# Is glass a liquid or a solid **URL:** \ **Category:** Factual Questions\ **Created:** [August 7, 2005, 12:53am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936 "2005-08-07T00:53:26Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [August 7, 2005, 11:31pm UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/21 "2005-08-07T23:31:38Z")
> [@bizzwire](#): > > Gotta disagree. Science only works by way of very specific definitions that everyone agrees to. Included in this are words and concepts such as “liquid” and “solid” which have been given very concrete definitions which encompass both microscopic and macroscopic properties and behaviors. > > If you want to debate whether glass is a solid or a liquid, you **have** to comply with the nomenclature. If you’re gonna propose that a solid is whatever you feel it should be, if you want to to go with what \* works\*, then all bets are off. This is chemistry, not psychology. You don’t change definitions to better fit people’s ignorance. Oh rubbish. That may be the way that _science_ works, but it isn’t the way _language_ works. It’s important to realize that words can have both a popular and a technical meaning, and both are equally valid within their own realms. Glass may very well be a liquid to a scientist, and it’s fine to refer to it as such in technical applications. But it is certainly a solid the way that most people understand the word. That’s not ignorance, it’s plain English. It’s fine if scientists wish to take common words and redefine them for technical applications, but to allege that it is “ignorant” to continue to use the word according to its original meaning is pure arrogance. (And my take on this is as a professional scientist.) ---
**Author:** ![bizzwire](https://avatars.discourse-cdn.com/v4/letter/b/958977/32.png) [@bizzwire](https://boards.straightdope.com/u/bizzwire)\ **Post date:** [August 8, 2005, 12:31am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/22 "2005-08-08T00:31:12Z")
> [@Colibri](#): > > Oh rubbish. That may be the way that _science_ works, but it isn’t the way _language_ works. It’s important to realize that words can have both a popular and a technical meaning, and both are equally valid within their own realms. Glass may very well be a liquid to a scientist, and it’s fine to refer to it as such in technical applications. But it is certainly a solid the way that most people understand the word. That’s not ignorance, it’s plain English. It’s fine if scientists wish to take common words and redefine them for technical applications, but to allege that it is “ignorant” to continue to use the word according to its original meaning is pure arrogance. > > (And my take on this is as a professional scientist.) “Ignorance” was a tad on the harsh side, I’ll admit. I took issue with an existential answer to a reasonably cut-and dried question in the assumption that the **OP** was asking for a call from a scientific viewpoint. Otherwise, wouldn’t it be better suited to IMHO (“Hey! Who here thinks glass is a solid?”) or perhaps GD (“where do we draw the line between true solids, amorphous solids, and liquids, and what do we mean by the word ‘solid,’ anyway?”)?. I thought GQ was intended for “factual” questions and answers. Shoot bullets through me. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [August 8, 2005, 12:55am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/23 "2005-08-08T00:55:29Z")
> [@bizzwire](#): > > Shoot bullets through me. Well, if we shot glass pellets at you, they probably wouldn’t hurt much, since they’re liquid. 🙂 ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [August 8, 2005, 12:59am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/24 "2005-08-08T00:59:15Z")
Why is it that the “liquid” designation seems to be only applied to glass? A little superficial Googling and Wikipedia reading tells me that plastics are amorphous solids as well. Should they be considered to be liquid as well? Certain igneous rocks are not crystalline - are they liquid? What about liquid crystal; they have crystalline structure, but they flow. Are they solid? ---
**Author:** ![stockton](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@stockton](https://boards.straightdope.com/u/stockton)\ **Post date:** [August 8, 2005, 1:15am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/25 "2005-08-08T01:15:43Z")
> [@bizzwire](#): > > I thought GQ was intended for “factual” questions and answers. Shoot bullets through me. Oooooh! Shoot bullets made of ICE! 'Cause then, see, before the autopsy, the previously-solid bullets would have melted away into… never mind… ---
