August 16, 2005 | David F. Coppedge

Can Atheism Breathe in an Anthropic Universe?

Astronomers Martin Rees and Mario Livio considered “Anthropic Reasoning” in a Science perspectives article.1  The question bears not only on SETI, and whether intelligent life exists elsewhere, but why it exists here.  They state the issue:

We can imagine universes where the constants of physics and cosmology have different values.  Many such “counterfactual” universes would not have allowed the chain of processes that could have led to any kind of advanced life.  For instance, even a universe with the same physical laws and the same values of all physical constants but one—a cosmological constant lambda (the “pressure” of the physical vacuum) higher by more than an order of magnitude—would have expanded so fast that no galaxies could have formed.   (Emphasis added in all quotes.)

And that’s not the only constant that appears finely tuned.  They also discuss the presence of baryons (like protons and neutrons), the fact that our universe is not perfectly smooth, allowing structure to form (designated by the parameter Q), and “a gravitational force that is weaker by a factor of nearly 1040 than the microphysical forces that act within atoms and molecules—were gravity not so weak, there would not be such a large difference between the atomic and the cosmic scales of mass, length, and time.”

A key challenge confronting 21st-century physics is to decide which of these dimensionless parameters such as Q and are truly fundamental—in the sense of being explicable within the framework of an ultimate, unified theory—and which are merely accidental….
If some physical constants are not fundamental, then they may take different values in different members of the ensemble [of universes].  Consequently, some pocket universes may not allow complexity or intelligent life to evolve within them.  Humans would clearly have to find themselves in a pocket universe that is “biophilic.”  Some otherwise puzzling features of our universe may then simply be the result of the epoch in which we exist and can observe.  In other words, the values of the accidental constants would have to be within the ranges that would have allowed intelligent life to develop.

Anthropic reasoning investigates the nature of such biophilic domains.  Some cosmologists used to assume that inflation theory put these enigmas to rest, but new ones have arisen recently.  “Anthropic considerations are beginning to be seriously discussed,“ they say, “especially in relation to dark energy.”  This factor not only impinges on the question of whether life could arise in a universe of arbitrary constants, but why it should exist now:

The question that arises is why we happen to live in the first and probably only time in the history of the universe in which the matter density and dark energy density are roughly equal.
    The questions used to be: Why should empty space exert a force?  Why should there be a cosmological constant lambda?  Now we ask: Why is the force so small?  If there was an inflationary era with a large cosmic repulsion, how could that force have switched off (or somehow have been neutralized) with such amazing precision?  In our present universe, lambda is lower by a factor of about 10120 than the value that seems natural to theorists.

If lambda were larger, the universe would have expanded too fast for galaxies to form.  Is lambda a random variable, one that could take on any conceivable value?  If so, its precision today is amazing enough, but that’s not all: “The situation becomes more complex when more than one physical parameter is postulated to be a random variable.”  Is Q also contingent, or is it dependent on the value of lambda?  The more random variables there are, the luckier our presence appears.
    The authors discuss two reasons why anthropic reasoning “tends to raise the blood pressure of some physicists.”  First, proposing an ensemble of unobservable universes seems to run counter to the scientific method of observation and experimentation.  It lies within metaphysics, not physics.  The authors counter that the more we test our cosmological models, the more we can infer that alternate universes might exist.  Second, some physicists feel that “anthropic reasoning seems to point to a fundamental limitation of physics,” the end of physics as it were.  The authors respond that this is merely a psychological objection.

Physicists would like, above all else, to discover a uniquely self-consistent set of equations that determines all microphysical constants, and the recipe for the big bang.  They therefore hope that future theories will reveal that all physical parameters are uniquely determined.  But there is no reason why physical reality should be structured according to their preferences.  It is good that many physicists are motivated to seek a theory that uniquely derives all fundamental numbers and constants, but they may be doomed to failure.
    The quest for first-principles explanations may prove as vain as Kepler’s quest for a beautiful mathematical formula that described the solar system.  If future developments bear out the possibility of a multiverse, then anthropic arguments will offer the only “explanation” that we will ever have for some features of our universe.  At the moment, we have no firm reason to close off any of the options.  In view of our current ignorance as to what is truly fundamental and what is not, we should keep an open mind about all the options.

Last, they discuss whether anthropic reasoning has any predictive power.  They argue that, in principle, it does.  If lambda is random, they say, there would be a “an upper limit above which structure and complexity would not emerge.”  Assuming we inhabit a mediocre universe in the ensemble “(as Copernican humility would require,” they reason that we ours would be just below the upper limit.  “As it turns out, however, the value determined from observations of high-redshift supernovae and from the spectrum of the fluctuations in the cosmic microwave background is smaller than the threshold by only a factor of 5 to 10, not inconsistent with anthropic expectations.”
    In conclusion, they anticipate that better measurements of dark energy, and the detection of gravity waves from inflation, might eventually shed light on whether a multiverse exists – and whether our laws of physics are unique.  “Our universe isn’t the neatest and simplest,” they claim.  It has the rather arbitrary-seeming mix of ingredients in the parameter range that allows us to exist.  Until we know for sure which type of universe or multiverse we live in, anthropic reasoning is certainly one option in the physicists’ arsenal.”


1Mario Livio and Martin J. Rees, “Perspectives: Cosmology: Anthropic Reasoning,” Science, Vol 309, Issue 5737, 1022-1023, 12 August 2005, [DOI: 10.1126/science.1111446].

This entry is offered for your amusement and amazement at the mental gymnastics atheists go through to deny the obvious: that our universe was designed for life.  Rees and Livio mourn that “anthropic arguments will offer the only “explanation” that we will ever have for some features of our universe.”  This is the despair of atheism.  Have they not known?  Have they not heard?  Has it not been told them from the beginning?  Isaiah has a lot to say about that, but those unwilling to look at ancient sources might instead at least be willing to listen to what secular scientists like Robert Jastrow, Donald Brownlee and Paul Davies had to say in the recent film, The Privileged Planet.  The design features in our universe that make life possible were not abstruse or hidden to these secular astronomers; they were abundantly evident – astonishingly so.  Why should anyone run so hard from the obvious interpretation, that our universe really was designed for a purpose?  It would seem that the evidence for a Creator would be a source of hope, joy and gratitude, provided one is willing to swallow his pride.
    The anthropic principle is not an explanation.  It is a cop-out that commits the post hoc fallacy, a sophistical dodge to avoid the design inference.  It appeals to metaphysical entities (alternate universes) that require far more faith than belief in God – in fact, 10120 times as much faith.  As a substitute for religion, it has become a religion itself.  See, for instance, the conclusion of The Anthropic Cosmological Principle by Barrow and Tipler, where they speculate that intelligence will evolve toward omniscience and omnipotence.  Too bad they won’t live long enough to see it.
    The anthropic principle (AP), arguably the religious anthropic principle (RAP), comes in several flavors.  The weak anthropic principle (WAP) says that if the universe were not structured the way it is, we wouldn’t be here to worry about the question.  The strong anthropic principle (SAP) postulates a multiverse–an ensemble of universes, and reasons that a kind of cosmic natural selection led to our finding ourselves inhabiting this one (this is the position taken by Livio and Rees).*  Yet atheist escapism knows no bounds.  There is an even stronger form of the anthropic principle that actually asserts that humans created the universe!  The suggestion is that by observing the universe, we gave reality to the parameters that made such observations possible.  One critic called this the Completely Ridiculous Anthropic Principle.  The acronym is left as an exercise.

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Categories: Astronomy, Cosmology, Physics, SETI

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