A person living in the year 1000 could scarcely have imagined how much we would now understand about the physical world. So forecasting the next millennium in science is certainly rather foolhardy. Looking a century ahead is less unreasonable. After all, some of the most revolutionary insights in what is still taught as "modern physics" are now almost a century old: Planck’s discovery of the quantum in 1900, and Einstein’s of relativity in 1905. Of course, a truly new idea cannot be forecast, but we can at least say what the big questions are now that have some relevance to religion, and whether the answers to them are likely to come in the next century. Here is my list of the top ten questions in science.
1) What are the ultimate laws of physics? 2) Are those laws deterministic? 3) What is the correct physical description of what happened at the Big Bang? Was it the beginning of time? And, if not, did time have a beginning? 4) Is the universe infinite in size? And are there an infinite number of planets? 5) How did life begin? 6) How did evolution happen? Is natural selection enough to account for it? 7) Did life begin elsewhere, and are there other intelligent creatures in the universe? 8) How does the human brain work in detail? 9) What is consciousness, and how does it fit into our theories of the physical world? 10) What are the limits of computers, and can the human mind be completely explained in computational terms?
Every one of these questions is far harder than any scientific question that has ever been answered before. For most of them, a solution by direct observation or experiment is out of the question. We can never directly observe what (if anything) existed before the Big Bang. We can never directly see the entire universe and thus verify that it is finite (if it is) since relativity theory does not permit us to. There are no fossils of the first living things or the prebiotic entities from which they are presumed to have sprung. It is unlikely that we will ever completely map out the neural circuitry of a human brain because of the number of nerve cells and connections involved. And as far as consciousness and free will are concerned, scientists and philosophers seem divided between those who think that there is nothing to explain and those who think that the explanations are too hard for us ever to understand. Except for the first, perhaps, I see no grounds for confidence that any of the questions on this list will be answered definitively by the year 2100.
The three questions in this list of greatest theological importance (because they intersect with dogma) are the determinism of physical law, the beginning of time, and the nature of the human mind. While science may never be able to give definitive answers to these three questions, one can make educated guesses.
Determinism was overthrown by quantum mechanics in the 1920s, so the question here is really whether determinism will make a comeback. There does exist a way to reinterpret the mathematical formalism of quantum mechanics deterministically—it is called the "many worlds interpretation." However, there are certain serious technical objections to this interpretation; and even if it can be shown to be technically viable, it is thought to be impossible, even in principle, to verify whether it is correct. Another possibility is that quantum theory itself will be overthrown. But if the superstring theorists are right, then the fundamental principles of quantum theory are probably here to stay. The bogey of physical determinism is thus likely gone for good.
As far as the beginning of time is concerned, there are certainly interesting speculations according to which something existed before the Big Bang. However, it is very hard to imagine at present how these ideas could ever be tested. And even if one of them were found to be right, it is hard to see how it could be settled whether or not time had a beginning at some point earlier than the Big Bang. But since the idea of a universe without temporal beginning does not seem to sit very well with the Second Law of Thermo dynamics, I would guess that cosmological theory at the end of the next century will not prefer an eternal universe.
Finally, in spite of the unfounded optimism of the proponents of "strong Artificial Intelligence," there are compelling reasons to disbelieve the computational theory of the mind. And so, while I would expect dramatic advances in what computers can do, I do not expect that machines will be built which can understand abstract concepts or exercise the other powers that philosophers traditionally attributed to the "active intellect" in man.
This brings us to some broader reflections. What gave birth to science and remains its motive force is a belief in the power of human reason. But this belief can be grounded only in a transcendent view of man and thus, ultimately, in religion. The early modern era lost sight of this fact, in part because the attempt of the Church to repress error was seen as an attempt to repress man himself and his intellect. Thus, for many, the scientific spirit came to be defined in opposition to faith. This hostility to religion on the part of some scientists, however, really involves an inner contradiction that is now coming to the surface.
As a human enterprise, science magnifies man. It displays in an unparalleled way the tremendous power of human reason. And yet, as a horizon of thought, physical science is extremely narrow. It deals with matter in motion, with what can be measured, and weighed, and clocked. It is all too tempting for the scientist to try to fit the human being within that horizon. But what is left when that is done? One is left with the human mind as "nothing but a pack of neurons," in the words of Sir Francis Crick, and nothing but a "machine made of meat," in the words of Marvin Minsky. One is left with human concepts, even the very mathematical concepts out of which science itself is built, as "neurological creations," in the words of cognitive scientist Stanislas Dehaene. The scientist who succumbs to materialism is conflicted in his view of man. Like Hamlet he says, "How noble in reason! How infinite in faculty! . . . In apprehension, how like a god! . . . And yet, to me what is this quintessence of dust?"
As the present Pope has emphasized, revelation is not only about God; it also contains "the truth about man." God reveals man to himself. Man is revealed to be a rational being, made in the image of God. Pope John Paul II has stated that human freedom is rooted ultimately in this truth about man. Science, too, is rooted in it. And that is why the battle of the next century will not be between science and religion, but within science and for its soul. By proclaiming the truth about man, religion will be found to be not an enemy of reason, which of course it never was, but perhaps its last defender.
Stephen M. Barr is a theoretical particle physicist at the Bartol Research Institute of the University of Delaware.