The Majesty and Misery of String Theory
Science Fact or Science Fiction
A great crooner, if not exactly a great scholar, named Frank Sinatra once sang that he had the whole world upon a string. And as we all know song lyrics can sometimes paint a rather accurate picture of real life, while at other times they venture into altogether imaginative and existentially uncharted territory. Adopting a perhaps excessively critical attitude it is still by no means unfair to say that string theory1 is a theory en route to nowhere. It is a theory which, at its best, could conceivably capture the essence of material reality at its deepest level; or, at its worst, might be nothing more than an overblown tale with an overly complicated mathematical storyline. It is thought by many to represent a colossal attempt to trade atomism in for a theoretical framework involving multiple dimensions and vibrating Planck length pieces of primal string which supersede point particles as the basic building blocks of nature. String cognoscenti might also note that in recent years their theory has been enveloped within an even more extensive theory known as M-Theory which peddles in such exotica as multiple universes that are causally disjunct from our own. The goal of string theory is ambitious and includes: the elimination of all the explanatory enigmas which continue to plague the foundations of theoretical physics as well as the incorporation of all facets of our physical understanding into one wholly unified blueprint of material reality. But so far the victories of string theory, not to mention M-Theory, are only mathematical and its experimental pedigree only wishful thinking. Despite twenty or so years of touting in the popular scientific press by its leading exponents, the early promise of string theory is sagging under the weight of numerous and seemingly intractable problems, the most regrettable perhaps being its lamentable lack of empirical backing. Thus the once gloriously heralded future of this peculiar theory of everything could already be behind it. Without the prerequisite empirical corroboration necessary for a good scientific theory, a latter day David Hume might recommend that string theory be consigned to the flames along with various other dubious and theatrically excessive Idols of the mind.
We can venture to say that string theory is both miserable and majestic as a theory of material reality. String theory is majestic, in the eyes of its proponents, in that it encompasses, at least in principle as well as in aspiration, all that physical science purports to explain: both macroscopically â€“ on the scale of the universe; and microscopically â€“ on the subatomic or quantum scale at which General Relativity is thought to fail. It is at one and the same time utterly miserable and empirically impoverished in that it can, as yet, recite no litany of experimental successes to reinforce any of its as of now perhaps unjustified high hopes. Even an experimental falsification of the theory would be a welcome result. Should string theory somehow be able to overcome its plethora of problems, then for religious believers its true majesty would consist not merely in its explanatory scope in regard to material reality, nor in its successful unification of all the fundamental forces of nature including gravity, but in that it could conceivably constitute a comprehensive material pointer to a reality that is not of this world. But while string theory may purport to offer scientific solutions to scientific problems, we all know that no purely scientific theory can ever offer anything approaching a solid metaphysical foundation. Thus any proposed or purported metaphysical majesty for string theory would be limited at best. For it can never enable us in a Lear-like fashion to take upon ourselves the mystery of things. My aim in this essay is to straddle both sides of the string theory coin, the miserable and the would-be majestic. First I will side with those who maintain that string theory does not merit the status of a scientific theory, and secondly I will briefly consider the credentials of string theory in relation to the realm of religion.
When Mathematics Masquerades as Science
If you were to visit the Rugby school in England you would find a plaque which states that in 1823 a certain student named William Webb Ellis picked up a soccer ball in the midst of competition and ran with it, with a fine disregard for the rules of the game. Thus the game of rugby was born. Many practitioners and students of science and its philosophy might espouse something similar concerning the nature of string theory in that its dream team of theoretical all- stars might be said to have utterly disregarded what we ordinarily consider to be the conventional, by this I mean empirical, way of doing science in a post-Baconian world. On the one hand string theory can be likened to medieval scientific theories of old in that it is a purely mathematical theory without experimental support. An important caveat to such a comparison of course is that medieval theories were much more qualitative than quantitative in nature. Francis Bacon once compared such a medieval and non-empirical approach to theory construction to the spider who spins a web of marvelous ingenuity from the material contained within its own body. On the other hand Edward Witten, one of the high priests of the string revolution, once suggested about twenty years ago that string theory was futuristic, calling it a twenty first century theory that somehow accidentally managed to make its way onto the scientific stage well ahead of its appointed time. By this he meant that the mathematics needed to insure the theory against various mathematical calamities, such as the cropping up of unwanted infinities, had not yet been invented. Regarding the mathematical nature of string theory, Witten also points out that its development has been the reverse of that of General Relativity.2 Whereas Einstein employed the non-Euclidean geometry of Riemann in order to flesh out his own previous intuition of a physical equivalence between acceleration and gravity, string theory was introduced as a mathematical theory still in search of a physical intuition analogous to that which guided Einstein.
