I have often sat in a physics lecture or talk and questioned why obviously intelligent people can communicate so uselessly. Communication is not an easy problem, and academics generally do not get that much practice or feedback (c.f. the peer review system for scientific content) in order to improve. I am sure there have been poor talks throughout history, but I think in this key domain technology is certainly a crutch. In this post I'm going to go through two great articles I've read on the topic, which have defined my view: we should endeavour to entirely over-simplify our talks, and we should place oration at the centre of a talk instead of slides or other props.

Each of these articles are very short and highly entertaining. I highly recommend you go and read each¹ of them⁴.

Mermin: What's Wrong with Those Talks?

First we will discuss this somewhat famous diatribe, published in David Mermin's Physics Today (1992) column¹. You may know Mermin from his classic textbook Solid state physics (with Neil Ashcroft), the Mermin-Wagner theorem, or perhaps his foundational work in quantum mechanics and information theory. Mermin himself states he is better known for his essays, foremost of which was an article in 1991 that inspired Paul Ginsparg to establish the arVix². He also coined the term "Shut up and calculate!" as a description of the Copenhagen interpretation³.

Mermin is pretty eviscerating of the conventional talk:

... pretending that the standard physics talk of today is an acceptable form of communication breeds hypocrisy in the old and experienced and nurtures self-doubt in the young and innocent, who not only have to undergo the wretched experience of attending physics talks but also torture themselves worrying why they're not enjoying the ordeal.

I will outline Mermin's key recommendations here.

Recommendation 1: It is impossible to give too simple a talk

If you have taught physics you know it is virtually impossible to write too easy an exam. Yet nobody acknowledges that the same is even more true of the physics talk. It is absolutely impossible to give too elementary a physics talk. Every talk I have ever attended in four decades of lecture-going has been too hard. There is therefore no point in advising you to make your talk clear and comprehensible. You should merely strive to place as far as possible from the beginning the grim moment when more than 90% of your audience is able to make sense of less than 10% of anything you say.

And

Never, ever, have I heard anybody complain about a talk on the grounds that "I understood everything in it."

Recommendation 2: Convey your initial enthusiasm

Mermin makes a big deal of the fact that talks are a good opportunity for self-reflection,

The best reason to lecture on your work is that it affords you the opportunity to rediscover why you did it.

and elegantly links this to the basis of a good talk: you need to understand why you originally found it interesting in order to convince the listener!

What is there in the subject to capture the imagination of one lacking your highly specialized skills? Give yourself a week. If you still can find no reason why anyone not directly involved in the work should find it anything but tediously obscure, then you should find something else to talk about.

And I'll add the comment here that an entertaining talk on a niche topic is always more better than a comprehensive tour-de-force on a large topic, with a correspondingly comprehensively lost audience. Regardless, your enthusiasm is the key to the listener's attention:

But suppose you do remember why you got into your current line of research. If you succeed in conveying that early freshness and excitement to somebody else, your talk will be an unqualified success, even if you never manage to describe a single one of the splendid things you uncovered when the project was well under way. [...] Your only goal must be to furnish ordinary physicists with some modest glimpse of what sustains your own interest in your subject.

Recommendation 3: You don't - shouldn't - centre the talk on yourself

But what if the niche, interesting topic that you think will be entertaining does not involve talking about your work!? Here Mermin is somewhat radical:

What brings even well-intentioned efforts to grief is the misconception that it is necessary for speakers to talk about their own contributions. There is no need to say anything whatever about what you did yourself.

Keeping the talk focused on ourselves, and what we did, also detracts from time we could spend discussing interesting stories:

On those few occasions when a physics talk delves into the history, sociology or social psychology of the subject, the audience wakes up and listens. [...] Reading aloud from the reports of hostile referees, for example, almost invariably rouses an audience from its stupor as well as giving you a rare opportunity to make it vividly and painlessly aware of your own contributions.

Recommendation 4: Consider preparing a written text

Mermin detests reading from slides, suggesting speakers write a prepared script:

Humanists, who take words more seriously than physicists do, often read their talks from a prepared text. When the talk is delivered with animation and impromptu asides, the results can be spectacular, for the written language is more powerful and concise than informal speech, and a richer and more attractive medium. Most physicists deem it undignified or unsporting to read a prepared text. Rubbish!

Recommendation 5: Omit the summary

The ubiquitous heavy-handed concluding summary should be omitted; a talk should tell such a good story that a summary is uncalled for. Imagine War and Peace ending with a summary.

I think moving to a primarily oral talk will make the summary redundant, regardless.

Recommendation 6: Finish early

There is no better way to make an audience happy than briskly finishing a talk five minutes earlier than it expected you to.

Personally, I find I have been much happier when I finish talks early, e.g. a 12+3 minute slot that I finished in 9 minutes and had more time for questions.

Ridgen and Stuewer on Props

Ridgen (molecular physicist) and Stuewer (historian) wrote an Editorial (2010) for Physics in Perspective^{4 5} on the topic of props in physics talks. By props they mean blackboards, slides and the like. Mermin in the above article also had some choice words:

The physics talk has, in any event, evolved toward the reading of a prepared text, but in an entirely unsatisfactory way. Many physicists do read their talks, not from a paper text, but from a sheet of transparent plastic projected on a screen.

I find his commentary on the usage of slides quite foreign - certainly the contemporary context (1992) sounds quite different to the reality today!:

Sheets of plastic are only for illustrative figures, graphs or data, and unavoidable elementary mathematical analysis in the absence of a blackboard. If your analysis or diagram is too intricate to present in this way, it is too intricate to be in a talk at all. [...] Most details are better supplied orally.

Ridgen and Stuewer highlight the benefits of a blackboard, one I remember from my better (perhaps more old-fashioned) lecturers who wrote everything on the (white-)board:

[The blackboard] prop had both advantages and disadvantages. The principal advantages -- huge advantages -- are that the rate at which listeners are expected to digest the material being presented is limited by the writing speed of the speaker; also, the same writing speed limits how much technical terrain a speaker can cover in a typical 50-minute talk.

Alas, the projector took over:

When technology brought the demise of the blackboard, the overhead projector took its place. For about 30 years, virtually no talks were given by physicists without this prop. [...] Sometime around the turn of the century, a projection camera appeared in auditoria and PowerPoint replaced the overhead projector. [...] By its glitzy nature, PowerPoint encourages a physicist who is preparing a talk for a general audience to bring together far too much material. [...] Yet many speakers go through 30 or more PowerPoint screens and, in the process, leave the audience far behind.

I think we have all been the victims and the perpetrator of the latter many times. The final point they make is one I had not considered; that the speaker should be focused on the listeners, and engage in a (perhaps lopsided) dialogue:

The talks given by speakers using props—blackboard, overhead, or PowerPoint are generally, not always, monologues. In such cases, a speaker’s attention is focused on a display screen where information is being displayed. With a laser pointer, the speaker can call attention to a particular image on the screen or a particular set of words as he or she reads the words. Apart from occasional glances at the audience, the visual connection between speaker and audience is minimal. A monologue is not an effective way to communicate. An effective speaker knows how to involve the audience because an effective talk is a dialogue.

Outstanding Questions

• Can I write a talk with only minimal slides to display e.g. my image results? Are those still too complicated? What is the real story I want to convey in a talk?
• Do I have anything of value I do want to say? Do slides allow us to talk about nothing, verbosely?
• How will a modern audience react?

References