An important mental exercise: Next time you watch the sun 'go down' and dissapear behind the horizon, attack the comfortable relative concepts of direction you may have unwittingly fallen into. Remember; the sun is not going down, the Earth is turning away. I don't just mean 'oh that's a merry thought' then forget about it again. Concentrate for the full hour or so that you may be watching the sun. The Earth is turning away/around. If you're facing the sun then the direction of spin for the planet is through your front and away out your back. Please keep these sort of things in mind when watching nature. Plants are not motionless, they are in a different time frame. Glass is not solid, it's a very slow moving liquid. Rainbows are not semi-circular, they are circles cut off by the horizon from your position. etc,etc. (I have plenty more) So, try the above exercise out next time you're watching the side of the Earth eclipse the sun for another night. (it's even better lying down in the long grass of a smooth slope facing the sun). You may have a cosmic satori that'll blow your mind!! ~
In defence of those subjective boundaries, Elton John's classic "Don't Let The Earth Revolve To The Angle Where I Am Located On The Side Opposite To The Sun" would sound crap
You can actually see this in practice. If you look at original panes of glass in old victorian houses, you can see where the view is distorted, as the glass has actually 'run' over time, creating bubbles in the surface.
I looked it up: "There have been many claims (especially by tour guides) that such glass is deformed because the glass has flowed slowly over the centuries. This has become a persistent myth, but close inspection shows that characteristic signs of flow, such as flowing around, and out of the frame, are not present. The deformations are more consistent with imperfections of the methods used to make panes of glass at the time. In some cases gaps appear between glass panes and their frames, but this is due to deformations in the lead framework rather than the glass. Other examples of rippling in windows of old homes can be accounted for because the glass was imperfectly flattened by rolling before the float glass process came into use. It is difficult to verify with absolute certainty that no examples of glass flow exist, because there are almost always no records of the original state. In rare cases stained glass windows are found to contain lead which would lower the viscosity and make them heavier. Could these examples deform under their own weight? Only careful study and analysis can answer this question. Robert Brill of the Corning glass museum has been studying antique glass for over 30 years. He has examined many examples of glass from old buildings, measuring their material properties and chemical composition. He has taken a special interest in the glass flow myth and has always looked for evidence for and against. In his opinion, the notion that glass in Mediaeval stained glass windows has flowed over the centuries is untrue and, he says, examples of sagging and ripples in old windows are also most likely physical characteristics resulting from the manufacturing process. Other experts who have made similar studies agree. Theoretical analysis based on measured glass viscosities shows that glass should not deform significantly even over many centuries, and a clear link is found between types of deformation in the glass and the way it was produced. Conclusion There is no clear answer to the question "Is glass solid or liquid?". In terms of molecular dynamics and thermodynamics it is possible to justify various different views that it is a highly viscous liquid, an amorphous solid, or simply that glass is another state of matter which is neither liquid nor solid. The difference is semantic. In terms of its material properties we can do little better. There is no clear definition of the distinction between solids and highly viscous liquids. All such phases or states of matter are idealisations of real material properties. Nevertheless, from a more common sense point of view, glass should be considered a solid since it is rigid according to every day experience. The use of the term "supercooled liquid" to describe glass still persists, but is considered by many to be an unfortunate misnomer that should be avoided. In any case, claims that glass panes in old windows have deformed due to glass flow have never been substantiated. Examples of Roman glassware and calculations based on measurements of glass visco-properties indicate that these claims cannot be true. The observed features are more easily explained as a result of the imperfect methods used to make glass window panes before the float glass process was invented." http://math.ucr.edu/home/baez/physics/General/Glass/glass.html And also: "The "Glass Flows" Myth (It just ain't true)"http://www.glassnotes.com/WindowPanes.html
Great post Armadillo! I remember the first time I tried something similar, lying on my back looking up at the blue sky and the clouds and trying to envisage the whole universe beyond and the earth as a whizzing, turning body moving at vast speed through it all. By the end of it I started getting a feeling distinctly like vertigo - terrified I was going to fall off! The challenge, as you say, is not simply to think about it as a cute little mind game, but to try and actually experience it fully and viscerally.
