Assertion: arrow's force | /r/AtLocation | situation
Facets:
Source sentences:
text: In some situations the weak force is time-reversible, e.g. a proton and an electron can smash together to produce a neutron and a neutrino, and a neutron and a neutrino smashed together CAN also produce a proton and an electron (even if the chances of this happening in practice are very small).