Lex Fridman Podcast full episode: https://www.youtube.com/watch?v=A6m4iJIw_84
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*GUEST BIO:*
Janna Levin is a theoretical physicist and cosmologist specializing in black holes, cosmology of extra dimensions, topology of the universe, and gravitational waves.
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*PODCAST LINKS:*
The study identifies a new class of layered antiferromagnets with spin-valley locking, offering efficient spin control without relying on spin–orbit coupling.
Altermagnets are a newly recognized class of materials that show momentum-dependent spin splitting without requiring spin-orbit coupling (SOC) or net magnetization. These materials have recently garnered international attention.
A research team led by Prof. Junwei Liu from the Department of Physics at the Hong Kong University of Science and Technology (HKUST), together with experimental collaborators, published groundbreaking findings in Nature Physics.
During that meeting, three main black hole models were outlined: the standard black hole predicted by classical general relativity, with both a singularity and an event horizon; the regular black hole, which eliminates the singularity but retains the horizon; and the black hole mimicker, which reproduces the external features of a black hole but has neither a singularity nor an event horizon.
The paper also describes how regular black holes and mimickers might form, how they could possibly transform into one another, and, most importantly, what kind of observational tests might one day distinguish them from standard black holes.
While the observations collected so far have been groundbreaking, they don’t tell us everything. Since 2015, we’ve detected gravitational waves from black hole mergers and obtained images of the shadows of two black holes: M87* and Sagittarius A*. But these observations focus only on the outside — they provide no insight into whether a singularity lies at the center.
For the first time, physicists have demonstrated a phenomenon known as the Terrell-Penrose effect, which causes an object moving close to the speed of light to warp before our eyes.
The new findings, a collaboration between TU Wien and the University of Vienna, once again confirm a key prediction of Einstein’s theory of relativity by making an optical illusion of relativistic motion observable for the first time.
In a paper published in Physical Review C, the ALICE collaboration reports measurements that quantify the transmutation of lead into gold in CERN’s Large Hadron Collider (LHC).
Transforming the base metal lead into the precious metal gold was a dream of medieval alchemists. This long-standing quest, known as chrysopoeia, may have been motivated by the observation that dull gray, relatively abundant lead is of a similar density to gold, which has long been coveted for its beautiful color and rarity. It was only much later that it became clear that lead and gold are distinct chemical elements and that chemical methods are powerless to transmute one into the other.
With the dawn of nuclear physics in the 20th century, it was discovered that heavy elements could transform into others—either naturally, by radioactive decay—or in the laboratory, under a bombardment of neutrons or protons. Though gold has been artificially produced in this way before, the ALICE collaboration has now measured the transmutation of lead into gold by a new mechanism involving near-miss collisions between lead nuclei at the LHC.
Do we know everything about the Milky Way? A team of astronomers has arrived to change everything we know about our universe, and they have found strong evidence that super-Earths (planets larger than Earth but smaller than Neptune) could be much more common than previously thought! They discovered it thanks to a technique called gravitational microlensing. Don’t worry if you don’t understand it, keep reading and we’ll explain everything.
The study was led by scientists from the Harvard-Smithsonian Center for Astrophysics, and it reveals that one in three stars in the Milky Way could have a super-Earth. Isn’t that exciting?
Researchers demonstrate an active-fluid system whose behaviors map directly to predictions of the six-vertex model—an exactly solvable model that was originally developed to explain the behavior of ice.
Active fluids—collections of self-propelled agents such as bacteria, cells, or colloids—consume energy to move, flowing without being pushed [1]. These materials break the conventional rules of fluid dynamics, as they can flow spontaneously, switch direction without apparent cause, and organize into complex patterns with no external control. Active fluids were initially studied to understand the collective dynamics observed in biological systems. Now they offer a rich playground for exploring nonequilibrium physics. Yet, in the ever-expanding universe of active-fluid physics, it is rare to find an experimental system that maps precisely onto a mathematically exact model.
Scientists from the Faculty of Physics and Applied Informatics at the University of Lodz have published an article on friction in the journal Small. Their research on “bismuth islands” moving on the surface of graphite confirmed the existence of a totally new form of so-called superlubricity—a friction-free contact between two solid bodies.
This discovery could revolutionize the way we design nanoscale machines, and even vehicles, in the future. By understanding these processes, we can create devices that can operate much more efficiently, saving on energy and resources.
Scientists led by Dr. Hab. Paweł Kowalczyk, associate professor at the University of Lodz, have discovered a new phenomenon related to the disappearance of friction—superlubricity. This special phenomenon was observed at the contact of two solid materials, bismuth and graphite.