Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law by Peter Woit (PDF)

Description

At what point does theory depart the realm of testable hypothesis and come to resemble something like aesthetic speculation, or even theology? The legendary physicist Wolfgang Pauli had a phrase for such ideas: He would describe them as “not even wrong,” meaning that they were so incomplete that they could not even be used to make predictions to compare with observations to see whether they were wrong or not. In Peter Woit’s view, superstring theory is just such an idea. In Not Even Wrong , he shows that what many physicists call superstring “theory” is not a theory at all. It makes no predictions, even wrong ones, and this very lack of falsifiability is what has allowed the subject to survive and flourish. Not Even Wrong explains why the mathematical conditions for progress in physics are entirely absent from superstring theory today and shows that judgments about scientific statements, which should be based on the logical consistency of argument and experimental evidence, are instead based on the eminence of those claiming to know the truth. In the face of many books from enthusiasts for string theory, this book presents the other side of the story.

User’s Reviews

Editorial Reviews: About the Author Peter Woit is a lecturer in the mathematics department of Columbia University, where in recent years he has taught graduate courses in quantum field theory, representation theory, and differential geometry. His math and physics blog, Not Even Wrong (www.math.columbia.edu/~woit/wordpress), has been featured in Discover, Seed, and New Scientist. He lives in New York.

Reviews from Amazon users which were colected at the time this book was published on the website:

⭐When scientists propose a ‘Theory of Everything’, we expect it to be an all-encompassing theory. It must explain all known phenomena and make new predictions in the domains we are researching. In Physics, scientists believe String Theory is a ‘theory of everything’. It provides a framework, combining quantum mechanics and classical physics into a unified approach that explains the laws of the universe. However, many other physicists, the author of this book included, think this theory cannot qualify as science because its assumptions and conclusions are neither testable nor falsifiable. A proper scientific theory rests on testable assumptions, and we judge it by its predictive power. In this book, Peter Woit argues his case against String Theory and shows why he thinks this way. He wrote the book in 2003-04, but the core of his arguments is still valid in 2021.I shall recap here the terrain of String Theory before we get to Woit’s critique. String theory is not yet a finished product, though it came to prominence fifty years ago. The technical name for String theory today is M-theory, perhaps meaning the mother of all string theories. We have five consistent versions of string theory (and supergravity) at present. M-theory unifies them under a single mathematical structure. Depending on the physical regime, M-theory resembles each of the five theories. There is no empirical evidence for any of them or for their competitor theories like Loop Quantum Gravity or the E8 theory. But physicists favor M-theory because of its mathematical consistency. The key features and conclusions of the different string theories state:All objects in the universe comprise vibrating filaments called strings and membranes of energy.We exist in a universe with extra, curled-up spatial dimensions, perhaps ten excluding time. These extra dimensions ‘fold’ on themselves in a myriad number of shapes, resulting in a vast set of solutions.Each fundamental particle has a related particle called a super-partner. We call this supersymmetry.There are parallel universes, up to 10^500 of them. Our universe could just be a simulation. Or a hologram, projected from data on a distant two-dimensional surface. Since humanity exists, scientists can use it as an explanation for certain physical properties of our universe. This is the anthropic principle.The practitioners of String theory accept that the most promising positive experimental results would most likely not be able to prove string theory right beyond doubt. Negative results would most likely not be able to prove it wrong either. But they argue it must be right because it has mathematical elegance and beauty. Paul Dirac’s statement that it is more important to have beauty in one’s equations than to have them fit experiment comes handy for them. Physicists find beauty and elegance when theories have compact expressions in mathematics. Woit says Einstein bears a lot of the responsibility for this perspective in fundamental physics. When he discovered General Relativity employing this strategy, he became more mystical. He started believing that mathematical beauty alone, rather than experimentation, could point scientists on the right path. Woit is more than a critic of just String Theory. He believes many branches of Physics are in crisis now. Particle physics, on the theoretical front, suffers from the long-standing crisis in string theory, in its failure to explain or predict any large distance physics. It is incapable of determining the dimension, geometry, and particle spectrum of macroscopic spacetime. On the experimental front, high-energy particle physics faces fundamental technological obstacles.The Large Hadron Collider confirmed the Standard Model’s vision for how particles get their masses. It did not offer any concrete hint of any new particles besides the Higgs. It could not produce any evidence of the additional dimensions because they are 10 million billion times smaller than what the Large Hadron Collider can resolve. Hence they are unobservable. The next-generation accelerator, called FCC, that can explore higher energies than the LHC is far off in the future and very expensive at 21 billion Euros. Many physicists feel the energy regime the FCC might reach may be insufficient for new discoveries.On Multiverse theories, Woit says that the problem is not that they are not testable through direct means. The problem is there is no indirect evidence for multiverse. Or a plausible way of getting any. The anthropic principle makes an enormous number of assumptions regarding multiple universes, a random creation process, and probability distributions that determine the likelihood of various features. None of these is testable because they entail hypothetical regions of spacetime that are forever beyond the reach of observation. And there are seldom any predictions. Hence, he believes it is time to abandon such failed theoretical ideas.Peter Woit says superstring theory is a complicated idea. To understand it, we should first study and understand quantum field theory. This is a demanding task by itself. This presents students and researchers with a huge barrier of entry to the subject. By the time they achieve some concrete expertise, they often have invested a huge part of their careers in studying superstrings. Such investment is difficult to renounce in a psychological and professional sense. This difficulty makes it hard for researchers to leave the field, even if they are skeptical about it. Woit speculates that the level of complexity and difficulty of superstring theory is perhaps a sign that it is on the wrong track. It reflects the fact that no one has any idea whether there is some unknown simple fundamental M-theory.A second problem is even more serious. Because of its complexity, many scientists, referees, and students do not understand all the mathematics or physics in the papers they referee or peer review. So, instead of relying on their understanding of the subject, they depend on what others say about it. This results in papers being published in reputed journals, even though they are of dubious quality or just plain nonsense. Woit recalls three examples to illustrate this. In 1996, the physicist Alan Sokal crafted a hoax, writing a well constructed and meaningless article. Its title was “Transgressing the Boundaries: Toward a Transformative Hermeneutics of Quantum Gravity.” The article contained no rational argument. Instead, it strung together unsupported claims, breathtaking leaps of logic, and an extensive collection of the sillier parts of the writings of both postmodern theorists and some scientists. Sokal submitted the article to the well-known and rather prestigious academic journal ‘Social Text’, whose editors accepted it for publication in an issue on “Science Studies.”In October 2002, two French scientists and brothers, Igor and Grichka Bogdanov, published five articles on quantum gravity, three of which were almost identical, in peer-reviewed journals. Five sets of editors and referees had gone over these papers and accepted them for publication, without noticing that they were egregious nonsense. The papers were about the roots of space and time using topological quantum field theory. The Bogdanov brothers claimed all this related to quantum field theory at high temperatures. Woit says one can publish complete gibberish on quantum gravity with little effort in many journals, some of them rather prominent. He believes one reason is that many physicists are not willing to admit that they don’t understand many aspects of the theory.A third instance concerns a Harvard scientist, John Hagelin. By 1995, Hagelin had written 73 scientific articles, most of them published in very prestigious particle theory journals, many of them cited by more than a hundred later articles. Among them were a couple of titles, “Is Consciousness the Unified Field?” and “Restructuring Physics from Its Foundations in Light of Maharishi’s Vedic Science”. Woit says virtually every theoretical physicist in the world rejects this as nonsense. But Hagelin has a Ph.D. from the Harvard Physics Department and many cited papers published in the best peer-reviewed journals in theoretical physics. Considering all this, one would wonder ‘how come string theory still goes strong in academia’? Peter Woit explains its prominence in the US as follows. He says the particle theory community in the United States is not a large one, comprising about a thousand people. It is a talented group. But it has been working for two decades in an environment of intellectual failure and fierce competition for scarce resources. This is one reason it is the only game in town. The social and financial structures within which people are working are also an important part of this situation.The author admits that the discussion in this book is adversarial, criticizing the superstring theory program as a failed and over-hyped project. Still, I found it thought-provoking, though difficult to understand. About seventy percent of the book describes research leading to the standard model and then to string theory. The remaining portion contains his stinging critique of superstring theories. I found it hard to keep up with a lot of the material because it switches between high levels of technical writing and popular science writing. I had read Lee Smolin’s book on the same subject several years ago. It helped me understand the overall thrust of this book. I think the reader would need a knowledge of college-level physics to understand the book. People who have reservations on String Theory or how we practice science nowadays will find the book interesting.