While Descartes may have equated physics with mathematics, namely geometry, scientific theories still need to avoid, despite the growing popularity of unifying trends such as consilience and transdisciplinarity, any such parity between two such distinct disciplines. Admittedly, Aristotleâ€™s own metaphysical segregation of physics from mathematics may have contributed to the snail-like advancement of science in succeeding centuries; nevertheless, the line of demarcation he erected between them should not be torn down. While mathematics is a powerful tool for describing the present world, as well as for predicting its future states, we should nevertheless always remain wary in regard to whether any mathematical theory alone can ever perfectly model physical reality, without losing something in the translation. Recall that while Platoâ€™s cosmological tale in the Timaeus was wholly mathematical, it was also told in the spirit of what he meant by a noble lie in the Republic. G.K. Chesterton once suggested that skepticism is to the rich what demon rum is to the poor â€“ an easy way out of contemplating the complex and often sobering verities of life. But in the case of string theory skepticism comes very easily to anyone who cherishes corroboration over the mere intoxicating phantasms of the mathematical imagination. Yet it could still be correct and my admonitions nothing more than the droning of just one more devilâ€™s advocate.
String Theory and its Discontents
Most of you have probably heard the saying that absence of evidence is not, strictly speaking, evidence of absence. Those with some background in logic will also realize that such a piece of colloquial wisdom captures the gist of the informal fallacy known as the Argumentum ad ignorantiam. Thus string theory is not necessarily dead in the water simply because its predictions continue to dangle untested in the rarefied air of some Ivy League or government funded laboratory. Its growing list of critics however is quite impressive. Nobel laureate Sheldon Glashow is dead set against what he views as the â€œmagical coincidencesâ€ and â€œmiraculous cancellationsâ€ which crop up in string theory, which make it seem as if â€œmathematics and aesthetics supplant and transcend experiment.â€ Lawrence Krauss of Case Western Reserve University in Cleveland refers to string theory as â€œa colossal failure.â€ Whether on a good or a bad day he seems always willing to remind anyone who will listen of the fact that his professional colleagues once bemoaned the fact that Einstein spent the last thirty years of his life in a fruitless and premature search for a unified theory while, hypocritically, thousands of present day string theorists are praised to high heaven for frittering away entire careers in pursuit of the very same type of quest. Lee Smolinâ€™s recent book entitled The Trouble with Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next is meant to serve as an antidote to the plethora of books and articles in recent years which have served up a steady diet of still unfulfilled promissory notes to a by now string-besotted scientific public. And that former enfant terrible of physics Richard Feynman was perhaps the most scathing of all in his denunciation of the empirical shortcomings of string theory when he indicated that: â€œstring theorists donâ€™t make predictions, they make excuses.â€3
Impersonation of a Scientific Theory
While it may be a crime to impersonate a police officer or a member of the Metanexus Institute in good standing there exists no statutory penalty for dealing with theories which would wrongly claim the mantle of being scientific. Even as a purely mathematical conception string theory is not trouble free. The mathematical complexities of string theory continue to limit theorists to seeking â€œapproximate solutions to approximate equations.â€4 Its history so far has been a constant battle with Ockhamâ€™s razor in that multiple versions of the so-called theory, which allows as many as 10500 possible alternative solutions, once made it increasingly difficult for string theorists to discern which is the one that might fit our world, thus leading them to mathematically compensate with the concoction of the more fantastic and supposedly even more fundamental M-Theory from which each of these versions are thought to be derived. The universe in which we live therefore is now claimed by a host of string theorists to be the actualization of but one of an extremely large number of theoretical possibilities. In moral theory we often evaluate end of life scenarios in terms of ordinary versus extraordinary means of prolonging life. The vast majority of proposals for directly testing string theory have hitherto involved a probing into the minutest of spatial scales, and hence would require extraordinary and prohibitive amounts of energy, on the order of 1019 billion electron volts, that are certainly out of the reach of any existing or projected particle accelerators here on planet earth. If the empirical corroboration of string theory requires such extraordinary means then why should the scientific community not consider following in the footsteps of those moral theorists according to whom lives which have run their normal course, and which have no expectation of extension by the application of ordinary measures, are allowed to expire with dignity?
