Multiverse Cosmology and the Origin of Life
Scientists have increasingly recognized that the probabilistic resources of the observable universe are insufficient to explain—by chance alone—the origin of a minimally complex cell or even a self-replicating system of RNA molecules (or even, for that matter, a single protein of modest length). In response, some scientists have sought to explain the origin of life by invoking other materialistic mechanisms or self-organizational processes. But as noted in Chapters 11–14, theories of this kind have also fallen on hard times. As a result, a few scientists have looked beyond our universe for additional probabilistic resources by which to render a chance explanation for the origin of life more plausible.
In May 2007, Eugene Koonin, of the National Center for Biotechnology Information at the National Institutes of Health, published an article in Biology Direct entitled “The Cosmological Model of Eternal Inflation and the Transition from Chance to Biological Evolution in the History of Life.” In it, Koonin acknowledges that neither the RNA world nor any other materialistic chemical evolutionary hypothesis can account for the origin of life, given the probabilistic resources of the entire universe. As he explains: “Despite considerable experimental and theoretical effort, no compelling scenarios currently exist for the origin of replication and translation, the key processes that together comprise the core of biological systems and the apparent prerequisite of biological evolution. The RNA World concept might offer the best chance for the resolution of this conundrum, but so far cannot account for the emergence of an efficient RNA replicase or the translation system.”1
To address this problem, Koonin proposes an explanation for the origin of life based purely on chance. His particular chance explanation, however, does not refer to any process taking place on earth or even within the observable cosmos. Instead, he posits the existence of an infinite number of other life-compatible universes, since, he argues, the existence of such universes would render even fantastically improbable events (such as the origin of life) probable or even inevitable.
To justify his postulation of other universes, he invokes a model of cosmological origins based on inflationary cosmology dubbed the “many worlds in one” hypothesis by cosmologist Alexander Vilenkin. According to inflationary cosmology, in the first fraction of a second after the big bang our universe experienced an exponentially rapid rate of expansion, after which its expansion settled down to a more sedate pace. Inflationary cosmology was originally proposed in order to explain two features of the universe that were puzzling from the perspective of standard big-bang cosmology—its uniformity (homogeneity) and its flatness.
By homogeneity, cosmologists mean that the universe looks the same to all observers, no matter where they are located. One aspect of this homogeneity is the uniformity of cosmic background radiation, which has the same temperature throughout the observable cosmos. This is a problem in standard big-bang cosmology. According to the big-bang theory, up until about 300,000 years after the beginning of the universe, the photons in the background radiation would have been bouncing off the electrons in the hot plasma that filled the entire universe. At that point the universe would have cooled enough for electrically neutral atoms to form, releasing the background radiation. This radiation eventually reached us, giving us a picture of the universe at around 300,000 years of age.
The puzzling thing about this radiation is that it has the same temperature in every direction to about one part in a hundred thousand. This implies that the universe at 300,000 years old was incredibly uniform in temperature, which in turn would have required very precise initial conditions. It follows that the observed uniformity of the background radiation can be explained in the ordinary big-bang scenario only by postulating that the initial state of the universe was one of almost perfect uniformity in the temperature and distribution of the plasma, which in turn requires a very precisely fine-tuned initial explosion.2
A homogeneous universe is called “flat” if it is balanced between eventual gravitational collapse and eternal expansion; in such a case its geometry would be precisely Euclidean and space would not be curved. The universe achieves such flatness when the actual mass density in the universe is very close to the critical mass density (the density required to halt the expansion of the universe)—that is, if the ratio between the actual and critical mass densities is close to one. In our universe, the ratio of these two quantities is ever so slightly less than one. As a result, our universe will keep on expanding without a gravitational recollapse, and space has hardly any overall curvature. That these values were so precisely balanced is surprising from the standpoint of standard big-bang theory, because, again, for this balance to arise, the universe would have needed to have very finely tuned initial conditions.
Inflationary cosmology attempts to explain the horizon problem (homogeneity) not as the result of these finely tuned initial conditions (though it does invoke special conditions of its own; see below), but instead as a consequence of an early, exponentially rapid rate of cosmic expansion. According to the inflationary model, during the first fractions of a second after the big bang the temperature of the universe had a chance to homogenize. Then the rapid expansion of the universe distributed this homogeneous radiation throughout the observable universe. It also pushed any remaining inhomogeneity beyond the edge of the observable universe.3
In current models, inflation begins at around 10–37 seconds after the big bang and lasts until 10–35 seconds, during which space itself expands by a factor of 1060 or so. At the beginning of the inflationary epoch the observable universe was, say, about 10–60 meters in size and at the end of it about a meter across. At the start of inflation, however, the horizon size (the distance light traveled since the big bang) was 10–37 light-seconds, which is far larger than the tiny patch that was destined to grow into our observable universe. Thus, the inflationary process not only distributed the homogeneous background radiation throughout the observable universe, it also distributed any remaining inhomogeneity beyond the edge of the observable universe.
