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Leonard Kleinrock is Distinguished Professor of Computer Science at UCLA. Known as a "Father of the Internet," he developed the mathematical theory of packet networks, the technology underpinning the Internet,[…]

The centerfold of a Superman comic book inspired the inventor who sent the first-ever Internet message.

Question: How did you become interested in computer science? 

Leonard Kleinrock: So, way back when, I was six years old reading comic books and I loved comic books. In the centerfold of the Superman comic book was a description, not a comic, but a text of how to build something called a crystal radio. And what fascinated me was that you could build it out of parts you could find in your house or on the street at no cost. I mean, I needed an empty toilet paper roll, some wire, my father’s old razor blade, a pencil lead. That was pretty much free. I needed an earphone, which I stole from the candy store’s telephone booth, and I needed something called a variable capacitor. I had no idea what that was, but I knew I could buy it down on Canal Street. 

So, my mother took me down in the subway, I walked to the first electronic shop, banged my fist on the table and I said, I need a variable capacitor. And they guy said, what size. And it blew my cover! So, I explained what I wanted before and he said, “I know just what you need.” So, he sold us, for a few pennies, this variable capacitor. I brought it home, wired it up, and I heard music coming out of the earphone. No battery, no power, basically free. Now this was clearly magic. I decided I better figure out how this works. And that’s what launched me on this career, if you will, of engineering. And I’m still trying to figure out how it works. 

Question: When did you come up with the idea of packet switching? 

Leonard Kleinrock: I went to graduate school at MIT, and there I started working for the legendary Claude Shannon, the man who invented and created Information Theory. Brilliant guy and he was then, and still is, my role model. And I noticed that all of my classmates were doing their PhD research on the area that he had created, Information Theory. And in my mind, this was a very crowded area; Shannon had done most of the easy, good work, solid work. What was left was hard and probably inconsequential, so I imagined. But I was surrounded by computers, both at MIT and at MIT Lincoln Laboratory, where I spent my summers working. And I said, one day, these computers are going to have to talk to each other. And there was no adequate way by which they could do so. So, this really challenged me. This was a good problem, it’ll probably be important, there’s a lot of low hanging fruit, let’s go for it. 

So I started working in the area, which eventually became the Internet. And what I did for my dissertation was to basically create the mathematical theory of data networks, suggested and introduced the idea of taking messages and breaking them up into fixed length blocks, we now call those things packets, and develop the underlying technology of packet switching, which now drives the internet backbone. 

Question: What was it like to send the first Internet message? 

Leonard Kleinrock: September 2, 1969, the first packet switch, we now call those thing routers, arrived in my laboratory at UCLA. It was based on a design that we had specified the manufacturer create. It arrived there on Labor Day weekend. On the Tuesday following Labor Day, we hooked that switch up to our host computer at UCLA, the host computer was basically a time-shared computer serving the Computer Science Department at UCLA.  

So, we had a switch and we had a computer. It wasn’t going anywhere, but I like to say that the infant Internet took it first breath of life. This switch, which was part of the Internet, looked out into the world it was born and saw a computer. A month later, the second node received their switch up at Stanford Research Institute, otherwise known as SRI 400 miles to the north of us at UCLA. They’re up in the Bay Area. We put a high-speed line between our switch and their switch, they connected their computer, we had our computer. And what we wanted to do was not talk from our computer through this very small two-node network to their computer. This was October 29, 1969. 

So what was the message we wanted to send? All we wanted to do was login from our computer to their computer. Now, to login, you have to type L-O-G, and that remote machine was smart enough to know what you’re trying to do, it types the I-N for you. Ready to go, Charlie Klein, my program and myself, Bill up at the other end, and we had a telephone connection so we could communicate and make sure we watched what happened. 

So we typed the “L”, and we say, “Did you get the “L”?” He says, “Got the “L”.” Got the, did you get the “O”? Got the “O”. Got the “G”? Crash! The SRI computer crashed. So the first message every on the Internet was “Lo”. As in “Lo and Behold.” We couldn’t have anticipated a shorter, more prophetic, more succinct message than “Lo.” 

Question: Did you have a sense then of the communications revolution that would result? 

Leonard Kleinrock: Two months before the September date, on July 3, 1969, a Press Release was put out of UCLA and in there, I’m quoted in writing—I’ve got a copy of the Press Release—where I do articulate the vision I had and basically what I said was that the internet would be always available, always on, everywhere, that anybody with any device could get on there anytime, and it would be invisible, just like electricity is invisible. What I did not anticipate was that my 99-year old mother would be on the Internet—and she was until she passed away two years ago. I didn’t see this social side. Our vision then was computers talking to each other and people talking to computers, but not people to people. And of course, that’s what’s driving the Internet these days. The communities that form, the Facebooks, all the social networking, all the email is about people communicating with each other. I missed that side of it.
Recorded on May 14, 2010