- slide 1 of 3
The anthropic principle is most generally a principle in a theory that takes into account an observer. Such as in quantum mechanics, where it must be asked whether or not the presence of an observer influences what is being observed. The anthropic principle is also a broad concept encompassing many dressings of the essential idea that the universe happens to be the way it is to allow for the emergence of intelligent life. Basically, to move into mixed-metaphor, there's a fallow energy that has been cultivated with physical laws that create enhanced circumstances, give advantage to, exclusive advantage to, make almost impossible the not-emergence-of, life, and intelligent, conscious life for that matter.
In other words again: The universal laws and characteristics of the universe are all the way they are to allow for the existence of intelligent life.
The foundation of this principle is based upon the observation that it has taken a remarkable set of coincidences to allow for the formation of carbon-based life in the universe. Even beyond our improbable local situation that finds Earth in the habitable zone, the right size, etc., that heavy elements have formed in the first place to allow for the formation of galaxies, planets, and eventually people.
It may also be worth mentioning that the anthropic principle and intelligent design are not necessarily synonymous. Intelligent design implies a god, the anthropic principle can simply take the "self-consciousness" of the universe into account, with observers providing the consciousness; and so we can wander into philosophy...and so it may be better to say that the anthropic principle takes the observer into account, as part of the system being studied.
There are two popular forms that the anthropic principle comes in: The Weak Anthropic Principle and the Strong Anthropic Principle. Each one revolves around the ideas mentioned above.
- slide 2 of 3
Weak Anthropic Principle
The weak anthropic principle (WAP) says that our observations of the universe will tend to be verify factors that allowed for the creation of life, being that life is required for observations to take place. So, a scientist could look at the fact that carbon is required for the occurrence of life as we know it, and then make allowances for that information, such as the resonance of carbon in the formation of heavy elements, when trying to figure out how the universe evolved. The WAP describes why the value for the emergence of intelligent life in the universe is non-zero.
The WAP does allow that we may indeed be part of a larger multiverse, and that the universe we find ourselves in is suited for life, but that others may not be.
- slide 3 of 3
Strong Anthropic Principle
The strong anthropic principle generally states that the only possible universe that could exist is one that functions toward the creation of observers, carbon-based; and that the observability of the universe necessarily constrains the universe, and relies on intelligent life.
Is this a testable theory in fact? Well, an issue arises here because in order to falsify the theory there would have to exist universes in which there is no observer, which situation cannot be verified or denied without an observer. Does that prove the Strong Anthropic Principle, or does it complexly toy with logic, and/or become simple circular reasoning? Is the SAP in principle a concrete application of philosophical idealism?
Certainly an argument could be made to say yes to all of these questions. However, for now, as for this principle constraining physics and cosmology somehow, or putting it within some rational framework, it certainly doesn't prove a creator or even bring a creator into the realm of scientific experiment or verification; with that said, the SAP seems to be most intriguingly related to quantum mechanics, where, indeed it can appear that an observer is needed to make reality concrete.