Assertion: principle | /r/HasProperty | invalid
Facets:
value: in double refraction
type: OTHER
Source sentences:
text: Manuscript evidence cited by Alan E. Shapiro tends to confirm that Huygens believed the principle of least time to be invalid "in double refraction, where the rays are not normal to the wave fronts".[Note 9]
text: So although the principle of individuality is a valid observation, it does not explain anything.