Ultimate Explanations of the Universe (15 page)

Both in contemporary cosmological research as well as in the various aspects of speculation continuously arising in connection with it there is a persistent urge to tackle more and more radical questions. In Chap. 1 I called this tendency “the longing for ultimate explanations.” I have tried to trace its progress in the recent developments in cosmology. Admittedly, our account of the theories, models and the more speculative reflections has been far from a full overview, but I hope it has presented a sample representative enough to serve as a basis for at least some schematic conclusions.

First of all, it is rather obvious that what is at issue is, generally speaking, a justification of the universe: its existence, its laws, the way it works. But insurmountable problems start as soon as it comes to taking a closer look at that “justification.” Perhaps this is so because, as the history of science has often shown, putting the right question is only possible once we know the right answer. But so far no answer has emerged to the question of an ultimate explanation of the universe, and there does not seem to be much of a chance for one emerging “within a finite period of time.” Nonetheless, the review we have carried out enables us to observe certain regularities both as regards the asking of questions as well as the searching for answers to them.

There is certainly nothing novel about the statement that very often the endeavour to understand something boils down to breaking down that thing into its parts and trying to reduce it to its most fundamental components. This method has for a long time been the prime path for progress in science, and it is to this procedure that physics, both in its classical version as well as in its most modern embodiments, owes its biggest successes. This approach is distinctly present in contemporary cosmology, and is becoming even more prominent. Although relativistic cosmology started with the search for solutions to Einstein’s equations which would come up with models of the universe on its grandest scale, from the very beginning questions concerning the processes which may have occurred in space-time were lurking in the background. The status of cosmology became firmly established only once its global geometrical methods merged with local physics. This coalescence soon led to the emergence of the standard cosmological model, and today the successes and problems attendant on the standard model are staking out cosmology’s paths of development. One of these directions is “inward bound.” It is no coincidence that physicists working on elementary particle research and wanting to test their ideas look to models of the early universe, where they have not only high enough energies but also the chance to make empirical predictions that may be verified by contemporary astronomical observation. The work to construct a quantum cosmology go even deeper, to where the foundations of cosmology meet and unite with the laws of physics.

However, cosmology has never abandoned its original perspective – the perspective of wholeness. In Part II of this book we saw that in recent times the scope of speculation is expanding in this aspect of the research, too – no longer is there talk just of one universe, but of an entire family, perhaps an infinite family, of universes. But even if we take a sceptical attitude of this idea, in cosmology we shall still have to consider an infinite number of possible universe, if only because there exists an infinite number of solutions to Einstein’s equations which may be treated as possible universes, many of which are interesting from the theoretical point of view.

Reductionist methods and holistic (integrative) methods have been known and practised for a long time in science, but the efforts made in cosmology to justify the universe have given rise to a new phenomenon – an idiosyncratic linking up (or indeed identification) of these two trends. Certainly the discovery of a superdense state (the Big Bang) at the beginning of cosmic evolution is a success which must be attributed to global methods. The cosmological singularities made their first appearance in solutions to Einstein’s equations, which were to describe the global structure of the universe. Furthermore, thanks to the global methods it has been shown (in theorems on the singularities put forward by Hawking, Penrose, and others) that there are no simple means to eliminate the singularities from cosmology. But the really exciting things started to appear when the methods of high-energy physics were applied to the reconstruction of the physical processes that must have occurred in the neighbourhood of the initial singularity. And moving down even further, down to Planck’s threshold and beyond, the global becomes indistinguishable from the local. The difference between what is global and what local becomes blurred and finally disappears altogether. Even our idea of the universe in the Planck era being tiny (“reduced almost to a point”) turns out to be completely erroneous. It would be truer to say that our idea of magnitude – big and small – which has developed out of our spatial experience, ceases to have any meaning in the vicinity of the Planck era. If the concepts of space and time have any meaning at all in the Planck era, they must certainly be very different from what we are accustomed to.

Along with the development of cosmology, our efforts to understand the universe have been proceeding along the reductionist and the holistic paths, until these two directions meet in the Planck era. But how did the mechanism of our understanding work? Note that the reductionist type of understanding, too, works by means of elucidating the relations between respective parts. These relations may well be oriented to “the inner bound,” but if we are proceeding in this direction, we are doing so only because we are being directed along that path by our reasoning, and reasoning which is correct always follows a path of logical inferences, in other words along the relations between the premises of reasoning. The relations of logical inferences determine a certain logical structure. Therefore the understanding in question is a structuralist understanding.

Needless to say, in the physical sciences (and cosmology is one of them) the role of a network of logical inferences is performed by mathematical structures. Experimental results on their own do not allow us to understand a phenomenon; they only tell us that this is what things are like (within the limits of experimental error). Or at least would be like if there was such a thing as “experimental results on their own.” We have to bear in mind that the designation of a phenomenon for observation, the design of an experiment and the apparatus needed to conduct it, the control required for it to be carried out, the discussion of errors and interpretation of results obtained are in themselves a far-reaching advance into and entanglement in a structuralist network of theoretical inferences. Nonetheless the aim of the experimental side of science is to determine the actual status quo (with all of the conditions attending it, as we have already said), while understanding – also the understanding of the experiment and its results – comes from the mathematical structure of the model or theory. The experimentally observed phenomenon becomes intelligible only when it is “fed into and read” by the appropriate mathematical structure.