Semantic indeed! How about going a step further in human subjectivity destruction? Why not attack the hideous generalisations that form from our ambiguous categorisations of the world around us? Are we 'mammals' or are we a fractal energy echo that certain amoebic colonies have created to perpetuate their current DNA pattern variance? Thats the very point of view i wish to flip on its head! If we are to be the sum of our senses, why trust what other people/society says your senses should be representing to you? The mind is capable of lateral thought. Give its 'legs' a stretch now and again (all the time would mean you'd seem insane to other people, relatively speaking, and some of us want to keep their day job ) Reality is amazing!! Hit the nail on the head with that one mate. ~
No! No no no! Can I highlight the part that says: "It is worth noting, too, that at room temperature the viscosity of metallic lead has been estimated to be about a billion times less viscous-or a billion times more fluid, if you prefer than glass." [size=+2]The "Glass Flows" Myth (It just ain't true)[/size] A friend of mine by the name of Albert Lewis sent me an email apprising me of the following article debunking the "glass flows" myth. I think this myth is so pervasive it can be called an urban legend. As many of you know the "Glass Flows Myth" concerns the belief held by many that because glass is a "super cooled liquid" it actually has a degree of "flow" at temperatures you and I find comfortable. Those who believe this urban legend point to the fact that the windows in colonial homes and in old stained glass windows are thicker at the bottom than at the top. There was a time, in the dim dark past that, in my ignorance I believed in the myth of glass flow. What could I have been thinking? I mean doesn't it seem exciting to think that all the glass in the world is actually flowing as we speak. That the Rose Window will soon spill out of the confines of the lead cames that have held it in place all these years. Well, we can all sleep easy tonight. I was made aware of the fallacy of this myth many years ago by the late great Nick Labino. He put it very simply to me when he said, and I paraphrase Nick, "...if the windows found in early Colonial American homes were thicker at the bottom than the top because of "flow" then the glass found in Egyptian Tombs should be a puddle." A Great visual don't you think. Now I know you who are still skeptical are saying "the Egyptian glass formulas were different as well as the formulas for all those other dead cultures. Not so! If you still don't believe it, read on. When that know - it- all antique dealer proposes to you the urban legend of glass flow, send him or her to this page. Old myths die hard. If they still refuse to believe have them email me with a reason other than "thicker at the bottom." Read on. [size=+2]No, It Doesn't Flow[/size] Robert H. Brill, Research Scientist The Corning Museum of Glass July, 2000 Early one spring morning in 1946, Clarence Hoke was holding forth in his chemistry class at West Side High School in Newark, New Jersey. "Glass is actually a liquid." the North Carolina native told us in his soft Southern tones. "You can tell that from the stained glass windows in old cathedrals in Europe. The glass is thicker on the bottom than it is on the top." Now, more than half a century later, that is the only thing I can actually remember being taught in high school chemistry. I didn't really believe it then, and I don't believe it now. In the years that followed, I came across the same story every now and then. Most often it popped up in college textbooks on general chemistry. And now, thanks to the Internet, our Museum has received dozens of inquiries about whether or not this is true. Most people seem to want to believe it. *** It is easy to understand why the myth persists. It does have a certain appeal. Glass and the glassy state are often described by noting their similarities with liquids. So good teachers, such as Mr. Hoke was, like to quote the story about the windows. As is the case with liquids, the atoms making up a glass are not arranged in any regular order-and that is where the analogy arises. Liquids flow because there are no strong forces holding their molecules together. Their molecules can move freely past one another, so that liquids can be poured, splashed around, and spilled. But, unlike the molecules in conventional liquids, the atoms in glasses are all held together tightly by strong chemical bonds. It is as if the glass were one giant molecule. This makes glasses rigid so they cannot flow at room temperatures. Thus, the analogy fails in the case of fluidity and flow. *** There are at least four or five reasons why the myth doesn't make sense. Some years ago, I heard a remark attributed to Egon Orowan of the Massachusetts Institute of Technology. Orowan had quipped that there might, indeed, be some truth to the story about glass flowing. Half of the pieces in a window arc thicker at the bottom, he said, but, he added quickly, the other half are thicker at the top. My own experience has been that for earlier windows especially, there is sometimes a pronounced variation in thickness over a distance of an inch or two on individual fragments. That squares with the experience of conservators and curators who have handled hundreds of panels. Although the individual pieces of glass in a window may be uneven in thickness, and noticeably wavy, these effects result simply from the way the glasses were made. Presumably, that would have been by some precursor or variant of the crown or cylinder methods. One also wonders why this alleged thickening is confined to the glass in cathedral windows. Why don't we find that Egyptian cored vessels or Hellenistic and Roman bowls have sagged and become misshapen after lying for centuries in tombs or in the ground? Those glasses are 1,000-2,500 