#glassphysics

This morning I found myself staring at the old window in the library, running my finger along the uneven glass. The bottom pane was noticeably thicker than the top, and I caught myself almost repeating the myth I'd heard a dozen times: that glass is a slow-moving liquid, flowing downward over centuries. A colleague walked by and said,

"See? That's why medieval windows are always thicker at the bottom."

I wanted to correct her, but I hesitated. The myth is so persistent, so intuitively appealing.