Inflation explains the near flatness of the universe as a consequence of the hyper-expansion as well. During the inflationary epoch, all the distances in the universe increased by a measure of 1060, which means the radius of the observable universe increased by this factor as well. Suppose the four-dimensional space-time of the universe prior to inflation had positive curvature, like the surface of a balloon does in three dimensions, and that its radius was a billionth of a meter (a nanometer). After inflation, its radius would be 1051 meters, or about 10 billion trillion trillion light-years. Just like inflating a balloon to larger and larger sizes makes a small patch of it look flatter, so inflating the whole universe makes the observable patch of space-time look flatter and flatter.
Inflationary cosmology is relevant to discussions of the origin of life, because some cosmologists think that it provides a mechanism for generating many universes other than our own, and also because one prominent molecular biologist has recently invoked those other universes in an attempt to explain the origin of life. According to the currently dominant “chaotic eternal inflationary model,” the rapid expansion of the universe was driven by an “inflaton field”—a repulsive gravitational field. After an initial phase of expansion, the inflaton field decayed locally to produce our universe. However, it also continued to operate at full strength outside the local area to produce a wider expansion of space into which other universes were birthed as the inflaton field decayed at other locations. Thus, inflationary cosmologists postulate the decay of the inflaton field as a mechanism by which other “bubble universes” can be created. They also postulate that inflation can continue indefinitely into the future and, therefore, that the wider inflaton field will spawn an endless number of other universes as it decays in local pockets of the larger and larger expansions of space. Since the inflaton field continues to expand at a rate vastly greater than the bubble universes expanding within it, none of these bubble universes will ever interfere with each other. The one inflaton field therefore gives birth to endless bubble universes—“many worlds in one,” as Vilenkin colorfully describes it.4
Koonin has appropriated this cosmology in order to explain the origin of life by chance. Following Vilenkin, he argues that since the inflaton field can produce an infinite number of other universes, every event that has occurred in our universe was bound to occur somewhere endlessly many times. Thus, events that appear to be extremely improbable when considering the probabilistic resources of our universe are actually highly probable—indeed, inevitable—given the plethora of other universes that do—and will—exist. As Koonin himself explains: “In an infinite multiverse with a finite number of distinct macroscopic histories (each repeated an infinite number of times), emergence of even highly complex systems by chance is not just possible but inevitable…. it becomes conceivable that the minimal requirement (the breakthrough stage) for the onset of biological evolution is a primitive coupled replication-translation system that emerged by chance. That this extremely rare event occurred on earth and gave rise to life as we know it is explained by anthropic selection alone.”5 By “anthropic selection,” Koonin simply means that our perception that life is incredibly improbable is just an artifact of our particular vantage point. Since we observe only one bubble universe, we do not realize that the existence of other universes and the mechanism that produced them makes life in a universe such as our own inevitable.
So has Koonin’s use of inflationary cosmology solved the problem of the origin of life and the origin of the biological information necessary to it? Has he proposed a better explanation for the origin of biological information than intelligent design? There are several reasons to think not.
Do Inflaton Fields Exist?
First, there are good reasons to doubt that inflaton fields even exist. Inflaton fields were postulated mainly to explain the homogeneity and flatness problems, but they may not explain these features of the universe well at all, as several prominent physicists have long pointed out. In order to explain the homogeneity of the universe using inflaton fields, physicists have to make gratuitous assumptions about the singularity from which everything came. As Oxford physicist Roger Penrose points out, if the singularity were perfectly generic, expansion from it could yield many different kinds of irregular (inhomogeneous) universes, even if inflation had occurred.6 Thus, inflation alone, without additional assumptions, does not solve the homogeneity problem. Getting workable results requires imposing the right metric (distance measure) on space-time.
