A Myth for Our Time
In his new book, The Grand Design, Stephen Hawking has generated the most heat and light for his statement, found on the next-to-last page, that “it is not necessary to invoke God to light the blue touch paper and set the universe going.”
But for some people, a more controversial statement is found on Page One, in the second paragraph: “Philosophy is dead.”
If God is unnecessary and philosophy is dead, the field is clear for science to explain the world: to answer all the age-old questions like: “What is the nature of reality? Where did all this come from? Did the universe need a creator?”
These are the questions Hawking proposes to tackle in his book, armed only with science, because, as he writes: “Scientists have become the bearers of the torch of discovery.”
But then, in the book’s first sixty pages or so, Hawking mainly philosophizes, as he surveys the history of science and the philosophy of science. He concludes emphatically: ”There is no picture- or theory-independent concept of reality.” The italics are his. What is this if not a philosophical stance? Since we do not have direct access to reality, Hawking explains, we must then employ what he calls “model-dependent realism” to build pictures of the world.
I think Hawking does not really want to suggest that all of philosophy is dead. I think he means that philosophy of a certain sort is dead: philosophy that takes little or no account of scientific findings. And there is such philosophy. Some metaphysicians insist that metaphysics can do just fine without reference to scientific findings or observation of any sort. Other metaphysicians disagree, and so this is a debate within the field of metaphysics itself.
Then, of course, there are scientists who insist that metaphysics itself is just bunk: like theology, these scientists would claim, it is a field without a proper object of study. I don’t think Hawking is among the scientists who would claim this, because otherwise he wouldn’t talk so much about metaphysics in his book.
Hawking writes that under model-dependent realism, there is no single model that can explain the universe. There are, instead, a series of models that overlap. That’s fine, he says, provided that where the models overlap, they make the same predictions. If they don’t, one or more of the models is flawed. Hence Newtonian and General Relativistic models can account for big objects in the world, and quantum mechanical models can account for little things like subatomic particles.
The tricky part, it seems, is where these models overlap. And so far there is no model that accounts for the overlap of quantum mechanics and general relativity, for example. This would seem to be a bit of a sticking point if, as Hawking suggests, we are on the cusp of obtaining the scientific holy grail: the theory of everything.
But the theory of everything that Hawking describes is not the TOE as traditionally conceived, when it was thought that a single equation – a string of numbers that could be written on a T-shirt – would eventually be discovered (invented?) to explain all of physics.
The new Theory of Everything, Hawking writes, is something called M-Theory: As described above, M-Theory is a network of theories, or models, which model different domains of reality, but which will end up making the same predictions where they overlap.
But Hawking also writes of M-theory: “No one seems to know what the ‘M’ stands for, but it may be ‘master,’ ‘miracle’ or ‘mystery.’ It seems to be all three. People are still trying to decipher the nature of M-theory, but that may not be possible.” I suppose many people might feel that if this is the case, it could perhaps be premature to declare either God or philosophy dead, especially when M theory is deemed miraculous (God) and mysterious (philosophy)!
M theory derives from string theory. It describes a world of eleven space time dimensions, in which all but the 3+1 dimensions that we normally experience are curled up into tiny little balls far too small to see or experience.
The mathematics of the theory says that the way these minuscule dimensions are curled up accounts for the “apparent” laws of physics that we experience. So our laws of physics, Hawking explains, are not laws at all, but simply incidental consequences of the way that the extra dimensions are curled up under M theory.
However, M theory requires a successful formulation of models that fall under the domain of quantum field theory. I will skip the details, pointing the reader to book, in which Hawking guides the layperson through this abstruse terrain. Quantum field theory is an effort to make those “overlaps” between classical and quantum theories coincide, as required under Hawking’s model-dependent realism.
The first problem is that this effort is so far incomplete. There still is no quantum description of gravity, for instance. Hawking covers all this. But the second problem is that string theory itself, according to many scientists, is not science. Hawking does not broach this subject, does not meet this objection, and it seems a curious omission.
