Vibration. Vibration. And whats a wiggle in time through space called . Begin with a w. Wave. A wave. So were gonna talk about wiggles in time and wiggles in space, vibrations and waves. We talk about vibrations, something may be bobbing up and down, or a pendulum swinging back and forth, or something that occurs and recurs. I could take my chalk on the board i can vibrate it up and down. Im vibrating a little bit, too, okay . These are vibration, all right . Now, how frequently i go to and fro has to do with frequency. We talk about frequency with the letter f. Heres a low frequency. Wanna see a High Frequency . This is commonsense stuff. See that . Aint that neat . Guess what a very High Frequency is. How many say, gee, i dont know what come on, you guys know. Whats a very High Frequency . [makes sounds] like that, yeah . Okay. But when then a High Frequency is propagated through space, watch. It traces out what we call a. Sine curve. Its really a sine curve but a representation of a