What is the Official Definition of Glass?

In summary, the conversation discusses the debate over whether glass is a liquid or a solid. Some argue that it is an amorphous liquid due to its lack of crystalline structure, while others believe it to be a solid. The discussion also touches on the misconception that old panes of glass are thicker at the bottom because the glass has slowly flowed over time, and the fact that glass does not have a freezing point like other substances. Ultimately, the classification of glass as a solid or liquid may vary depending on the definition used.
  • #1
mceddy2001
21
0
Ive heard some arguments for and against glass being a liquid. But what is it officially?
 
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  • #2
An 'amorphis' liquid. (means 'without shape')
 
  • #3
It's also heard by me...

But first we have to purely define

WHAT IS SOLID AND WHAT IS LIQUID ?

What's your opinion?
 
  • #4
Originally posted by Moni
It's also heard by me...
But first we have to purely define
WHAT IS SOLID AND WHAT IS LIQUID ?
What's your opinion?
It's NOT an opinion, 'solids' do not (generally speaking) change shapes, 'liquids' take on the shape of the vessel that they are deployed within, but do not change volume, as a 'gas' would...see chemistry; 101
 
  • #5
Supercooled liquid is the way I had it explained to me.
 
  • #6
It is my understanding that this entire debate get started because certain very large very old (400 years plus) panes of glass in the old cathedrals and the like were found to be significantly thicker at the bottom then they were at the top. This led to the conclusion that the glass was actually a highly viscous fluid and over its 400-500 years of existence was slowly "flowing" to the bottom of the pane.

However, I later heard that further research revealed some of 400-year-old panes of glass that were thicker at the top then at the bottom. Still others were thicker on the right side or the left.

Turns out, 400 years ago glassmakers simply did not have the technology to extrude a large pane of glass of uniform thickness. After that, I rather lost track of the subject.
 
  • #7
Originally posted by LURCH
It is my understanding that this entire debate get started because certain very large very old (400 years plus) panes of glass in the old cathedrals and the like were found to be significantly thicker at the bottom then they were at the top. This led to the conclusion that the glass was actually a highly viscous fluid and over its 400-500 years of existence was slowly "flowing" to the bottom of the pane.

However, I later heard that further research revealed some of 400-year-old panes of glass that were thicker at the top then at the bottom. Still others were thicker on the right side or the left.

Turns out, 400 years ago glassmakers simply did not have the technology to extrude a large pane of glass of uniform thickness. After that, I rather lost track of the subject.


Too right. I'm sick of hearing that glass is a liquid. This is one of those stupid urban myths that just gets retold all the time. What other scientific 'fact' depends on the study of old artefacts. (actually I can think of many...but you know what I mean)
Evidence please!
 
  • #9
glass is a supercooled liquid.

Glass is amorphous substances that has no crystalline form. Amorphous substances can be thought of as supercooled liquids. The application of an external force over a period of time causes these materials to flow and become permanently deformed.

-Benzun
All for god.
 
  • #11
Pretty slick, heh?
 
  • #12
Yes - that's one way out of a conumdrum, redefine things!

And as I said - it DOESN'T flow!
 
  • #13
So I stand corrected.
 
  • #14
So... A liquid can be defined as a substance that flows? How many liquids flow in outerspace and thefore would glass be a liquid if the gravity of the planet it was on, was not strong enough to accelerate the particles down towards the ground. At a certain pressure would glass be a solid and what is the freezing point of glass?
 
  • #15
Originally posted by mceddy2001
So... A liquid can be defined as a substance that flows? How many liquids flow in outerspace and thefore would glass be a liquid if the gravity of the planet it was on, was not strong enough to accelerate the particles down towards the ground. At a certain pressure would glass be a solid and what is the freezing point of glass?

regular glass does not have a freezing point, per se. (and I'm talking about normal pressures; I don't know what the deal is in very high or very low pressures). Glass changes its viscocity as temperature increases. Most things do, but glass never hits a point where temperature stops going up while it melts. So the opposite is also true: temperture does not stop going down while it freezes.

So glass will go from a "solid" that will change its shape if pressure is applied slowly, to a thick fluid, to a thinner fluid, and etc.

By the way, a "fluid" is defined as anything that flows. THis includes gasses as well as liquids.
 
  • #16
The chemistry textbook in front of me classes glass as an amorphous solid. Same class as rubber and butter.
 
  • #17
Originally posted by Adam
The chemistry textbook in front of me classes glass as an amorphous solid. Same class as rubber and butter.
Isn't that an oxymoron?
 
  • #18
Originally posted by Mr. Robin Parsons
Isn't that an oxymoron?
No. "Amorphous" just means "Lacking distinct crystalline structure." Though most solids have a distinct chrystal structure, it isn't required. And even those that do have many flaws in the structure. A perfect chrystal is extremely difficult to achieve. However, given what we have seen in this thread, I'd say the definition of "glass" in Adam's textbook may be incomplete. What level is the book, Adam?
 
  • #19
University level, first year chemistry. I did not copy in everything the book says, merely wanted to say what class of matter glass is.
 
  • #20
here's one for ya, couldn't all things be determined to be liquid? i'd imagine that after a long enough time that the atoms in "solid" objects would begin to droop (if gravity is applied for the duration) thus allowing for a say a rock to occupy any shape of container. would i be incorrect in assuming that would be possible?
 
  • #21
Originally posted by russ_watters
No. "Amorphous" just means "Lacking distinct crystalline structure." Though most solids have a distinct chrystal structure, it isn't required. And even those that do have many flaws in the structure. A perfect chrystal is extremely difficult to achieve. However, given what we have seen in this thread, I'd say the definition of "glass" in Adam's textbook may be incomplete. What level is the book, Adam?
Russ, I may have spelt it wrong but I got the definition of it right, first page, second post...
Originally posted by MRP
An 'amorphis' liquid. (means 'without shape')
Clearly spelt "Amorphous" not the manner in which I originally spelled it.
 

1. Is glass a solid or a liquid?

Glass is technically considered to be an amorphous solid, meaning that it does not have a distinct crystalline structure like other solids. However, it behaves more like a supercooled liquid, which is why it is often mistakenly thought to be a liquid.

2. Why do some people believe that glass is a liquid?

One reason for this belief is that old glass windows appear to be thicker at the bottom, giving the impression that the glass has flowed over time. However, this is actually due to the way the glass was made and installed, not because it is a liquid.

3. Can glass change from a solid to a liquid?

Glass does not have a melting point like other solids, but it can become softer and more pliable when heated. This is known as the glass transition temperature, and it is different for each type of glass.

4. How is glass made if it is not a liquid?

Glass is made by melting together a combination of raw materials, such as sand, soda ash, and limestone, at extremely high temperatures. The melted mixture is then cooled quickly to form a solid before it has a chance to crystallize.

5. Is glass always considered an amorphous solid?

While most types of glass are considered to be amorphous solids, there are some exceptions. For example, some types of glass, such as certain kinds of metallic glasses, do have a distinct crystalline structure and are therefore not considered amorphous solids.

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