But string theorists, perhaps properly so, still rally around various flickers of hope. Let me mention just two. One such as yet unrealized hope is based upon the possibility that the seemingly sacred inverse square relationship between the force of gravity and the distance of separation between massive objects could in principle be violated in certain regions of space according to the predictions of string theory. While the gravitational force, as well as the electrostatic force between electrically charged objects, varies according to the relation 1/r2 (r = distance) in three spatial dimensions, it would vary by 1/rD-1, where D equals the number of physical dimensions comprising space, in larger dimensional spaces. If string theory is correct in predicting that extra dimensions of space exist then we might expect to find a fluctuation in the force of gravity somewhere in our universe. Quite mind numbing is the M-Theory claim that hidden universes exist whose detection would also involve a change in the gravitational force, for example, from 1/r2 to 1/r3 at some critical point of separation between our visible universe and some ghostly partner.5 String theory also predicts what is known as supersymmetry, which stipulates that all mass bearing particles are related to corresponding force bearing particles. String theorists state they are sanguine that the new Large Hadron Collider at CERN in Geneva might provide confirmation of this crucial string theory prediction in the near future with its projected capacity for proton collisions anticipated to be around seven trillion electron volts. The alert reader will no doubt note that such a figure is nonetheless orders of magnitude below the 1019 billion electron volts previously indicated as a minimum requirement.
Given all of these albeit brief considerations we can legitimately cast suspicion upon the credentials of string theory as a scientific theory. It would not be far wrong in the view of many to characterize string theory, with its experimentally unsubstantiated commitments to unseen physical dimensions and alternative universes, as a set of beliefs that has transgressed the bounds of common sense into the realm of the kind of superstition which scientific materialists often ascribe to religious believers. This might sound like a cheap criticism to make, but it scarcely comes close to the level of ridicule once heaped upon the formidable mathematical abstractions of string theory by physicist Murray Gell-Mann when he referred to such a mathematical monstrosity as a form of self abuse. To be fair Gell-Mann has since recanted his opposition to string theory.
Harvard particle theorist Lisa Randall defines a theory as â€œa definite physical framework embodied in a set of fundamental assumptions about the world — and an economical approach that encompasses a wide variety of phenomena. A theory yields a specific set of equations and predictions — ones that are borne out by experimental results.â€6 In other words a theory is a conceptual structure that is used to explain existing facts and predict new ones. A scientific theory which makes erroneous predictions qualifies as a bad theory. A theory whose advocates continue to defend it against the caviling of pontificating Popperazzi, if I may borrow the clever phrase of Leonard Susskind, who insist at the very least that string theory ought to be amenable to possible experimental refutation is not only not right, it is not even wrong.
As it now stands it is not that farfetched to condemn string theory as a pseudoscience, a piece of science fiction which just happens to be written in the language of mathematics. While string theory has siphoned off mathematical resources on its own behalf, it has also returned the favor. Yet while it is true that various mathematical spin-offs from string theory have already begun to enrich other branches of physics, such as condensed matter physics and quantum gravity; let us not forget, as Lee Smolin has pointed out, that Ptolemaic astronomy at one time was a breeding ground for trigonometric advances. Yet as we all know its vast assortment of epicycles and other astronomical devices never did quite manage in the long run to convince us of its conformity with nature. There does not as yet exist a complete formulation of string theory. Its basic principles and fundamental equations have yet to be worked out to any degree of formal rigor. On the other hand one might defend string theory in this regard by pointing out that quantum field theories are also defined in terms of approximation procedures. It is by no means an admission of ignorance to endorse the view that string theory is not really a scientific theory. It is a proliferating collection of promissory notes, a cluster of hopes that such a theory may yet exist. Thomas Henry Huxley once said that â€œthe great tragedy of science consists in the slaying of a beautiful hypothesis by an ugly fact.â€ String theory should be so lucky.
