According to James Ussher, archbishop of Ireland in the 17th century, the universe was created on the 23rd of October, 4004 BC. (It happened to be a Sunday.) According to the latest figures of cosmologists, the Big Bang occurred 13.77 billion years ago. The first dating was based on a thorough study of the Bible, the second on a thorough study of the Cosmic Microwave Background Radiation. What they have in common is an implausible precision, given the uncertainties involved in both.
No less than biblical exegesis, the latest figure for the age of the universe depends on complicated interpretation. Yet it is happily announced as a fact. This is a general tendency of a science with little place for dwelling on its own assumptions. Though not a scientist, I find there is always room for doubt. Skepticism has a creative role to play in science, as in life, at each stage of the game—not only at those critical points when new evidence (or accumulation of old failures) forces abandonment of current cherished belief.
It is commonly thought that science, unlike the arts, represents a growing body of objective knowledge. This fits well with our modern idea of progress. However, what actually accumulates is data, which always remain open to new or revised interpretations. Evidence grows (if we preserve it), while theories come and go. If one assumes from the outset that there is a truth of the matter (“the butler did it in the library”), on which the evidence must converge, then it would make sense to believe that theories get closer to the truth over time. However, the evidence often is not consistent, does not converge. (Even in law, new evidence can reopen a case or reverse a decision.) Scientific bravado, abetted by the media, may present the verdict as beyond a reasonable doubt—that the evidence unambiguously dictates it. Even in science, however, what is “reasonable” doubt is a matter of opinion. While official tolerances for error are prescribed, tacit underlying assumptions involved in measurement may go unexamined. The latest measurements of the Cosmic Microwave Background Radiation are only meaningful when coordinated with distance scales that remain sketchy. Conclusions are only as valid as the premises on which they are based.
Is science a search for truth? Perhaps, but no more so than jurisprudence, which often requires a unanimous jury. Both are social institutions, not open windows on reality. Especially now that scientists rarely work alone, it is all the more important to be tentative—not to deny the hard-won advances, but to keep limber for further progress. The exact age of the universe is beside the (decimal) point if the whole big picture could go at any moment.