A South Pole neutrino experiment has measured radio waves induced by cosmic rays—thus demonstrating that its detection method works.
Detection of high-energy neutrinos, elusive particles produced in supernovae and other astrophysical events, is opening up a new window on the Universe. One way to spot them is to search for signals of neutrino collisions with molecules in large sheets of polar ice. An international collaboration working in Antarctica has now reported the detection of ice-traversing radio waves that originate from cosmic-ray-induced particle showers [1]. Even though the radio waves were generated by cosmic rays rather than neutrinos, the result establishes a proof of principle that the technique should work for neutrinos too.
Ice-sheet-based detection of cosmic neutrinos has been reported previously from the IceCube Neutrino Observatory at the South Pole [2]. In that experiment, neutrino collisions with water molecules produce flashes of visible light, called Cherenkov radiation, generated by fast-moving collision by-products. This method becomes challenging for neutrinos of extremely high energy (around 1018 electron volts, or 1 exa-electron-volt) because these neutrinos are expected to be exceedingly rare. Researchers would need detectors spread over hundreds of cubic kilometers of ice to have a chance of seeing Cherenkov radiation from such a rare exa-electron-volt event.
Scientists have directly observed muonic molecules in resonance states for the first time, using a high-resolution X-ray detector, a new Science Advances study reports.
Resonance states are critical in determining the reaction rate of muon catalyzed fusion (µCF), a process that utilizes elementary particles known as muons. Within muonic molecules, the nuclei are confined in extremely close proximity, enabling nuclear fusion to occur even at room temperature without the need for plasma.
Currently, research aimed at the practical application of nuclear fusion is underway worldwide. In principle, fusion offers highly safe energy with no risk of runaway accidents. It utilizes fuel easily extracted from seawater and produces clean energy without carbon dioxide emissions.
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To progress to the next level in understanding reality, we need to combine quantum mechanics and Einstein’s general relativity. And to do that, most physicists believe we need a theory of quantum gravity… which means we need gravitons. But it also seems like the laws of physics make it impossible to ever detect this quantum particle of gravity. Almost like the universe is set up to keep the final answer forever out of our reach. So, can we outsmart the universe, catch a graviton, and finally solve physics?
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We human beings sit roughly midway between the sizes of atoms and galaxies, and both must be so perfectly structured for us to exist. It’s called ‘fine-tuning’ and it’s all so breathtakingly precise that it cries out for explanation. To some, fine-tuning leads to God. To others, there are non-supernatural explanations. Both are startling.
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There are a whole lot of people with “theories of everything” – theories which supposedly explain how the whole universe works. Most of the time, these theories fall very short of that goal. Causal Fermion Systems are an approach that actually seems promising… though it still has its flaws. Today I have a brief summary of what might be the most underreported theory of everything out there.
Also known as magnetoelectronics, spintronics rely on electron spin rather than electron charge, as found in traditional electronics. Although spintronics is still an emerging field, spintronic technologies are already found in hard disk drives and giant magnetoresistance sensors used in industrial and automotive applications. Once the right foundational materials are discovered and verified, including economical materials for altermagnets, spintronics could advance technologies from wireless communication to quantum computing.
Researchers using neutrons at the Department of Energy’s Oak Ridge National Laboratory’s Spallation Neutron Source (SNS) discovered that hematite, essentially rust, can help design energy-efficient spintronics.
The team’s findings, published in Physical Review Letters, confirmed a key signature of altermagnetism (a new type of magnetism discovered in 2022) in hematite. Altermagnets are magnetic materials in which electron spins align in opposite directions, allowing pure spin currents to flow without a net electric charge—ideal conditions for spintronics. The team measured spin waves, which move through a material’s magnetic order similar to how sound waves move through air. They discovered that these waves show a clear separation in energy, a unique signature that confirms the material’s altermagnetic nature.
By directing pulses of laser light at atoms, researchers can study how radioactive elements decay in a matter of seconds. The method is described in a new thesis from the University of Gothenburg, which shows that the atomic nuclei of the elements neptunium and fermium are shaped like rugby balls.
Actinides are a group of elements at the bottom of the periodic table. They have a high density, are radioactive, and several of them only exist for a few seconds before they decay. Only four of the 14 elements in this group occur naturally on Earth. The others can be produced in an accelerator, but only in very small quantities. Uranium is the best-known actinide, but a new thesis from the University of Gothenburg focuses on neptunium and fermium.
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Physics is this close to understanding the entire universe. And what lives in this gap? Many physicists think it’s the elusive graviton—the quantum particle of gravity—whose discovery will finally allow us to stitch together our two great theories of nature into a single master theory. But what is the graviton, and does it even exist?
Snapshot measurements of cold-atom gases reveal hidden spin correlations that could force an update of some superconductivity theories.
Our understanding of nature is inherently bound to the experimental tools we build to observe the world. Superconductivity, for example, has been traditionally studied using current and voltage meters under a variety of temperatures and other environmental conditions. From these observations, theorists have developed models—notably the Bardeen-Cooper-Schrieffer (BCS) theory, which assumes that the zero-resistance flow in a superconductor arises from electrons forming so-called Cooper pairs. This theory has been successful in explaining a large class of superconductors, but Tarik Yefsah from the Ecole Normale Supérieure in Paris and colleagues have now observed behavior that contradicts BCS predictions [1]. Using a recently developed technique called atom-resolved continuum quantum gas microscopy, the researchers directly observed spatial correlations in cold atoms that mimic superconducting electrons.
