The Anthropic Principle, in its weak form, is a response to
the realization that the parameters that comprise the Laws of Physics have to
be very, very unique in order for something as complex as a star to form, much
less something as complex as a human being.
By “very, very unique” we are talking something in the order of 120
magnitudes of uniqueness. (To put this
into perspective, the number of atoms in the whole universe is estimated to be
a few less than 80 magnitudes.)
The fundamental parameters are things like the masses of the
various fundamental particles and the strength of the fundamental forces -- for
instance the mass and charge of the electron and the strength of gravity. Physicists used to assume that a
final theory of nature would explain why each parameter had the value it has,
but it increasingly appears that there is no necessity for these values. It appears that they could
take on any value along a continuum of values (indeed it is contingent that
they exist with any value at all). So
the question arises: Why do they exist and why do they have the values they
have?
The Anthropic Principle provides a very simple answer to
this question: we are here, therefore the parameters provided the right
conditions for us to be here; we should not be surprised that the parameters are those that allow us to exist, whatever the odds against them. An analogy
might be that if we win the national lottery, we might be surprised to do so,
but we should not be surprised that somebody wins it.
As far as it goes, this “explanation” is true, but it doesn’t
actually explain much. A proper
scientific explanation would provide a mechanism by which these parameters
become determined, and the Anthropic Principle does not even attempt to provide
such a mechanism. (In my experience, the only attempt to answer the question of the parameters that provides a mechanism and is falsifiable is
the theory of Cosmological Natural Selection developed by Lee Smolin.) The analogy with the lottery is not really
apt, either, because there is no good reason why there has to be a winner in
the cosmic lottery, unless we assume an infinite number of universes, each
capable of having a different set up parameters. It has become fashionable to assume this, but
I don’t think many people think through the consequences of this assumption –
indeed I feel rather certain that no human being is capable of thinking through
the consequences of this assumption.
The Anthropic Principle, in its weak form, seems to me like
an intellectual curtain. Behind the
curtain is the huge mystery of our being here. But for those who temperamentally dislike
mystery or anything that the human mind is powerless to
penetrate, the Anthropic Principle conveniently hides the mystery from
view. If like me, you love a good
mystery, than you also would prefer to throw open the curtain and contemplate the
great darkness beyond. Somewhere in that
darkness, after all, is the reason we are here.
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