Anthropic principle

The anthropic priciple is a controversial cosmological principle that the observable universe, as it is, must be compatible with our powers of observation, or else we would not be able to observe it. The universe appears to be "fine tuned" to allow the existence of life as we know it.

Although there are several versions of the principle, they fall into the two categories of the "Weak Anthropic Principle," which simply states that the existence of human life itself implies that nature must be consistent with having evolved carbon-based life, and the "Strong Anthropic Principle," which relates to the possibility of alternative universes, stating that our observable universe must be the only type of universe capable of evolving observers.

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