Grad School Years
Dennis graduated from Harvard in Spring 1963 with a major in Physics. That spring he had been accepted into the Harvard Graduate School of Arts and Sciences to study towards the A.M. degree in the subject of Applied Mathematics, under the Division of Engineering and Applied Physics, special field of “theory and use of computing equipment”. As described in his essay, he did not have a clear idea of where he was headed.
“My plans for graduate school are, at this point, somewhat undefined… exactly what I would do depends, of course, on the results of my first year of graduate study… I do not, particularly, wish an academic career… I feel that my interests in the whole field of mathematics and mathematical machines is broad enough to enable me to work happily in almost any branch of this field.”
Dennis never talked to family members about his grad school experience, so we’re speculating here. But it seems like there may have been something of a mis-match between the Harvard program and Dennis’ natural interests.
At the risk of being presumptuous, here are our observations. Harvard had not developed a vision for computer science in the early 1960s. According to professor Harry Lewis in his article, A Science is Born, in Harvard Magazine…
“(In the 1960s) Harvard didn’t even call what we were doing computer science; our degrees are mostly in applied mathematics, mathematics, or physics. The University remained blind to the future of computing for a long time.”
For the most part Harvard looked towards computers and computation as a means to develop and test theory. Dennis’ student colleague and co-author on two papers, Albert Meyer, described it this way…
“Applied mathematics was a huge subject in which this kind of theory of computation was a tiny, new part… Okay, this is the big idea that brings us back to Dennis Ritchie because this was a time when the– well, first of all, there were hardly even any computer science departments in the country then. This was in the early ’60s. And there was just coming to be a vision that there was something special about computation. In the 1930s and ’40s, the notion of what was and wasn’t computable was very extensively worked on, was understood. There were logical limits due to Gödel and Turing about what could be computed and what couldn’t be computed. But the new idea was that, ‘Let’s try to understand what you can do with computation.’ And in order to understand what you can do with computation, that was when the idea of computational complexity came into being that yeah, there were things you could do, all sorts of things you could do with computation, but not all of it was easy. And you could actually try to get a theory of which things were theoretically doable but were so impossibly hard that, pragmatically, you couldn’t do them. So, there was a sudden new vision that was an extension of these ideas in the ’30s of ‘yes or no’ computing where in the ’60s, it began to be a degree of computability. How well could it be computed?”
Here’s what Dennis himself said in an Interview with Michael Sean Mahoney, history of science professor at Princeton University:
“But, ah, this was at Harvard. The computer situation was fairly – reasonably backward there, it characterized… quite well-known people. But they didn’t really have a comprehensive program. Of course this was early 1963. At that point there were really weren’t any, any computer science probably was not even called that practically anyplace. Harvard has always been part of the sort of strange relationship with the subject… At that time in particular there were individual courses that were for people who were quite well-known…”
Dennis was hired as a 1964 summer research assistant for one of Harvard’s “well-known people”… Patrick Fischer, a young professor with an interest in the nature of computation. That summer Fischer had a list of 11 open problems, he asked Dennis to work on number 4. Dennis solved the problem in a particularly elegant way, this became the core concept for his doctoral thesis. Fischer became his faculty thesis advisor.
Dennis never talked about any of this to his family. But… it turns out that Fischer also hired Albert Meyer as a research assistant that summer, and he asked Meyer to work on the same problem 4.
“So Patrick offered Dennis and me these research assistantships for the summer. Dennis might have been in that class, but I don’t remember having any interaction with him other than I knew that he was another student of Pat’s and somebody that I thought would be interesting to kind of talk to. But what happened was that, you know, Patrick says he’s going to hire me for the summer and there’s this list of papers– I actually found the paper– there’s this list of 11 open problems, he points to number four and says, ‘I want you to work on that one.’ So I said, ‘Okay.’ Well, you know, I don’t know what the hell it was, but, ‘You want me to work on that, that’s fine.’ So I’m happy. ‘I’ll read the paper right away. When do you want to meet? And he looks at me and says, ‘Meet? I’m going to be away for the summer. Just work on it.’”
“So I remember that as being one of the more miserable times in my life where I spent the entire summer, and I’d sit at my desk for hours at a time reading this paper and rereading and thinking about it. Have nothing to show for it. I could never tell whether I was actually working or not. And it made you little crazy, and it was a kind of a, a first test of could I do research or not.
“So that was the story of me and this research and getting– and so then that was my first result. I’d solved the problem. It was an open problem that my advisor had said was important, so it proved that I could go somewhere. So then a little while later, I was, I would say, surprised and a little disappointed to hear that Pat said that Dennis had also solved the problem. I don’t know exactly the timing, but Dennis was working on it over the summer, and I believe it.
