Ok, what I meant was my friends point was that glass was liquid even its solid state. He went on to explain if

Question

you ever looked at a pane of glass on a house a hundred years old you can actually see small waves in the glass or minute sagging.

Answer 1

The so-called "proof" that glass flows has be debunked a long time already. Medieval glass making was very imprecise and a survey of glass from that era shows glass that's thin at the bottom as well as glass that's thick at the bottom.

Answer 2

That's an old wives tale. Old windows are thicker at the bottom because they were made that way. They needed to be stronger on the bottom to support the weight. And the irregularities in old glass are because of the imprecise methods they used to manufacture it back then. Glass isn't a crystal, so it can deform over millions of years if there's a force acting on it. Just like any other non crystaline solid.

Answer 3

Since no one else has tried this yet I will...

What he means is glass doesn't crystalize. If you freeze water there is a very sharp distinction at the 0 degree point, the water crystalizes into ice - it is either a liquid or a solid.

Glasss does not. At high temperatures it is obviously a liquid, and as you cool it it gets thicker and thicker (more viscous), until at room temperature it appears solid. But it never goes through the phase change most materials do when changing from liquid to solid.

Hope that helps.

Answer 4

See the below. The Straight Dope column ran something on this before. Glass does flow, but it takes millions of years to notice it.

Answer 5

sofar got it right. Those old panes will actually measure thicker at the bottom than the top due to the glass flowing downward.

Answer 6

MY EXPLANATION A FEW MINUTES AGO, WAS THAT IF YOU STAND THE GLASS ON ITS EDGE FOR A VERY LONG TIME, THE BOTTOM EDGE WOULD BE THICKER THAN THE TOP EDGE. THIS IS BECAUSE THE VICOSITY OF GLASS IS VERY HIGH, AND IT THEREFORE IS VERY SLOW TO FLOW (OR SAG).

Answer 7

i answered to your other question.
you can add on info at a later date you don't need a new question.