To appreciate the importance the new computer-aided communication can have, one must consider the dynamics of “critical mass,” as it applies to cooperation in creative endeavor. Take any problem worthy of the name, and you find only a few people who can contribute effectively to its solution. Those people must be brought into close intellectual partnership so that their ideas can come into contact with one another.

After I had found the answers it was always painful to write them up or to publish them (which is how you get the acclaim).” In short, mathematics for Shannon was more like a game, something that he did for the pure intellectual joy of it. And indeed, that’s what his friends tend to remember best about him: his extraordinary playfulness.

Another participant, Ivan Sutherland, remembers his first meeting in 1964: “These people met, period. The group had no charter, no responsibilities, no budget, no purpose—but it was a great thing. We would discuss what was important, what was current, and what was going on. Precisely because the group had no charter, it was a wonderful way of getting information flow between the agencies.”

But even that wasn’t good enough, not for a machine whose tubes would number in the tens of thousands: the odds of one’s failing at a critical moment were still just too great. So after working and reworking the numbers, the group decided that the only answer was redundancy. Every computer in the air-defense system would have to be paired with an identical backup computer that would be ready to take over at a moment’s notice.

This free-wheeling “ARPAstyle” of management was radical for 1961, and nothing like the rigidly top-down hierarchy that prevailed elsewhere in the Pentagon. But it worked. Old Washington hands who transferred into the agency could only shake their heads in disbelief: decisions that would take months anywhere else were made at ARPA in a matter of days.