“So that was the crazy story. I mean, what kind of a supervisor? You know, I feel great affection for Pat, really. He led me– he made this career possible for me. He supported us, he was encouraging, he defined the problems we were working on. He was a tremendous influence, both intellectually and professionally. But what a way to manage two students, you know? It was such a painful, lonely summer! And somehow or other, it didn’t occur to him to link Dennis and me. He was off doing whatever he was doing for the summer.”
Dennis (Interview with Michael Sean Mahoney, history of science professor at Princeton University):
“The kind of work that I was doing as a graduate student was in some sense fairly abstract. The kind of theorems that were being proved referred – it was kind of strange actually. It was the area of computational complexity. What functions are inherently more complex take longer time to compute than others. This particular bulk of hierarchies of functions. But the interesting is that that hierarchy began at exponential time. So that was sort of the unit [inaudible] size of its input or the value of its input. And, this really is – in some sense dealing with it was partly like programming because when you design a function to exemplify something it bears a strong resemblance to programming a machine. But the results you get are really totally theoretical because, of course, exponential time things are typically too hard… I guess the point is that this particular aspect of things really does not have very much direct applicability.”
Dennis seems to have lost faith in the applicability of purely theoretical research to practical results. On top of this, his thesis advisor Pat Fischer left Harvard and moved to Cornell in summer 1965. Fischer stayed in touch as an informal advisor. Dennis did not find a new thesis advisor.
When asked by Mahoney about who he was working with “in the recursive function area”, Dennis replied:
“Pat Fischer. He is now at Vanderbilt. Pat was sort of not really the Harvard advisor. I was fairly independent.”
Maybe independent, but not unnoticed by his Harvard faculty. Twice during his grad school years, February 1964 and February 1967, he received “Dear Mr. Ritchie” warning letters about his academic performance.
“By the time I finished school it was fairly clear that I didn’t want to work anymore in, I didn’t want to stay in theoretical. I was just more interested in real computers and what they could do. And particularly struck by the – how much more pleasant it was to have interactive computing as opposed to decks of cards and so forth.”
So what did Dennis do during these years to satisfy his intellectual interests? He headed to MIT.
The following dialogue is also from the Princeton interview. Some word order has been changed, words and meaning remain the same.
MSM: “You worked on Multics didn’t you?”
Ritchie: “That’s right. I was a graduate student; I worked part time at Project Mac. And there that was sort of the beginning days of Multics.”
MSM: “You worked on CTSS there at MIT?”
Ritchie: “Yes, I used CTSS because that was what was used during the development of Multics. I didn’t work on that – I didn’t have anything to do particularly with the development or maintenance of that system. I was just a user.”
Ritchie: “At MIT mostly what I did was documentation. I sort of read things. Wrote some descriptions of various aspects of the file system. Did not really do very much programming at all. At least on Multics.”
MSM: “So you wandered down to Project Mac for a summer job?”
Ritchie: “It wasn’t a summer job. I think by that time I guess I was just more interested in doing programming. I don’t know how I even found my way to it, precisely. But it was a part-time job throughout the year. Basically to support myself.”
Dennis says he didn’t remember how he found his way to MIT to begin with. But Albert Meyer remembers. He describes his interactions with Dennis during the Summer of 1964…
“I would have loved to collaborate with him, because he seemed like a smart, nice guy who’d be fun to work with, but yeah, you know, he was already doing other things. He was staying up all night playing Space war in the basement of MIT. Well, the main thing was that they were in the gravitational pull of a strong sun. I mean, you can navigate in trajectory, so that you didn’t fall into the sun, but you could use it to make amazing curves, getting up behind your opponent. So apparently Dennis was all caught up in that. That summer apparently that we were both working on this problem, he was spending many hours at night hacking this computer game. And so, in fact, I would say that although we collaborated on that paper, we never really worked together. And there was a second paper that we– he was a co-author with me on which was stuff of mine that was related to what we were doing, and I felt that he should be a co-author, because it grew right out of what we were doing. And, but, and I think I remember trying to get his attention, and maybe even his formal permission to put his name, and I never heard from him. He never responded. He just wasn’t interested anymore.”
In his Harvard Magazine article, Harry Lewis tells the story of Bob Metcalfe.
“Metcalfe started graduate school at Harvard in 1969 after earning undergraduate degrees in engineering and business at MIT. When Harvard got its ARPAnet node in 1971, Metcalfe wanted to manage it. Harvard rebuffed him: that was a job for a professional, not a grad student. So Metcalfe talked his way into managing MIT’s node instead, and thereafter was seen only rarely around Harvard. Then one day in 1972 shocked whispers raced through Aiken: Metcalfe had failed his Ph.D. defense. Nobody ever fails their Ph.D. defense; it’s a symbolic and celebratory occasion, with champagne chilling outside the examination room. But somehow Metcalfe had fallen so far out of touch with his faculty committee that they walked into that room with different expectations.”
Bob Metcalfe mended his fences and eventually received his doctorate. Perhaps Dennis had a similar experience, but didn’t.