As the second millennium comes to a close, I am prompted to ponder on some of the major problems as yet unsolved by science, and to speculate on what progress science will make during the coming century. Will the scientific advances of the 21st century match, exceed, or be outshone by the scientific advances of the 20th century?
Some respected commentators feel that science has already explained all the major features of the natural world and all that remains is the unexciting phase of filling in various details. However, there is no doubt in my mind that science is near the beginning and not the end of its journey.
Towards the end of the 19th century a feeling of completion existed among many scientists, similar to the feeling mentioned above. Newton's laws were known to act in the heavens as well as on Earth, and it was a source of deep satisfaction to science to note the clockwork regularity and predictability with which the universe worked. And, in biology, Darwin's and Wallace's theory of evolution by natural selection offered a satisfying explanation for the immense diversity of life.
Many scientists felt that the major questions were answered and that what remained was largely a matter of filling in details.
How different it turned out to be. The 20th century began with the rediscovery of the results of Mendel's brilliant experiments on plant genetics. This lit a slow-burning fuse in biology that eventually exploded in the middle of the century with the dramatic developments in molecular genetics, culminating in the biotechnological and genetic-engineering revolution. As the century closes, the cloning of adult mammals is becoming a routine technique.
Our conception of the physical universe was also revolutionised this century, beginning in the early decades with the theories of relativity and the development of quantum mechanics. Astronomical observations showed us an expanding universe, and this harmonised with the subsequent development of big-bang cosmology which proposes that the universe began about 15 billion years ago in an explosion from an infinitely dense and hot point, and has been expanding outwards ever since.
Physics has now reached the stage where some scientists are trying to formulate a theory of everything (TOE), i.e. a set of master equations that will completely describe the universe on all scales. Stephen Hawking said in his book A Brief History of Time: "The development of such a grand unified theory would be the ultimate triumph of human reason - for then we would know the mind of God." Hawking is a professed atheist, so God knows what he means by this remark!
In my opinion TOE is not yet even remotely realisable. Science knows little or nothing of the nature of the matter that constitutes over 90 per cent of the universe. We know of this "dark matter" only indirectly, because of the gravitational attraction it exerts on neighbouring visible matter. Recent evidence indicates that neutrinos have a tiny mass and, therefore, the vast number of these tiny little entities in the universe may add up to a significant fraction of dark-matter mass.
However, I suspect that this proposal is made more in hope than in confidence and that we still have a long way to go to understand dark matter. Since we know so little about so much, it seems to me to be wildly off the mark for anyone to think that little of real substance remains for science to discover.
Turning again to biology, it is clear that many huge questions remain to be answered. Two examples of such question are (a) what is the physical basis for consciousness? (b) how did life arise on Earth? Science has mapped out the physical and biochemical plan that underlies many vegetative aspects of life and many properties of animal life, e.g. sensation and locomotion. But how the brain produces consciousness remains a mystery. Some people feel that this problem is so complex it will never yield to science, but I would be more optimistic. I expect dramatic advances in the scientific understanding of brain function during the coming century.
Another major problem that awaits a scientific solution is the riddle of how life spontaneously arose on Earth about 3.5 billion years ago. The prevailing scientific opinion is that the basic chemical constituents of life formed naturally on the early Earth and, later, these chemicals self-assembled into the first simple living cell. On the face of it this is an enormously improbable sequence of events, even if a billion years was available in which it could happen.
If this is how it did happen, we should, in principle, be able to reproduce the event by mixing the right ingredients and incubating them under the right conditions. Will science ever be capable of doing this? If so, the day that it happens will be the most significant day to date in world history. Personally I think that understanding the physical basis for human consciousness will be simple compared to uncovering the mechanism whereby life arose from a chemical soup.
We are only at the start of a long, and possibly endless, road of scientific discovery. I believe that a vast series of wondrous discoveries about the nature of the world are in store for mankind. I agree with J.B.S. Haldane (1892-1964) who said: "I have no doubt that the future will be vastly more surprising than anything I can imagine. Now my own suspicion is that the universe is not only queerer than we suppose, it is queerer than we can suppose."
William Reville is a senior lecturer in biochemistry and director of microscopy at UCC