The anthropic principle says that in the universe, our presence as observers compels conditions for our presence. While the idea was not entirely new, the phrase came up in 1973 by Brandon Carter, who proposed the weak and strong forms of anthropic principle.
The weak anthropic principle (WAP) merely says that you need to take into account those things in the environment that you can see vs those things you are unable to see. Or it simply says that the life-free universes cannot be observed it’s just a selection bias.
An example is the cosmological constant (lambda). The number must be within certain limits. If the constant were large-negative, the universe would have collapsed long ago; if it were large-positive, it would have expanded too fast for the stars to form. Either way, we wouldn’t be here to talk about it.
