Is the Universe Fine-Tuned for Life?

• Let us look first at what AP is all about.
• There are many flaws in the AP:
  • The Weak Anthropic Principle is a trivial statement.
  • The Strong Anthropic Principle is just a disguised version of the god of the gaps argument.

Today there are actually four versions of the AP, the weak anthropic principle, the strong anthropic principle, the participatory anthropic principle [a] and the final anthropic principle[b]. Only the first two are relevant to our discussion here:

The Weak Anthropic Principle (WAP): J.D. Barrow and F.J. Tippler in their 1986 book The Anthropic Cosmological Principal presented this principle as follows:

the observed values of all physical and cosmological quantities are not equally probable but take on values restricted by the requirement that there exists sites where carbon based life can have evolved and by requirement that the universe be old enough for it to have already done so.[2]

In other word the WAP states that what we can expect to observe in the universe must be constrained by the requirement that the physical laws and other aspects of the universe allow us (a carbon based intelligent life form) to exist.

The Strong Anthropic Principle (SAP): Carter's claim can be grouped under this. The SAP goes one step further than the WAP. Put simply the SAP states:

The universe had to be such as to permit the emergence of observers at some stage.[3]

It's basic argument is simple. The fundamental constants of the universe are, at the moment, not predicted by any cosmological theory-thus values such as the gravitational constant, the mass of the proton or the strong nuclear force are derived empirically (i.e. from experiments). Yet, according to proponents of the SAP, if these values were to vary even a little the universe as we know it would not exist. Some examples Carter listed included:

• The ratio of the gravitational constant to electromagnetism. This is roughly 10^-39. If the gravitional force is increased a million fold such that the ratio is 10^-33, stars would be a billion times more massive and would also burn a million times faster. This means that there would not be enough time for main sequence stars to "cook" the heavy elements such as carbon that would be essential for the development of life as we know it.
• The strong nuclear force. The strong nuclear force too seems finely tuned. A little stronger and protons fail to form, a little weaker and the formation of stars would be impossible.
• The masses of the proton, neutron and electron. These masses also seem fine tuned in just the right way. The mass of the neutron is slightly more than the combined masses of the proton and electron. This allows a neutron to decay into a proton, an electron and a neutrino. If this is not the case, and the mass of the neutron is exactly equal to the combined masses of the proton and electron, then all the protons and electrons of the premieval universe would simply have combined into stable neutron. Then there would not have been enough hydrogen lying around to act as the fuel for stars.[4]

There are more examples of these "coincidences", some interesting, some, in the words of physicist Victor Stenger, "quite strained".[5] But the above three should give a flavor of what the SAP is all about. In short the SAP asserts that the universe is fine tuned for the development of life. God, according to the SAP, is a "fine tuner".

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The Weak Anthropic Principle

One example of the use of the weak anthropic principle is to "explain" why the big bang occured ten thousand million years ago-it takes about that long for intelligent beings to be involved. ...an early generation of stars first had to form. These stars converted some of the original hydrogen and helium into elements like carbon and oxygen, out of which we are made. The stars then exploded as supernova, and their debris went to form other stars and planets, among them those of our solar system, which is about five thousand million years old. The first one or two thousand million years of the earth's existence were too hot for the development of anything complicated. The remaining three thousand million years or so have been taken up by the slow process of biological evolution, which has led from the simplest organisms to beings capable of measuring time back to the big bang.[7]

In a sense the WAP is trivial. Thus in Stephen Hawking's example above, it simply states the obvious. As far as we understand the universe, there could not have been any carbon based intelligent life that could ask such a question, say, a million years after the big bang. Thus the answer to why the big bang occured so long ago is simply this: it took that long before any living thing capable of asking such a question could have evolved!

Thus the "fine tuning" of fundamental constants are such simply because if they are not these values no one would be around to ask such questions! The philosopher Robin Le Poidevin aptly calls the WAP the "what-else-would-you-expect-to-observe?" principle.[8]

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The Strong Anthropic Principle

Note how the SAP uses gaps in current scientific knowledge to make their case:

• We do not know if the fundamental constants of physics are the ultimate brute fact of the universe or whether there could be a final grand unified theory that could explain it. The proponents of SAP argue that because we do not know this, a "fine-tuner" must have fine tuned these constants.
• We do not know of any type of life form apart from chemically based carbon life forms. From this position of ignorance, the SAP enthusiasts argue that the whole universe is geared for carbon life forms only.
• We do not know if there are other intelligent life forms elsewhere in the universe. From this lacuna, the SAP people argues that humankind, being the only intelligent life form we are currently aware of, is the sole reason for the existence of the universe.

