Colleague "Differential Equations" asserts, "The first thing people did with early electronic computers was numerically solve differential equations." Different colleague Matt reacts, "I thought it was just straight trig for artillery calculations ? Serious q." Who's right?
My short answer: neither, or arguably both. To my mind, a slightly longer answer involves explanation at least of:
I underline that I regard engineering history as a species of history, in the sense that engineering is a human activity.
I'm on a tight schedule this week. While I'd happily write on this subject for days, it occurs to me that the /r/AskHistorians collective might synthesize something greater than I'd do on my own, even with hours to spare. This is a bit of an experiment.
The problem with this argument is that it is entirely dependent on what you define "the first computer" (electronic or otherwise) to be. And I will just tell you that the historians of computing that I know have essentially abandoned this as a coherent question, because there are a million possible candidates because the term "computer" is excessively vague. If you want to say, "first fixed program, digital, electronic computer" — sure, fine (though even there, the experts can probably debate a bit), but keep in mind how many qualifiers and adjectives you are adding to it, because there were analog computers, for example (e.g. the Differential Analyzer), and there were non fixed-program computers, and so on.
I think one can say that differential equations, artillery tables, cryptographic problems, and nuclear weapon calculations were among the first programs used by the first electronic computers and feel pretty safe with it, but again, the devil is in the (definitional) details. And whenever I find myself in such a situation, I instead start to ask: "What are the stakes in assigning one of these priority over the others? Why does it matter, if it does? If the goal, for example, is to try and distance the progress in computing from military applications, then seizing on one of the few non-military uses as most important seems disingenuous if all of the other major uses (and work in computing in general) was indeed accelerated by military work (as I think it can be pretty plausibly argued). But this is just one possible example of "stakes" that one might have.
Another way to think about this: the term "computer" is vague enough to describe a lot of things. Asking what was the "first computer" is like asking what was the "first duck." This doesn't mean that it isn't a valid categories (ducks are a mostly coherent category), but the category did not suddenly and immediately spring into existence fully-formed. There were proto-ducks and pre-ducks and things that are not quite ducks but are recognizably related in the context of ducks (for computers, think for example of Leibniz's stepped-reckoner). Eventually you presumably had things that started collecting the various aspects of the duck that we think as defining (webbed feet? check. flat bill? check. flies and floats? check.), and so it is easy to point to a final duck and say, "ah, that's a duck," and it's even easy to point to a broad genealogy and say, "all of this led to the duck," but it's very hard to say, "here is where the first duck really comes into being." If however you broaden your goal to "the first duck_s_" then it becomes pretty straightforward and, I would argue, more useful as a historical narrative. Which again comes to the question of stakes and goals — what's the incentive for identifying the first duck? (That is not how evolutionary biologists would talk about duck evolution, just as this is not the way that historians of computing want to talk about computer evolution.)
No: "Colossus is sometimes referred to as the world's first fixed program, digital, electronic, computer", and it used statistical arithmetic to solve a codebreaking problem (essentially the Lorenz SZ-42, not the Enigma) posed by Max Newman.
More detailed references in follow-up.
What was the first electronic computer? Usual claimants to the title are:
ABC was built explicitly to attack systems of partial differential equations. Its success was at best partial, and it wasn't programmable. Also, the parts that worked best on it, as I understand, really focused on systems of linear equations; numerical solution of interesting PDEs didn't advance as much as might be expected. I'm still uncertain whether the documented facts justify that impression of mine.
Colossus wasn't about dif-eqs.
ENIAC and EDVAC were undeniably in the possession of physicists who more-or-less gleefully solved weather models, designed nuclear weapons, experimented with wind-tunnels, and, for demonstration purposes, charted artillery fire. DEs abounded.
SSEM did number theory, from what I know. While it was late to the party in the sense of first running in 1948, it nicely combined everything a modern might regard as essential to qualify as an "electronic computer".
Z3 was designed for engineering arithmetic. Its memory was electromechanical.
Note Harvard Mark (ASCC) I-III all had mechanical storage (among other elements), so I'm excluding them.
A heretic might also want to consider telephone switching machines of the '30s and '40s as potential general-purpose computers. Some of them were fully electronic, in an appropriate sense.
What's all this chatter about artillery? While it would take several books to approach comprehensiveness, the essentials are these: