Assertion: neutrino's existence | /r/HasProperty | established in theory
Facets:
value: by 1934
type: TEMPORAL
value: firmly
type: MANNER
Source sentences:
text: Difficulties in explaining beta decay led to the prediction of the neutrino in 1930, and by 1934 the existence of the neutrino was firmly established in theory, although it was not actually detected until 1956.