The mention the asymetry is here: "When the high energy protons in cosmic rays slam into the atmosphere, they produce particles called pions, and the rapid dec

The mention the asymetry is here: "When the high energy protons in cosmic rays slam into the atmosphere, they produce particles called pions, and the rapid decay of pions is governed by the weak force — the only fundamental force with a known mirror asymmetry." Pion decay is apparently not symmetric. I don't know much about the topic, maybe start here: https://en.wikipedia.org/wiki/Weak_interaction#Violation_of_symmetry https://en.wikipedia.org/wiki/Weak_interaction#Violation_of_... It doesn't seem to be the case that "we don't have any cosmic rays with inverted polarization" - just that there is more in one direction than in the other. Even a slight bias would add up over time.