Animated particle tracks of a matter-antimatter collision. An antiproton (pale blue) enters from left and collides with a proton in the bubble chamber. In the resulting annihilation, the energy released rematerialises as four positive pions (red) and four negative pions (green). The left-most pions have less energy and curve more in the chamber's magnetic field. The negative pion travels a short distance and is captured by a proton. The positive pion spontaneously decays into an anti-muon (yellow) and an invisible muon neutrino. Tracks not caused by the interaction, including the curlicues of low-energy electrons, are coloured dark blue.