ANTHROPIC PRINCIPLE

Clearly, humanity's very existence shows that the current structure of the universe and the values taken by the constants of nature permit life to exist. Indeed, it appears that many features of the universe that are necessary for the evolution and persistence of life are the results of unusual coincidences between different values of the constants of nature- quantities such as the mass of the electron, the strength of gravity, or the lifetime of the neutron. The significance, if any, of these coincidences is not understood. What is understood is that if these quantities were slightly altered, then no form of complexity or life could exist in the universe. At present, it is not known why the constants of nature take their observed values. Perhaps their values are the only possible ones they could take; in other words, there may be only one possible universe. If so, then it must be judged entirely fortuitous that the combination of values taken by the constants allows the existence of life. The anthropic principle implies life could not exist in a universe that was significantly smaller than the observed universe. That we are here to observe the universe- that we are actively engaged in the act of observing- implies that the universe is wired in such a way to allow our existence. This is the essence of the anthropic principle. The laws of the universe are the way they are because if they weren't, no intelligent beings would be able to consider the laws of the universe at all.