Neutron stars are some of the densest objects in the universe. They are the core of a collapsed megastar that went supernova, have a typical radius of 10 km—just slightly more than the altitude of Mt. Everest—and their density can be several times that of atomic nuclei.

Physicists love extreme objects like this because they require them to stretch their theories into new realms and see if they are confirmed or if they break, requiring new thinking and new science.

For the first time, researchers have used lattice quantum chromodynamics to study the interior of neutron stars, obtaining a new maximum bound for the speed of sound inside the star and a better understanding of how pressure, temperature and other properties there relate to one another.

Scientists are hunting for axions, tiny particles that could solve major physics mysteries, including why neutrons don’t have an electric dipole moment and what dark matter is made of. Using the powerful European XFEL in Hamburg, researchers fired X-rays through special crystals, hoping to witness axions converting into light—a sign of their existence. This pioneering experiment, already competitive with major particle accelerator studies, demonstrates that XFEL technology could be a game-changer in particle physics.

Dark matter is an elusive type of matter that does not emit, absorb or reflect light and is thus impossible to detect using conventional techniques employed in particle physics. In recent years, groups of physicists worldwide have been trying to observe this matter indirectly using advanced detectors and equipment, by detecting signals other than electromagnetic radiation that could be linked to its activity or interactions with other matter.

Researchers at Tokyo Metropolitan University, PhotoCross Co. Ltd, Kyoto Sangyo University and other collaborating institutions recently released the findings of the first search for dark matter that relied on data collected by WINERED, a near-infrared and high-dispersion spectrograph mounted on a large telescope in Chile.

Their paper, published in Physical Review Letters, sets the most stringent constraints to date on the lifetime of dark matter particles with masses between 1.8 and 2.7 eV.

We show via an explicit construction how an infinite tower of higher-curvature corrections generically leads to a resolution of the Schwarzschild singularity in any spacetime dimension.