Dark matter

Years of conflicting neutrino measurements have led physicists to propose a “dark sector” of invisible particles — one that could simultaneously explain dark matter, the puzzling expansion of the universe, and other mysteries.

After a search of neutron stars finds preliminary evidence for hypothetical dark matter particles called axions, astrophysicists are devising new ways to spot them.

Today’s long-anticipated announcement by Fermilab’s Muon g-2 team appears to solidify a tantalizing conflict between nature and theory. But a separate calculation, published at the same time, has clouded the picture.

Black holes seemed to come only in sizes small and XXL. A new search strategy has uncovered a black hole of “intermediate” mass, raising hopes of more to come.

The theoretical physicist Frank Wilczek explained what holds atomic nuclei together, and he is still pushing at the limits of what the standard model can tell us.

Physicists plan to leave no stone unturned, checking whether dark matter tickles different types of detectors, nudges starlight, warms planetary cores or even lodges in rocks.

It was an old idea of Stephen Hawking’s: Unseen “primordial” black holes might be the hidden dark matter. A new series of studies has shown how the theory can work.

Cosmologists have concluded that the universe doesn’t appear to clump as much as it should. Could both of cosmology’s big puzzles share a single fix?

Modified gravity theories have never been able to describe the universe’s first light. A new formulation does.