Furthermore, as physicists Stephen Hawking and Don Page note, it has proven difficult to explain why inflaton fields and gravitational fields (as described by general relativity, which we have strong reasons to accept) should work together to produce the homogeneity of the background radiation and the flatness of space-time in our observable universe. Indeed, when the fields are linked, there is no guarantee that inflation will even take place.7 Moreover, these inflaton fields, with their uncanny ability to decay at just the right time (between 10–37 to 10–35 seconds after the big bang) and in just the right measure, have properties associated with no other physical fields. (Conversely, they have properties that were invented solely for the purpose of solving the horizon and flatness problems, which they can’t solve without additional arbitrary assumptions and specifications of initial conditions.)
Causal Adequacy Considerations
There is another reason that inflationary cosmology does not provide a satisfying explanation or a better explanation than intelligent design for the origin of biological information. Inflationary cosmology relies for its explanatory power on the presumed causal powers of an entirely unknown entity—one posited solely to explain a mysterious class of effects—and one whose causal powers have not been demonstrated or observed. We do not know if inflaton fields exist. And we do not know, if they exist, what exactly they can actually do. Nevertheless, we do know (from direct first-person awareness, if nothing else) that conscious intelligent minds exist and what they can do.
Further, as philosopher of physics Robin Collins argues, all things being equal, we should prefer hypotheses “that are natural extrapolations from what we already know” about the causal powers of various kinds of entities.8 In a slightly different context he argues that multiple-worlds hypotheses fail to meet this test in their explanations of the anthropic fine-tuning of the universe, whereas design hypotheses do not. To illustrate, Collins asks his readers to imagine a paleontologist who posits the existence of an electromagnetic “dinosaur bone–producing field,” as opposed to actual dinosaurs, as the explanation for the origin of large fossilized bones. Although certainly such a field qualifies as a possible explanation for the origin of the fossil bones, we have no experience of such fields or of their producing fossilized bones. Yet we have observed animal remains in various phases of decay and preservation in sediments and sedimentary rock. Thus, most scientists rightly prefer the actual dinosaur hypothesis over the apparent dinosaur hypothesis (i.e., the “dinosaur bone–producing field” hypothesis) as an explanation for the origin of fossils.
In the same way, we have no experience of anything like an inflaton field generating infinitely many universes (or, for that matter, any experience of any machine or mechanism capable of producing something as finely tuned as our universe that is not itself designed). Yet we do have extensive experience of intelligent agents producing finely tuned machines or information-rich systems of alphabetic or digital code. Thus, Collins concludes, the postulation of mind to explain the fine-tuning of the universe constitutes a natural extrapolation from our experience-based knowledge of the causal powers of intelligent agency, whereas postulation of multiple universes (including those produced by inflaton fields) lacks a similar basis. It follows a fortiori that the design hypothesis is a better explanation than inflaton-field decay for the origin of the information necessary to produce the first life, because it depends upon the known causal powers of an entity familiar from repeated and direct experience. Inflationary cosmology depends upon an abstract entity whose causal powers have not been observed or demonstrated.
Return of the Displacement Problem
There is an additional problem with using inflaton fields to explain the origin of the information necessary to produce the first life. In order to explain the origin of certain features of our observable universe, and (as an unintended bonus) the origin of presumably innumerable life-friendly universes such as our own, inflationary cosmology must invoke a number of unexplained sources or infusions of information. For example, both inflaton fields, and the fields to which they are coupled, have to be finely tuned in order to produce new bubble universes of the right sort. The “shutoff” of the energy of the inflaton field (which occurs during its decay) alone has to be finely tuned to between one part in 1053 and one part in 10123 (depending on the model of inflation invoked) to produce a bubble universe compatible with life. Additionally, inflationary cosmology makes the already acute fine-tuning problem associated with the initial low-entropy state of our universe exponentially worse. According to calculations by Roger Penrose (who regards inflationary cosmology as a very dubious enterprise), the initial entropy of our universe is already finely tuned to an accuracy of one part in 10exp (10exp(123)).9 Inflation not only does nothing to explain this fine tuning; it actually exacerbates it.
Some cosmologists argue, of course, that these improbabilities can be overcome by the number of bubble universes that the original inflaton field produces. But aside from the inelegance and lack of parsimony of this explanatory strategy, generating a larger inflaton field that produces the right results (i.e., a universe with the properties of our observable universe) itself depends on a number of gerrymandered assumptions and finely tuned initial conditions. As noted above, physicists make a number of gratuitous assumptions about the initial singularity in order to get the inflaton field to mesh with the theory of general relativity. For example, to get inflationary cosmology to harmonize with general relativity, cosmologists have to assume a specific way of measuring distance in space-time (a so-called metric) and reject others. In addition, there are a number of possible inflationary cosmological models, only some of which (when conjoined with general relativity) would actually cause universes to inflate. In order to ensure that inflaton fields will create bubble universes, physicists have to select some inflationary models and exclude others in their theoretical postulations. Each of these choices constitutes an informative intervention on the part of the modeler—one that reflects unexplained information that would have had to have been present in the initial conditions associated with the universal singularity.