**Author:** ![Hakuna\_Matata](https://avatars.discourse-cdn.com/v4/letter/h/a88e4f/32.png) [@Hakuna\_Matata](https://boards.straightdope.com/u/Hakuna_Matata)\ **Post date:** [August 8, 2005, 1:17am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/26 "2005-08-08T01:17:53Z")
> [@bizzwire](#): > > “Ignorance” was a tad on the harsh side, I’ll admit. I took issue with an existential answer to a reasonably cut-and dried question in the assumption that the **OP** was asking for a call from a scientific viewpoint. Otherwise, wouldn’t it be better suited to IMHO (“Hey! Who here thinks glass is a solid?”) or perhaps GD (“where do we draw the line between true solids, amorphous solids, and liquids, and what do we mean by the word ‘solid,’ anyway?”)?. > > I thought GQ was intended for “factual” questions and answers. Shoot bullets through me. No you are correct–I was seeking a scientific viewpoint. I can see for myself that glass is a solid as a lay person. But her comment was that her science teacher stated this-so I was going on the base assumption that technically there was something beyond what the common assumption would be. thank you all for your explanations–I should have done a search :smack: but you live and learn thanks again! ---
**Author:** ![Hyperelastic](https://avatars.discourse-cdn.com/v4/letter/h/a3d4f5/32.png) [@Hyperelastic](https://boards.straightdope.com/u/Hyperelastic)\ **Post date:** [August 8, 2005, 3:05am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/27 "2005-08-08T03:05:07Z")
> [@bizzwire](#): > > Gotta disagree. Science only works by way of very specific definitions that everyone agrees to. Included in this are words and concepts such as “liquid” and “solid” which have been given very concrete definitions which encompass both microscopic and macroscopic properties and behaviors. The trouble is that the microstructural and (continuum) mechanical definitions have nothing in common. They don’t even address the same question. This is at the root of the “glass is a liquid” business. Glass shares certain microstructural characteristics with other materials that everyone recognizes as liquid. For people who are interested in microstructure, there is value in classifying glass as a liquid (I guess; I’m not a materials scientist.) But the mechanical definition is a lot closer to the layperson’s intuition than the microstructural definition. That’s why people looked at the thickness of old windows and such things - they learned that microstructurally, glass is amorphous like liquids, therefore, they reason, it must flow like a liquid. Only it doesn’t flow. There is a correlation between amorphousness and flow, but there are exceptions. Glass is amorphous but doesn’t flow. Liquid crystals are crystalline, but they do flow. ---
**Author:** ![Arjuna34](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@Arjuna34](https://boards.straightdope.com/u/Arjuna34)\ **Post date:** [August 8, 2005, 6:33am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/28 "2005-08-08T06:33:18Z")
> [@bizzwire](#): > > True solids have a melting point: a narrow temperature range where it goes from solid to liquid. Glass doesn’t. Heat it, and it starts to soften, getting less and less viscous as you increase its temperature. Ergo, glass is not a true solid. What about solids that don’t melt - e.g. wood, sulphur, dry ice, etc.? Arjuna34 ---
**Author:** ![snailboy](https://avatars.discourse-cdn.com/v4/letter/s/97f17d/32.png) [@snailboy](https://boards.straightdope.com/u/snailboy)\ **Post date:** [August 8, 2005, 11:23am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/29 "2005-08-08T11:23:33Z")
> [@Arjuna34](#): > > What about solids that don’t melt - e.g. wood, sulphur, dry ice, etc.? > > Arjuna34 All of those can melt under the right circumstances. Wood and sulphur would have to be in an absence of oxygen. Dry ice (aka carbon dioxide) would have to be under pressures greater than 1 atmosphere. I don’t think there’s any crystalline solid that doesn’t melt under the right circumstances, whereas amorphous solids never will. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 8, 2005, 11:55am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/30 "2005-08-08T11:55:50Z")
Glass is 99.999…% solid, which is the same as 100%. 😉 ---