Why is string theory not science, according to some scientists? Because it makes predictions that can’t be tested. Probably they can’t be tested even in principle; this also makes the theory unfalsifiable. For example, to “see” these other rolled-up dimensions would require energies produced by a supercollider that is about the size of the Milky Way galaxy. We are not going to build any such machine, obviously.
Other scientists like string theory because it provides elegant mathematical descriptions of the world, and all so-far valid theories do seem to have elegant mathematical descriptions. The idea here appears to be that we should take string theory to be true because the math is so elegant!
All of this, of course, raises troubling philosophical problems.
Still, if we grant that string theory can be science, and if the effort to model quantum field theory succeeds and if M theory falls out of all that, what is the upshot?
According to M theory, the way that the dimensions are curled up to instantiate our apparent “laws” can be modeled a number of different ways. That is an understatement. The number of ways that universes can be modeled under this theory turns out to be on the order of 10 to the power of 500. And from this, evidently, we should conclude that all these different universes actually exist, and that each has its own unique physical laws.
But why should we take it that all these universes actually exist, as opposed to being useful fictions? Hawking does not directly address this issue. I take it that one answer would be that there is no reason to expect that our universe alone should exist, if there is nothing special about its particular laws. Why should it be that our own utterly contingent set of laws be the sole universe in which the “blue touch paper” is lit?
It’s a fair question, but the question alone does not establish the actual physical reality of all these other universes. And if no empirical evidence can be found for their existence – if their existence simply falls out of the math – then we have another troubling philosophical problem. It’s funny how a discipline deemed to be dead on Page One of this book keeps kicking throughout its pages, like a lively corpse that never received the telegram informing it of its own demise.
As to other universes, there seem to be at least a couple of different kinds of them in Hawking’s picture of reality. Based on Feynman’s sum-over histories solution to the peculiar behavior of quantum particles in the two-slit experiment, we are invited to believe that the universe takes all possible histories, even as a quantum particle in the experiment takes all possible paths to the detector screen. So every possible universe exists, and each universe takes every possible history that it can.
A new problem arises, though, in that Feynman’s sum-over histories is an interpretation of QM. Hence, it’s philosophical. (There’s that word again.) There are other, different interpretations. As Hawking explains, the Feynman interpretation is perfectly consistent with a different view, that quantum particles have no properties until they are observed. Both interpretations yield the same results, and as Hawking notes, if two different models of reality make the same predictions, then both models are acceptable.
But surely there is an ontological difference between a particle taking all possible paths to a detector and taking no paths to a detector, because it lacks properties when unobserved.
So the problem is that if both models are fine, under model-dependent realism, because they yield the same predictions (and they do), but if each model requires a totally different ontology, one simply can’t say anything about the real world. The idea that there are multiple histories and universes may thus be nothing but a useful fiction. And Hawking clearly understands all this, since he himself is endorsing model-dependent realism. But his own model of QM has a competing model that is inconsistent with the ontology that he is promoting. Hawking does not address this contradiction.
The picture that Hawking paints of reality is a mind-blowing one but, given that it is model-dependent, its presumed ontology might well be fictitious. It consists of the aforementioned multiple universes and multiple histories. There are versions of reality in which electrons are as massive as golf balls, and in which gravity is a stronger force than electro-magnetism rather than the other way around, as in our world. There may be a universe in which the moon is made of Roquefort cheese, Hawking writes.
Hawking says that the picture that science gives us of this New Reality is somehow “top down” and not “bottom up.” Once cannot, because of the indeterministic nature of quantum mechanics, start with initial conditions and calculate future outcomes (expect as probability distributions). Instead, one must start with present conditions, and reconstruct the past from the present. This is a topsy-turvy world in which the delayed-choice two-slit quantum experiment shows that human observations made in the present can actually retroactively make the past be what it was. “We create history by our observation, rather than history creating us,” Hawking writes.
The cosmological argument — the idea that the universe was created by God — is circumvented in this picture of reality. That’s because in the cosmology Hawking describes, the universe did not have a beginning. This does not mean that time extends infinitely into the past. It means rather that like space, time has no edge: it is finite but unbounded. He likens the so-called beginning of the universe to a location on earth like the South Pole, and says to ask “What happened before time began?” is akin to asking “What lies south of the South Pole?” The question has no meaning. Because of this, he writes, the entire universe, and all its different quantum histories, is a self-contained object in which scientific laws alone, deriving from M theory, dictate the nature of the various versions of reality. No supernatural creator and no outside intervention is required to make reality be what it is.
