Isaac Newton, when he wasn’t revolutionizing mathematics and almost single-handedly inventing physics as a systematic discipline, wrote some really ridiculous stuff. Alchemy, occult esoterica, you name it. In his defense, it was the 1600s. He didn’t have a whole lot of prior scientific understanding to help him sort the wheat from the chaff.
Until he reached the age at which the position is traditionally handed to a successor, Stephen Hawking occupied Isaac Newton’s chair at Cambridge University. I don’t know what his excuse is.
Stephen Hawking’s book The Grand Design should be read by all physicists – as a warning that brilliance is no immunization against developing dreadfully dumb ideas with insipid prose and committing them to alarmingly permanent print. And permanent this print indeed is, as if nothing else the book is gloriously printed on expensive paper with beautiful if rather impressionistic full-color graphics. Regrettably that’s about the best thing one can say about the book.
What’s wrong with this book? I’ll let it speak for itself in a moment, but for now let me outline the objective of the book. For some time, Hawking has been interested in the metaphysics question of “How come existence?” His book is a claim to have answered that question. Though it’s not a part of his argument, Hawking does go out of his way several times to make the point that the existence of God is superfluous in his metaphysics. The less said about this the better, but I note that the very minor God issue (in terms of percentage of the text) has served as a fantastic distraction in the popular press which has allowed the god-awful physics in the book to escape without much notice.
On to Hawking’s physics/metaphysical argument. We’ll start with the questions he poses, and move quickly through the book to evaluate his answers. The questions:
Why is there something rather than nothing?
Why do we exist?
Why this particular set of laws and not some other?
Hawking begins with an argument for what he calls model-dependent realism, which is essentially the idea that it’s pointless to talk about what’s real except in the context of what’s observable. This isn’t so fishy in itself. In the quantum mechanical context, for instance, there’s no point to talking about what a particle’s position and momentum are simultaneously. They’re not simultaneous observables and so there’s no point arguing about what they “really” are at a given instant. He goes on to try to explain what amount to the path integral formulation of quantum mechanics and marries this to an interpretational framework that’s pretty much the consistent histories idea.
Like the Titanic steaming out of port, so far so good. The presentation is a little sketchy in places, but as far as it goes it’s nothing too wildly implausible. But the iceberg comes into view and Hawking orders ramming speed with the argument that in fact both the history of the universe and the laws of nature themselves are not observer-independent:
The idea that the universe does not have a unique observer-independent history might seem to conflict with certain facts we know. There might be one history in which the moon is made of Roquefort cheese. But we have observed that the mood is not made of cheese, which is bad news for mice. Hence histories in which the mood is made of cheese do not contribute to the present state of the universe, though they might contribute to others. That might sound like science fiction, but it isn’t.
Yikes. It gets worse. Those familiar with string theory may be aware of the fact that there’s something like 10^500 possible ways to construct string theory, with each of those possibilities allegedly leading to a different set of the laws of nature. Hawking explicitly rejects the idea that string theory should be able to predict, well, just about anything. Instead, he asserts that:
We cannot predict discrete features such as the number of large space dimensions or the internal space that determines the physical quantities we observe[...] Rather, we use those numbers to select which histories contribute to the Feynman sum.
We seem to be at a critical point in the history of science, in which we must alter our conception of goals and what makes a physical theory acceptable. It appears that the fundamental numbers, and even the form, of the apparant laws of nature are not demanded by logic of physical principle. The parameters are free to take on any form that leads to a self-consistent mathematical theory, and they do take on different values and different forms in different universes.
This theory, he tells us, is nonetheless testable. How? At risk of holing my Titanic metaphor below the waterline, he loads his passengers into the rickety lifeboats of the anthropic principle. Obviously, he tells us, we will observe a universe with the characteristics that allow life to exist. Because string theory postulates an effectively infinite number of universes, surely some of ‘em are bound to be like the one we’re in. We are in the universe we’re in, so presto! String theory correctly predicts that we exist.
Perhaps I’m not a fan of Barack Obama. Perhaps I think I can do a better job as president. If I go to the courthouse and change my name to The President of the United States, then presto! I’m now The President of the United States. But I think you’d agree that I’d rather spectacularly managed to miss the point. You might also agree that a physical theory misses the point if it predicts literally every possible universe and then claims victory for explaining the one that actually exists.
Honestly though, I don’t think I can damn the book any more effectively than by quoting its penultimate paragraph, the one that summarizes the answers to the questions I mentioned at the beginning of this review. I hope in doing so I’m not offending the truly very generous publisher who sent me this book free of charge. But I’d be derelict in my duties if I didn’t (numbers are my test markers for explanation below):
Why are the fundamental laws as we have described them? The ultimate theory must be consistent and must predict finite results for quantities we can measure. We’ve seen that there must be a law like gravity, and we saw in Chapter 5 that for a theory of gravity to predict finite quantities, the theory must have what is called supersymmetry between the forces of nature and the matter on which they act. M-theory is the most general super symmetric theory of gravity. For these reasons M-theory is the only candidate for a complete theory of the universe. If it is finite – and this has yet to be proved – it will be a model of a universe that creates itself. We must be part of this universe, because there is no other consistent model.
In , his argument is that the total amount of energy in the universe must be 0, hence a requirement for an attractive force producing a negative potential energy. The book is not so clear (as far as I can tell) what  means.
So there you have it. Hawking has explained literally everything, with only the minor assumptions that there exist 10^500 universes that are unobservable even in principle, that the supersymmetric model of particle physics is correct despite the fact that there’s never been the slightest experimental evidence for it, the correctness of string theory/M-theory for which evidence is arguably not even possible, and a set of metaphysical assumptions which would strike Timothy Leary himself as ludicrously dippy.
You can grant those assumptions if you want, but don’t kid yourself that you’re doing science.