What is Digg?240 Comments
- CasinoJack, on 10/10/2007, -2/+47Dugg for the awful pun.
- kuwan, on 10/10/2007, -3/+47I'll smack you on the head with a glass bottle and you can tell me whether it's a solid or a liquid.
- theholotrope, on 10/10/2007, -13/+51"Physicist opens new window on glass puzzle."
Are you taking English 101? - SillyRabbits, on 10/10/2007, -1/+34Not really. It's pointless to argue solid/liquid. They aren't scientifically precise and it's just semantics. When scientists talk about the distinction they refer to whether the material has a long or short range order, or the viscosity, etc. Arguing solid/liquid is like trying to explain the flavor of coffee just using the terms bitter and sweet. This looks like another example of a researcher making the material easier for the author to understand and the author missed what was really neat about the research (which in this case seems to be whether glasses have a sort of quasi-long or medium range order - but I can't tell from what the author wrote).
- OutThisLife, on 10/10/2007, -0/+22Is this host dead or merely an extremely slow-moving server?
- Bipedal, on 10/10/2007, -5/+24The reason older glass is thicker at the bottom is because of the way sheets of glass used to be made. They would put the molten glob of glass on a sort of spinning disc and let it flatten out. this caused the edges to be thicker, so they put those on the bottom for strength. There are even examples of things like churches and older buildings where the windows were put in upside-down, so the thick part is at the top. Distorted glass isn't a good way to prove the 'liquid' bit of the argument.
- jackhole, on 10/10/2007, -2/+21To clarify: the old glass used in those churches was formed by blowing molten glass into an orb, then spinning the glass into a disc. The disc was then cut into panes. This centripetal process accounts for the ostensibly liquid "ripples" seen in old glass panes, along with the uneven glass thickness. After cutting the panes, the glazers obviously and sensibly arranged the panes so that the larger end would be pointing down. Glass does not "flow" downwards, it was made that way.
- IanCal, on 10/10/2007, -2/+19"but this can be easily disproven, since if I put a glass jar in a tray and just leave it there - if I were to come back in a million years (assuming nothing happens to the jar and tray), the glass will still be glass and not a pool of liquid."
It can be easily disproven by assuming it's not true? Good circular reasoning there - AaronCSU, on 10/10/2007, -1/+16Engineering grad student here, this is an old debate.
Glass is an amorphous solid. That means it has no crystal structure. It also has no precise melting point. You may often seen a melting point given for glass but this is simply a temperature where the glass flows easily. As you lower the temperature it will simply become more and more viscous until it is essentially a solid. A crystalline solid has a distinct melting point where the crystal structure suddenly breaks down. The question is does glass ever actually become solid, or does it still flow, just very slowly.
Many people point to old windows that are thicker on the bottom as proof of glass flowing. As I understand it this has been well debunked. Old panes of glass do not have uniform thickness due to manufacturing methods used then and you will very often see panes that are thicker on the top. Plus if glass flowed quickly enough that a piece of it just 100-150 years old displayed measurable deformation there would be no debate, that would be an easy to measure viscosity. Plus tempered glass would not be possible. I will not get into a discussion of how tempered glass works but suffice to say it would not function for decades, as it currently does, if the glass was flowing at that rate.
My best assessment is that, for all intents and purposes, glass is a solid. It has no measurable deformation over centuries. While its' viscosity may not be infinite it has to be so high that one could assume it is infinite. Of course I am an engineer, we always look at things this way, physicists may not like this answer. - DaJokerInU, on 10/10/2007, -1/+15I'm pretty sure that glass is an amorphous solid.
http://en.wikipedia.org/wiki/Amorphous - inactive, on 10/10/2007, -2/+16"Is glass a solid or merely an extremely slow-moving liquid?"
Yes. - rabidg00se, on 10/10/2007, -0/+13zip, you're a real pane.
- kibiz0r, on 10/10/2007, -1/+12Does it bother anyone else when people make comments that just say "great article"? I thought that's what the "digg it" button was for...
- kelpdip, on 10/10/2007, -1/+11What about a plane on a stairmaster?
- 10001, on 10/10/2007, -1/+11you should have stopped after the third word
- EXreaction, on 10/10/2007, -1/+11Is there anyone stupid enough to believe it wouldn't?
- alecks, on 10/10/2007, -0/+9I agree with what you're saying. You get my proverbial "thumbs up"!
