Liquid crystals are an integral part of modern technology, ranging from displays to advanced sensory systems. In a study published in Scientific Reports, researchers from the Institute of Experimental Physics of the Slovak Academy of Sciences (IEP SAS) in Košice, in collaboration with international partners, have demonstrated how minute changes in material composition can achieve precise control over behavior in electric and magnetic fields.
The research focused on cholesteric liquid crystals, which naturally form spiral (helical) structures. These structures provide unique optical properties used in displays, smart windows, and virtual reality devices.
The team investigated how the addition of a specific substance, a chiral dopant, affects the “unwinding” process of this helix.
One of the inventions that may be realized by advances in nanotechnology is the creation of a Von Neumann probe, which is essentially a virus, a self-replicating probe that can then explore the universe near the speed of light.
Dr. Michio Kaku is the co-founder of string field theory, and is one of the most widely recognized scientists in the world today. He has written 4 New York Times Best Sellers, is the science correspondent for CBS This Morning and has hosted numerous science specials for BBC-TV, the Discovery/Science Channel. His radio show broadcasts to 100 radio stations every week. Dr. Kaku holds the Henry Semat Chair and Professorship in theoretical physics at the City College of New York (CUNY), where he has taught for over 25 years. He has also been a visiting professor at the Institute for Advanced Study as well as New York University (NYU).
TRANSCRIPT:
Dr. Michio Kaku: Recently there was a conference, the One Hundred Year Starship, and of course many people came in with designs to have gigantic fusion rockets take us to Mars and beyond Jupiter, into the stars. Other people said yes, antimatter rockets, that’s the way to go, and we all had this mental vision of the Enterprise going to the nearby star systems… here is another way to do it. Think of Mother Nature. When Mother Nature wants to propagate life, one possibility is to send out seeds, not just one or two, but millions of seeds. Most of the seeds never make it, but one or two do and as a consequence that’s how trees in forests propagate. So why not create a nano ship using nanotechnology? How big would it be? Some people like Paul Davies say it could be as big as a bread box. Other people say it could be even smaller than that. Why not something the size of a needle? And because they’re so small it wouldn’t take much to accelerate them to near the speed of light.
Physicists studying active matter — materials that can use their own internal energy to respond to forces — have uncovered surprising behaviors that challenge conventional ideas in mechanics.
What do physicists really think about the biggest mysteries in the universe?
In this video, leading voices in theoretical physics come together to unpack the results of the Big Mystery Survey—the largest survey ever conducted of professional physicists, prepared in collaboration with the American Physical Society’s Physics Magazine.\.
The twinkling stars in the night sky are not just beautiful to look at. Their flickering reveals something about the varying temperatures and densities in the layers of Earth’s atmosphere, which refract the light as it travels toward us. Certain stellar remnants that emit radio waves can exhibit a very similar effect.
Although their radio waves—which have longer wavelengths than visible light—can penetrate Earth’s atmosphere almost undisturbed, they are scattered by the thin gas between the stars. Their twinkling—known as scintillation—thus provides unique insights into interstellar space.
An international team led by Tim Sprenger from the Max Planck Institute for Radio Astronomy (MPIfR) has measured the flickering radio radiation from an object using an innovative observation technique. The results are published in Astronomy & Astrophysics.
Researchers have developed a technique to analyze how black holes “ring” when they collide and merge: one of the universe’s most dramatic events. When black holes merge, the collision produces a new, larger black hole that “rings” like a plucked guitar string or a bell while it settles into its final, stable shape. But instead of sound waves, the new black hole rings with gravitational waves: ripples in spacetime first predicted by Albert Einstein.
The new black hole vibrates at a specific set of frequencies, depending on its mass and spin, which help scientists learn about the object formed in the collision.
These vibrations, known as quasinormal modes, are the fingerprint of a black hole. Detecting them is central to testing Einstein’s general theory of relativity in the most extreme gravitational environments in the universe.
Researchers at The University of Osaka, in collaboration with Ritsumeikan University, have demonstrated that growing europium-doped gallium nitride (Eu-doped GaN) on a semipolar crystal plane dramatically improves red light emission. The team found that this approach selectively promotes the formation of highly efficient Eu luminescent centers, resulting in red emission intensity more than 3.6 times higher than that of conventionally grown polar-plane material.
The study is published in the journal Applied Physics Letters.
Red emitters based on Eu-doped GaN are attracting attention as promising light sources for next-generation micro-LED displays because they can provide narrow-linewidth, wavelength-stable red emission based on intra-4f-shell transitions of Eu ions. This is particularly important for full-color monolithic integration with blue and green InGaN LEDs, where wavelength stability under device operation is essential.
Dark matter is thought to make up most of the matter in the universe, but the only way it interacts with its surroundings is through gravity. If two colliding black holes spiral through a dense region of dark matter and merge, gravitational waves rippling across space and time could carry an imprint of that dark matter.
Now, physicists may be able to spot such imprints of dark matter in gravitational waves that are detected on Earth.
Researchers at MIT and in Europe have developed a method that makes predictions for what a gravitational wave should look like if it were produced by black holes that moved through dark matter, rather than empty space. They applied the technique to publicly available gravitational-wave data previously recorded by LIGO-Virgo-KAGRA (LVK), the global network of observatories that detect gravitational waves from black hole mergers and other far-off astrophysical sources.
Gravitational wave researchers working on the world’s most sensitive scientific instruments have found a way to tune their detectors using a process akin to the pitch-correction used in music production.
Scientists at the international LIGO, Virgo and KAGRA (LVK) gravitational wave observatory collaboration have employed the technique, which they call astrophysical calibration, to use gravitational-wave signals to measure the response of their incredibly sensitive instruments.
It enables them to ensure that they can clearly “hear” the sounds of colossal cosmic events like the collision of black holes, even when one gravitational wave detector is slightly out of tune. This is crucial to accurately interpret the signals and find their source location.
The universe may not be perfectly uniform after all, a new series of papers hints. If confirmed, this could upend a nearly 100-year-old model of cosmology.
