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.
Does room temperature glass deform to fit the shape of its container? That is the definition I remember from 7th grade, and it doesn’t seem to qualify glass as a liquid at room temperature and pressure.
According to Wikipedia, the glass transition temperature for soda lime glass is 573 °C (1,063 °F) . This is the point where it goes from its glassy, amorphous solid state to the rubbery, viscous liquid state. https://en.wikipedia.org/wiki/Glass_transition
From Wikipedia:
The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle “glassy” state into a viscous or “rubbery” state as the temperature is increased.[2] An amorphous solid that exhibits a glass transition is called a glass. The reverse transition, achieved by supercooling a viscous liquid into the glass state, is called vitrification.
The glass-transition temperatureTg of a material characterizes the range of temperatures over which this glass transition occurs (as an experimental definition, typically marked as 100 s of relaxation time). It is always lower than the melting temperature, Tm, of the crystalline state of the material, if one exists, because the glass is a higher energy state (or enthalpy at constant pressure) than the corresponding crystal.
[…]
Despite the change in the physical properties of a material through its glass transition, the transition is not considered a phase transition; rather it is a phenomenon extending over a range of temperature and defined by one of several conventions.[4][5] Such conventions include a constant cooling rate (20 kelvins per minute (36 °F/min))[2] and a viscosity threshold of 1012Pa·s, among others. Upon cooling or heating through this glass-transition range, the material also exhibits a smooth step in the thermal-expansion coefficient and in the specific heat, with the location of these effects again being dependent on the history of the material.[6] The question of whether some phase transition underlies the glass transition is a matter of ongoing research.[4][5][7]^[when?]^
[…]
Thus, the liquid-glass transition is not a transition between states of thermodynamic equilibrium. It is widely believed that the true equilibrium state is always crystalline. Glass is believed to exist in a kinetically locked state, and its entropy, density, and so on, depend on the thermal history. Therefore, the glass transition is primarily a dynamic phenomenon. Time and temperature are interchangeable quantities (to some extent) when dealing with glasses, a fact often expressed in the time–temperature superposition principle. On cooling a liquid, internal degrees of freedom successively fall out of equilibrium. However, there is a longstanding debate whether there is an underlying second-order phase transition in the hypothetical limit of infinitely long relaxation times.^[clarification needed][6][18][19][20]^
In a more recent model of glass transition, the glass transition temperature corresponds to the temperature at which the largest openings between the vibrating elements in the liquid matrix become smaller than the smallest cross-sections of the elements or parts of them when the temperature is decreasing. As a result of the fluctuating input of thermal energy into the liquid matrix, the harmonics of the oscillations are constantly disturbed and temporary cavities (“free volume”) are created between the elements, the number and size of which depend on the temperature. The glass transition temperature Tg0 defined in this way is a fixed material constant of the disordered (non-crystalline) state that is dependent only on the pressure. As a result of the increasing inertia of the molecular matrix when approaching Tg0, the setting of the thermal equilibrium is successively delayed, so that the usual measuring methods for determining the glass transition temperature in principle deliver Tg values that are too high. In principle, the slower the temperature change rate is set during the measurement, the closer the measured Tg value Tg0 approaches.[21] Techniques such as dynamic mechanical analysis can be used to measure the glass transition temperature.[22]
[…]
Glass is a “frozen liquid” (i.e., liquids where ergodicity has been broken), which spontaneously relax towards the supercooled liquid state over a long enough time.
Glasses are thermodynamically non-equilibrium kinetically stabilized amorphous solids, in which the molecular disorder and the thermodynamic properties corresponding to the state of the respective under-cooled melt at a temperature T* are frozen-in. Hereby T* differs from the actual temperature T.[27]
Glass is a nonequilibrium, non-crystalline condensed state of matter that exhibits a glass transition. The structure of glasses is similar to that of their parent supercooled liquids (SCL), and they spontaneously relax toward the SCL state. Their ultimate fate is to solidify, i.e., crystallize.[23]
There are Roman glass artifacts that are older than any window panes that haven’t moved a millimetre.