Our understanding becomes the fuller the more structural relationships we discern between the various parts of a structure. Whenever we follow such a course, the given phenomenon or process reveals its dependence on other, sometimes conceptually distant, phenomena or processes, rather than just “being what it is because it is such.” This holds true both for the reductionist as well as for the holistic path. In both cases the mathematical and experimental method yields understanding.

But a structural explanation cannot transcend the structure. Chains of logical inferences, be they infinitely long, will always remain within their structure. For they are the things that make up the structure. That is why a structural explanation is unavoidably committed to, and constrained within itself. If we ask for an explanation of the structure, all we get is the structure itself.

We have seen how this crucial constraint on the method works in cosmology. Can there be a better explanation for the existence of the universe than that the universe needs no explanation, since it has always existed? However, a closer look at this problem in cosmology immediately reveals a series of assumptions which have to be adopted if a model of a universe that has always been in existence is to be constructed. Strictly speaking, from the purely methodological point of view it does not matter whether we are to construct a model of an eternal universe or of a universe which had a beginning, we still have to assume some mathematical structures (mathematical formalism) to model these universes, and the following questions: where do these structures come from? Why these particular, and not other structures? And how is the transition to be made from the mathematical formalism to the real existence? In both cases they are the same questions.

And if we adopt the mathematical structures of the general theory of relativity, which lie at the basis of contemporary cosmology, then, as we have seen, the idea of an eternal universe breaks down when confronted with the theory (the problem of the cosmological constant, the expanding models) and observation (the red shifts in the galactic spectra). The universe was in a state of expansion, starting from the singularity; and new investments had to be made in order to get rid of the singularity. A variety of these were suggested: a cyclical universe, a universe with closed timelines, the continuous creation of matter in the steady state theory. None of these proposals brought any permanent results. Not only because the results of observation turned out to be unfavourable, but also because they got tangled up in theoretical problems. In the background of all of these attempts to understand – both in the purely speculative ones as well as those which were confirmed by observation – lurked Leibniz’s haunting question: “why is there something rather than nothing?” Perhaps the boldest attempt to face up to this question came in the model of the quantum creation of the universe put forward by Hartle and Hawking. But even if we admit that the mechanism proposed by this model really does produce something out of nothing, Leibniz’s question is merely relegated from the realm of research in physics to the realm of the laws of nature. Nothing can be produced without the laws of nature. But why do the laws of nature exist – rather than there being nothing, genuine nothingness, with no regularities and no rationality?

The concept of an infinite number of universes does not take the edge off these questions at all, quite the contrary – it makes them all the more urgent. Although it offers an answer to the question of the special character of our universe, it calls for a justification not just for one but for an infinite number of universes. And even what it does explain is achieved at the cost of a considerable departure from the rigours of the scientific method. For we can hardly call a concept “strictly scientific” which conjures up so many existences (universes) beyond the possibility of any experimental verification whatsoever.

In spite of all these shortcomings we should not underrate the philosophical significance of the mathematical and experimental sciences, and in particular of relativistic cosmology. All the successes science has scored have been accomplished “within the framework of the method,” and they are such huge successes, and they all endorse the method. The mathematical and experimental method itself has a philosophical relevance which can hardly be overestimated. For why does the universe submit to examination only if it is examined according to this method? The entire history of science shows that this is the case. Before the invention of the mathematical and experimental method the progress made in understanding the world was negligible, or rather non-existent, since all the results of any value were in fact merely steps towards the formulation of this method, if not its foreshadowing. All of this indicates that the universe has a property (or a set of properties) thanks to which it can be investigated successfully by the mathematical and experimental method, while all other methods have proved fruitless (or little better than fruitless). Elsewhere I have called this property (or set of properties) the mathematical nature of the world, devoting a considerable amount of attention to the analysis of this feature.
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All the efforts we have made to understand the universe, as expressed in contemporary science, and especially in cosmology, have been made on the assumption that the world is mathematical. Or, in other words, all these efforts are being accomplished within the framework of the universe’s mathematical structure. But the drive to understand does not stop at the discovery of the world’s mathematical nature. Since the mathematical and experimental method does not reach beyond the world’s mathematical nature, the drive to understand must transcend this method.

Einstein used to say that the world’s intelligibility was the greatest miracle and that we would never understand that miracle. He was right insofar as in order to realign our drive to understand with that miracle we shall have to transcend the boundary of the mathematical and experimental method. If never ceasing in our drive to understand is a crucial feature of rationality, then the limits of the mathematical and experimental method are not the limits of rationality. And that is why we have to continue on the quest.