It should be noted that none of this is new, not even for Hawking, who used to use the North Pole rather than the south in explicating his no-boundary proposal for time. What is new is the packaging, bringing all the latest conjectures of science together in one handy-dandy package tied up with a bright ribbon in the form of nice pictures and some funny cartoons.
In the penultimate chapter, Hawking talks about fine-tuning. Our universe is fine-tuned for life, in the sense that if any number of delicate parameters, or physical laws, were tweaked, the conditions for making life as we know it possible would be removed. As Hawking explains, the weak anthropic principle states that we must observe a universe whose properties are consistent with our existence, for otherwise we would not exist to observe anything at all.
Why is the universe fine-tuned? It’s because there are so many of them, Hawking says. With ten to the power of five hundred universes floating about, each with its own different physical laws, it’s unsurprising that at least one of them – our own – would randomly and contingently just happen to take the parameters making life possible.
The fine-tuning of our universe, as Hawking explains, has often been invoked as a theistic argument. The idea is that since it is outlandishly unlikely that all the free parameters would randomly fall in just the right pattern to assure the possibility of life, it is much more parsimonious to assume that a designer, presumably God, endowed the parameters with the values that they have, so that life would arise. The multiverse idea presumably puts paid to this notion. Given enough universes, sooner or later one of them is bound, by chance alone, to take life-permitting values.
There is a thick literature on the fine-tuning issue and various versions of the multiverse. I’ll just mention in passing that some people who have studied these topics contend that the existence of a multiverse does not, in fact, account for the fine-tuning of our universe. The reason for this, I take it, is that the probabilities of each universe having the values that they do are independent of one another, and hence once cannot say that just because a billion universes will not support life, it’s somehow more likely that the next universe in line will support it. If the odds are, say, a billion to one against any particular universe having life-supporting parameters, then those odds remain the same for each universe no matter how many other universes exist.
At the end of the penultimate chapter, Hawking writes: “But is M Theory unique, or demanded by any simple logical principle? Can we answer the question, ‘Why M Theory?’” The question seems to be accompanied by a dramatic drum roll and a flourish of trumpets, for now we are getting down to the nitty gritty, which amounts to: why is there something rather than nothing?
The final chapter is short. Mostly it’s about Conway’s Game of Life, which demonstrates that complex properties can arise from simple rules, with a detour into the question of whether humans have free will. It closes with this thesis: because on a global scale the negative and positive energy of the universe cancels out, it is possible (entailed?) that universes (though not the objects within them) will spontaneously arise out of nothing in accord with M Theory. This idea isn’t new either, by the way. Victor Stenger has written extensively on this subject of universes popping into existence out of “nothing.”
But now, for me, the drum roll and flourish of trumpets is gone, replaced by the sour blat of horns. Unless I have missed a step in Hawking’s reasoning, it certainly does not seem as if he has answered the question “Why M Theory,” or the bigger question, “Why is there something rather than nothing?” I could be mistaken about this. Perhaps the defect lies with my reading comprehension, and not with his argument. But for me, what we end up with is: “M Theory said, Let there be light, and there was light.”
Hawking spices the text with allusions to ancient human mythology, which put Man at the center of the cosmos as its reason and purpose. Implicitly we are invited to contrast such anthropocentric tales with the disinterested wisdom supposedly underlying the discoveries of modern science. Yet Hawking and other scientists are constructing a modern myth. A myth does not mean a “lie.” It just means a narrative, a conceptual scheme that gives order and purpose to our experience. And even while modern science beginning with Copernicus has been steadily evicting Man from the literal “center of the universe,” man remains at the center even under Hawking’s own schema: model-dependent realism, which of course means that realism depends on us – on the structure of our cognitive faculties, on the architecture (and limitations) of our brains, on the mediation and interpretation of sense data by our mysterious minds. We see through a glass darkly because we are the glass.