Cosmological Principle

The Cosmological Principle is a philosophy in which observations in astronomy must be interpreted under the context of current astronomical theories, regardless of what reality shows. Read the following quote carefully:

  “ ‘For instance, if the universe were finite and had a centre, and if the Milky Way were not near that centre, then the total brightness of all the rest of the matter in the universe should be slightly greater on one side of the earth than the other. But the night sky beyond the Milky Way is not noticeably brighter in one direction than the other; therefore astronomers are forced to conclude that the universe extends indefinitely far in all directions. The only other possibility is that the earth is the centre of everything – one planet serving as a focal point for thousands and millions of galaxies and millions of millions of other probable planets. This alternative is so preposterous that cosmologists have ruled it out from the beginning. In fact, they have made it a fundamental tenet of their creed that the Milky Way’s position in the universe is not peculiar or untypical in any way. From this idea they derive a basic axiom known as the cosmological principle: namely, that the universe must be the same on average everywhere and in all directions. ” --‘Space, Time and the Universe,’ The Universe, Time-Life Books, 1962, p.170.