String Theory and the Rock of Ages
Sociologically, string theory has taken on the status of a cult-like phenomenon, reminiscent of the heydays of Marxism, psychoanalysis, and even sociobiology. In some of the upper echelons of job hiring within physics string theory enjoys a virtual monopoly. With few exceptions, for example, no assistant professorships have been awarded by U.S. research oriented institutions since 1990 to researchers working in the field of quantum gravity whose work is not based upon either string theory or the existence of extra dimensions, according to bestselling science author and physicist Lee Smolin.7 And according to particle physicist JoAnne Hewett, more than a few of the most fanatical of the string theorists exude an arrogance that is utterly astounding, even in comparison to the often supercilious demeanor of many professional physicists.8 Writers such as Ian Barbour and John Haught have developed well known taxonomies which describe the possible ways of understanding the interface, incommensurability, or degree of estrangement between science and religion. Purported Theories of Everything (TOEâ€™s) such as string theory, push the frontiers of our natural knowledge, at least in principle, to their furthest possible extent. String theory thus has the potential for transporting us to the point where the natural and the supernatural either come into contact, clash, or reinforce each other. For religiously minded people string theory, should it be both bona fide science and ultimately correct, cannot be anathema to religion. As Ralph Waldo Emerson points out: â€œthe religion which fears science, insults God and commits suicide.â€9
Gerald Cleaver of Baylor University writes that â€œstring theory, if correct, presents us with Godâ€™s blueprints for creation. Rather than the music of the spheres, all creation is literally composed of the music of the strings.â€10 Cleaver thus paints a picture of string theory in its most majestic pose. In recent years Leonard Susskind, one of the original architects of string theory, has become a champion for the string-based resuscitation of the Anthropic Principle.11 Does this mean that he endorses the view, following Cleaver, that string theory provides a vital clue to the teleological handiwork that may have been inscribed into the fabric of the universe by some unseen Author? Not quite. For Susskind the mechanism known as eternal inflation, which represents an exponential cloning of space that spawns infant universes, coupled with the built-in plenitude of string/M theory not only allows for, but indeed requires, a landscape consisting of an unfathomable yet still finite number of possible universes in which probability dictates that the probability of a universe arising so as to support intelligent life is practically equal to 1. In this way string theory is claimed to provide a real world alternative to the Many Worlds interpretation of quantum theory. But surely this is little more than, in the eyes of its most virulent detractors, speculatively unsupported hogwash. It also begs the ultimate question of origination for those who side with Kant, despite the latterâ€™s skepticism regarding traditional theistic proofs, that the teleological is subsidiary to the cosmological argument. Susskindâ€™s position is surely anthropic in name only. It does however point up the need for theists to allow for the possible existence of many more as yet undiscovered levels of intermediate efficient causes, in attempting to account for the fine tuning of the various constants and other physical parameters, situated between our present cosmic reality and its primary causal origin.
One seemingly obvious but unnoticed tie between string theory and religious belief is that strings, as far as I can tell, are not material things. Material particles are said to result from the vibrations of strings. When string theorists inform us that strings are not point particles it is easy to jump to the conclusion that they then must be some other type of basic but nevertheless material building block. String theorist Gerald Cleaver describes the string as a â€œparticleâ€ of length 10-33 cm which is comprised of pure energy.12 String theorist and bestselling author Michio Kaku, adopting the famous mathematical relation of Einstein, offers an explanation of matter as a condensation of energy. What could possibly be clearer than that? Numerically equating a certain amount of matter with a certain amount of energy however does not in itself render them in any way qualitatively equivalent. Should strings represent the irreducible atoms that the Greek atomists once sought then, despite their spatial extension, the question of their own composition could very well be without any content according to string theorist Brian Greene.13 If energetic strings are fundamental to matter but are not material themselves then it would seem that science must face the same type of realization as Aristotle did when, just like a bottle blond, he came to understand that he could not completely deny his Platonic roots.
