The difference between engineering and science is profound, but not very complicated. The scientist analyzes Nature as he finds it. The engineer makes something, then analyzes it !
Note that the engineer’s materials are those provided by nature. That is, he uses matter: the elements of the periodic table, and compunds of them to make what we may safely call a machine. Note further that the fact that his invention is complicated means that a) an atom by atom analysis is impossible, and not particularly useful; and b) a simpler analysis is called for, and is necessary.
This simpler analysis often takes the form of the construction of a model–a schematized diagram with components that are exactly defined mathematically. The reason the model is necessary is that the engineer is designing his machine to do some task. He must be able to understand his machine as he progresses, so that he can modify it intelligently, with some hope of sucess. The engineer modifies his model to agree with his experience of his machine, and modifies his machine when it does not perform as desired. In this way, he is able to “steer” his design to its conclusion.
Note further that this makes the engineer an “odd duck!” For he builds something from scratch, something he only imperfectly understands, then analyzes the thing he has built in an attempt to understand it! He agonizes over it when it behaves in ways he didn’t expect or even when he simply can’t understand the cause of its behavior in the first place. Then when he is done, rather than being satisfied with it, he tries to improve it, and the design process starts all over….
In retrospect, he might have been better off leaving well enough alone!
Our scientist meanwhile, is only too happy to unify his theories, and reduce his understanding to the simplest terms. He would never go out of his way to make more “stuff” to analyze, as it would only mean more work for him!
As an example of the general principle, think of the internal combustion engine. The first working automobile was built over a century ago. It would take one from here to there without human or horse power. Yet for decades, the automobile engine has intrigued the men who design, redesign, build and drive it. Problems with such things as horsepower and torque, knocking and pinging, run-on, pollution, fuel efficiency and incomplete combustion have been recognized and addressed in considerable detail over the decades. Yet it is hard to imagine that Herr Otto*, the deviser of the internal combustion engine, forsaw that he was incorporating these “gremlins” into his design!
The unfortunate conclusion is that one does not necessarily know in advance what a thing will do, just because one created it! Only through experience are we sure to learn the limits of a new invention!
Parenthetically, a very excellent book exists, called “Why Things Bite Back” or “Technology and the Revenge of Unintended Consequences.” It explores, in plain English rather than Mathematics or Tech talk, the duplicitous nature of household appliances and other everyday things. The problem with them, author Edward Tenner explains, is that although one buys [my own made up example] a window air conditioner, one gets in the bargain a heavy, drippy, noisy thing that consumes lots of electricity and forever requires a clean filter! In other words, one can’t have purely a room cooler–all of the rest of an AC unit comes along with it!
I encountered this phenomenon many years ago from this standpoint: Although an engineer puts much time and effort, and love and passion even, into his design; in the end, it is only an inanimate object that ships to the customer. The thing simply obeys the laws of nature, for better or for worse! Whether a characteristic is spec’ed out, or a performance parameter is tested in production makes no difference, any more than the definition of terms (ripple, gain, etc.) influence its behavior. The device will simply do what Nature’s laws determine that it must.
This fact is rather unsettling to the beginning engineer, since he can’t “be there” to tweak his design if it doesn’t perform as desired, or “smooth things over” with a customer when it comes up short of expectations. At the same time, it should be a comfort as well, since the principle guarantees that with “all the right parts in all the right places,” a machine will perform reliably! This is the principle of Mass Production: If the 1st of N identical units performs, the 2nd thru Nth will too**!
* He is the counterpart of Herr Diesel, also a German, who invented the engine that bears his name. The “Otto cycle” is a little different thermodynamically from the Diesel cycle, and relies on a spark plug for combustion, while the Diesel engine “sparks” on its own heat and pressure. That each is appropriate for a certain type of vehicle, the Otto for the automobile, and the Diesel for heavy trucks is worth pondering! [true, the Mercedes and a few other cars feature Diesel engines, but I have ridden in a Mercedes, and they ride rough, owing to the necessarily large mass of the engine. Too, they are smelly and loud, and never really run smoothly!]
**Especially if one remembers Malcom Baldridge, and “six-sigma” design;)