year 2000 of direct observational evidence for the changing temperature of the cosmic microwave background that more bizarre constructions could be ruled out. Until that time, it was based purely on an assumption that the universe did not behave as one with the Milky Way sitting at the middle of a fixed-metric with a universal explosion of galaxies in all directions (as seen in, for example, an early model proposed by Milne). Yet before this evidence, many rejected the Milne viewpoint based on the mediocrity principle. More direct results of the expansion, such as change of redshift, distance, flux, angular position and the angular size of astronomical objects, have not been detected yet due to smallness of these effects. Change of the redshift or the flux could be observed by Square Kilometre Array or Extremely Large Telescope in the mid-2030s. See also Comoving and proper distances Notes References Printed references Eddington, Arthur. The Expanding Universe: Astronomy's 'Great Debate', 1900-1931. Press Syndicate of the University of Cambridge, 1933. Liddle, Andrew R. and David H. Lyth. Cosmological Inflation and Large-Scale Structure. Cambridge University Press, 2000. Lineweaver, Charles H. and Tamara M. Davis, "Misconceptions about the Big Bang", Scientific American, March 2005 (non-free content). Mook, Delo E. and Thomas Vargish. Inside Relativity. Princeton University Press, 1991. External links Swenson, Jim Answer to a question about the expanding universe Felder, Gary, "The Expanding universe". NASA's WMAP team offers an "Explanation of the universal expansion" at a very elementary level Hubble Tutorial from the University of Wisconsin Physics Department Expanding raisin bread from the University of Winnipeg: an illustration, but no explanation "Ant on a balloon" analogy to explain the expanding universe at "Ask an Astronomer". (The astronomer who provides this explanation is not specified.) Physical cosmology General relativity Big Bang Concepts in astronomy