years. When one examines the utilization of engineering library reference documents, these tend to have an even shorter useful half-life—about 1 to 2 years. And it has even been demonstrated that my own books reach their half-life the moment they hit the shelves!

Another quantitative measure of the pace of technology is the interval between generations of integrated circuits. In the case of random access memory, a generation turns over every 2 to 2 1/2 years. This has been true since the invention of the semiconductor chip, which itself represented a great technological leap. For most of us who are members of this Academy—whose median age, I have computed, is 70—the principal calculating tool for the bulk of our careers was the slide rule. The invention of the Friedan and the Marchant seemed like an enormous breakthrough to most of us. Along with the slide rule, we used blueprints and French curves. Compare that with engineering projects today, in which you have teams of engineers working on computers all around the world interacting every few moments without ever coming in direct contact.

Qualitatively, just in my lifetime, we have seen the advent of nuclear weapons, sent a dozen Americans to the surface of the moon, created television, launched weather satellites, created jet travel, designed and built electronic computers, cellular telephones and precision navigation systems, invented polio vaccines, and perfected heart surgery. The list of accomplishments is as astonishing as it is seemingly endless. And the pace of such developments would seem, if anything, to be accelerating.

Similarly, in the area of national security concerns, the only constant seems to be change. When I was a youth, the overriding national security objective was to win the Big War. We did that. For the next 40 years, the principal goal was to deter a Bigger War. We did that, too. Today, our objective has once again changed substantially. The objective, as I would characterize it, is to deter smaller conflicts, and that has proven to be no less daunting than our previous goals. Somehow, the end of the balance of terror seems to have made the world safe —for smaller wars. That is the irony of the situation in which we find ourselves today.

National security considerations have changed vastly as the world ’s political underpinnings were restructured following the fall of the Berlin wall in 1989. For example, one of the things that now distinguishes the United States from the former Warsaw Pact nations is that the United States has a legal Communist party. The last time I was in Moscow, the lines outside of McDonald’s restaurant were substantially longer than the lines outside Lenin’s tomb. (I might add that the crowds outside McDonald’s were generally happier and more flamboyant, too!) And when I was in what was then Leningrad, I met a very distraught politician who had just run for re-election unopposed—and lost.

These are just a few vignettes I have personally observed, but they suggest the vast transformation we’ve seen in a very short period of history. Looking back, I have to remind myself that it was just a few years ago that a NASA

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