The content of this post extends beyond condensed matter physics, but I’ll discuss it (as I do most things) within this context.
When attending talks, lectures or reading a paper, sometimes one is struck by what I will refer to as a “gem of insight” (GOI). These tend to be explanations of physical phenomena that are quite well-understood, but can be viewed more intuitively or elegantly in a somewhat unorthodox way.
For instance, one of the ramifications of the Meissner effect is that there is a difference between the longitudinal and transverse response to the vector potential even in the limit that . This is discussed here in the lecture notes by Leggett, an effect I find to be quite profound and what I would call a GOI. Another example is the case where Brian Josephson was famously inspired, by P.W. Anderson’s GOI on broken symmetry in superconductors, to realize the effect now known after him. Here is a little set of notes by P.B. Allen discussing how the collective and single-particle properties of the electron gas are compatible, which also contains a few GsOI.
My concern in this post, though, is how such information is spread. It seems to me that most papers today are not necessarily concerned with spreading GsOI, but more with communicating results. Papers are used for “showing” and not “explaining”. Part of this situation arises from the fact that the length of papers are constrained by many journals, limiting the author’s capacity to discuss physical ideas at length rather than just “writing down the answer”.
Another reason is that it sometimes takes a long time for ideas to sink in among the community, and the most profound way to understand a result is only obtained after a period of deep reflection. In this case, publishing a paper on the topic is no longer appropriate because the topic is already considered solved. Publishing a paper with only a physical explanation of an already understood phenomenon is “not new” and likely to be rejected by most journals. This is part of the reason why the literature on topological insulators contained the most clear expositions on the quantum hall effect!
So how should we disseminate GsOI? It seems to me that GsOI tend to be circulated in discussions between individual scientists or in lectures to graduate students, etc — mostly informal settings. It is my personal opinion that these GsOI should be documented somewhere. I had the privilege to learn superconductivity from Tony Leggett, one of the authorities on the subject. Many ideas he expressed in class are hardly discussed in the usual superconductivity texts, and some times not anywhere! However, it would probably be extremely fruitful for his lectures to be recorded and uploaded to a forum (such as YouTube) so that someone interested could watch them.
This is a difficult problem to solve in general, but I think that one of the ways we can rectify this situation is to include more space in papers for physical explanations while cleaning up lengthy introductions. Furthermore, we should not necessarily be discouraged from writing papers on topics that “aren’t new” if they contain important GsOI.
Do you agree? I’m curious to know what others think.