Let us recall that some of the PreSocratics provided us with a precedent for thinking that materiality is not sufficient for explaining the existence of the material world. And in a very real way it is not a stretch to say that the PreSocratics are always with us. But the PreSocratic enchantment with material reductivism was never unanimous. The first serious philosophical critic of materialism was of course Anaximander who held that the immaterial Apeiron is the ultimate source of all material reality. Even the ultra-materialistic atomists had to posit the existence of a real yet immaterial void in which their atoms could have enough elbow room in which to collide. More than two thousand years have gone by since this first golden age of philosophical speculation, but the philosophical credentials of materialism have not improved appreciably in the interim. In the well known physics textbook by Douglas Giancoli there exists no definition of matter. And in works such as Philosophical Problems of Quantum Physics and Physics and Philosophy Werner Heisenberg went on record in documenting his doubts concerning the material character of the elementary particles. String theory thus puts the lie to the fundamaterialist belief that nothing exists except for matter and its many inflections. Years ago Gilbert Ryle attempted to argue for materialism by denying the prospect of a ghost in the machine. If string theory should eventually prevail then his dismissal might be proven wrong, not because there is no ghost but because, ultimately, there is no machine. 14
1 In this essay the term â€œstringâ€ theory is employed rather loosely as a convenient means for describing the myriad theoretical variations, historical twists and turns, and extensions which have involved strings in some way. The term â€œsuperstringâ€ would be more accurate in some instances. In recent years string theory has itself been incorporated into the even more inclusive theory cryptically known as M-theory. One alternative to string theory in replacing point particle physics is the twistor theory of Roger Penrose. For more on this see: F. David Peat, Superstrings and the Search for the Theory of Everything (Chicago: Contemporary Books, 1988), cf. chs. 7-9.
2 Paul Davies and Julian Brown, eds., Superstrings: A Theory of Everything (Cambridge: Cambridge University Press, 1988), p. 98. Wittenâ€™s remark was first coined by Dr. Daniele Amati.
3 These quotes from both Krauss and Feynman are from memory. In a debate on the merits of string theory conducted at the American Museum of Natural History in New York Krauss was very vitriolic in his numerous animadversions against string theory. I heard the Feynman quote on some Science channel show on which Feynman was interviewed. The aforementioned book by Davies and Brown contains chapters in which both Glashow and Feynman are interviewed at length concerning their views on string theory. The quote from Glashow is cited by Brian Greene in The Elegant Universe (New York: W.W. Norton and Company, 1999), p. 212. Its source is the article by Glashow and Paul Ginsparg entitled â€œDesperately Seeking Superstringsâ€ which appeared in Physics Today in May, 1986 (p.7).
4 Brian Greene, The Elegant Universe,p. 140.
5 E. Adelberger, B. Heckel, and C.D. Hoyle,, â€œTesting the Gravitational Inverse-Square Law,â€ Phys. World 18N4 (2005), pp. 41-45.
6 Lee Smolin, The Trouble with Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next (Boston: Houghton Mifflin, 2006), p. xvi.
7 Lee Smolin, The Trouble with Physics, p. 264.
8 Lee Smolin, The Trouble with Physics, p. 268.
9 Max Jammer, Einstein and Religion (Princeton: Princeton University Press, 1999), p. 155.
10 Gerald Cleaver, â€œBefore the Big Bang: String Theory, God, and the Origin of the Universe,â€ Metanexus Institute Conference on Science and Religion, (see metanexus.net â€“ Proceedings of 2006 conference).
11 Leonard Susskind, The Cosmic Landscape: String Theory and the Illusion of Intelligent Design (New York: Little, Brown and Company, 2006).
12 Cleaver, â€œBefore the Big Bang: String Theory, God, and the Origin of the Universe,â€ p. 1.
13 Brian Greene, The Elegant Universe, p. 141.
14 John Gribbin and Paul Davies, The Matter Myth (New York: Simon and Schuster, 1992), p. 309.