Teaching Physics: Abstract or Concrete?

Concrete

In physics-teaching we try to make the subject relatable by giving concrete examples to illustrate the principles at hand.

For example, in an introductory mechanics course, we show the students a ball rolling down a slope (rather than general spheres and inclines), cannonballs and divers jumping from cliffs (rather than abstract projectile motion), hockey pucks on ice (representing frictionless motion), etc.

In a more advanced course, like electromagnetism or quantum mechanics, this becomes challenging, because a realistic situation is complicated, but we need to 'learn the ropes' of the subject by first looking at somewhat artificial but simple examples (such as charges located at the corners of a square in electromagnetism, or a particle in an infinite well).

Nonetheless, each model system being studied needs to be motivated clearly (students must be told why that model is important - 'why do we need to study this?'). Preferably, even before we get into the details of the model, the relevant outcomes (a list of objectives that we expect to learn) of the study should be outlined (e.g. 'this will help us understand how radioactivity occurs'), and the list needs to be checked off at the end of the exercise, for full customer satisfaction.

Abstract

All this is well and good. However, those who are looking to make original contributions to the subject may want to consider this kind of thinking (clarified and predictable) carefully and understand it for what it is. Because in physics research, advances both great and small often result from just `playing around' without any clear aim or agenda in mind.

The history of physics is filled with discoveries which were made by alert minds but motivated by obscure reasons, and certainly not by following any kind of 'scientific method' or declared aim (Roentgen was not trying to pioneer imaging techniques in medicine when he discovered X-rays; Hertz was not trying to build a radio when he found radio waves). In fact, many scientists have famously wrongly predicted the development of science (Rutherford didn't think nuclear physics would be of much use; the head of IBM said computers were not going to be very important).

In pure science, often such a discovery reveals secrets which were not even suspected to exist (Dirac's equation introduced the concept of anti-matter). Even in technology, often previously unconnected advances come together to enable life-changing utilities (mobile phones combined microprocessors, touchscreens, GPS, cameras, batteries, wifi, internet...)

Certainly in my own bread-and-butter research, we are excited by what is proposed in the grant proposal that funds the research; but we are just as (and sometimes more) excited by things which we discover along the way whose discovery we could not have predicted. (That such discoveries are made is not entirely a surprise - it is only their specific nature that cannot be predicted). Indeed, review articles which summarize a subfield of physics often end with the hope that progress in the mirror (crystal ball?) may be rendered nearer by fortuitous discoveries which, however, cannot be found by fiat or agenda.

Conclusions

Making such advances requires being willing to play with the theoretical framework or experimental apparatus, without a rigid framework of motivation or expectation. It is when we drop our preconceived notions, when we remove our imagination from a strait jacket, that we become able to discover new things.

So while it is important while initially being trained in the subject to have a clear aim, as we advance to the frontiers of physics research, I believe it is also very important to start regarding the activity of subject study as rewarding and interesting for its own sake. Such an activity, as I mentioned in my previous post, is autotelic, and optimal for creativity.