UNDERSTANDING LIFE

Figuring out how the chemical operations essential for survival are carried out within every cell of living creatures (people included) is a task dominated by complexity. The Human Genome Project aims to specify the location and structure of all 100,000 or so genes in the human body. But that catalog, which will soon be completed, will be simply the springboard for understanding what all the genes do. Only when the network of their interactions with one another has been mapped will enduring benefits follow: in the surer design of drugs, in the growth of replacement organs, in the early detection and treatment of many kinds of diseases, including cancer. Only then shall we understand the subtleties of human behavior and how human personality evolves in the course of early life by the interaction of genetic and environmental influences.

THINKING

How the brain manages to think is a conundrum with a millennial time scale. All animals have brains so as to be able to move about. Signals from the senses — eyes, ears, nostrils or skin, as the case may be — send messages to the spinal cord, which moves the limbs appropriately. But thinking involves the consideration of alternative responses, many of which have not been experienced but have been merely imagined. The faculty of being conscious of what is going on in the head is an extra puzzle. A century from now, electronics shops (or websites) will be advertising all kinds of gadgets that simulate some of the workings of the human brain, but neuroscientists will still be struggling to understand the thinking machine in all our heads.

A THEORY OF EVERYTHING

Only 70 years ago, the universe was found to be expanding, but now there is a model of how it began: the Big Bang. At the beginning, it is said, there was literally nothing ("the void" of Genesis), not even space. Then there came into being a tiny speck of superheated space that contained enough energy to create all the stars and galaxies that fill the sky-with enough left over to drive the expansion of the universe ever since.

One of the intellectual triumphs of our century, which stems from what is called quantum physics, is the understanding of how very high temperatures can create matter. Temperature is inseparable from radiation. Even in empty space, radiation has energy, and thanks to Einstein's special theory of relativity we know that energy is equivalent to mass, or matter. Laboratory scientists have been turning electromagnetic radiation into mass since the 1930s. (The inverse of that process, turning mass into energy, makes nuclear bombs.)

There is something wrong, however, with this account of how the universe began. There is not nearly enough matter in the universe to match the predictions of the Big Bang, and our current list of the particles of matter is almost certainly incomplete. We need a more sophisticated view of what is meant by "empty space," which turns out not to be empty at all. There are also serious philosophical problems created by the Big Bang, which can be described but not explained. Worse, nobody has been able to reconcile quantum physics with the other great triumph of 20th century physics: Einstein's theory of gravitation. Until that is done, the true nature of our universe will remain beyond our ken.

So must we enter the new century in a state of ignorance? There is no shame in that. All previous centuries have been justly proud of their achievements, yet those have been found, in retrospect, to be deficient. We must learn to be patient. We should also discard the idea that scientific inquiry will ever be complete. What we know so far is that each question answered merely spawns another. Why should it not be like that for the rest of time?

Sir John Maddox is the author of What Remains to Be Discovered

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