Simplicity is a deceptively simple thing. Recently, a scientist who was trying to explain something in general relativity to me did so in the following way:

One simple way to understand … is as follows. Imagine that one sets up spherical polar coordinates, so that space is described by r, \theta, \phi and time is described by t. Then in this frame what one would normally call a non-rotating observer is one who has no angular velocity in \theta and \phi i.e. if the proper time of the observer is \tau, then {d \theta \over d \tau} = {d \phi \over d \tau} = 0.

(Emphasis added)

This is anything but simple, and this problem isn’t limited to this scientist alone. Lots of them regularly conflate explanation with elaboration. More recently, another scientist – by way of describing a peer’s achievements – simply listed them in chronological order. It was the perfect example of ‘tell, don’t show’:

Starting with the discovery of strangeness, called Gell-Mann-Nishijima formula, the Eightfold Way of SU(3), current algebra, he finally reached the theory of strong interactions, namely quantum chromodynamics. So his name is there in all the components of the theory of strong interactions, now a part of Standard Model. His other fundamental contributions are in renormalisation group, an important part of quantum field theory and in the V-A form of weak interaction. He also proposed a mechanism by which neutrinos acquire very small masses, the so called the See-Saw mechanism. He had broad interests going beyond his contributions in theoretical physics.

Explanation requires the explainer to speak multiple languages. For example, explaining the event horizon to someone in class X means being able to translate what you know in the language of graduate-level physics to the language of Newtonian mechanics, first principles of optics, simple geometric shapes and recourse through carefully chosen metaphors. It means enabling the listener to synthesise knowledge in other contexts based on what you have said. But not doing any of this, sticking to just one language and using more and more words from that language cannot be an act of explanation, or even simplification, unless your interlocutor also speaks that language fluently.

Ultimately, it seems that while not all scientists can also be good science writers, there is a part of the writing process on display here that precedes the writing itself, and which is less difficult to execute: the way you think. To be able to teach well and explain well, I think one needs to be able to think in ways that will mitigate epistemological disparities between two people such that the person with more knowledge empowers the one with less to climb up the knowledge ladder.

This in turn requires one to examine the precise differences between why you know what you know and why your audience doesn’t know what you know. This is not the same as “the difference between what you know and what the audience knows” because it is then simply an exercise in comparison – an exercise in preserving the status quo even. Instead, to know the why of the difference is also to know how the difference can be bridged – resulting in an exercising in eliminating disparity.