Review of The Grand Design by Stephen Hawking

I make no secret about the fact that I love science, and of all the sciences, I will make no secret about my love for physics, for theoretical physics, and for cosmology. These fields help us understand the universe, that crazy thing that’s all around us, and the fact that we have come so far is simply amazing. In The Grand Design, Stephen Hawking and Leonard Mlodinow reflect upon how physics achieves this understanding of the universe, with a particular emphasis on how physics can explain the origin of the universe in a way that removes the need for a deity (whom we’ll call God).

Mlodinow gets his name on the cover, but this is clearly a Hawking book first and foremost. His name is bigger, and the inside of the dust jacket begins, “The first major work in nearly a decade by one of the world’s great thinkers…" (emphasis mine). Sorry, Mlodinow! You’re a nice guy, but I guess you’re just not a “great thinker”. (Actually, although I think I’d heard of him before, this is the first time I have encountered one of his “his” books, and now I can go and mark down a bunch of his other books to read. But I should probably talk about this book now.)

I shall hereafter refer to Hawking and Mlodinow as “H&M” because it tickles my fancy to fantasize that a clothing chain might write a book on physics.

The Grand Design is certainly an engaging treatise, but it is also problematic. I had a lot of fun reading it, and although I have a lot of experience reading about science, I feel confident recommending it for people who might otherwise quirk an eyebrow and say, “Erm … science? I don’t know….” It’s a very short book; it’s extremely conversational in tone, with plenty of analogies; and there are no tests at the end. There are even pictures (albeit not very good ones)! By problematic I mean that, from my own reading and from what I have read of reviews here on Goodreads, H&M confront the role of physics vis-à-vis religion in a way that doesn’t lend itself to clarity and suasion. There seems to be a disconnect between the evidence they present (which is very good) and how they phrase or otherwise communicate the conclusions they draw. This results in an ambiguity that means people will often misinterpret those conclusions or dismiss them out of hand. The Grand Design, one might say, suffers from a grand design flaw.

(I am so sorry for that last sentence.)

I can give an example from the very first page of the book, which, by the way, begins not with a foreword, preface, or introduction, but Chapter 1. It’s true that this first chapter is very much an introductory chapter that lays the ground for the rest of the book, but I have to give H&M and their editors credit for not subjecting us to another scientist pontificating about these guys or a token preface. The conciseness of this book is appreciated, even if it leads to pithy statements like this:

Traditionally these are questions for philosophy, but philosophy is dead. Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge.

As someone who unequivocally supports science as a way to discover and understand the universe, I must nevertheless shake my head at this passage. Taken literally, it seems like an unnecessarily harsh indictment of philosophy, particularly contemporary philosophy, which is very much alive. Even leaving aside philosophy that concerns itself with things other than those questions (such as “Who are we? Where did we come from?”), philosophers routinely discuss developments in science in their philosophy. Indeed, I would go so far as to argue that most scientists also become philosophers—as you will see if you read this book, it is clear that H&M are. However, to be fair to them, I think that what H&M are trying to distinguish—albeit sensationally—is the difference between purely attempting to reason about our existence and our origins (rationalism) and using tools to collect data and make inferences about that existence and those origins (empiricism). The program founded in the Western world by Aristotle and raised onto a pedestal by the Enlightenment scientists has failed: we cannot know the world through reason alone. Bacon, Newton, Galileo, Franklin, etc., realized that we must experiment—we have to conduct tests that anyone with the appropriate knowledge and equipment can reproduce. So philosophy alone cannot take us the entire way, and science provides that next crucial step.

If you haven’t read the book, and especially if you approach physics with more wariness than I do, you will find this very weird, but I found the first half of the book much heavier than the last half (with one notable exception). Following that incendiary introductory passage, H&M segue into a deep discussion of what science is, where it is coming from, and where it might be going. Specifically, they introduce a concept called model-dependent realism. And I think this is a fascinating, perhaps even peculiar decision on their part, because I doubt many of their readers would have ever heard of this term—whereas, in comparison, even most laypeople will have heard words like “quantum mechanics” and “general relativity”. H&M have great confidence in their audience, for they have faith that the audience will not be deterred when they drop some philosophy of science in the first chapter.

It makes sense to talk about model-dependent realism, though, because it is relevant to M-theory, which is the group of theories that H&M discuss as a candidate for the ultimate “theory of everything”. And kudos to H&M for trying to pull back the curtain on the somewhat mystical way “theories” are constructed and viewed (at least by some scientists). In particular, I love the analogy they use with a map of the world: we can’t accurately transfer a three-dimensional sphere to a two-dimensional surface, so no matter what projection we use (e.g., Mercator, Robinson), it will always be distorted. So just as different projections provide different but useful models of our world, different theories provide different but useful models of the universe. Some of these theories have been collected under the name “M-theory”, and together they might be “the answer” when none of them alone could make the cut.

Of course, I like model-dependent realism, because I am a realist, and as H&M say, it “short-circuits all this argument and discussion between the realist and anti-realist schools of thought”. I won’t go into realism versus anti-realism here; that is probably best left for a deeper discussion of the philosophy of science. Suffice it to say, science is not about establishing a single, fixed “truth” outlined by a single set of theories. As H&M point out, Ptolemy and Kepler’s model of a geocentric orbit using epicycles is as valid as our heliocentric model—one certainly can regard the rest of the solar system as “orbiting” the Earth. Yet the geocentric model is fiendishly complex and quickly becomes unwieldy if one ever wants to perform actual calculations; the heliocentric model has the advantage of being simpler and more elegant. So these are all thoughts that H&M want us to consider as they launch into an overview of the state of physics in the twenty-first century.

