What's up in
Inside the Proton, the ‘Most Complicated Thing' Imaginable
The positively charged particle at the heart of the atom is an object of unspeakable complexity, one that changes its appearance depending on how it is probed.
The Mysterious Forces Inside the Nucleus Grow a Little Less Strange
The strong force holds protons and neutrons together, but the theory behind it is largely inscrutable. Two new approaches show how it works.
‘Impossible’ Particle Discovery Adds Key Piece to the Strong Force Puzzle
The unexpected discovery of the double-charm tetraquark has given physicists a new tool with which to hone their understanding of the strongest of nature’s fundamental forces.
Squishy Neutron Star Setback Dampens Hopes of Exotic Matter
Groundbreaking results show that neutron stars of different masses may have the same size — upending astrophysical models.
Physicists Pin Down Nuclear Reaction From Moments After the Big Bang
The newly-measured rate of a key nuclear fusion process from the Big Bang matches the picture of the universe 380,000 years later.
Neutron Lifetime Puzzle Deepens, but No Dark Matter Seen
Two methods of measuring the neutron’s longevity give different answers, creating uncertainty in cosmological models. But no one has a clue what the problem is.
Squishy or Solid? A Neutron Star’s Insides Open to Debate
The core of a neutron star is such an extreme environment that physicists can’t agree on what happens inside. But a new space-based experiment — and a few more colliding neutron stars — should reveal whether neutrons themselves break down.