Solution God Exists

Chance is perhaps God's pseudonym when he does not want to sign.

Anatole France, Le Jardin d'Epicure

Some have suggested SETI scientists are engaged in a theological pursuit: since ETCs are likely to be far in advance of us, we will think of them as almost omniscient, omnipotent beings. We would think of them as gods. Many SETI scientists would disagree: ETC's technology might indeed be so far advanced that it is, to use Clarke's phrase, indistinguishable from magic, but surely we know enough to consider these beings as master engineers. At worst, we would look on them as thaumaturgists. We know enough not to think of them as gods.

Others have argued that God — the creator of our Universe — exists. And that, since God is everywhere, our search for extraterrestrial intelligence would be satisfied if we found God. I am hopelessly unqualified to argue these points. However, there is a speculation from the realms of theoretical physics that might, if proved true, demonstrate the existence of many other universes that are conducive to the development of ETCs; an even more speculative suggestion is that one of those civilizations created our own Universe. They would, in a sense, be God. The work is highly speculative, but the theory makes a definite prediction that can be tested.

The argument is as follows.

Physicists may be on the verge of discovering a "theory of everything": a theory that unifies gravity with the other forces and that explains the observed relationships between the various forces. (There are two points to note here. First, a "theory of everything" would answer basic physics questions. Every type of question a physicist might ask could in principle be answered in terms of the theory. In practice, most questions would not be explained in terms of ultimate principles, any more than present problems in protein synthesis require a knowledge of QCD for their answers. A theory of everything certainly does not have to explain love or truth or beauty. Second, physicists expressed similar sentiments about a final theory as far back as the 19th century, so we should take such announcements with a pinch of salt. But this time it really may be different.)

The present candidate for a final theory is called M-theory. The mathematics of M-theory is exceedingly difficult; indeed, much of the mathematical machinery needed to develop the theory has yet to be invented. But suppose in the next few decades M-theory is developed to a high degree of sophistication. Will it explain "everything"? Perhaps it will; that is the hope of most workers in the field. There are indications, however, that the theory will have a number of parameters — such as the masses of the fundamental particles and the relative strengths of the fundamental forces — whose values must be put into the theory "by hand." The equations of our final theory might say, for example, that the electron mass should be nonzero or that the mass associated with the cosmological constant should be non-zero — but the equations might say nothing about why those masses, in natural units, should be so tiny: 10-22 and 10-60, respectively. It might turn out that those masses, and the various other parameters in the theory, could have taken any value.

If a theory of everything fails to explain why fundamental parameters have the values we observe, we would have a final theory that describes a multitude of possible universes. Each universe would have different values for the various fundamental parameters. How, then, could physicists answer a perfectly reasonable question, such as: "Why is the mass of the proton 10-19 in natural units when we would naively expect its mass to be about 1?" How can we proceed?

One approach is to say the parameter values were set by chance. How, though, can we explain the fact that the observed values of these parameters seem to be necessary for life? You can tinker with the parameters a little, but not much: life requires chemistry, chemistry requires stars, stars require galaxies. . . and all of these require the parameters to lie within a narrow range of values. Decrease the strength of the strong interaction by a factor of 4, say, and no stable nuclei can exist; we would not have stars. Change the cosmological constant by a factor of 10, say, and you end up with a universe totally unlike the one we inhabit. Lee Smolin estimates the probability of picking a set of random parameters that generate a universe favorable to life is 1-in- 10229. It is difficult to convey just how fantastically unlikely this is. For example, imagine you have a single ticket in a cosmic lottery that has roughly the same odds as the UK National Lottery: about a 13 million-to-1 winning chance. You might think it worth entering: you are not likely to win but, hey, someone has to. Now suppose the commissioners of this cosmic lottery are miserly beings. Their lottery has been drawn once a second, every second, since the start of the Universe some 13 billion years ago — so there have been roughly 1017 draws. But they pay out on only one of those draws; all other draws are void, and they keep the money. So there is only one chance in a hundred million billion that your ticket is eligible for the prize draw; and even if it is eligible, there is only a 13 million-to-1 chance that it will win. With these odds you would not bother to enter. But the chance of winning such a lottery does not even begin to convey the sheer improbability of a 1-in- 10229 chance coming up. If Smolin's probability estimate is correct, then we simply cannot appeal to good luck.

A second approach is to invoke some form of anthropic principle (see page 143 for more discussion of the principle). In other words, the parameters are tuned to these unlikely values in order for rational creatures to exist. Perhaps God explicitly set the parameters to create a Universe with life; or, taking a less theological view, perhaps there are many universes, each of which has different laws and constants of physics. We then must find ourselves in a Universe where the parameters are conducive to life — after all, we can hardly find ourselves in a Universe where physics does not allow life to exist. Many scientists feel uneasy with such arguments, since anything can be explained this way; to argue like this is almost an abdication of scientific responsibility. Furthermore, a persistent criticism of the anthropic approach is that, with a couple of debatable exceptions, it fails to make predictions that can be tested by observation.

