Assertion: expansion | /r/HasProperty | measured in principle
Facets:
value: by taking a standard ruler
type: MANNER
Source sentences:
text: In principle, the expansion of the universe could be measured by taking a standard ruler and measuring the distance between two cosmologically distant points, waiting a certain time, and then measuring the distance again, but in practice, standard rulers are not easy to find on cosmological scales and the timescales over which a measurable expansion would be visible are too great to be observable even by multiple generations of humans.