Theoretical Framework
• Section 5.1, the “Cosmological Principle”
– Geodesics are “world-lines” of galaxies and
do not intersect except at a singular point in
the past.  Weyl’s idea predates Hubble’s law.
– Fundamental observers on each world line,
each with standard clock measuring cosmic
time from that singular point.
• “We are not located at any special
location in the universe.”