Indeed, the need to make such assumptions and restrict theoretical postulations implies that the initial singularity itself would have had to have been finely tuned in order for any inflaton field to be capable of producing a universe such as our own. Yet we know that our universe exists. We also have good reasons for thinking that general relativity is true. Thus, if an inflaton field exists, it could operate the way that inflationary cosmologists envision only if the singularity from which the inflaton field emerged was itself finely tuned (and information-rich).
Thus, by relying on inflationary cosmology to explain the information necessary to produce the first life, Koonin has once again created an information problem in the act of purportedly solving one (see Chapter 13). Even assuming that inflaton fields exist and that they can create an infinite number of universes (by no means a safe bet), Koonin solves the problem of the origin of biological information by creating a new problem of cosmological information—information that, in his model, is nevertheless entirely necessary to explain the origin of life. Additionally, all inflationary models assume that the inflaton field operates within and creates new universes with the same basic laws and constants of physics that exist within our universe. Yet the laws and constants of our universe are themselves extremely fine-tuned to allow for the possibility of life. This fine tuning represents another source of information that has to be accounted for in order to explain the origin of life in our cosmos. Yet inflationary theory presupposes, rather than explains, the existence of this fine tuning.
An Epistemological Cost
Inflationary cosmology has yet another liability: once permitted as a possible explanation for anything, it destroys practical and scientific reasoning about everything. Inflationary cosmology can explain the origin of all events, no matter how improbable, by reference to chance because of the infinite probabilistic resources it purports to generate. It follows that events we explain by reference to known causes based upon ordinary experience are just as readily explained in inflationary cosmology as chance occurrences without any causal antecedent. According to inflationary cosmology, all events consistent with our laws of nature will eventually arise as the result of random fluctuations in the quantum vacuum constituted by the inflaton field. This means that an exquisitely designed machine or an intricately crafted piece of poetry is just as likely to have been produced by chance fluctuations in the quantum vacuum as by a human being. It also means that events such as earthquakes or regular phenomena such as condensation are just as likely to have been the result of chance fluctuations in the quantum vacuum as they are to have been the result of an orderly progression of discernible material causes. In short, if inflationary cosmology is true, anything can happen for no reason at all, beyond the supposed random fluctuations in the quantum vacuum of the inflaton field.
To make matters worse, inflationary cosmology actually implies that certain explanations that we regard as extremely improbable are actually more likely to be true than explanations we ordinarily accept. Consider the “Boltzmann brain” phenomenon, for example, over which quantum cosmologists have been greatly exercised. Within inflationary cosmology, it is theoretically possible for a fully functioning human brain to pop spontaneously into existence, due to thermal fluctuations in the quantum vacuum, and then disappear again. Such an entity has been called a “Boltzmann brain.” Under standard conditions for bubble-universe generation in inflationary cosmology, Boltzmann brains would be expected to arise as often, or more often, than normal occurrences in our universe. Indeed, calculations based upon some inflationary cosmological models lead to a situation in which these free-floating Boltzmann brains infinitely outnumber normal brains in people like us.10
The epistemological implications of this possibility have raised issues that cosmologists cannot ignore. If these inflationary cosmological models are accurate, it becomes infinitely more probable that we ourselves are free-floating Boltzmann brains than real persons with a history living in a universe 13.7 billion years old. In some models, it’s even more probable that a whole universe like ours could have spontaneously fluctuated into existence than it is that our universe with its extraordinarily improbable initial conditions would have evolved in an orderly and lawlike way over billions of years. This means that the many-worlds-in-one hypothesis generates an absurdity. It implies that we are probably not the people we take ourselves to be and that our memories and perceptions are not reliable, but quite possibly chance fabrications of quantum fields. Neither is our universe itself what it appears to be according to the hypothesis of eternal inflation. In short, the proposal Koonin has adopted to solve the origin-of-life problem renders all scientific reasoning and explanation unreliable, thus undermining any basis for his own explanation of how life came to be. It would be hard to invent a more self-refuting hypothesis than that!