**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\ **Post date:** [August 8, 2005, 12:00pm UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/31 "2005-08-08T12:00:17Z")
[QUOTE=Hyperelastic A better way to look at it is from a mechanical point of view. The most common definition of a fluid (which generally comprises what physicists refer to as liquids and gases) is a material whose shape can be changed without affecting the way it responds to subsequent shape changes, i.e., it has no “mechanical memory”. .[/QUOTE] what about viscoelastic or thixotropic fluids? They certainly have a “memory” !. Sorry, nature is never so cut and dry ---
**Author:** ![Hyperelastic](https://avatars.discourse-cdn.com/v4/letter/h/a3d4f5/32.png) [@Hyperelastic](https://boards.straightdope.com/u/Hyperelastic)\ **Post date:** [August 8, 2005, 5:28pm UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/32 "2005-08-08T17:28:39Z")
> [@scm1001](#): > > what about viscoelastic or thixotropic fluids? They certainly have a “memory” !. Sorry, nature is never so cut and dry You bring up a valid point - this is why I admitted to a loss of clarity when I gave the definitions of fluid and solid. To go into more detail, elastic fluids do have “memory”, but they do not recognize one configuration as different from another. So it limits the way in which the “memory” can affect the response. The past only affects them in so far as it differs from the present configuration, but that is always changing. This is a subtle issue that I didn’t want to go into. It’s easier, but inaccurate, to just say that fluids don’t have “memory”. Also, note that we’re talking about mathematically idealized materials here, not real materials. So the problem isn’t with nature, it’s with our inability to unambiguously describe phenomena that are inherently ambiguous. ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [August 8, 2005, 5:52pm UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/33 "2005-08-08T17:52:44Z")
**Hyperelastic** \* Also, note that we’re talking about mathematically idealized materials here, not real materials. So\*\* the problem isn’t with nature, it’s with our inability to unambiguously describe phenomena that are inherently ambiguous.\*\*\* And our inability to explain all phenomena of the natural world is that we are _not_ taking into account the tenets of Intellgent Design. 😃 (The above is stated as a 100% tongue-in-cheek posting.) ---
**Author:** ![JustAnotherGeek](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@JustAnotherGeek](https://boards.straightdope.com/u/JustAnotherGeek)\ **Post date:** [August 8, 2005, 7:46pm UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/34 "2005-08-08T19:46:41Z")
> [@Terminus Est](#): > > Why is it that the “liquid” designation seems to be only applied to glass? A little superficial Googling and Wikipedia reading tells me that plastics are amorphous solids as well. Should they be considered to be liquid as well? Certain igneous rocks are not crystalline - are they liquid? What about liquid crystal; they have crystalline structure, but they flow. Are they solid? Now you’re getting my point! A lot of things we perceive to be solid have slightly different characteristics than those that we attribute to “pure solids.” Hence my discussion of candies and rocks. Again, to my understanding, molecules in “solid” crystalline structures have more… reason… to stay put. (Intermolecular bonds) Molecules in amorphous structures lack the bonds between molecules. Said molecules may move so slowly that we consider the overall sample to be “solid,” but molecular movement happens. Granted, it happens in metals as well. **matt** mentioned lead as an example, but all metals (which are usually crystalline) can display creep, from the kind of intermolecular bond that’s present. This is problem related to our definitions. We think in terms of pure characteristics (solids don’t change shape, ever; liquids change their shape easily). I actually like terms like “semi-solid” or “semi-liquid” to describe substances with unusual combinations of characteristics. ---
**Author:** ![JustAnotherGeek](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@JustAnotherGeek](https://boards.straightdope.com/u/JustAnotherGeek)\ **Post date:** [August 8, 2005, 8:02pm UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/35 "2005-08-08T20:02:39Z")
Here would be some examples of how I use terms (Material Scientist may have multiple aneurysms, but they work for me to get the message across 😉 ) Crystalline solid: Rock candy, Quartz, diamonds, ice Crystalline metal solids: pure metals that hold their shape Amorphous solid: Glass, lollipops, plastics Semi-solid: asthenospheric materials, toothpaste Semi-liquid (or, simply viscous liquids): Lava, moleasses Liquid (fluid, inviscid, with minimal viscosity): water, alcohol, oil Gas (fluid, compressible): air… Although each term may share characteristics with other terms, no two terms share all charateristics. Of course, most substances here are “pure.” When you want to define things like ice cream or fudge, you would need definitions like “crystalline particles suspended in an amorphous gel or matrix.” Me, I’d rather eat them and call 'em “snacks.” ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [August 8, 2005, 8:17pm UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/36 "2005-08-08T20:17:38Z")
