This is the first part of a two-part review of Stephen Hawking’s latest book, which is co-authored by Leonard Mlodinow. Let me first put this book in context for the uninitiated.
- Stephen Hawking is a very famous British physicist with an unfortunate neuro-muscular dystrophy. He is mostly known for his prediction that black holes should slowly evaporate, his appearances on the Simpsons and his artificial voice.
- Leonard Mlodinow is an American physicist author of several popular science books and he has been a screenwriter for Star Trek: The Next Generation and MacGyver.
- Why is there something rather than nothing?
- Why are we here?
- Why these laws of physics and not others?
If you know me just a little, you can understand why I had to read this book. I have been craving popular science books about physics, and this book was bridging the gap between modern science and the big philosophical questions with answers that had nothing to do with the supernatural.
Another aside I should make before I go on with my own thoughts about the book is that Stephen Hawking has been known to use the God metaphor to designate the laws of nature, as Einstein did. The problem I have with this is that it creates a lot of confusion. Believers interpret this as being an indication of religious belief, while those who know better don’t like that Hawking remains oblivious (at least publicly) to the confusion he is creating.
The Grand Design addresses the confusion. Hawking and Mlodinow are positioning themselves clearly in the debate about the existence of God. According to what they believe to be our best shot at a theory of everything, there is simply no use for God at all to explain anything. To the first question, they say that the interplay of gravity and quantum fluctuations can allow for the separation of a 0 energy state (or if you prefer, nothingness) into positive and negative parts, the gravitational interaction hosting the negative energy part. To the second and third questions, they invoke the weak and the strong anthropic principle respectively.
What I like about the book
This book made a lot of fuss in the media. There were a lot of headlines about this one, and a lot of reactions on the part of the faithful community. Just Google it. To me, I see it as another atheist coming out of the closet, and a very famous one indeed.
The book contains a very good account of what modern science is, and how it came into being. The first three chapters are excellent, and they convey the essence of the book. I had more trouble appreciating the rest, which is what the remainder of this post is about.
M-theory and the beginning of everything
I am not a fan of string theory. I have read a couple of books on the topic, including Brian Greene’s The Elegant Universe and Lee Smolin’s The Trouble with Physics. I actually like both physicists, but I came to side with Smolin. To give you a very short story, physics has been in a frustrating situation ever since the 1920’s. We have a theory to describe the very small which is incredibly successful (quantum field theory) and one theory to describe the very large which is also outstandingly accurate (general relativity). Together, these theories explain every (with a few exceptions) phenomena ever observed. They are also inconsistent. We have two pieces of a puzzle that don’t fit together.
The thing is, we can get away with the inconsistency because gravity (described by general relativity) is negligible at small scales and the other forces, electromagnetic and nuclear (described by quantum field theory), are mostly neutralized at large scales. There are two notable exceptions for which all forces become important. One of them is the interior of black holes, and the other one is the beginning of the universe. You can probably see a little bit better where this is going now.
String theory is the mainstream effort to make a quantum theory of gravity. In the early efforts, there were many ways to make string theories. They all required some fancy new stuff that we haven’t observed yet like extra spatial dimensions, and supersymmetry. Eventually, it was realized that there were domains of overlap between the different string theories, and it was conjectured that they were all approximations to one deeper theory. This deeper theory received the name of M-theory, M standing for whatever pleases you the most (seriously).
Even now, M-theory lacks a foundation. We don’t know its equations, we don’t know its predictions. All we have are the string theories, making many unfalsifiable predictions. This is a very frustrating state of affair for an experimentalist like me, or to any person who considers we should check if reality agrees with our ideas before we take them seriously.
Nevertheless, Hawking and Mlodinow bring M-theory in the picture, saying that we may have a theory that can tell us what happened at the beginning of the Universe. Despite our imperfect knowledge of the theory, it is still possible to have a peak at some answers. When we look at what string theory has to say about the beginning of the Universe, we find a surprising turn. It turns out the question itself is irrelevant, since the dimension of time may not have existed as we know it. More specifically, time was “fully” rotated into a dimension of space. This sounds crazy, but it actually isn’t. Fundamental physics is just very counter-intuitive, and crazy stuff like this is also happening (to a lesser degree) in the presence of gravity. If this kind of effect wasn’t taken into account, GPS systems would lose their accuracy in a matter of days.
Hawking’s point seems to be that to the best of our knowledge, we don’t need a creator to explain how the Universe came to be. He is most probably right on this, but I think that using M-theory to sustain this claim is a mistake. There are other quantum gravity theories out there that have similar predictions as M-theory regarding the early Universe. None of them requires a creator. I think Hawking could have used the whole body of approaches to quantum gravity to make his point. It would have been more fair and more realistic. The argument could have been, according to what we know about the interplay of quantum forces and gravity, the Universe needed no creator to exist.
Until M-theory is confirmed by experiment, the best reason to take it more seriously than other approaches is that there are more physicists working on it. This is pretty much an argument from authority, which I have no problem dismissing.
Part 2 will cover other aspects of the book that are essential to Hawking’s and Mlodinow’s point that need a bit of deliberation.