The SAP is subject to many philosophical flaws. For instance the very laws that are fine tuned for the existence of human life (why else would it be called the anthropic-from the Greek anthropos or man-principle?), can also be seen as fined tuned for the existence of, say, cockroaches! So why would human beings be put on center stage? One possible suggestion by theists is that we are moral animals and thus we alone among all creatures holds a privileged position in the cosmos. I find that very hard to take seriously. Apart from the problems with equating morality with God in any fashion (see for instance the critique on Kant's categorical imperative), this seems merely an arbitrary extension of the SAP. [10]

Scientifically there are even more holes in the SAP:

• It is by no means clear that our carbon based life-form is the only one possible given the current laws (and fundamental constants) of physics. In their book Life Beyond Earth: The Intelligent Earthlings's Guide to Life in the Universe (William Morrow 1980), Gerald Feinberg and Robert Shapiro speculated on other forms of life that may be possible in this universe. Some of their speculations include plasma life, a non chemical based life form that may be possible inside the plasma environment of stars like the sun. These "plasmobes" are "composed of patterns of magnetic force, together with groups of moving charges, in a kind of symbiosis". [11] Of course this is highly speculative but it does show that life forms may be possible without the formation of heavy atoms such as carbon and nitrogen. Our requirement that life be carbon based may be nothing more than "carbon chauvinism".

• Furthermore our knowledge of physics and cosmology is far from complete. Nothing in our knowledge explicitly rules out the possibility of finding a grand unified theory that could account for these fundamental constants of the universe. If such a theory is found, there would be no need to suggest any further "fine tuning", just like Darwin's discovery of evolution did away with any teleological arguments based on the complex anatomical features of animals (such as the eye).[12]

• Another scenario that had been suggested is the multiple universes scenario. This means simply that our universe is simply one of a large number of "mini-universes" in an infinite super universe. Each of these may have different constants and/or physical laws-some may have different life forms other may be forever devoid of anything at all. This is actually a simpler scenario than postulating a "grand cosmic fine-tuner" that has not been required to explain anything else. In fact such a scenario is actually suggested by the modern inflationary model of the big bang. In quantum mechanics a space-time "foam" without any matter or energy will experience some random local quantum fluctuations. The cosmologist Andre Linde had suggested that these fluctuations form bubbles that will inflate into mini universes with random physical characteristics.[13]

• Finally the physicist Victor J. Stenger had shown that perhaps the fine-tuning of constants may not be that big a deal after all. In a program he called MonkeyGod, Stenger randomly put in different values for the four fundamental constants; the electromagnetic force, the strong nuclear force, the mass of the electron and the mass of the proton. In the randomly generated 100 universes, many were able to have stars with long enough lifetimes for the formation of heavy elements such as carbon and for life to evolve. As Prof. Stenger wrote: "I think it is safe to conclude that the conditions for the appearance of life are not so improbable as those authors enamored by the anthropic principle would have people think."[14]

To these issue we can add one more. Since Copernicus, the general trend of scientific discoveries had tended to remove humankind away from both the physical and metaphorical center of the universe. Stephen Hawking's critique of this aspect of the SAP is on the mark:

[T]he strong anthropic principle...runs against the tide of the whole history of science. We have developed from the geocentric cosmologies of Ptolemy and his forebears, through the heliocentric cosmology of Copernicus and Galileo, to the modern picture in which the earth is a medium-sized planet orbiting around an average star in the outer suburbs of an ordinary spiral galaxy, which is itself one of about a million million galaxies in the observable universe. Yet the strong anthropic principle would claim that this whole vast construction exists simply for our sake.[c] This is very hard to believe. Our Solar System is certainly a prerequisite for our existence, and one might extend this the whole of our galaxy to allow for an earlier generation of stars that created the heavier elements. But there does not seem to be any need for all those other galaxies, nor for the universe to be so uniform and similar in every direction on the large scale.[15]

Thus the SAP is unconvincing as an argument for God's existence. I leave the last word to the agnostic philosopher Bertrand Russell:

If I were granted omnipotence, and millions of years to experiment in, I should not think Man much to boast of as the final result of all my efforts.[16]

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Notes

References

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