Art Of Making

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Even if we assume the flat infinite universe, we are still confronted with the question
of why something like life (here and now at least) is actually happening. Even though
any system with nonzero probability would occur infinitely often in such a universe,
this doesnt mean that anything can happen: the possibility of something happening
depends on the ingredients and the physical laws of that universe. A lattice structure
repeating itself in all directions, such as that pictured by Maurits C. Escher in his famous
Cubic Space Division (Escher 1952), makes an infinite universe with a very sharp
and low limit to complexity. In an infinite FLRWuniverse, complexity and life would
not appear unless the physics has highly specialized characteristics. In fact, it turns out
that many basic parameters in our universe, such as the value of coupling constants, the
mass and charge of elementary particles, the rate of cosmic expansion, the amplitude of
density perturbations in the early universe, the number of space and time dimensions,
and the form of physical laws, are extremely sensitive to life-supporting conditions. In
fact, their measured values turn out to be precisely tuned for complex structures and
life to emerge (Barrow and Tipler 1986).

Generalized versions of physical infinities have been invoked to mitigate this impression
of a cosmic interconnectedness oriented toward life (Rees 2003).Various scenarios
have been proposed in which selection effects are a key to explaining the apparent peculiarity
of our cosmic setup. Interestingly, in this attempt many have been willing to give
up the long-lived cosmological principle and to go nearly to its opposite: from infinite
uniformity to limitless diversity. Starting from different theoretical standpoints (Linde
1994; Giulini et al. 1996; Kallosh and Linde 2003), recent speculations have proposed
that our universe could be regarded as one of an infinity of parallel universes, causally
disconnected from each other, characterized by different realizations of those parameters
and properties that locally we perceive as life-encouraging. Thus, the fine-tuning
issue would be reduced to an anthropic selection effect by observers in the multiverse.
Although interesting, these ideas are problematic from several points of view (Ellis,
Kirchner, and Stoeger 2004), including their intrinsic difficulty to undergo empirical
verification.
If taken too far, infinite multiverse scenarios lead to rather embarrassing paradoxical
situations (Bersanelli 2005). It has been argued that the ultimate form of multiverse is
one in which every subuniverse is identified as a mathematical structure possessing an
actual physical existence (Tegmark 2004). In accepting this view, one should realize
that, even in this most general case, a particular criterion has been assumed to define
existing universes within the infinite multiverse, that is, the requirement of being a
mathematical structure. This would mean that a particular capability that the brain
of our species has achieved through biological evolution, such as the development of
the mathematical language, is believed to define what does or does not exist at the
multiverse level. We end up with a picture of reality that is dangerously similar to
a materialized projection of the set of logical possibilities of our human mind. This
may appear even more rigidly homo-centered than the anthropic flavor that multiverse
speculations seek to remove.
How would we judge these ideas from their aesthetic angle? Science, of course,
is not driven by our own taste, and eventually it is the persistent reality of the facts,
gathered by careful and repeated observations,that prevails and defeats any undue
prejudice we may have tacitly nursed. On the other hand, it is also clear that physicists
are motivated and guided in their work in some important way by their aesthetic
perception. Cosmologist Mario Livio quite correctly notes (Livio 2000) that although
the central role of aesthetics in fundamental science is normally not explicitly recognized,
in practice it is adopted wholeheartedly by physicists, suggesting an underlying
cosmological aesthetic principle. Aesthetic guidance may be particularly relevant in
scarcely constrained situations that leave ample room for conjectures and speculation,
such as the one we are discussing here. Although the evidence of a deep aesthetic
component in scientific research is compelling, we are, of course, left with the challenge
of clarifying what we mean by beauty in this context. Most physicists identify
symmetry, effectiveness, and simplicity as some of the key words defining the canons
of scientific beauty.21 It is also rather conventional to include various forms of the
generalized Copernican or mediocrity principle as an aesthetic element that a credible
scientific theory is expected, or even required, to exhibit. However, I think that this
aspect of the debate deserves some attention. Pushing too much on the mediocrity ideal
of nature is questionable from the aesthetics point of view, and it may hide a pitfall for a
sound attitude toward knowledge. The ultimate mediocre universe is indeed maximally
symmetric and infinitely simple, but it is also absolutely uninteresting. Things dont get
better in plenitude multiverses, such as those described earlier, in which every thing
that can exist, does exist; although at first sight they may appear to offer a most rich
and diverse reality, they can also be seen as ultimately boring and featureless. Nothing
really happens in a world where everything always goes on infinitely often.
Both the strong cosmological principle and the plenitude universe paradigms seem to
lead to a rather poor aesthetic appeal. Perhaps the reason is that, although for opposite
reasons, such models are ill-assorted with the concepts of rareness and uniqueness,
which have deep aesthetic significance on their own. Aesthetics has its requirements.
It seems that spatial infinity, in order to be perceived as a fascinating concept, has
to maintain some kind of element of selected variety and genuine surprise. Perhaps
a new theory will turn out to include some of these aspects, apparently lost in our
present attempts to describe a global vision of the universe. However, as we shall see,
things become more clear and interesting when we look at the aesthetic content of the
observable universe.