Incidentally, the term “true solid” seems to be something **bizzwire** made up. A non-scientific Google search finds only [11,600 hits](http://www.google.com/search?hl=en&q=%22true+solid%22&btnG=Google+Search) for the phrase, the first page of which seems to be mostly companies selling refrigerators. “Crystalline solid”, on the other hand, get [88,200 hits](http://www.google.com/search?hl=en&q=%22crystalline+solid%22&btnG=Google+Search) while “amorphous solid” gets [31,100 hits](http://www.google.com/search?hl=en&q=%22amorphous+solid%22&btnG=Google+Search). So my take on this is that scientists classify “solids” into two types, “crystalline” and “amorphous”. Glass is an example of the latter type, which makes it … still a solid. ---
**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\ **Post date:** [August 8, 2005, 9:22pm UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/37 "2005-08-08T21:22:56Z")
> [@JustAnotherGeek](#): > > Here would be some examples of how I use terms (Material Scientist may have multiple aneurysms, but they work for me to get the message across 😉 ) > > Crystalline solid: Rock candy, Quartz, diamonds, ice > > Crystalline metal solids: pure metals that hold their shape > > Amorphous solid: Glass, lollipops, plastics > > Semi-solid: asthenospheric materials, toothpaste > > Semi-liquid (or, simply viscous liquids): Lava, moleasses > > Liquid (fluid, inviscid, with minimal viscosity): water, alcohol, oil > > Gas (fluid, compressible): air… > > Although each term may share characteristics with other terms, no two terms share all charateristics. Of course, most substances here are “pure.” When you want to define things like ice cream or fudge, you would need definitions like “crystalline particles suspended in an amorphous gel or matrix.” Me, I’d rather eat them and call 'em “snacks.” you forgot supercritical fluids which share some of the characteristics of fluids and gases ---
**Author:** ![JustAnotherGeek](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@JustAnotherGeek](https://boards.straightdope.com/u/JustAnotherGeek)\ **Post date:** [August 9, 2005, 12:01am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/38 "2005-08-09T00:01:15Z")
> [@scm1001](#): > > you forgot supercritical fluids which share some of the characteristics of fluids and gases :smack: Yup. And I left out plasmas, too. Good point! ---
**Author:** ![bizzwire](https://avatars.discourse-cdn.com/v4/letter/b/958977/32.png) [@bizzwire](https://boards.straightdope.com/u/bizzwire)\ **Post date:** [August 9, 2005, 2:40am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/39 "2005-08-09T02:40:54Z")
> [@Terminus Est](#): > > Incidentally, the term “true solid” seems to be something **bizzwire** made up. A non-scientific Google search finds only [11,600 hits](http://www.google.com/search?hl=en&q=%22true+solid%22&btnG=Google+Search) for the phrase, the first page of which seems to be mostly companies selling refrigerators. “Crystalline solid”, on the other hand, get [88,200 hits](http://www.google.com/search?hl=en&q=%22crystalline+solid%22&btnG=Google+Search) while “amorphous solid” gets [31,100 hits](http://www.google.com/search?hl=en&q=%22amorphous+solid%22&btnG=Google+Search). So my take on this is that scientists classify “solids” into two types, “crystalline” and “amorphous”. Glass is an example of the latter type, which makes it … still a solid. Huh… so, according to your rigorous analysis, 11,600 other entities also employ the term “true solid,” yet somehow, I’m making it up? **Colibri** was right, this _is_ about language. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [August 9, 2005, 3:16am UTC](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936/40 "2005-08-09T03:16:36Z")
Hey, at least I gave some cites, however superficial. Where are yours? [Previous page](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936.md?page=1) [Next page](https://boards.straightdope.com/t/is-glass-a-liquid-or-a-solid/315936.md?page=3)