- smackhero, on 10/10/2007, -0/+8and yet there are at least 20 morons in this discussion saying how they learned that glass is liquid in grade school, repeating that fallacious argument.
even if you simply "knew" that glass is a slow moving liquid--which is still a debated grey area--these scientists are researching the yet unknown reason why it exhibits these physical characteristics. unless you have the answers, don't be a smart ass. - Cerialthriller, on 10/10/2007, -1/+9i dont know about the timeline, but eventually over a long enough timeline, the theory is that the glass will not hold the original shape, even if only fractions off, even in a completely erosion free environment
- smackhero, on 10/10/2007, -0/+7let me guess, your science teacher misinformed you about glass window panes in old churches like the other 20 morons have already commented above?
- asteron, on 10/10/2007, -0/+7From wikipedia
"A myth does exist that glass rods and tubes can bend under their own weight over time. To test this, in the 1920s, Robert John Rayleigh, son of the Nobel Prize winner John William Rayleigh, conducted an experiment on a 1 metre (~39 in) long, 5 millimetre (~3/16 in) thick glass rod, which was supported horizontally on two pins with a 300 gram (~0.66 lb) weight in the middle. Apart from the initial bending of 28 millimetre (~1.1 in), the position of the weight did not change until the end of the experiment, which lasted for 7 years. At the same time, another man, a worker of General Electric named K. D. Spenser, conducted a similar experiment independently. Two months after Rayleigh, he published his own results which also disproved the myth. Spenser suggested that the myth was composed before the 1920s, when the tubes were made by hand, and naturally some of them were curved to begin with. Over time the straight tubes were taken away, and only the curved ones remained. Some people probably thought it was the glass flowing." - Richman777, on 10/10/2007, -1/+8As with so many other people who have posted this, your chem teacher was wrong. That was due to manufacturing. Dear god, read the comments.
- SillyRabbits, on 10/10/2007, -3/+10Old windows have never been an "argument" for glass as liquid. It is well known that the thickness difference was due to manufacturing techniques and there are many examples where the windows are installed with the thick part at the top. Besides, it is in no way, shape, or form a scientific test. It can also be easily calculated that, based on the viscosity of the window glass, that is will literally take several million years to see the degree of flow required for the observed thickness variation.
- Bdog2g2, on 10/10/2007, -0/+7its an amorphous solid, meaning it does not have a true regular crystalline structure. Basically the crystals are heterogenous in size and will not lock into place with others in a regular pattern.
- Tgg161, on 10/10/2007, -1/+8Myth myth myth. I can't believe people are digging the window 'evidence'.
http://math.ucr.edu/home/baez/physics/General/Glass/glass.html - Davedave, on 10/10/2007, -2/+9gee, couldn't be because old methods of glass manufacturing resulted in less precise panes? or that people were smart enough to put the thicker side of a piece of glass downward for stabiliy... and the glass artifacts we have from thousands of years ago that have somehow NOT melted into a puddle over the time are just a fluke.
your chemistry teacher was a moron. - Tgg161, on 10/10/2007, -2/+9You learned wrong! Windows are not 'thicker on the bottom' -- it's a myth.
http://math.ucr.edu/home/baez/physics/General/Glass/glass.html
You may call glass 'liquid' if you want, since it has molecular structure different from most solids, but stop perpetuating the window myth as 'proof'. - Cykaos, on 10/10/2007, -1/+7as a degree holder in physics you should know that the thickness of glass windows over a few hundred years has nothing to do with glass being a liquid but more to do with manufacturing style.
- jackspratmich, on 10/10/2007, -1/+7Seriously guys, please educate yourself before commenting on these things. Glass in the old days was made by stretching the molten material then cooled. When you stretch liquid glass it ends up being distorted, because you cannot do it uniformly. Current technology uses liquid tin which the molten material is pulled over very slowly allowing the glass to be uniformly thick and flat on both sides. Go to a glass manufacturing plant and take a tour. It is quite amazing. As far as glass being a liqud or solid according to physics, I don't know, but no glass changes it's shape over time naturally. The windows in old churches looks exactly like it did when it was made aside from some normal wear over time.
- madtaco, on 10/10/2007, -3/+9FTA: "Weeks has devoted his career to probing the mysteries of "squishy" substances"....."they include everyday substances such as toothpaste, peanut butter, shaving cream, plastic and glass"
Wife: "How was work today, honey?"
Weeks: "Not bad, the peanut butter and shaving cream are proving to be a little trickier than we had first thought."
