The → world lines of galaxies form in the 4D space-time
a bundle of non-intersecting
→ geodesics orthogonal to a series of space-like hyperstructures
(e.g. Narlikar 2002, An Introduction to Cosmology,
3rd Edition, Cambridge Univ. Press). Expressed differently: The world lines of galaxies, or
“fundamental particles,” form (on average) a space-time filling family of
non-intersecting geodesics converging toward the past (Rugh & Zinkernagel, 2010,
astro-ph/1006.5848). The statement is sometimes denoted postulate, assumption, or
hypothesis. The importance of Weyl’s principle is that it asserts that cosmic matter
moves according to certain regularity requirements. See also
→ cosmological principle.
See also: First introduced by the German mathematician Hermann Weyl (1885-1955)
in 1923 in his Raum, Zeit, Materie; → principle.
