Like all hyperons, Λ hypernuclei can decay through the weak interaction, which changes it to a lighter baryon and emits a meson or a lepton –antilepton pair. In free space, the Λ usually decays via the weak force to a proton and a π meson, or a neutron and a π, with a total half-life of 263 ± 2 ps. A nucleon in the hypernucleus can cause the Λ to decay via the weak force without emitting a pion; this process becomes dominant in heavy hypernuclei, due to suppression of the pion-emitting decay mode. The half-life of the Λ in a hypernucleus is considerably shorter, plateauing to about 215 ± 14 ps near Λ Fe, but some empirical measurements substantially disagree with each other or with theoretical predictions.