Are You Fine-tuned? (Or: the story of Goldilocks and the three dimensions)

The fine-tuning problem is the notion that the physical universe appears to be precisely adjusted to allow the existence of life. It is the apparent fact that many fundamental parameters of physics and cosmology could not differ much from their actual values, nor could the basic laws of physics be much different, without resulting in a universe that would not support life. Creationists point to this coincidence as evidence of intelligent design by God. Some thinkers point to it as evidence that our universe was engineered by advanced aliens. And some even propose that physical reality is actually a computer simulation we are living in (created, of course, by advanced aliens). But perhaps fine-tuning is a set-up that simply points to the need for a different a way of thinking.

First of all, the problem assumes that the universe could be different than it is—that fundamental parameters of physics could have different values than they actually do in our world. This presumes some context in which basic properties can vary. That context is a mechanistic point of view. The Stanford Encyclopedia of Philosophy defines fine-tuning as the “sensitive dependences of facts or properties on the values of certain parameters.” It points to technological devices (machines) as paradigm examples of systems that have been fine-tuned by engineers to perform an optimal way, like tuning a car engine. The mechanistic framework of science implicitly suggests an external designer, engineer, mechanic or tinkerer—if not God, then the scientist. In fact, the early scientists were literally Creationists. Whatever the solution, the problem is an historical residue of their mechanistic outlook. The answer may require that we look at the universe in a more organic way.

The religious solution was to suppose that the exact tweaking needed to account for observed values of physical parameters must be intentional and not accidental. The universe could only be fine-tuned by design—as a machine is. However, the scale and degree of precision are far above the capabilities of human engineers. This suggests that the designer must have near-infinite powers, and must live in some other reality or sector of the universe. Only God or vastly superior alien beings would have the know-how to create the universe we know. Alternatively, such precision could imply that the universe is not even physical, but merely a product of definition, a digital simulation or virtual reality. Ergo, there must be another level of reality behind the apparent physical one. But such thinking is ontologically extravagant.

Apart from creationism, super-aliens, or life in a cosmic computer, a more conventional approach to the problem is statistical. One can explain a freak occurrence as a random event in a large run of very many. Like an infinite number of monkeys with typewriters, one is bound to type out Shakespeare eventually. If, say, there are enough universes with random properties, it seems plausible that at least one of them would be suitable for the emergence of life. Since we are here, we must be living in that universe. But this line of reasoning is also ontologically costly: one must assume an indefinite number of actual or past “other universes” to explain this single one. The inspiration for such schemes is organic insofar as it suggests some sort of natural selection among many variants. That could the “anthropic” selection mentioned above or some Darwinian selection among generations of universes (such as Lee Smolin’s black hole theory). Such a “multiverse” scheme could be true, but we should only think so because of real evidence and not in order to make an apparent dilemma go away.

It might be ontologically more economical to assume that our singular universe somehow fine-tunes itself. After all, organisms seem to fine-tune themselves. Their parts cooperate in an extremely complex way that cannot be understood by thinking of the system as a machine designed from the outside. If nature (the one and only universe) is more like an organism than a machine, then the fine-tuning problem should be approached a different way, if indeed it is a problem at all. Instead of looking at life as a special instance of the evolution of inert matter, one could look at the evolution of supposedly inert matter (physics) as a special case involving principles that can also describe the evolution of life.

Systems in physics are simple by definition. Indeed, they are conceived for simplicity. In contrast, organisms (and the entire biosphere) are complex and homeostatic. Apart from the definitions imposed by biologists. organisms are also selfdefining. Physical systems are generally analyzed in terms of one causal factor at a time—as in “controlled” experiments. As the name suggests, this way of looking aims to control nature in the way we can control machines, which operate on simple linear causality. Biological systems involve very many mutual and circular causes, hard to disentangle or control. Whereas the physical system (machine) reflects the observer’s intentionality and purposes—to produce something of human benefit—the organism aims to produce and maintain itself. Perhaps it is time to regard the cosmos as a self-organizing entity.

Fine-tuning argues that life could not have existed if the laws of nature were slightly different, if the constants of nature were slightly different, or if the initial conditions at the Big Bang were slightly different—in other words, in most conceivable alternative universes. But is an alternative universe physically possible simply because we can conceive it? The very business of physics is to propose theoretical models that are free creations of mathematical imagination. Such models are conceptual machines. We can imagine worlds with a different physics; but does imagining them make them real? The fact that a mathematical model can generate alternative worlds may falsely suggest that there is some real cosmic generator of universes churning out alternative versions with differing parameters and even different laws. “Fundamental parameters” are knobs on a conceptual machine, which can be tweaked. But they are not knobs on the world itself. They are variables of equations, which describe the behavior of the model. The idea of fine-tuning confuses the model with the reality it models.

The notion of alternative values for fundamental parameters extends even to imagining what the world would be like with more than or less than three spatial dimensions. But the very idea of dimension (like that of parameter) is a convention. Space itself just is. What we mean literally by spatial dimensions are directions at right angles to each other—of which there are but three in Euclidean geometry. The idea that this number could be different derives from an abstract concept of space in contrast to literal space: dimensions of a conceptual system—such as phase space or in non-Euclidean geometry. The resultant “landscape” of possible worlds is no more than a useful metaphor. If three dimensions are just right for life, it is because the world we live in happens to be real and not merely conceptual.

The very notion of fundamental parameters is a product of thinking that in principle does not see the forest for the trees. What makes them “fundamental” is that the factors appear to be independent of each other and irreducible to anything else—like harvested logs that have been propped upright, which does not make them a forest. This is merely another way to say that there is currently no theory to encompass them all in a unified scheme, such as could explain a living forest, with its complex interconnections within the soil. Without such an “ecology” there is no way to explain the mutual relationships and specific values of seemingly independent parameters. (In such a truly fundamental theory, there would be at most one independent parameter, from which all other properties would follow.)

The fine-tuning problem should be considered evidence that something is drastically wrong with current theory, and with the implicit philosophy of mechanism behind it. (There are other things wrong: the cosmological constant problem, for instance, has been described as the worst catastrophe in the history of physics.) Multiverses and string theories, like creationism, may be barking up the wrong tree. They attempt to assimilate reality to theory (if not to theology), rather than the other way around. The real challenge is not to fit an apparently freak world into an existing framework, but to build a theory that fits experience.

Like Goldilocks, it appears to us that we live in a universe that is just right for us—in contrast to imaginary worlds unsuitable for life. We are at liberty to invent such worlds, to speculate about them, and to imagine them as real. These are useful abilities that allow us to confront in thought hypothetical situations we might really encounter. As far as we know, however, this universe is the only real one.