Published in Skeptical Inquirer Vol. 23, No. 4, July/August 1999.
Claims that scientists have
uncovered supernatural purpose to the universe have been widely reported
recently in the media. The so-called anthropic coincidences, in which the
constants of nature seem to be extraordinarily fine-tuned for the production
of life, are taken as evidence. However, no such interpretation can be
found in scientific literature. All we currently know from fundamental
physics and cosmology remains consistent with a universe that evolved by
purely natural processes.
As the argument goes, the data are said to reveal a universe that is exquisitely fine-tuned for the production of life. This precise balancing act is claimed to be a highly unlikely result of mindless chance. An intelligent, purposeful, and indeed personal Creator must have made things the way they are.
As cosmologist and Quaker George Ellis explains it: "The symmetries and delicate balances we observe require an extraordinary coherence of conditions and cooperation of laws and effects, suggesting that in some sense they have been purposefully designed" (Ellis 1993: 97). Others have been less restrained in insisting that God is now required by the data and that this God must be the God of the Christian Bible (see, for example, Ross 1995).
The fine-tuning argument is based on the fact that earthly life is very sensitive to the values of several fundamental physical constants. Making the tiniest change in any of these, and life as we know it would not exist. The delicate connections between physical constants and life are called the anthropic coincidences (Carter 1974, Barrow and Tipler 1986). The name is a misnomer. Human life is not singled out in any special way. At most, the coincidences show that the production of carbon and the other elements that make earthly life possible required a sensitive balance of physical parameters.
For example, if the gravitational attraction between protons in stars had not been many orders of magnitude weaker than their electrical repulsion, stars would have collapsed long before nuclear processes could build up the chemical periodic table from the original hydrogen and deuterium. Furthermore, the element-synthesizing reactions in stars depend sensitively on the properties and abundances of deuterium and helium produced in the early universe. Deuterium would not exist if the neutron-proton mass difference were just slightly displaced from its actual value; neutrons, unstable in a free state, were stored in deuterium for their later use in building the elements.
The existing relative abundances
of hydrogen and helium also implies a close balance of the relative strengths
of the gravitational and weak nuclear forces. A slightly stronger weak
force and the universe would be 100 percent hydrogen as all neutrons decayed
away before assembling into deuterium and helium. A slightly weaker weak
force and we would have a universe that is 100 percent helium; in that
case neutrons would not have decayed and left the excess of protons that
formed hydrogen. Neither of these extremes would have allowed for the existence
of stars and life, as we know it, based on carbon chemistry. Barrow and
Tipler (1986) list many other such "coincidences," some remarkable, others
This argument, however, has at least one fatal flaw. It makes the wholly unwarranted assumption that only one type of life is possible --the particular form of carbon-based life we have here on earth. Even if this is an unlikely result of chance, some form of life could still be a likely result. It is like arguing that a particular card hand is so improbable that it must have been foreordained.
Based on recent studies in the sciences of complexity and "Artificial Life" computer simulations, sufficient complexity and long life appear to be primary conditions for a universe to contain some form of reproducing, evolving structures. This can happen with a wide range of physical parameters, as has been demonstrated (Stenger 1995). The fine-tuners have no basis in current knowledge for assuming that life is impossible except for a very narrow, improbable range of parameters.
Amusingly, the new cosmic creationists contradict the traditional design argument of the biological creationists, that the universe is so uncongenial to life that life could not have evolved naturally. The new creationists now tell us that the universe is so congenial to life that the universe could not have evolved naturally.
Since all scientific explanations
until now have been natural, then it would seem that the first step, before
asserting purposeful design, is to seek a natural explanation for the anthropic
coincidences. Such a quest would avoid the invocation of supernatural agency
until it is absolutely required by the data.
The inflationary big bang offers a plausible, natural scenario for the uncaused origin and evolution of the universe, including the formation of order and structure--without the violation of any laws of physics. These laws themselves are now understood far more deeply than before, and we are beginning to grasp how they too could have come about naturally. The natural scenario I will describe here has not yet risen to the exalted status of a scientific theory. However, the fact that it is consistent will all current knowledge and cannot be ruled out at this time, demonstrates that no rational basis exists for introducing the added hypothesis of supernatural creation. Such a hypothesis is simply not required by the data.
According to the proposed natural scenario, by means of a random quantum fluctuation the universe "tunneled" from pure vacuum ("nothing") to what is called a false vacuum, a region of space that contains no matter or radiation but is not quite nothing. The space inside a bubble of false vacuum is curved, or warped, and a small amount of energy is stored in that curvature, like the potential energy of a strung bow. This ostensible violation of energy conservation is allowed by the Heisenberg uncertainty principle for sufficiently small time intervals.
The bubble then inflated exponentially and the universe grew by many orders of magnitude in a tiny fraction of a second. (For a not-too-technical discussion and original references, see Stenger 1990). As the bubble expanded, its curvature energy transformed (naturally) into matter and radiation. Inflation stopped, and the more linear big bang expansion we now experience commenced. As the universe cooled, its structure spontaneously froze out--just as formless water vapor freezes into snowflakes whose unique and complex patterns arise from a combination of symmetry and randomness.
In our universe, the first galaxies began to assemble after about a billion years, eventually evolving into stable systems where stars could live out their lives and populate the interstellar medium with the complex chemical elements such as carbon needed for the formation of life.
So how did our universe happen to be so "fine-tuned" as to produce wonderful, self-important carbon structures? As I explained above, we have no reason to assume that ours is the only possible form of life and life of some sort could have happened whatever form the universe took--however the crystals on the arm of the snowflake happened to get arranged by chance.
If we have no reason to assume ours is the only life form, we also have no reason to assume that ours is the only universe. Many universes can exist, with all possible combinations of physical laws and constants. In that case, we just happen to be in the particular one that was suited for the evolution of our form of life. When cosmologists refer to the anthropic principle, this is all they usually mean. Since we live in this universe, we can assume it possesses qualities suitable for our existence. Humans evolved eyes sensitive to the region of electromagnetic spectrum from red to violet because the atmosphere is transparent in that range. Yet some would have us think that the causal action was the opposite, that the atmosphere of the earth was designed to be transparent from red to violet because human eyes are sensitive in that range. Stronger versions of the anthropic principle, which assert that the universe is somehow actually required to produce intelligent "information-processing systems" (Barrow and Tipler 1986), are not taken seriously by most scientists or philosophers.
The existence of many universes is consistent with all we know about physics and cosmology (Smith 1990, Smolin 1992, 1997, Linde 1994, Tegmark 1997). Some theologians and scientists dismiss the notion as a gross violation of Occam's razor(see, for example, Swinburne 1990). It is not. No new hypothesis is needed to consider multiple universes. In fact, it takes an added hypothesis to rule them out-- a super law of nature that says only one universe can exist. But we know of no such law, so we would violate Occam's razor to insist on only one universe. Another way to express this is with lines from T. H. White's The Once and Future King: "Everything not forbidden is compulsory."
The hundred billion galaxies
of our visible universe, each with a hundred billion stars, is but a grain
of sand on the Sahara that exists beyond our horizon, grown out of that
single, original bubble of false vacuum. An endless number of such bubbles
can very well exist, each itself nothing but a grain of sand on the Sahara
of all existence. On such a Sahara, nothing is too improbable to have happened
This is a much abridged version of a longer essay entitled The Anthropic Coincidences: A Natural Explanation to appear in the British Skeptical Intelligencer.
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