Wife: "You want some nachos?" - krakelohm, on 10/10/2007, -1/+7Can't forget Ice Ice Baby...
- yosempai, on 10/10/2007, -0/+5My highschool science teacher taught me about this. Freshman year.
- SillyRabbits, on 10/10/2007, -6/+11Ummm, NO! True, glass has a viscosity, but that's not why old windows are thicker at the bottom. I wish people would stop repeating this.
- DeeprBlue, on 10/10/2007, -2/+7Degree holder in physics, my ass.
- Apokalyps2547, on 10/10/2007, -2/+7More on what jackhole said:
Some glazers DIDN'T put the thicker side down, and in some churches, the thicker side is on TOP because of it! - Frothy, on 10/10/2007, -1/+6Physics degree revoked! The thickness of very old windows are proof of nothing except the method of their manufacture.
http://www.sciencenews.org/pages/sn_arc98/5_30_98/fob3.htm - catalysis, on 10/10/2007, -2/+7No, it doesn't hold. That is a myth which has been thoroughly debunked.
- DeeprBlue, on 10/10/2007, -1/+6Wow. Digg is becoming ugly. If people even bother to read the article, it really has nothing to do with "solving" the puzzle of glass being a liquid or a solid. It's a very interesting read, because they explain their technique of examining how glass becomes "glassy" since the phase change isn't obvious. Instead, most of the commenters here are preoccupied with showing off their knowledge when really, no one asked their "expert" opinion on the subject.
- SkippyDoorknob, on 10/10/2007, -1/+6Because it was installed with the thicker part at the bottom in order to be more stable. It used to be very hard to make glass at a consistant thickness.
- altgeeky1, on 10/10/2007, -0/+5>Its easy to see in very old windows that they get wavy and it looks like water running down a window at an incredibly slow rate.
No, that's different: you are referring to "leaded glass". Pre-modern glass contained lead - that and production methods caused the 'wave' effect you see.
You can see the same effect in antique stained glass.
http://en.wikipedia.org/wiki/Lead_glass
Now I am not commenting one way or the other on the article... just your 'it's very easy to see..' comment. - noahhoward, on 10/10/2007, -0/+5It was an Amorphous Solid 5 years ago when I started my physics degree.
- inactive, on 10/10/2007, -3/+7Its been proven a solid. The theory of old glass being wavy therefore its a liquid, has 100% to do with the way they used to make glass, not with any "flowage" of glass molecules.
- Richman777, on 10/10/2007, -1/+5I guess being a Physics major they didn't teach you that this is Chemistry. You'll argue that it has to do with physics but molecular structures is all chemistry. Go watch some planets rotate.
Also the whole bottom is thicker than at the top has been debunked a LONG LONG LONG time ago and is attributed to manufacturing processes of the time. Stop citing that as proof. - inactive, on 10/10/2007, -1/+5Why does this remind me of discussions on 4chan?
Wood is a liquid.
http://img514.imageshack.us/img514/2200/woodisaliquidyv7.png - alexforcefive, on 10/10/2007, -0/+4"Old windows have never been an "argument" for glass as liquid"
Tell that to my old chemistry teacher. British education system FTL :( - DeeprBlue, on 10/10/2007, -0/+4Just because it doesn't form a lattice structure doesn't mean that it's a slow-moving liquid. Glass challenges the notion that you need to have crystalline structure to have a solid. Hence why it's an amorphous solid. And if you bothered to read the article, they test to see how small one can make glass before it no longer exhibits characteristics of a solid.
- Tgg161, on 10/10/2007, -0/+4Here's a well researched and sourced article that discusses the urban myth of a 'liquid glass':
http://dwb.unl.edu/Teacher/NSF/C01/C01Links/www.ualberta.ca/~bderksen/florin.html
If you don't want to additional information in to challenge your pre-conceived notions, you aren't much of a scientist. Do they give those physics degrees out at McDonald's now? - 10001, on 10/10/2007, -1/+5^^ 8 types of ice:
dry ice, ice cubes, ice cream, black ice, shaved ice, ice berg, ice tea, ice age - gwhardyiv, on 10/10/2007, -0/+4Did you even bother to read the article? The headline totally misses the point.
- Cykaos, on 10/10/2007, -1/+5Haha.. How is it easily disproven? Have you actually put a glass jar in a tray and then left it there for a million years? I would thinking running an experiment over a million years would be very hard to prove or disprove.
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