“There is a voice inside of you
That whispers all day long,
‘I feel this is right for me,
I know that this is wrong.’” -Shel Silverstein
When it was first proposed in 1973 by Brandon Carter, there were only two simple statements that one could hardly disagree with concerning the anthropic principle:
1.) We must be prepared to take account of the fact that our location in the Universe is necessarily privileged to the extent of being compatible with our existence as observers.
2.) The Universe (and hence the fundamental parameters on which it depends) must be as to admit the creation of observers within it at some stage.
A young star cluster in a star forming region, which may be giving rise to future observers right now. Image credit: ESO / T. Preibisch.
Somehow, that’s evolved into a line of thinking where you can make probabilistic arguments about the initial conditions that spawned the Universe, about the necessary emergence of humans or about the string landscape. In other words, what started as a reframing of the obvious has become an oft-abused scientific principle, yet one that still has a germ of validity and usefulness at its core, if ...