Possible Responses to Coincidences
The modern approach to the issues that used to be the raw material of
Design Arguments is characterized by the cosmological approach to anthropic
coincidences. We know that there are many aspects of the Universes global and
local structure, and of its laws and other defining constants, which appear
crucial for the existence of life as we know it. Rather than try to use this state
of affairs to produce a modern version of the Design Argument, we ask the
anthropic question: what are the necessary conditions for the existence and
persistence of complexity (life) in a Universe? The absence of a real
definition of life prevents us being more specific, but the relaxation to
complexity allows us to avoid being rigidly anthropocentric. We would like to
know how special these necessary conditions are in some space of possibilities.
If, as is increasingly seen to be the case, there are aspects of the early
evolution of the Universe which introduce random variations in the structure of
the Universe (for example, to the distribution of matter density, temperature,
matter-antimatter balance, cosmological expansion rate, etc) or to the quantities
that we call constants of physics through symmetry breakings or quantum
gravitational corrections, then we must introduce the anthropic question in
order that we evaluate the relevant probabilities when asking how likely it is
that the Universe possesses some particular property. At present we believe
that Nature is pointing us towards a description of her laws which are far more
unified and economical in their schema than we have so far been able to see. At
present we are able to contemplate the consequences of altering the values of
different fundamental constants of physics or aspects of the Universes large
scale structure independently. One suspects that in the future these different
defining features of the Universal laws will turn out to be linked together and
there will be very few (perhaps only one, or zero??) independent changes that
are self-consistently possible.
The chaotic and eternal inflationary universes mean that we must take
seriously the possibility that the global structure of the Universe displays
significant variations. The different self-reproducing regions of the chaotic
and eternal inflationary universe pictures should display different densities
and fluctuation levels. In some versions they will display different
fundamental physical constants and even different numbers of large dimensions
of space. Subsequently, the symmetry breakings that occur at phase transitions
during the early history of the universe can introduce further random variation
in cosmological quantities like the matter-antimatter asymmetry. With regard to
the existence of apparent coincidences between the values of constants of
physics and the large scale structure of the Universe which make our existence
possible, we have several options. We can shrug our shoulders and say there is
one and only one possible universe it is just good luck that we are here. This
option includes the traditional teleological interpretations which appeal to
theistic design.
A second option is that some (unknown) physical process creates the
fine tunings. That is, they are not disconnected. Attempts to provide partial
explanations of this sort can be found in the speculations of Edward Harrison  and Lee Smolin. Theories of this sort need to harness the
possibility of producing sequences of universes, in the way suggested by
eternal inflation, in order to create an population of possible universes upon
which some selection process can operate. In Harrison’s case that selection
process is artificial selection imposed by intelligent beings who are aware of
the need for certain structural properties of the universe to be tuned from
cycle to cycle in order to optimise the conditions for the subsequent evolution
of life. In Smolin’s case the selection is for the maximal production of black
holes. Both scenarios have their problems.
Harrison’s has to get going in the first place. Smolin’s is undermined
by the fact that there appear to be small changes (like those that lead to the
binding of the diproton) that will
increase the black hole production. Also the values of the constants that
maximise black hole production may not allow life to exist. Moreover, such
maxima may not exist for all conceivable variations of the constants
(especially for the variation of G).
A third option is that all possibilities exist, either in some quantum
cosmological ensemble or actually in an infinite space and time of the sort
suggested by the chaotic and eternally inflating universes. In this case the
anthropic coincidences just tell us something about the size of the region of
life-supporting universes in the collection of all possibilities. In this
picture life evolves in some (or even all) of the places where it is possible
for it to do so no matter how improbable that sequence of events might be. A
problem with this perspective is knowing how large to make the ensemble of
variations. It could include structural properties of the universe and its
constants, but it might also include the underlying mathematical and logical
structures upon which our description of it is based.
A fourth possibility is that
life is a good deal easier to evolve than we have concluded from the particular
situation that is on view to us. It may be that there are many other routes to
biological complexity which would also be possible if the constants and laws of
physics were markedly different. In this case the fine tunings that we see are
illusory, a consequence of our limited understanding of life and the conditions
required for its emergence. These four options alone show how difficult it is
to draw firm theological or philosophical conclusions about any aspect of the
Universe from cosmology. The four options we have listed, like that of
teleological Design,are all consistent with the evidence.
Acknowledgements
The author was supported by a PPARC Senior Fellowship.
Contributed by: Dr. John Barrow
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