The old windows panes being thicker at the bottom is just a combination of the fact that old glass wasn’t very even, and that when you put a pane into a window, chances are that the thickest side will be at the bottom, because that feels right to a craftsman.
You were taught wrong. It’s from how the glass was made, and sometimes it’s thicker on top, or on the sides, depending on how it was installed. Glass doesnt sag.
Did you even read the article you posted yourself? The first sentence is:
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid
So it’s absolutely a solid. The reason for the name is because the structure being non-crystalline gives it interesting properties and is something that doesn’t usually happen. For most substances there is at least some sort of repeating or self-organising structure.
With another state of matter, for example gas or liquid, the structure can’t be seen as it’s constantly changing. Structures might form and then go away. Only when transitioning into a solid the structure becomes fixed. For most materials this is some kind of pattern or repeating structure, with amorphous materials it’s essentially random without any structure. So by definition these are solids, otherwise the structure wouldn’t be there at all.
You didn’t even post the entire sentence that goes on to describe why it’s different than a solid. You are like the media cherry picking a sound bite to try to make somebody look bad. Wow… I genuinely don’t understand the desire to be this pedantic.
All I originally said was not a true solid. If you’re seriously going to take me to task on that ELI5 explanation then you need to reevaluate your priorities.
Solid means it can deform elastically under shear stress, or equivalently can hold it’s shape indefinitely under shear. Crystal means the atoms are arranged in a repeating lattice. Glass is both solid and non-crystalline.
It’d be pedantry, if that didn’t also match our intuitive understanding of solids. What you said implies to people that glass might have fluid-like properties.
No, it does not imply that it has fluid like properties. The sentence that I posted simply implies that there’s something different about it than a normal solid.
I mean, there’s no real way for any of us to prove it will be interpreted one way or another, even if the rest of us are sure. So, in the name of not being a pedant, I guess you can see it that way.
It’s not a “false solid”, which would be the antonym. Glass is not an ordinary solid, I guess that would be true.
What is It with pedantry In this thread for real? So because I said true and not ordinary, everybody’s gonna take me to fucking task? This was supposed to just be a fun thread about interesting scientific facts. It is a scientific fact that glass is different than other solids, which is what I said. I’m not understanding why everybody has to be an asshole. But I’m fucking done with it.
That article never says amorphous solids are liquids, and repeatedly says they’re solid. Your claim is like saying modern TVs aren’t true TVs because they’re really HD TVs as if HD contradicts the TVness of something. It’s just nonsense.
Anything that’s not a true x isn’t x at all, it just resembles it. That’s why the ‘no true Scotsman’ fallacy is a fallacy. For example, ‘bugs’ that aren’t ‘true bugs’ aren’t bugs at all, they just look enough like bugs that laypeople would call them bugs despite being a different kind of insect (or if the layperson is being especially flexible with what they’re calling a bug, potentially not even an insect). Saying glass isn’t a ‘true solid’ is literally the same as saying it’s not a solid, but with the added implication that lots of people get it wrong. There’s also a common myth that glass is really a slow-moving liquid. You said something that is literally the exact opposite of the truth in a thread about scientific facts that sound up but are 100% real, and landed on something that gets commonly repeated as a surprising fact, so of course people are going to correct you.
It is. Glass is truly solid. It is an amorphous solid, meaning it has no repeating crystalline structure, unlike most other solids, which is pretty cool!
Glass is not a true solid.
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.
Ah OK, I thought on geologic timescales it would separate out and form back into quartz, etc at STP but I’m happy to be wrong and learn something new.
Does room temperature glass deform to fit the shape of its container? That is the definition I remember from 7th grade, and it doesn’t seem to qualify glass as a liquid at room temperature and pressure.
According to Wikipedia, the glass transition temperature for soda lime glass is 573 °C (1,063 °F) . This is the point where it goes from its glassy, amorphous solid state to the rubbery, viscous liquid state. https://en.wikipedia.org/wiki/Glass_transition
From Wikipedia:
[…]
[…]
[…]
There are Roman glass artifacts that are older than any window panes that haven’t moved a millimetre.
