The Edge of Evolution
Page 24
Let me be clear. I am not saying the origin of life was simply an extremely improbable accident. I am saying the origin of life was deliberately, purposely arranged, just as the fundamental laws and constants and many other anthropic features of nature were deliberately, purposely arranged. But in what I’ll call the “extended-fine-tuning” view, the origin of life is merely an additional planned feature culminating in intelligent life. The origin of life is simply closer to the very same goal that the other, more distant anthropic features (laws, chemical properties, and so forth) were also put in place to bring about. Nonetheless, just as it was possible to discover a set of proximate conditions that would lead to the origin of the moon, it may also be possible to arrange a local set of conditions that would lead to life, and that would be a scientifically interesting project. If it succeeded, some would claim that it revealed that life needed no miracle. But in fact it would show the beginning of life needed a directing intelligence.
DESCENT BY NONRANDOM MUTATION AS MULTIPLE FINELY TUNED EVENTS
Fine-tuning doesn’t stop at life’s origin. One can view all necessary biological features that are beyond what it’s biologically reasonable to expect of unintelligent processes—for example, all cellular protein complexes containing two or more protein-protein binding sites—as just more and more and more examples of the fine-tuning of the universe for life, akin to the unique events that produced the moon. But in these cases the fine-tuning is actually within the fabric of life itself. As Darwin thought, life descended with modification from one stage to another. Mutations arose in a long series—but many were not random. After the first DNA was formed by purposeful, anthropic events, felicitous mutation kept piling on felicitous mutation, either one by one or in larger clusters, at just the right times they were needed, in a way we have no statistical right to expect, like cosmic detail after cosmic detail in the universe, like ball after ball in the side pocket, to yield the multiple coherent features we find in the cell.
As with the origin of life, it may be possible for scientists to select proximate physical conditions in the laboratory, and deliberately cause batches of certain mutations to occur at the right times, and that would be a scientifically interesting project. But without the intimate involvement of a directing intelligence, they would not come about in nature.
From what has been learned in the past few decades about the complexity of the genetic basis of animal development, it seems reasonable to think that purposeful design extends into biology at least to the level of the major classes of vertebrates, perhaps further. Figure 10.1 illustrates this view. As the figure suggests, design of the universe at large and design in biology can be viewed as all of a piece—simply the purposeful arrangement of all the surprisingly many parts that science has discovered are necessary for life, both internal and external to it. The planning that went into the laws of the universe or the properties of water is no different in principle from the planning that went into details of the molecular machinery of life. In the extended fine-tuning view I am presenting, general anthropic coincidences are just the very beginning, akin to the smooth pool table in a trick shot. The depth of the black region in Figure 10.1 simply takes into account that scientific progress has shown enormously greater planning is needed for life, far beyond the general laws of nature.
FIGURE 10.1
The surprising degree of fine-tuning of nature required for life on earth.
Deep consilience wells up from a consideration of the basic laws of the universe, the chemistry of certain molecules, terrestrial features, and life itself. That consilience is reminiscent of Isaac Newton’s uniting of celestial and terrestrial motion under a single explanation. Just as he demonstrated that the heavens are governed in the same way as the earth, so too has the hard work of many scientists across many scientific disciplines in the past century unexpectedly demonstrated that both the universe at large and the earth in particular were designed for life. The heavens and earth—and life itself—alike are fine-tuned.
That need not have been the case. Compared to modern scientists, nineteenth-century scientists knew little of the depth of fine-tuning in nature. When unknown laws of physics were later discovered, when new properties of elements were elucidated, when the environments of other planets such as Venus and Mars were explored, for all scientists knew or expected, these discoveries might have shown that producing life was not very difficult. When the cell was probed, it might have turned out to be the “simple little lump of albuminous combination of carbon”13 that Ernst Haeckel innocently expected more than a century ago, rather than the elaborate mechanized factory it is now known to be.
From the far reaches of the universe to the depths of the cell, separate branches of modern science have all discovered astonishing, unexpected fine-tuning—design. As philosopher William Whewell, who coined the term consilience, noted in the nineteenth century, “When an Induction, obtained from one class of facts, coincides with an Induction, obtained from another different class,” we can be very confident it is correct.
IS EVERYTHING DESIGNED?
Here’s an important question. If design extends from the bottom of physics up to higher levels of biology, is everything in between also designed? Is nothing left to chance? No, there’s no scientific reason to think that any but a minuscule fraction of the details of the universe or life are intended. To understand why, let’s briefly reconsider the pool table illustration, but with a twist. Suppose on an oversized pool table there were ten numbered red balls and a thousand unnumbered green ones. The cue strikes a ball, which hits another, and at the end of the videotape we see the ten red balls all falling one by one, in numerical order, into the side pocket, but the green balls come to rest scattered on the pool table surface. We could confidently conclude that the trick shot was meant to sink all the red balls, but couldn’t say much about the fate of the great majority of green balls. For all we could tell, where the green balls ended up—after playing whatever role they had in affecting the path of the red balls—was of no concern to the pool shark who set up the shot. The path of the red balls to their resting point certainly was designed, but the path of everything else probably was a chance artifact of that plan.
