anthropic principle

The assertion, occurring in several different formulations, that the universe is in some sense constructed in a way that makes it suitable for the development of intelligent life such as human beings. It arises from the observation that if the laws of science were even slightly different, it would have been impossible for intelligent life to evolve. For example, if the strengths of the fundamental forces were only slightly different, stars would have been unable to burn hydrogen and produce the chemical elements that make up our bodies. Such a remarkable coincidence requires an explanation. One such explanation is that the universe has been intelligently designed, but this does not satisfy the desire for a scientific explanation. An alternative explanation is that the universe we inhabit is only one of a stupendous number of universes, or ‘multiverses’, with a spread of values for the fundamental constants. In the vast majority, the properties of the universe are unfavourable to life; we necessarily find ourselves in one of the few where the physical constants are favourable to life, so that the universe presents the illusion of having been adapted from the beginning to our needs.