Leading scientists on the anthropic principle For additional discussion, see Multiverse. In other words, our very existence places stringent boundaries on several aspects of the design of our universe. Thus scientists note, in the spirit of the weak anthropic principle, that we should not be surprised to be living in a universe that is some 13.8 billion years old, because if it were much younger, say less than about three billion years old, carbon atoms could not exist, and thus carbon-based sentient creatures like us could not exist, much less be reading articles like this one and contemplating the meaning of their existence. But carbon and all elements heavier than carbon were not formed in the big bang, but instead are formed in the explosion of first-generation stars at the end of their lifetimes.

Consider for a moment the fact that carbon, and elements heavier than carbon, appear essential to any conceivable form of intelligent life - the handful of lighter elements do not form any complex atomic structures among themselves. On the other hand, if gravitation were slightly stronger, then the universe would have reached a maximum extent and then recollapsed in a big crunch long before carbon-based intelligent life could have arisen. If it were slightly weaker, then in the early stages of the big bang, matter would have dispersed too rapidly to permit stars, much less galaxies, to form. It must be balanced very closely to the expansion of the universe to provide a universe that fosters intelligent beings. Intelligent information-processing must come into existence in the universe, and, once it comes into existence, it will never die out.Īs a single example of the weak anthropic principle, consider the force of gravitation. The universe must have those properties which allow life to develop within it at some stage in its history. The observed values of all physical and cosmological quantities are not equally probable, but they take on values restricted by the requirement that there exist sites where carbon-based life can evolve and by the requirement that the universe be old enough for it to have already done so. Carter himself mentioned two variations of the term, and Barrow and Tipler defined three : In 1986, astronomer John Barrow and astrophysicist Frank Tipler published the landmark work The Anthropic Cosmological Principle, which elaborated on the anthropic principle and the “cosmic coincidences” in considerable technical detail. In discussing the “large number” coincidences then evident in physics and cosmology, Carter used the term to refer to the fact that our making any scientific observation is necessarily contingent on our existence.

The term “anthropic principle” was first introduced into the scientific literature in 1974 by Brandon Carter.

Anthropic principle