitant with a transition into an insulating state).

“Previous works on the rare-earth nickelates (RNiO₃) have found them to host a rather exotic phase of magnetism known as a ‘noncollinear antiferromagnet,’” Qi Song, Spencer Doyle, Luca Moreschini and Julia A. Mundy, Four of the researchers who carried out the study, told Phys.org.

“This type of magnet has unique potential applications in the field of spintronics, yet rare-earth nickelates famously change spontaneously from being metallic to insulating at the exact same temperature that this noncollinear antiferromagnet phase turns on. We wanted to see if we could somehow modify one of these materials in a way so that it remained metallic, but still had this interesting magnetic phase.”

Arctic and save Greenland’s glaciers.

George Soros proposes geoengineering project to save Greenland’s glaciers.

Less problematic geoengineering already is underway with CO₂ direct air capture. But more controversial sunlight blocking is being proposed.

Continue reading “A Globalist Billionaire Pitches Geoengineering While Others Propose Putting Particles into the Atmosphere and Space” »

Two groups demonstrate innovative ways to capture the ultrafast motion of electrons in atoms and molecules.

Electrons move so quickly inside of atoms and molecules that they are challenging to “capture on film” without blurring the images. One way to take fast snapshots is to ionize an atom or molecule and then use the released electrons as probes of the cloud out of which they originate. Now Gabriel Stewart at Wayne State University in Michigan and colleagues [1] and Antoine Camper at the University of Oslo in Norway and colleagues [2] have improved this “self-probing” technique. The demonstrations could lead to a better understanding of the electron motion that underpins many fundamental processes.

Scientists need to complete three key tasks to measure the evolution of an electron cloud that moves and changes on an ultrafast timescale. The first is to exactly record the beginning of the evolution—analogous to pressing “start” on a mechanical stopwatch. The second is to track how much time has gone by since the starting event—analogous to precisely measuring the ticking of the stopwatch’s second hand. And the third is to take a quick snapshot of the electron cloud so that it looks frozen in time.

Scientists want to use quantum mechanics to capture higher-resolution images of the night sky.

For the purposes of astronomy, the two beams are collected by two telescopes that are separated by some distance (called baseline interferometry). But despite its effectiveness, classic interferometry is subject to some limitations. Andrei Nomerotski, an astrophysicist with the BNL and a co-author on the paper, explained to Universe Today via email.

“Interferometry is a way to increase the effective aperture of telescopes and to improve the angular resolution or astrometric precision,” he said. “The main difficulty here is to maintain the stability of this optical path to very high precision, which should be much smaller than the photon wavelength, to preserve the photon’s phase. This limits the practical baselines to a few hundred meters.”

Continue reading “Quantum Telescopes Could Offer Clearer Views of Our Solar System and Beyond” »

Scientists said they recorded particles travelling faster than light – a finding that could overturn one of Einstein’s fundamental laws of the universe. Antonio Ereditato, spokesman for the international group of researchers, saidthat measurements taken over three years showed neutrinos pumped from CERN near Geneva to Gran Sasso in Italy had arrived 60 nanoseconds quicker than light would have done.

Andrew Strominger is a theoretical physicist at Harvard. Please support this podcast by checking out our sponsors:
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EPISODE LINKS:
Andrew’s website: https://www.physics.harvard.edu/people/facpages/strominger.
Andrew’s papers:
Soft Hair on Black Holes: https://arxiv.org/abs/1601.00921
Photon Rings Around Warped Black Holes: https://arxiv.org/abs/2211.

Continue reading “Andrew Strominger: Black Holes, Quantum Gravity, and Theoretical Physics | Lex Fridman Podcast #359” »

Physicists at the University of Wisconsin-Madison have directly measured the fluid-like flow of electrons in graphene at nanometer resolution for the first time. The results appear in the journal Science today.

Graphene, an atom-thick sheet of carbon arranged in a honeycomb pattern, is an especially pure electrical conductor, making it an ideal material to study electron flow with very low resistance. Here, researchers intentionally add impurities at known distances, and find that electron flow changes from gas-like to fluid-like as the temperature rises.

“All conductive materials contain impurities and imperfections that block electron flow, which causes resistance. Historically, people have taken a low-resolution approach to identifying where resistance comes from,” says Zach Krebs, a physics graduate student at UW-Madison and co-lead author of the study. “In this study, we image how charge flows around an impurity and actually see how that impurity blocks current and causes resistance, which is something that hasn’t been done before to distinguish gas-like and fluid-like electron flow.”