I am noticing waves these days. They can be peaceful, violent, calming, or frightening. What got me thinking was listening to breathing, especially sleep breathing. As we fall asleep, our breathing becomes more rhythmic and sounds just like ocean waves. Illustrating this is not such an easy thing, but as I searched for illustrations of waves, I realized there are all sorts of invisible waves around us all the time. Sound travels in waves, as illustrated above. Light, liquids, radio frequencies—all various waves. If you are using a wireless Internet connection, there you go—more waves. Physicists and mathematicians can go on endlessly about the properties and behavior of these waves.