The KISS principle was something I was introduced to when I was training to be an instructor for the navy. Someone asks a question, and you shouldn’t get bogged down in unnecessary detail in answering it, or in explaining a concept.

A couple of Chad’s recent posts touch on the theme of explaining physics to the non-physicist. The first is The Popular Science Writing Process, in which he discusses the interaction with the editor:

Get back an edit letter saying “AAAAAAAHHHH!!! Much too difficult! Make it simpler!”

and in Continuity, Discretion, and the Perils of Popularization there is a lengthy discussion of a previous post on QM basics concepts

Last week’s Seven Essential Elements of Quantum Physics post sparked a fair bit of discussion, though most of it was at the expert level, well above the level of the intended audience. such is life in the physics blogosphere.

And this isn’t the first time this has happened; I recall an earlier exchange about the photon that went many layers deep in the discussion as well. The underlying theme here is that one needs to know the audience to whom you are speaking — the advantage of the editor saying “Ensimplify!” is that if s/he is not an expert in the field, and if the book is targeted at the general reader, the editor is probably a decent proxy for that audience. It would not do as much good to hand the book to a fellow physicist for the same kind of critique, because you’re likely to get the kind of objection that shows up in the Perils post. Some scientists have difficulty connecting with an audience that isn’t up to the same level of expertise; they won’t simplify their discussions. But here’s the thing:

All explanations are incomplete.

Incomplete is not necessarily the same as wrong.

We always assume some level of knowledge on the part of our listeners. It helps to know what that is, because you can miss and either go way over their heads or sound patronizing. But the goal in such situations is not to disseminate some complete set of information. To do that you might have to be explaining vector calculus and field theory, so that’s just not going to happen. It’s more important that whatever information you communicate, that it not be wrong. I think it’s very important to decouple the two concepts of completeness and correctness.

And it shouldn’t be that hard to do. If you think they are entwined, then you have to admit that teachers lie to their students all the time. We teach first-semester physics and tell our students that kinetic energy is 1/2 mv^2, and anyone who has taken relativity knows that that is just an approximation. But is it useful to throw relativity at first-semester physics students? No. The basic concepts are difficult enough. And everybody uses 1/2 mv^2, and other approximations, when circumstances say it’s OK to do so. Expanding some expression in a Taylor series to get an answer is a major part of physics, and we don’t consider it wrong as long as x << a. We use Newtonian gravity in many instances, because General Relativity need not be invoked. (Both of these being incomplete, but not wrong, if properly applied) We can explain that an atom won’t absorb a photon unless it matches the energy of an allowed transition without worrying about energy level linewidths, if that part of the discussion isn’t important to the conversation.

So I think that thinking has to be applied to explaining science to nonscientists, or to less-experienced scientists. If all they can handle is the first term in the expansion, then give that to them, and explain things at that level. I think not propagating falsehoods is more important than being precisely right.

I see this at work; we show off our handiwork on occasion, and to people who don’t have the background we do. A full quantum-mechanical discussion of atomic clocks just isn’t very pragmatic unless you actually want to bore or disillusion your audience. (if they represent possible funding, that’s usually a “No, let’s not do that.”) So you have to give the talk that’s technically correct but doesn’t go into graduate-level detail or beyond, unless your target actually invites that level of detail. And my immediate colleagues and I aren’t the only ones who like to brag about our work or hint loudly about the work we’d like to be doing in the future. But the other people who “sell” our accomplishments aren’t atomic physicists either, so there’s the same issue: give them bullet points that aren’t wrong, and don’t get bogged down in extraneous scientific detail.

See also Skulls in the Stars: To describe, or not to describe…