But the story of how that message ended up being sent has been told by people who understand computers better than I do. What I wanted to know was how he now sees the world he helped create.

What, if anything, would he change about the way the internet has evolved? Did he have any regrets?

Mr. Kleinrock said his feelings were complicated.

He noted that in a news release issued by U.C.L.A. announcing Arpanet’s deployment, he is quoted as accurately predicting that “we will probably see the spread of ‘computer utilities,’ which, like present electric and telephone utilities, will service individual homes and offices.”

He said he thinks the network will become even more invisible than it is now, which seems likely.

But what he and his researcher colleagues missed, Mr. Kleinrock said, was the social side of the network. And he missed the ways in which that capability would, he wrote in an email later, “impact every aspect of our society.”

A few years ago, as hacking and spam and other undesirable uses of the internet proliferated, he said he often told people that the internet was in its disobedient teenage years, that it would grow out of its immature period.