A third approach, promoted by Smolin, is to apply Darwin's evolutionary ideas to cosmology.67 Equations may not be able to explain why physical parameters have fine-tuned values like 10~60, but evolutionary processes can. Smolin suggests that the physical constants — and perhaps even the laws of physics — have evolved to their present form through a process that is similar to mutation and natural selection.

How can this be? Smolin's key assumption is that the formation of a black hole in one universe gives birth to another, different expanding universe. He further assumes that the fundamental parameters of the child universe are slightly different from those of the parent universe. (This process is thus rather like mutation in biology: the child has a similar genotype to the parent, but there can be a slight variation.) In this picture, the Universe we live in was generated through the formation of a black hole in a parent universe with similar physical constants to our own. A universe with parameters that permit the formation of black holes has offspring that will in turn produce black holes. A universe with parameters that lead to little or no black-hole formation will produce little or no offspring. Very quickly, no matter how fine-tuned the parameters need to be, universes with parameters that lead to black-hole formation will come to dominate: pick a universe at random and the chances are overwhelming that you pick a universe in which many black holes form.

Now, so far as we know, the most efficient way for a universe to produce black holes is through the collapse of stars. For example, our own Universe will create as many as 1018 black holes — and thus, in Smolin's picture, child universes — through stellar collapse. So, no matter how "improbable" the values of the fundamental physical parameters that allow stars to form, we expect cosmic evolution to generate a preponderance of universes in which there are innumerable stars. And a universe with physical parameters that gives rise to stars is a universe that inevitably has heavy nuclei, and chemistry, and long enough timescales for complex phenomena to emerge. In other words, it is a universe that may have life. The fine-tuning of the constants is for the benefit of black-hole production rather than the production of life. In Smolin's picture, life is simply an incidental consequence of a universe that has sufficient complexity to allow the formation of black holes.

This may sound like speculation, and it is. Indeed, the idea is almost entirely speculative. There is no evidence (and perhaps there never can be) that the formation of a black hole creates a different expanding universe. Even if a new universe does form, we cannot answer many of the questions we would like to ask. (Exactly how do the physical parameters change at the birth of each child universe? Does a single black hole always give rise to a single universe? Does the mass of the black hole play any

figure 21 An artist's impression of the supermassive black hole in MCG-6-30-15, a distant galaxy. Astronomers believe the cores of most galaxies contain supermassive black holes — perhaps each of these black holes creates a universe with physical parameters like our own? If so, our Universe may have given rise to billions of similar universes. Even more common than supermassive black holes are those formed in stellar collapse. Ifthese objects create new universes, then our own Universe may have 1018 offspring!

figure 21 An artist's impression of the supermassive black hole in MCG-6-30-15, a distant galaxy. Astronomers believe the cores of most galaxies contain supermassive black holes — perhaps each of these black holes creates a universe with physical parameters like our own? If so, our Universe may have given rise to billions of similar universes. Even more common than supermassive black holes are those formed in stellar collapse. Ifthese objects create new universes, then our own Universe may have 1018 offspring!

role? What happens if several black holes merge? And so on, and so on.) Until we have a quantum theory of gravity, we cannot begin to attack such questions. Nevertheless, Smolin's idea has a certain attraction: it links key scientific ideas — evolution, relativity and quantum theory — to explain the long-standing puzzle of the values of the fundamental parameters of physics. Moreover, it makes a specific forecast, a prediction against which the theory can be tested. The prediction is that, since we live in a Universe that creates many black holes and can therefore assume that the fundamental parameters are close to optimum for black-hole formation, a change in any of the fundamental parameters would lead to a Universe with fewer black holes.68

In a few cases, physicists have been able to calculate what would happen if a fundamental parameter differed from its observed value. In each case, it would indeed lead to a reduction in the number of black holes formed by stellar collapse. At present, though, we do not understand enough about astrophysics to calculate the effects of varying all the parameters. Smolin's idea is neither ruled in nor ruled out; it remains an intriguing speculation.

Edward Harrison takes the speculation one step further.69 He too highlights the long-standing puzzle of why the physical constants seem to be just right for the development and maintenance of organic life. Smolin's theory goes part of the way to explaining the puzzle, but Harrison argues that the link between black-hole formation and the conditions necessary for life is too tenuous. Suppose, though, some time in the future, Smolin's idea transmutes into established cosmological theory. Then, Harrison suggests, we might come to believe we should make as many black holes as possible, for in doing so we would increase the probability that other universes might contain intelligent life. If in the far future we might create child universes, perhaps our own Universe was created by intelligent life. Perhaps God did not labor for six days; maybe it was an ETC, in a universe with fundamental physical parameters much like our own, that labored to create a black hole — a black hole that led to the formation of our Universe.

I am not sure if Harrison's suggestion could ever resolve the Fermi paradox. Could the ETC squeeze some sort of message through the bounce that creates another universe? If not, how could we ever know whether our Universe was artificially produced in a laboratory inside some other universe? The notion that they could squeeze through a message is, however, intriguing. Even if it happened that our Universe was devoid of other intelligent life, we would at least know we were not alone ... sort of, anyway.70

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