ASTR 103 Lecture Notes - Lecture 27: Radial Velocity, Local Group, Cosmological Principle
Document Summary
Astronomers call it the big bang, and current measurements put the beginning of the universe at 13. 799 billion years ago. However, some things are so far away from us, their light has not yet reached us. No. new stars are born and old stars die. No. grouping of stars called clusters, and on a larger scale galaxies. These form clusters of galaxies and are far from being homogenous on small scales. Clumpy at small and medium scales (<500 mpc) If viewed on a sufficiently large scale, the properties of the universe are the same for all galaxies. About 10 million light years (mly) in diameter. Still some independent motion present (some blue shifted and some red shifted) After the local group all galaxies are red shifted. The doppler redshift of light and the cosmological redshift of light are two different things.
