  Neutron matter presents a unique system in chiral effective field theory
(EFT), because all many-body forces among neutrons are predicted to
next-to-next-to-next-to-leading order (N3LO). We discuss perturbative and first
Quantum Monte Carlo (QMC) calculations of neutron matter with chiral EFT
interactions and their astrophysical impact for the equation of state and
neutron stars.
