“Longitudinal vs. Transverse Waves – Learning from the Ocean,” by Charles Humphrey

I want to share something I was reflecting on today that has been with me for a while. This is about the imaginary distinction made in human perception between longitudinal and transverse waves. Anyone who has studied physics in high school will be well familiar with these two concepts. Light is generally described as having the properties of the former, with sound being the latter. In martial arts we often talk about waves as being the ideal for movement. I think many of us, like myself, fall into the trap of only thinking in longitudinal terms. Longitudinal movement is much more apparent to the eye and hence we are more conditioned to think of waves as longitudinal, never mind the fact that the two are co-dependent in a manner of speaking.

I think with few exceptions whenever we speak of “waves” we tend to use the image of water. This is a good starting point since we are often exhorted to be like water. It was from water that I learned that the longitudinal metaphor was a partial image that impeded my development. The up-down motion of the waves is the most apparent expression of what is fundamentally a transverse (back-and-forward, or compression-expansion) phenomenon. Rather than being a static system rippling, the longitudinal waves we easily perceive are an attempt to accommodate the excess pressure produced by transverse waves. In geology this is the same phenomenon which produces mountains. Pressure between the tectonic plates, or the “sea of earth” force the earth upward in ultra-slow motion longitudinal waves. The sea is no different save for the timelines being shorter.

By watching the waves and getting a feel for the deeper, transverse motion which lies at the heart of the longitudinal motion, we can gain a more complete understanding of how to generate power within our own dynamic systems. In my experience this is best done by moonlight since the contrast between the wave-crests makes for easier perception of the transverse dynamics at the heart of oceanic waves. In reality, what we refer to as waves are never entirely transverse nor longitudinal, in any situation, as any conceptual distinction is never a complete account. The true movement of water is much larger than either of the concepts either separate or together, but the transverse concept is a good starting point for deconceptualizing perception. Learning wave-movement from observing the ocean can give important hints on how to breathe and move. I am sad that I no longer live by the ocean where I used to practice. It was my best teacher.

I hope that beginner practitioners like myself will find this insight from nature to be helpful. Please try it and give feedback on your experience if you can. Not only has the specific concept been useful to me but lies at the heart of a larger idea that we are able to learn what we need from observing nature. This does not involve any complex analysis but merely a kind of patient watchfulness. I also recommend watching flocks of certain small birds. The relations between them as individuals functioning within a larger “organism” when they fly can provide a similar insight to that provided by water, with the addition that there is a more obvious “mind” present in the birds… Indeed, one can witness a kind of “mind” between them, which yields good insights about one’s own body-mind and one’s rightful place and function within human society in general. What a wonderful school we have been gifted with. Thank you.


  1. Interesting thought…
    …are California coastal wave/swell models. Note that there are waves generated from the soutwesterly quadrant, coming all the way from the South Pacific. These interact with the more local westerly and northwesterly wavetrains. The interaction is reminiscent of kokyu nage and koshinage. There are also some interesting coastal phenomena having to do with lees of islands, depths, and reflectivity of steep depth gradients. The “inside moves”, good nikyo and sankyo are probably the most common examples, remind me of the near coastal phenomena. The long-period movements of aikido, wide circles and swooping spirals, say ki-no-nagare ikkyo tenkan, remind me of the dominant wavetrains.

  2. Jim Clark says:

    I like the article, but I think you confused some things about waves that would actually be more instructive if looked at carefully. For a good idea of the different wave types (animations) go here:

    I teach High School physics and calculus and I have taught an after school Aikido club to HS students. I have found that the better the students understand physics, the easier it is to explain how more dynamic techniques work.

    In terms of water waves, if you looked at the animation in the link above, you will see that water waves are a combination of longitudinal and transverse waves. You have felt this if you have ever floated in the water as a wave passed by you: you were lifted up and down at the same time as you are shoved back and forth a little bit.

    I think Mr. Humphrey is right on in terms of studying water waves to inform Aikido technique. An uke should (ideally) feel disruptions in balance from as many different directions as possible during a technique. It is very difficult to follow if they have back-forth/up-down/side-side motions coming at them.

    I strive for the “feel” of a water wave, such that uke feels there is no choice except to get moved in the desired direction. Hopefully this is the result of a properly executed kuzushi…


    Jim Clark

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