Similarly, although we have compelling evidence that the universe was designed for life, we have no scientific evidence for the design of the details of most inorganic matter. Our nascent world might have benefited from a planned collision in order to prepare it for intelligent life, but there’s no reason to think that all—or even many—astronomical collisions in the universe are planned. The very great majority of the universe might proceed on its merry way without any particular relevance to life on earth, even if a prime goal of the universe was to produce intelligent life on earth.
The very great majority of terrestrial biology might proceed the same way, too, without any necessary, direct connection to the goal of intelligent life. The overwhelming number of mutations may be due to chance (to little constructive effect), numerically swamping the comparatively few due to design (which nonetheless are inordinately significant). Explicit design appears to reach into biology to a certain level, to the level of the vertebrate class, but not necessarily further. Randomness accounts perfectly well for many aspects of life. Contingency is real.
LUSH LIFE
Whenever one tries to address the most basic questions, such as where did the universe, life, and mind come from, some of the prospective answers sound strange. Design isn’t the only option. There is an alternative response to anthropic arguments: Our universe wasn’t designed—we’re just lucky. Our universe is just one of many universes, and we happen to live in the right one. Which idea is the stranger of the two?
The Oxford philosopher Nick Bostrom explains the multiple-universe idea this way:
[The multiverse hypothesis, or “ensemble” hypothesis] states that the universe we observe is only a small part of the totality of physical existence. This totality itself need not be fine-tuned. If it is sufficie
ntly big and variegated, so that it was likely to contain as a proper part the sort of fine-tuned universe we observe, then an observation selection effect can be invoked to explain why we see a fine-tuned universe. The usual form of the ensemble hypothesis is that our universe is but one in a vast ensemble of actually existing universes, the totality of which we can call “the multiverse.”14
In other words, just as medieval astronomers were wrong to take the universe to be only what they could see with their crude telescopes, so might we be wrong to take all of physical reality to be limited to what we can see even with our more advanced instruments. What we have been pleased to call “the universe” might actually be just a tiny part of a much larger “multiverse,” which, because it’s so big, we can’t see.
How might a multiverse help explain fine-tuning? As Bostrom indicates, if a multiverse consisted of a huge collection of relatively isolated universes, each of which was (somehow) randomly assigned values for the laws and constants of nature, the odds might be pretty good that some of the universes would have values that at least allow life. Most philosophers and physicists who think about such things stop there, because they assume life would then be able to get going without too much trouble. As we’ve seen in this book, that’s not the case. Even so, if the number of universes in the multiverse were extraordinarily large, then over that vast space the odds might be pretty good that some of them would have all of the extended fine-tuning we find in physics, astronomy, chemistry, and biology. There might be many universes that had the same laws and constants as our own. Most of these would not develop life, but by chance some might have experienced something like a Mars-sized planet hitting a developing earth at the right time. Of those, most would still not develop life, but by extraordinary chance some might have experienced the right molecule collisions for the origin of life. Of those almost all would not develop intelligent life, but again, by extraordinary chance some might have experienced the right mutations at the right times, singly or in large clusters as needed, and intelligent beings would appear.
Would it then be remarkable that we found ourselves in a universe that both permitted and actually developed life? The ensemble hypothesis says no. There might be a zillion dead universes that couldn’t develop life, and just one that could and did. But that’s the one we simply must be in. By definition we have to exist in a universe that not only was compatible with intelligent life, but also actually developed it, because any universe containing us by definition fits the bill.
Notice that the multiverse scenario doesn’t rescue Darwinism. Random mutation in a single universe would still be terribly unlikely as a cause for life. Incoherence and multiple steps would still plague any merely Darwinian scenario in any one universe. In the ensemble hypothesis, the extremely long odds against life are overcome only by brute numbers of universes, not by random mutation and natural selection. Still, although it doesn’t help Darwinism, the multiverse scenario would undercut design. If it were true, life wouldn’t be due to either Darwin or design. Seen from the proper perspective, it would be one big accident.
Needless to say, the multiverse is speculative.15 Some physicists have proposed mathematical models that they think might indicate something like a multiverse, but the models are pretty iffy. And some multiverse models themselves require much fine-tuning to make sure that, if real, they would generate universes with the right properties.16 Nonetheless, let’s assume two of the strongest possible general versions of the multiverse scenario and consider some of their serious shortcomings. The two versions: 1) a finite number of random17 universes in a multiverse; and 2) an infinite number.
