In Defense of Physics Pedantry

In yesterday’s Get a Grip, Drew asks a reasonable question in response to my pedantry about the use of terminology:

So when is the word ‘suck’ used appropriately (trying not to sound dirty, here)? Can’t there be a colloquial usage if we know what it actually means?

Used appropriately? Probably never, or rarely. And I have to admit, I can’t think of a situation (on short notice) where this conceptual mistake would cause a problem. We scientists can be rather anal meticulous about terminology, and there is a reason for it. Sloppy terminology might lead one to construct a flawed model of how things actually work, much like when one uses an analogy — there are always circumstances under which the explanation fails to hold. By using the proper terminology, the model is better and there are fewer circumstances under which it will fail.


This is not the only example of the sloppy language phenomenon. Others include heat and deceleration. Heat is probably the worst, and in no small part because physicists are sloppy in using it. To begin with, we present it in two different ways: as a process, by which energy is transferred because of a temperature difference, and also as the energy itself that is transferred. A problem arises when we use the two interchangeably. We then talk of heat flow or heat transfer, which is awkward if we are referring to a process. Beyond that, this reinforces the notion that heat (or, in general, energy) is a substance, as if you could have a little pile of heat somewhere, and heat transfer then invokes the image of pouring this substance from one container to another. The huge drawback here is that the misconception sidesteps thinking about the physical processes of conduction, convection and radiation. Heat (like work) isn’t something in a container, but we reinforce this error by using the term “heat capacity,” which tends to encourage this idea. All of this without even getting into the commonly-held misconception that infrared light and heat are the same thing.


Deceleration is an unnecessary term in physics, because acceleration is a vector, which just makes it a special case where the acceleration and velocity are in opposite directions. But some students have a hard time with the concept of vectors, and decoupling the terminology probably isn’t helpful, especially when you get into circular motion, where there’s an acceleration that doesn’t change the speed at all.


As I said at the outset, I can’t think of the pathway where using “suck” leads one onto the moors of misconception and into the bog of bafflement (not to mention possibly going over the cliffs of insanity), but I’m sure there is one. Because if there is one thing I learned while teaching, it’s not to underestimate the ways in which students will misunderstand concepts.

(edit: I don’t mean this last remark in a bad way — it’s not meant to disparage students. The issue is that if a teacher erroneously assume s/he understands what a student’s misconception is, the misdiagnosis is going to make it harder to fix the problem.)

3 thoughts on “In Defense of Physics Pedantry

  1. Wow, I feel like a celebrity!

    Being a practitioner and not a teacher, I think these terms are all useful for concise communication, as are things like centrifugal and coriolis forces. One would have to go to unreasonable lengths and awkward phrasing at times to avoid their use.

  2. Look, if we’re going to be pedantic (and I love being pedantic) one could make the case that the pedantry in yesterday’s post was just as inaccurate as the original “sucking” comment. Perhaps even more so.

    Re: “Pretty neat (other than the part where they talk about a vacuum sucking the air out — it’s the external pressure that forces the air movement.)”

    It is not merely the external pressure that forces the air movement, it is the DIFFERENCE in pressure that causes net air flow.

    As such, I think that saying the vacuum sucks the air out (I think it’s implied that the experiment was conducted in the earth’s atmosphere) is just as legitimate as saying the external pressure causing the air flow. Perhaps even MORE legitimate: in the environment we’re in it takes work to create sub-atmospheric pressures; it takes no work to create atmospheric pressure.

  3. Point taken about differential pressure (though I could argue that “in this case” was implied), but it’s the “in the environment we’re in” where I think the trouble lies, because if you build your model that works only under conditions of near-atmospheric pressure, it’s not going to be as robust as a model that works under other conditions.

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