It’s a sin(θ).

“I get a kick out of thinking…”

-Richard Feynman, PhD

In honor of his birthday, it seems only right to start this post with a video of the late Dr. Feynman, exemplifying the sharing of science knowledge and wonder. Here’s a piece of an interview I particularly enjoy, as does TED. I’ll see you in a few minutes when we’ll continue with the article.

If a conversation with with someone turns towards either physics or Jiu Jitsu for the first time, I’ll often give a lighthearted warning.  “Just to let you know, there are two topics (physics/Jiu Jitsu)  I can talk about indefinitely so please let me know if ramble on or you have to be somewhere.” A friend recently asked if we could find time to talk about the physics in some of the Jiu Jitsu moves he’s seen in fights. Luckily, I didn’t scare him off by asking if I could bring a white board. I have awesome friends.

Richard Feynman, Carl Sagan, the other role models I mention in the site’s History page, were and are all wonderful story-tellers with some of the most important and wise tales to tell. I can honestly say I don’t know why (yet) storytelling in this way seems so repugnant to the majority of scientists and textbook authors. I hope the video included here sparked some wonder in your day.

And so, on on the anniversary of his birth, an anniversary he shares with a very dear friend of mine (so this is for you, too, Doug), I say Happy Birthday and Happy Science to all!

Tomorrow I will be attending a social media event at NASA’s Armstrong Flight Research Center to see some sweet new technology they’re showing off.  I feel a bit like I’m going on a field trip for (totally cool) adults. In preparation for the trip’s story to come, I wanted to write a quick introduction to a particular way my brain thinks about waves. Since waves describe so much of the universe — perhaps all of it with some light, philosophical stretching — I refer to their behavior often and in a variety of contexts, especially using the jargon of my former people, the optical physics researchers.

Thankfully many of the words are familiar to daily discourse, so that clarifying can also provide the reader with some possible Bar Trivia points should the topic be “words that describe physical phenomena.” You never know.

Please imagine for me, if you will, yourself on a swing. If you remember those black, tire-like plastic strips dangling from rusty chains of death, hopefully you miss them as much as I do. But that’s not really important here. What’s important is that you remember how to swing higher by moving your body on the swing. As you are daydream-swinging, I’ll describe the setting in terms of the wave motion.

The wave here is your back and forth motion. The wavelength, perhaps un-intuitively, is determined by the length of the chains. (Common physics tests love to use this property to trick the uninformed pupil, whose distributor is supposed to be doing the informing, by the way. Typically they’re in the form of a lazily composed problem about a pendulum, drawn suspended in mid air; or as in the image included here, hanging from a base that is suspended in mid air.)


How high you go is the wave’s amplitude. You put energy into the wave by burning the calories in your food to move your body with careful timing. Since the wavelength can’t be changed without risking at least a finger with those chains, the energy you put into the wave will only give you more height.

If you were lucky enough to live an a neighborhood with well cared for youth equipment, where swing joints were always well lubricated, reaching that optimal height (as close to the swing set height as possible without adult reprimands) meant your legs could take a well deserved break while you let conservation of momentum work her fun magic. Machinery is oiled in an interest to get to that idealistic wonder of frictionless-ness and preventing those poor children from having to pump their legs too veraciously to make up for the part of their energy lost friction. (“Ignore friction.” Another one commonly hung at the end of physics questions by the lazy diagnostic composer.)

The harmonic oscillator is, perhaps, the most fundamental concept in physics. And it’s nothing but you on a greased up swing, relaxing as you enjoy the vast height of one peak to the other, moving in a wave. I love that kind of thing.


Even though they may be your trigonenemies (oh yes, that one is all mine!), the Sin and Cos functions (along with their relatives) come out of this motion, too. If you have interest in visualizing trigonometry, the animation above might convince you this is true for now.

I’ll follow up this article in the coming days with some brief stories about electricity (certainly with an appearance by Nikola Tesla), how it relates to a playground swing, and some teaser photos from NASA before tying it all in to one final piece!


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