years older than the cathedral windows. Speaking of time, just how long should it take theoretically-for windows to thicken to any observable extent? Many years ago, Dr. Chuck Kurkjian told me that an acquaintance of his had estimated how fast-actually, how slowly-glasses would flow. The calculation showed that if a plate of glass a meter tall and a centimeter thick was placed in an upright position at room temperature, the time required for the glass to flow down so as to thicken 10 angstrom units at the bottom (a change the size of only a few atoms) would theoretically be about the same as the age of the universe: close to ten billion years. Similar calculations, made more recently, lead to similar conclusions. But such computations are perhaps only fanciful It is questionable that the equations used to calculate rates of flow are really applicable to the situation at hand. *** This brings us to the subject of viscosity. The viscosity of a liquid is a measure of its resistance to flow-the opposite of fluidity, Viscosities are expressed in units called poises. At room temperature, the viscosity of water, which flows readily, is about 0.01 poise. Molasses has a viscosity of about 500 poises and flows like... molasses. A piece of once proud Brie, left out on the table after all the guests have departed, may be found to have flowed out of its rind into a rounded mass. In this sad state, its viscosity, as a guess, would be about 500,000 poises. In the world of viscosity, things can get rather sticky. At elevated temperatures, the viscosities of glasses can be measured, and much practical use is made of such measurements. Upon removal from a furnace, ordinary glasses have a consistency that changes gradually from that of a thick house paint to that of putty, and then to that of saltwater taffy being pulled on one of those machines you see on a boardwalk. To have a taffy-like viscosity, the glass would still have to be very hot and would probably glow with a dull red color. At somewhat cooler temperatures, pieces of glass will still sag slowly under their own weight, and if they have sharp edges, those will become rounded. So, too, will bubbles trapped in the glass slowly turn to spheres because of surface tension. All this happens when the viscosity is on the order of 50,000,000 poises, and the glasses are near what we call their softening points. Below those temperatures, glasses have pretty well set up, and by the time they have cooled to room temperature, they have, of course, become rigid. Estimates of the viscosity of glasses at room temperature run as high as 10 to the 20th power Scientists and engineers may argue about the exact value of that number, but it is doubtful that there is any real physical significance to a viscosity as great as that anyway. As for cathedral windows, it is hard to believe that anything that viscous is going to flow at all. It is worth noting, too, that at room temperature the viscosity of metallic lead has been estimated to be about 10 to the11th power, poises, that is, perhaps a billion times less viscous-or a billion times more fluid, if you prefer than glass. Presumably, then, the lead caming that holds stained glass pieces in place should have flowed a billion times more readily than the glass. While lead caming often bends and buckles under the enormous architectural stresses imposed on it, one never hears that the lead has flowed like a liquid.
*** When all is said and done, the story about stained glass windows flowing-just because glasses have certain liquid-like characteristics-is an appealing notion, but in reality it just isn't so. Thinking back, I do recall another memorable remark by Mr. Hoke. One day, our self-appointed class clown sat senselessly pounding a book on his desk at the back of the room. "Great day in the mawnin', son! " shouted Hoke. "Stop slammin' your book on the desk. Use your head!" That was good advice-no matter how you read it. Reprinted with permission from Dr. Robert Brill, brillrh@cmog.org The Corning Museum Education Page And for those of you who still refuse to believe as well as for conservators who might still believe that glass flows, Corning offers the solution below. <H3>[size=+2]Analysis Shatters Cathedral Glass Myth[/size] By C. Wu</H3> A new study debunks the persistent belief that stained glass windows in medieval cathedrals are thicker at the bottom because the glass flows slowly downward like a very viscous liquid. Edgar Dutra Zanotto of the Federal University of Sao Carlos in Brazil calculated the time needed for viscous flow to change the thickness of different types of glass by a noticeable amount. Cathedral glass would require a period "well beyond the age of the universe," he says. Suffice it to say that the glass could not have thickened since the 12th century. Zanotto reports his finding in the May American Journal of Physics. The study demonstrates dramatically what many scientists had reasoned earlier. "You would have to bring normal glass to 350 deg. Celsius (662 deg. F.) in order to begin to see changes," says William C. LaCourse, assistant director of the NSF Industry-University Center for Glass Research at Alfred (N.Y.) University. Viscosity depends on the chemical composition of the glass. Even germanium oxide glass, which flows more easily than other types, would take 10 to the 32 power years to sag, (that's a 10 with 32 zeros) Zanotto calculates. Medieval stained glass contains impurities that could lower the viscosity and speed the flow, but even a significant reduction wouldn't alter the conclusion, he remarks, since the age of the universe is only 10 to the 10th power. Editors Note: That's 100,000,000,000,000,000,000,000,000,000,000 years folks. Try saying that number with a mouthful of marbles. The difference in thickness sometimes observed in antique windows probably results from glass manufacturing methods, says LaCourse. Until the 19th