As much as we want to tell Mr Sulu to “Take us to warp factor five”, dangerous causality problems, tricky maths and negative energy could get in the way.
Category: particle physics – Page 56
Colloidal gels are complex systems made up of microscopic particles dispersed in a liquid, ultimately producing a semi-solid network. These materials have unique and advantageous properties that can be tuned using external forces, which have been the focus of various physics studies.
Researchers at University of Copenhagen in Denmark and the UGC-DAE Consortium for Scientific Research in India recently ran simulations and performed analyses aimed at understanding how the injection of active particles, such as swimming bacteria, would influence colloidal gels.
Their paper, published in Physical Review Letters, shows that active particles can influence the structure of 3D colloidal gels, kneading them into porous and denser structures.
A method for imaging spin waves in magnetic materials uses flash-like intensity variations in a laser beam to capture the wave motion at specific moments in time.
The magnetic moments, or spins, in certain materials can twirl in a coordinated wave pattern that might one day be used to transmit information in so-called spintronic devices. Researchers have developed a new way to image these spin waves using an infrared laser that essentially flashes on and off at a frequency that matches that of the spin waves [1]. Unlike other spin-wave probes, this strobe method can directly capture phase information that is relevant to certain applications, such as hybrid devices that combine spin waves with other types of waves.
A spin wave can be triggered in a magnetic material when some perturbation causes a spin to oscillate, which can then generate a wave of oscillations that ripple through neighboring spins. Spin waves have several properties that make them good candidates for information carriers. For one, they have relatively small wavelengths—a few hundred nanometers at a frequency of 1 GHz, whereas a 1-GHz photon has a wavelength of about 30 cm. This compactness could conceivably allow researchers to build spintronic components, such as waveguides and logic gates, at the nanoscale. Another advantage of these waves is that the spins remain in place, and only their orientation changes. So the heat losses that affect the moving charges in traditional electronics don’t exist.
UC Santa Barbara researchers developed a compact, low-cost laser that matches the performance of lab-scale systems. Using rubidium atoms and advanced chip integration, it enables applications like quantum computing, timekeeping, and environmental sensing, including satellite-based gravitational mapping.
For experiments requiring ultra-precise atomic measurements and control—such as two-photon atomic clocks, cold-atom interferometer sensors, and quantum gates—lasers are indispensable. The key to their effectiveness lies in their spectral purity, meaning they emit light at a single color or frequency. Today, achieving the ultra-low-noise, stable light necessary for these applications relies on bulky and expensive tabletop laser systems designed to generate and manage photons within a narrow spectral range.
But what if these atomic applications could break free from the confines of labs and benchtops? This is the vision driving research in UC Santa Barbara engineering professor Daniel Blumenthal’s lab, where his team is working to replicate the performance of these high-precision lasers in lightweight, handheld devices.
A new model reveals how molecular interactions drive order in active systems.
Scientists from the Department of Living Matter Physics at the Max Planck Institute for Dynamics and Self-Organization (MPI-DS) have found that non-reciprocal interactions can enhance order in active systems. Using a newly developed model, they demonstrated how the degree of non-reciprocity influences the formation of patterns, providing deeper insight into the organization of complex, dynamic systems.
Living matter exhibits unique characteristics not found in simpler physical systems. One striking example is the uneven interaction between different types of particles. For instance, one molecule may be attracted to another, while the second is repelled — similar to how a predator pursues its prey, which instinctively tries to escape. This phenomenon, known as non-reciprocal interaction, can produce complex, large-scale patterns, as has been shown previously. These patterns often resemble essential structures found in living systems, such as the organization within a cell.
Scientists have found evidence of a strange state of matter called a quantum spin liquid in a material known as pyrochlore cerium stannate.
In this mysterious state, magnetic particles don’t settle into a fixed pattern but stay in constant motion, even at extremely low temperatures. Researchers used advanced tools like neutron scattering and theoretical models to detect unusual magnetic behavior that behaves like waves of light. This breakthrough could lead to new discoveries in physics and future technologies like quantum computing.
Quantum Spin Liquids
Scientists teasing through six billion particle smashups detect roughly 16 “antihyperhydrogen-4” particles.
Most of Earth’s meteorites also trace their origins to S-type asteroids, yet they contain minimal organic material. This scarcity has made analyzing their organic content a significant challenge. In contrast, the Hayabusa mission’s meticulously curated samples are free from terrestrial interference, enabling groundbreaking studies of organic compounds.
Among the particles returned by Hayabusa, one named “Amazon” has proven particularly revealing. Measuring just 30 micrometers wide, Amazon offers a rare opportunity to investigate both water and organic content. Its unique shape, reminiscent of the South American continent, underscores its distinctiveness.
Amazon’s mineral composition includes olivine, pyroxenes, albite, and traces of high-temperature carbonates. These minerals confirm its origin as an S-type asteroid, linking it directly to ordinary chondrites.
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Blog post with audio player, show notes, and transcript: https://www.preposterousuniverse.com/podcast/2024/03/04/267-…f-reality/
In the 1860s, James Clerk Maxwell argued that light was a wave of electric and magnetic fields. But it took over four decades for physicists to put together the theory of special relativity, which correctly describes the symmetries underlying Maxwell’s theory. The delay came in part from the difficulty in accepting that light was a wave, but not a wave in any underlying “aether.” Today our most basic view of fundamental physics is found in quantum field theory, which posits that everything around us is a quantum version of a relativistic wave. I talk with physicist Matt Strassler about how we go from these interesting-but-intimidating concepts to the everyday world of tables, chairs, and ourselves.
Matt Strassler received his Ph.D. in physics from Stanford University. He is currently a writer and a visiting researcher in physics at Harvard University. His research has ranged over a number of topics in theoretical high-energy physics, from the phenomenology of dark matter and the Higgs boson to dualities in gauge theory and string theory. He blogs at Of Particular Significance, and his new book is Waves in an Impossible Sea: How Everyday Life Emerges from the Cosmic Ocean.
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Wearing sunscreen is important to protect your skin from the harmful effects of UV radiation but doesn’t cool people off. However, a new formula, described in Nano Letters, protects against both UV light and heat from the sun using radiative cooling. The prototype sunblock kept human skin up to 11 degrees Fahrenheit (6 degrees Celsius) cooler than bare skin, or around 6 °F (3 °C) cooler than existing sunscreens.
Radiative cooling involves either reflecting or radiating heat away from something, cooling whatever’s underneath. It is already used to create cooling fabrics and coatings that could both cool and heat homes, among other applications.
Some passive radiative cooling technologies rely on an ingredient called titanium dioxide (TiO2) because the whitish substance reflects heat. TiO2 particles are also used in mineral sunscreens to reflect UV light, but the particles aren’t the right size to produce a cooling effect. So, Rufan Zhang and colleagues wanted to tune the size of TiO2 nanoparticles to create a sunscreen that works both as a UV protector and a radiative cooler.