nuclear physics

Richard Feynman’s path integral is both a powerful prediction machine and a philosophy about how the world is. But physicists are still struggling to figure out how to use it, and what it means.

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 strong force holds protons and neutrons together, but the theory behind it is largely inscrutable. Two new approaches show how it works.

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.

Groundbreaking results show that neutron stars of different masses may have the same size — upending astrophysical models.

The newly-measured rate of a key nuclear fusion process from the Big Bang matches the picture of the universe 380,000 years later.

Computer simulations and custom-built quantum analogues are changing what it means to search for the laws of nature.

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.

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.