In 1973, physicist Brandon Carter introduced the idea of the anthropic principle. While there are many variations of the principle, they mostly hinge on the idea that there are many universes and that physical laws can vary from one universe to another. In some universes, the physical laws are hospitable to life as we know, but in some universes they’re not. In seeking an answer to why the laws we observe have their particular form, anthropic reason replies that there is no first principles explanation — the laws can and do vary from universe to universe. We see our laws we do because had they been different they’d be incompatible with life, and so we wouldn’t be here to observe them. Do you find this convincing? Circular? Do you think anthropic reasoning has a place in scientific thinking?
I resented accepting the anthropic reasoning for a long time. However, having noticed that there is an undeniable logic to it, I’ve come to accept it as a “last resort”, if other explanations fail and the anthropic reasoning makes sense.
Does the multiverse require string theory? At the moment string theory is struggling with no signs of super symmetry detected at the LHC. In addition string theory is not a complete theory as it is background dependent and does not in itself explain space. Quantum loo gravity or some variant of it seem to be more promising paths at the moment,. Can a multiverse theory remain consistent if quantum loop gravity is found to be the correct description of the basis of our universe.
It sounds to me like a ´Cogito ergo sum´ theory. I think, therefore I am, or – differently put – I observe this type of universe, therefore its laws must be hospitable to our kind of intelligent life. If it were inhospitable to life as we know it, we would not be here to observe it. It may be circular, but no more circular than Descartes.
Descartes was a precise philosopher and his principle (though unproven) still holds good. As does Darwinian evolution – life evolved from the simplicity of microbial structures to the complexity (and cul de sac specialisation) of an Orchid, a Human, or a Blue Whale (consider the: Dodo, Mamoth or T Rex). Under the stress of change it is the complex that will face extinction and the Microbes will probably inherit the Earth. William of Ockham’s ‘Razor’ is still sharp! Also, we do have eternity to play with 🙂