⭐I purchased this book mostly based on the positive Amazon reviews. Boy, what a disappointment. First of all, I don’t know what kind of audience Dr. Woit was hoping to reach. Over half the book (the first ten chapters) were devoted to verbally “explaining” quantum theory, quantum field theory, gauge symmetry and the standard model of particle physics using only words. These topics are intensely mathematical, yet not one mathematical equation appeared anywhere in these explanations. Nor did any helpful analogies or illustrations appear that would allow the reader to get a grip on what Dr. Woit was explaining. Although Dr. Woit does provide a comprehensive bibliography at the end of each chapter, a verbal explanation without any math or illustrations related to these very deep concepts conveyed little, if any, information to novices like me. His approach was like trying to teach calculus to a six year old using only words. I also doubt if any subject matter expert in these fields would glean any new useful information from these chapters.The discussion of string theory (which is presumably the topic of this book after all) starts in Chapter 11. The genesis of string theory involved something called the S-Matrix, where the S stands for scattering. In basic terms, the S-Matrix predicts what happens when two elementary particles “collide” or interact. The S-Matrix makes predictions of possible outcomes based on probabilities. Some outcomes are scattering angles of particles as when two billiard balls collide, or the production of new particles from the energy of the interacting particles. The S-Matrix emerged sometime in the 1930s and it fell in and out of favor over the years. Then in 1968, physicist Gabriele Veneziano found a mathematical formula involving Euler’s beta function that generates a certain type of S-Matrix that seems to describe the behaviors of strongly-interacting particles. Around 1970, Leonard Susskind and two other physicists searched for and found a “physical interpretation” of Veneziano’s formula. This interpretation represents particles as tiny strings instead of points; thus, string theory was born. (Some people refer to Susskind as the Father of String Theory.)Dr. Woit goes on at great lengths to discredit string theory in the remaining chapters of the book. Critics argue that string theory makes predictions that cannot be falsified, or that there are too many variations of string theory, etc. However, I believe the standard criticisms completely miss the mark. The real reason that string theory fails is because “physical interpretations” of quantum scattering effects simply don’t exist: Outcomes of quantum interactions are purely probabilistic and they cannot be based on any causal model.Here’s why:John S. Bell produced a theorem in 1964 that described a class of experiments that could show whether quantum measurements result from the actions of “hidden variables” as Einstein and others believed, or if they are purely random per the Copenhagen interpretation. Bell’s experiments could not be carried out until 1980, when a group led by Alain Aspect and other experimental teams showed unequivocally that no quantum “hidden variables” exist. In other words, Susskind et al had based their string model in the 1970s on a faulty premise that was completely disproven in the1980s. But despite the fact that it was proven that physical interpretations of quantum effects based on causality are impossible, string theorists forged full steam ahead through the 1990s and into the 21st century nonetheless.There is another fundamental problem with string theory: It was not based on the scientific method using deductive logic. Instead, it is based on abductive reasoning, where an explanation is proposed based on a known outcome. An example of abductive reasoning is as follows: “If A is true, then it is 100% certain that B will occur. So if B has in fact occurred, it is therefore 100% certain that A is true.” The fallacy is that the conditional probability of B given A is true has absolutely no bearing on the unconditional probability of A itself being true. Using abductive reasoning, you can literally substitute any imaginary or implausible thing for A and prove it’s true, like string theory and the multiverse.The final seven chapters of the book cover the “progress” that string theorists claim is being made, along with criticisms from the detractors of string theory. String theorist argue that such an exceptionally elegant and beautiful mathematical structure like string theory simply must represent an elegant and beautiful physical universe (another fallacy referred to as a category error). The main argument from detractors of string theory is that it is unfalsifiable, and it is therefore not a scientific theory. These final chapters are the most entertaining chapters in the book, which is the only reason why I ranked the overall book as two stars instead of one. However, I think Dr. Woit could have saved a lot of time and effort if he had simply pointed out the obvious fallacies that led to string theory in the first place (see the paragraphs above). My main criticism of this book is that it wastes a lot of space trying to explain some extremely difficult mathematical concepts in the first ten chapters without the benefit of math. I would recommend saving time and headaches by skipping those initial chapters.

⭐A superb book, an antidote to almost any kind of group- think. The title refers to my only two minor criticisms: Woit underplays the role played by imperial college theorists Thomas Kibble and John Ward in developing unified gauge theories. Secondly, the charm quark almost completely cancels out flavour changing neutral currents, but they are not forbidden absolutely. What Woit does not say is how the minimal supersymmetric extension of the standard model recreates the problem: by giving more paths and hence too high a reaction rate contrary to experiment?

⭐As a trained organic chemist, the fields of string theories, quantum mechanics, Lie Groups, etc. are usually way beyond the normal comprehensible territories. Somehow, Peter Woit managed to produce a tome on these fields which made some sense to someone as clueless as I am. A great piece of science writing. Highly recommended.

⭐This is an excellent book, a lot of interesting information for science enthusiasts with a basic understanding of quantum theory. I felt at times that the narration is accessible only to physicists or mathematicians who have already an understanding of group theory, I work in stochastic analysis but not in this area of maths and I felt many things rather obscure. However, I really enjoyed the narrative part of the book and the history of particle physics and accelerators is truly excellent.

⭐After reading Brian Greene’s Elegant Universe, I was disappointed with the lack of substance in it and came away thinking this doesn’t seem right. Peter Woit’s book explained why.Well written holding no punches. I’m now a daily reader of his blog of the same name.

⭐I didn’t buy this

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