Why did I believe that glass is a liquid at standard temperature and pressure? It's a common misconception that was imparted to me at a young age. I quickly incorporated into my understanding of how the world worked and it became one of those "facts" that I just knew.
Glass is not a high-viscosity liquid at room temperature: it is an amorphous solid, although it does have some chemical properties normally associated with liquids. Panes of stained glass windows often have thicker glass at the bottom than at the top, and this has been cited as an example of the slow flow of glass over centuries. However, this unevenness is due to the window manufacturing processes used in earlier eras, which produced glass panes that were unevenly thick at the time of their installation. ... In fact, the lead frames of the windows are less viscous than the panes, and if glass was indeed a slow moving liquid, the panes would warp at a higher degree.
In fact, I believed that glass was a high-viscosity liquid until less than an hour ago. What made me look it up?
I do, too. In fact, I'm marking my calendar: the first Tuesday in February shall henceforth be Misconception Day!