Let’s assume a multiverse with a tremendously large but finite number of random universes. In some universes life arises by chance, and we, of course, live in a universe that both permits and contains intelligent life. Beyond that, what should we expect of our world, our earth? Statistically, we should predict that the world has taken the fewest possible steps needed to produce intelligent life, and that no life in the world contains any complex, coherent machinery that isn’t required, directly or indirectly, to support intelligent life. (This is a game of pure logic, so bear with me.) The reason we should expect it is that the only thing that needs to be special about the universe, by the definition of our theory, is that intelligent life should exist to ask questions and observe what’s going on. Beyond that, the universe should be run-of-the-mill.
Here’s an analogy to help illustrate. Suppose in a large room were gathered everyone who had won a prize in the past year in the Powerball lottery, no matter how large or small. They were all having a party, closed to the public. You (who haven’t won a dime) are an autograph hound and want the signature of a grand prize winner. So you sneak into the guarded room and meet someone at random. What are the odds that the first person you meet is a big-money winner? Very slim.18 The great majority of folks there will be minimum or small prize winners. That is, a person selected at random from the “winners” category very likely will fulfill just the minimum requirements for getting into the room.
The same goes for universes. On the finite random multiverse view, we should very likely live in a bare-bones world, with little or nothing in life beyond what’s absolutely required to produce intelligent observers. So if we find ourselves in a world lavished with extras—with much more than the minimum—we should bet heavily against our world being the result of a finite multiverse scenario. Now let’s return from pure logic to the earth as we know it. Is it a bare-bones producer of intelligent life, or is it much more than that? It’s difficult to make a rigorous argument on such a question. Yet it certainly seems that life in our world is quite lush and contains much more than what’s absolutely needed for intelligence. Just as one familiar example from this book, the bacterial flagellum seems to have little to do with human intelligence, but is tremendously unlikely. If I am correct that it isn’t required to produce intelligent observers, then only one in a very large number of universes that had intelligent observers should be expected to also have bacteria with flagella. As a practical matter it’s impossible to absolutely rule out that at some point, in the history of life, the flagellum played a crucial role leading to intelligence.19 But until we find convincing evidence for that, and for the role of much else in biology whose connection to intelligence is obscure, we should regard the finite random multiverse as a beguiling but quite unlikely hypothesis.
BRAIN IN A VAT
What if a multiverse contained not just a tremendous number of universes, but an infinite number? In that case the situation changes utterly—and becomes very weird indeed. Infinity is not just some ultrabig number; it’s a completely different and strange case. If the number of universes in the multiverse were infinite, and if all the necessary factors such as laws, constants, and so on could vary in the right ways, there would not just be rare, occasional universes like ours—there would be an infinite number identical to it. There also would be an infinite number of universes almost identical to ours, where everything was the same except for some trivial detail; where, say, instead of hesitating for two seconds after the traffic light turned green last Tuesday morning, you (or your double) hesitated for three seconds. And there would be an infinite number where more and more aspects differed. There would also be an infinite number of dead universes, without the necessary or sufficient conditions for life.
If you think all that’s odd, consider this. There would also be an infinite number of universes that did not have what are usually considered the necessary conditions for the gradual development of intelligent life, but nonetheless contained it. An infinite number of universes would harbor an infinite number of “freak observers.” In his scholarly book Anthropic Bias philosopher Nick Bostrom explains:
Consider a random phenomenon, for example Hawking radiation. When black holes evaporate, they do so in a random manner such that for any given physical object there is a finite (although, typically, astronomically small) probability that it will be emitt
ed by any given black hole in a given time interval. Such things as boots, computers, or ecosystems have some finite probability of popping out from a black hole. The same holds true, of course, for human bodies, or human brains in particular states. Assuming that mental states supervene on brain states, there is thus a finite probability that a black hole will produce a brain in a state of making any given observation. Some of the observations made by such brains will be illusory, and some will be veridical. For example, some brains produced by black holes will have the illusory of [sic] experience of reading a measurement device that does not exist.
…It isn’t true that we couldn’t have observed a universe that wasn’t fine-tuned for life. For even “uninhabitable” universes can contain the odd, spontaneously materialized “freak observer,” and if they are big enough or if there are sufficiently many such universes, then it is indeed highly likely that they contain infinitely many freak observers making all possible human observations. It is even logically consistent with all our evidence that we are such freak observers.20
The Twilight Zone was never so bizarre. In a nutshell: In an infinite multiverse, probabilities don’t matter. Any event that isn’t strictly impossible will occur an infinite number of times. So (if thinking depends solely on a physical brain), by utter chance in an otherwise dead universe, matter might spontaneously arrange itself into a brain that would contain the true thought, “I am a spontaneously materialized brain in an otherwise dead universe.” That will happen a limitless number of times in an infinite multiverse. Matter may also arrange itself into brains with any of an infinite number of false-but-detailed thoughts and memories, such as: “I am a spontaneously materialized brain in a universe that contains one other brain” (but no other brain actually exists there); “I am the Vulcan Mr. Spock with a beard”21 (but really am a lone brain in outer space); “I am a person reading a book in the twenty-first century United States” (but, again…). All false thoughts, no matter how detailed, no matter how vivid, will occur without end.