I like that H&M go to the trouble of distinguishing between “probability” as we use the term colloquially and the role probability plays in quantum mechanics. Nancy Kress discusses probability in quantum mechanics at length in Probability Sun, but she only alludes to the difference rather than explicates it. Quantum mechanics is weird and strange and revolutionary precisely because of one word: uncertainty. It blew away the classical world, particularly the deterministic aspect. That pesky Heisenberg uncertainty principle means we’ll never know exactly where a particle is and how fast it is moving. Hence, according to quantum mechanics, asking where a particle is is a meaningless question. Rather, ask what the probability is of a particle being in a particular point in space-time. There is a probability that all the particles in my left arm might actually be in Switzerland right now, but the probability is tiny compared to the probability that they are, in fact, attached to my left shoulder! (And for this I am thankful.)

Similarly, The Grand Design finally clarified for me what a boson is. I just have these song lyrics stuck in my head:

They suppose that particles have mass because There is this Higgs field that extends through all space And some particles slow down while other particles race Straight through like the photon — it has no mass But something heavy like the top quark, it’s draggin’ its *** And the Higgs is a boson that carries a force And makes particles take orders from the field that is its source.

If you haven’t already seen it, the Large Hadron Rap is one of the most amazing science raps I have ever seen, and it does an excellent job at explaining what scientists are trying to achieve using the Large Hadron Collider at CERN. However, I still wasn’t clear on this idea of bosons and force fields. Something about the way H&M explain bosons in The Grand Design finally made it click for me:

… according to classical theories, forces are transmitted by fields. But in quantum ield theories the force fields are pictured as being made of various elementary particles called bosons, which are force-carrying particles that fly back and forth between matter particles, transmitting the forces.

So the field and particle are dual concepts, one of which applies to classical theories (like relativity) while the other applies to quantum theory. Particles are the language of quantum mechanics, and so force fields have been replaced by a particle that conveys each force: photons for electromagnetism, gluons for the strong force, W and Z bosons for the weak force, and perhaps gravitons for gravity (we haven’t found them yet!). That’s really cool, and I am glad H&M cleared that up for me. This is why I read so many books that cover the same scientific concepts, even similar books by one author: each different method of explaining a concept aids my understanding in some small way.

This kind of incremental learning is present in science as well. H&M mention, “Modern technology is sensitive enough to allow us to perform many sensitive tests of general relativity, and it has passed every one”. That relativity is testable and falsifiable—and, correspondingly, has passed all of the tests we have thus far devised—lends great credence to its accuracy as a scientific model. There are, of course, more subtle questions about the roles of testability and falsification play in judging a scientific theory (e.g.: Evolution is arguably not testable, nor is string theory.) What’s important is that H&M emphasize that science is not some kind of mysterious black box where we plug in data in order to obtain inviolable laws of nature. So that’s why I’m fine with people criticizing, say, evolution, because all science should be open to criticism—but the moment that criticism rests on an objection like “it’s only a ‘theory’!” I will stop listening. Our scientific principles are theories because science is self-correcting and constantly improving upon and revising those principles. That is why science is so powerful, so important, and so very cool.

By far the most mind-boggling concept in The Grand Design comes at the end, and it is the exception to my earlier remark that I find the first part of the book the heaviest in terms of mental exertion. The ultimate thesis of this book is that we can explain the origin of the universe without invoking a creator deity, a God. I think it is very important to note that H&M are not saying that science can disprove the existence of God, nor is that an objective of The Grand Design. While it is clear that H&M, like myself, do not believe a God exists, this is not their argument. Instead, they are merely removing the necessity of God’s existence. I can see how one can misinterpret the book—hence my initial comments about the disconnect and design flaw. H&M’s scepticism is vividly demonstrated, and they raise some of the problems with attempting to fit God into cosmogony—namely, if God created the universe, who created God? If the answer is that “God is eternal and has always been here,” then why can’t we just replace “God” with “the universe” and leave it at that?

This might seem impossible, for we know the universe is not eternal in that sense: we can measure its age (with some degree of precision), and it’s only 13.7 billion years old! Moreover, we know that the universe will eventually reach some sort of end, whether it is heat death, a Big Crunch, etc. H&M resolve this, and that unfortunate singularity at the origin of the universe that prevents our physics from explaining anything, by saying:

In the early universe—when the universe was small enough to be governed by both general relativity and quantum theory—there were effectively four dimensions of space and none of time. That means that when we speak of the “beginning” of the universe, we are skirting the subtle issue that as we look backward toward the very early universe, time as we know it does not exist! We must accept that our usual ideas of space and time do not apply to the very early universe.

Read that twice: asking what happened “before” the universe existed is meaningless, because time itself did not exist as we regard it today. If that sounds too strange and too incredible to accept, believe me: you are certainly not alone. Much like my experience with bosons, I am only now, after confronting this several times, beginning to wrap my head around this explanation. We are just so obsessed with our view of linear time that thinking of a universe where time functions differently boggles our intuition. It is definitely the most difficult concept H&M present in this book, and as with some of their other explanations, I do not think they entirely succeed in presenting it the way they probably hoped.

The Grand Design is ambitious. It is also brief and conversational, as physics books go, and at times this runs up against that ambition. As someone who loves the philosophy of science, loves physics, and has read quite a lot of books about physics, I enjoyed The Grand Design and found it enlightening. Although I recommend it to others with less experience, because it really is a very accessible book, I do so with one reservation: if this is your first physics book, don’t let it be your last. There are so many good ones out there, and while The Grand Design is a fine place to start, it is not the last word on the theory of everything.