Why is the Universe so Special?
A second reason for that
belief can be found in the answer to my second metaquestion, Why is the
universe so special? Of course, here I am referring to the findings of the
Anthropic Principle. Other contributors to this volume have already outlined
the many considerations that lead us to conclude that the laws of nature as we
observe them in our universe are precisely those that permit the development of
carbon-based life, in the sense that even very small changes in intrinsic force
strengths would have broken links in the long, delicate and beautiful chain of
consequences linking the early universe to the existence of life today here on
Earth. I agree with John Leslie`s analysis, presented in his book Universes, that suggests, firstly that
it would be irrational just to shrug this off as a happy accident, and secondly
that there are two broad categories of possible explanation: either many
universes with a vast variety of different natural laws instantiated in them,
of which ours is the one that by chance has allowed us to appear within its
history; or a single universe that is the way it is because it is not “any old
world”, but a creation that has been endowed by its Creator with just the
circumstances that will allow it to have a fruitful history. I simply want to
make two comments on this analysis.
The first is to emphasize
that both proposals are metaphysical
in character. That is clear enough in the case of creation, but it is also true
of a many universes proposal that is wide enough in scope actually to serve as
an explanation. Of course, an inflation-expanded structure, containing many
domains with differing consequences of spontaneous symmetry breaking, could
give vast regions in which effective force constants differed and in one of
which they might take the anthropically desirable values, but that would still
require that the overall Grand Unified Theory was constrained in its character
in order to permit this to happen. Something specific and requiring explanation
would remain. I regard quantum cosmology and baby universes as being too
precarious and speculative in character at present to rely on. In any case, the
underlying theory would again have to take an appropriate form. One might
comment that quantum theory, general relativity and suitable matter fields do
not “come for free”, so to speak. It is important to recognize that that
anthropic fruitfulness requires the right kinds of laws as well as the right
values for the parameters appearing in those laws. It is very difficult to see
what could ensure this right character
of fundamental physical law, realizing the necessary combination of flexibility
and stability required to make fruitful evolution possible, other than a strictly
metaphysical proposal.
The second point is to agree
with Leslie that, in relation to the Anthropic Principle, it is a
metaphysically even-handed choice between many universes and creation. It seems
to be six of one and half a dozen of the other, neatly illustrating the point I
made that these kinds of argument are not knockdown in their character.
However, I believe that, while the many universes hypothesis seems to have only
one explanatory piece of work that it can do, there are other kinds of
explanation that the thesis of theism can afford, such as granting an
understanding of the intelligibility of the universe, and also providing the
ground for the widely-attested phenomena of religious experience. (Of course,
the history of religions is a tangled tale. Weinberg is right to draw our
attention to the sad fact that religion can cause good people to do bad things,
but we should also recognize that religious conversion has often led to bad
people becoming able to do good things.)
My conclusion is to prefer the explanation of anthropic fruitfulness in
terms of a Creator, which strikes me as being more economic and forming part of
a cumulative case for theism.
Contributed by: Sir John Polkinghorne
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