The old windows panes being thicker at the bottom is just a combination of the fact that old glass wasn’t very even, and that when you put a pane into a window, chances are that the thickest side will be at the bottom, because that feels right to a craftsman.
You were taught wrong. It’s from how the glass was made, and sometimes it’s thicker on top, or on the sides, depending on how it was installed. Glass doesnt sag.
“Glass is the same as a solid it’s just different than a solid.”
Seriously? Why are you being pedantic?
Because the thing being solid has nothing to do with the structure being crystalline or not. You are confusing two unrelated different things.
Sure, that’s why it has a different name. I’m moving on now.
Did you even read the article you posted yourself? The first sentence is:
So it’s absolutely a solid. The reason for the name is because the structure being non-crystalline gives it interesting properties and is something that doesn’t usually happen. For most substances there is at least some sort of repeating or self-organising structure.
With another state of matter, for example gas or liquid, the structure can’t be seen as it’s constantly changing. Structures might form and then go away. Only when transitioning into a solid the structure becomes fixed. For most materials this is some kind of pattern or repeating structure, with amorphous materials it’s essentially random without any structure. So by definition these are solids, otherwise the structure wouldn’t be there at all.
You didn’t even post the entire sentence that goes on to describe why it’s different than a solid. You are like the media cherry picking a sound bite to try to make somebody look bad. Wow… I genuinely don’t understand the desire to be this pedantic.
All I originally said was not a true solid. If you’re seriously going to take me to task on that ELI5 explanation then you need to reevaluate your priorities.
Alright, tell me in your words why it isn’t a true solid?
Because like the other dude said, it’s like saying an HD TV isn’t a true TV because it’s HD. It makes no sense at all.
“Tell me something I’m already going to dismiss.”
No. Now go away.
Solid means it can deform elastically under shear stress, or equivalently can hold it’s shape indefinitely under shear. Crystal means the atoms are arranged in a repeating lattice. Glass is both solid and non-crystalline.
It’d be pedantry, if that didn’t also match our intuitive understanding of solids. What you said implies to people that glass might have fluid-like properties.
No, it does not imply that it has fluid like properties. The sentence that I posted simply implies that there’s something different about it than a normal solid.
I mean, there’s no real way for any of us to prove it will be interpreted one way or another, even if the rest of us are sure. So, in the name of not being a pedant, I guess you can see it that way.
It’s not a “false solid”, which would be the antonym. Glass is not an ordinary solid, I guess that would be true.
What is It with pedantry In this thread for real? So because I said true and not ordinary, everybody’s gonna take me to fucking task? This was supposed to just be a fun thread about interesting scientific facts. It is a scientific fact that glass is different than other solids, which is what I said. I’m not understanding why everybody has to be an asshole. But I’m fucking done with it.
That article never says amorphous solids are liquids, and repeatedly says they’re solid. Your claim is like saying modern TVs aren’t true TVs because they’re really HD TVs as if HD contradicts the TVness of something. It’s just nonsense.
I never said they were liquids either… just not true solids. More like saying that CRT’s are different from flat panels.
Anything that’s not a true x isn’t x at all, it just resembles it. That’s why the ‘no true Scotsman’ fallacy is a fallacy. For example, ‘bugs’ that aren’t ‘true bugs’ aren’t bugs at all, they just look enough like bugs that laypeople would call them bugs despite being a different kind of insect (or if the layperson is being especially flexible with what they’re calling a bug, potentially not even an insect). Saying glass isn’t a ‘true solid’ is literally the same as saying it’s not a solid, but with the added implication that lots of people get it wrong. There’s also a common myth that glass is really a slow-moving liquid. You said something that is literally the exact opposite of the truth in a thread about scientific facts that sound up but are 100% real, and landed on something that gets commonly repeated as a surprising fact, so of course people are going to correct you.
I think you might actually be thinking of the Pitch Drop Experiment?
https://en.wikipedia.org/wiki/Pitch_drop_experiment?wprov=sfla1
No.
Honestly, I probably won’t post anything like this again. Lemmy is turning into Reddit way too much.
Deleted
It is. Glass is truly solid. It is an amorphous solid, meaning it has no repeating crystalline structure, unlike most other solids, which is pretty cool!