I was taught glass is a supercooled liquid. If you look at window panes that are over 100 years old they are thicker at the bottom than at the top because they slowly flow down due to gravity.
That article doesn’t contradict what I was taught, just that the reason for the melted appearance of old glass isn’t due to this state, as that would take longer than the universe has existed to reach that effect, but due to old glass making techniques. We weren’t taught wrong, just given the wrong timeframe for it to happen. Doesn’t change the fact that glass isn’t a solid. Don’t know why my original comment is currently negative. I guess I’m taking the down votes earned by my chemistry teachers back in the 90s.
No matter how much you cool a glass, it won’t crystallise. You have to go over the glass transition temperature and cool down slowly enough for crystals to form. In the case of silica glass, that’s not going to happen, though, because it’s a “strong glass former” - it doesn’t crystallise unless you do something pretty extreme.
Glass is absolutely a solid, the term amorphous just refers to the structure being non-crystalline. It’s still a solid tho.
I was taught glass is a supercooled liquid. If you look at window panes that are over 100 years old they are thicker at the bottom than at the top because they slowly flow down due to gravity.
We were taught wrong. That is an artifact of how the glass was made.
https://www.scientificamerican.com/article/fact-fiction-glass-liquid/
That article doesn’t contradict what I was taught, just that the reason for the melted appearance of old glass isn’t due to this state, as that would take longer than the universe has existed to reach that effect, but due to old glass making techniques. We weren’t taught wrong, just given the wrong timeframe for it to happen. Doesn’t change the fact that glass isn’t a solid. Don’t know why my original comment is currently negative. I guess I’m taking the down votes earned by my chemistry teachers back in the 90s.
On the scale of millions of years, everything flows.
Well, if it is a type of glass, it will flow until it is able to cool enough to crystallize
No matter how much you cool a glass, it won’t crystallise. You have to go over the glass transition temperature and cool down slowly enough for crystals to form. In the case of silica glass, that’s not going to happen, though, because it’s a “strong glass former” - it doesn’t crystallise unless you do something pretty extreme.