Monday, March 29, 1999
One thing is certain about the century (or even the millennium) ahead. The pace of discovery is sure to be even faster than it is today and the social and ethical dilemmas created by the exploitation of new knowledge even more haunting. Our understanding of the world has deepened at an accelerating rate since the beginning of modern science 500 years ago. Our century, for example, has had the wit to ask how the universe is constructed, how even the tiniest particles of matter move and how life manages to exist in the face of all the odds against it.

	Leo Baekeland Tim Berners-Lee Rachel Carson Francis Crick & James Watson Albert Einstein Philo Farnsworth Enrico Fermi Alexander Fleming Sigmund Freud Robert Goddard Kurt Gödel Edwin Hubble John Maynard Keynes Louis, Mary & Richard Leakey Jean Piaget Jonas Salk William Shockley Alan Turing Ludwig Wittgenstein Wilbur & Orville Wright Categories Leaders/Revol. Builders/Titans Scientiests/Thinkers Heroes/Icons

Our century has also turned science into the principal agent of technology. When James Watt built the first steam engines 200 years ago, he had intuition but not the laws of thermodynamics to guide him. We do not sufficiently applaud our century's discovery that science can be useful — or the degree to which science has come to depend on technology for its new instruments: powerful telescopes, atom smashers, computers.

The 20th century has made science more exacting. We demand more of its explanations. To say that the earth goes around the sun is no longer sufficient; we insist on knowing why. And in some fields — space research, for example — decades can go by while novel instruments are designed and built. A further complication is that every discovery provokes new questions. The more we know, the more we do not know.

To predict what lies ahead, we must often rely on guesswork. But the nature of our present ignorance points to problems science cannot avoid. The most obvious of these is the question of what happens in our head when we are thinking. Nobody yet has a compelling answer for that. People surmise, but no surmise can yet meet the tyrannical test that every assertion about the nature of the world must be proved by experiment or observation.

Here, then, despite the dangers, is a checklist of some of the scientific and philosophical challenges for the century ahead:

HUMAN EVOLUTION

Human beings and the great apes had a common ancestor about 5 million years ago. The genes of the two groups differ hardly at all, but some of them are differently arranged. By using that information, along with hominid fossils, we shall learn what genetic changes made it possible for the ancestors of modern people to stand upright (about 4 million years ago) and then to speak. As a by-product, we shall be able to trace the migration routes of our human ancestors who emigrated from Africa and came to populate the surface of the earth. A half-century from now, we shall have a rich and authentic history of the human race.

LIFE'S BEGINNING

How life began is a grander question that will occupy most of the next century. The first task is to reconstruct the history of evolution over the past 4 billion years. Modern gene technology can use the DNA in every living thing as a vast repository of historical information. Even dna will not point all the way back to the beginning of life, but it will provide clues to the self-replicating entities first assembled from simple chemicals on the primeval earth. The century ahead will see the first laboratory proof that self-replicating systems can form from ordinary chemicals. Determining whether that is how life really began will take longer.

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