Lighten Up

Rant 25: Now that Facebook has a billion followers it might be a good rant to quote Hyman Rickover, the father of the US Nuclear Navy. A paraphrase of his quote is: "Great minds discuss ideas, ordinary minds discuss events, small minds talk about people." To which I would add: The mindless talk only about themselves.

Now, back to ideas: It is a simple property of sinusoidal waves that they exhibit the same shape (periodicity) in both space and time. Once you can imagine how that can be expressed it becomes obvious. I have never seen it expressed except to show the same two two- dimensional graphs plotted as amplitude versus distance and amplitude versus time, that is just to change the name of the horizontal axis. But a pseudo-3D plot of these two axes perpendicular to each other, called an orthogonal projection, shows some interesting relations. We can color code the amplitude with red at the crest (maximum amplitude) and violet at the trough (minimum amplitude)using the rainbow sequence (ROYGBIV). The while lines are sine waves running parallel to each axis. The graph shows what looks like a corrugated sheet cut at 45 degrees to the bends. It also clearly shows that any point (height) on the wave moves at the velocity of the wave - which is any upward (vertical) line (same color) on the graph since distance/time=velocity.