century, the only way to make window glass was to blow molten glass into a large globe then flatten it into a disk. Whirling the disk introduced ripples and thickened the edges. For structural stability, it would make sense to install those thick portions in the bottom of the pane, he says. Later glass was drawn into sheets by pulling it from the melt on a rod, a method that made windows more uniform. Today, most window glass is made by floating liquid glass on molten tin. This process, developed about 30 years ago, makes the surface extremely flat. The origins of the stained glass myth are unclear, but the confusion probably arose from a misunderstanding of the amorphous atomic structure of glass, in which atoms do not assume a fixed crystal structure. "The structure of the liquid and the structure of the [solid] glass are very similar," says LaCourse, "but thermodynamically they are not the same." Glass does not have a precise freezing point; rather, it has what's known as a glass transition temperature, typically a few hundred degrees Celsius. Cooled below this temperature, liquid glass retains its amorphous structure yet takes on the physical properties of a solid rather than a supercooled liquid. "At first, I thought that the [sagging window idea] was a Brazilian myth," Zanotto wrote, but he soon learned that people all over the world share the belief. Repeated in reference books, in science classes, and recently over the Internet, the idea has been repeatedly pulled out to explain ripply windows in old houses. "For the lay person, it makes a lot of sense," says LaCourse. In 1989, Robert C. Plumb of Worcester (Mass.) Polytechnic Institute suggested in the Journal of Chemical Education that definitive proof might require an instruction book written in the Middle Ages advising glaziers to install glass panes with the thick end at the bottom. Now if only such a handbook could be found. [size=+2]Origin of an Urban Legend?[/size] For a more complete explanation of this topic follow the links found at the bottom of this page ©1996 Florin Neumann How did the "glass is a supercooled liquid" urban legend originate? It is possible it began with an erroneous reading of an influential book by Gustav Tammann (1861-1938), a German physicist who was among the first to study glass as a thermodynamic system (Tammann, 1933). I was unable to locate a copy of Tammann's book to verify this, so the following is speculation. One or two papers I consulted attributed to Tammann the statement "Glass is a supercooled [or undercooled] liquid." But, from other papers, it appears that what Tammann actually wrote was "Glass is a frozen supercooled liquid" [my emphasis]. My speculation is that an author misquoted Tammann, and this misquotation was repeated by later authors who, since copies of Tammann's book are rather rare, did not refer directly to Tammann. Until about 20 years ago supercooling a glass melt was the only way to obtain glass, and the behaviour of melts as they passed through the glass transition (i.e., solidified) was very different from crystallization. But solid-state physics was almost entirely based on the study of crystalline solids, which made the behaviour of glass melts appear paradoxal. To emphasize this a professor would state "Glass is a liquid which has lost the ability to flow", and some undergraduate, with his mind more on the Friday night date than on the physics of glass, would remember only "glass is a liquid"... Perhaps now we can finally put this legend to its well-deserved rest. Conclusion Glasses are amorphous solids. There is a fundamental structural divide between amorphous solids (including glasses) and crystalline solids. Structurally, glasses are similar to liquids, but that doesn't mean they are liquid. It is possible that the "glass is a liquid" urban legend originated with a misreading of a German treatise on glass thermodynamics.
butterfly, please stop cutting and pasting other websites into the thread and READ my second post properly! It doesn't contradict your position on glass. starfly, thanks for bringing it round again. you said '...the thought that the sun was rising somewhere else in the world'. can i be semantic and change it to '...the knowledge that the sun was rising somewhere else in the world'? anyone got anymore subjectivity boundries to bend out of shape? what about things you don't normally notice, or take for granted? next time you see a dew drop in the morning, search for the circular rainbow inside it... ~
exactly! me too! Thats why New Zealand blew my mind. The spirals and ferns are all three times as large as here. So its easier to see the spirals within the spirals within the spirals as well. ~
I don't think I was replying to you...but whatever, I thought it was interesting! Sorry to clog up the thread! It's just I happen to have my physics exam on thursday, so with all this revising the laws of physics, I don't particularly want to imagine glass as a "slow-moving liquid", because, uh, it's not. (Well, not at room temperature anyway)
I tried something of the sort the other day. Me and JC lay on the top of box hill on a blanket and the stars were amazingly clear, hundred of little flashes we everfywhere and we were pondering all the possibilities of what they could have been... flys... bats... supernovas etc. The i just looked up and put myself up there...i dissapeared, i shot out of the atmosphere and looked down and i was nothing... and earth was miniscule. And arouns me were millions of rocks and burning balls of gas. Another.. is when you look at ants... and how they work in lines and things. I had an antfarm as a kid.. and i found that they stored all their food in one place, like a larder, and sotred all their dead bodies on the oposite side of the container liek a graveyard..i really should have put a queen ant in there but at the time i didnt really know much about reproduction in the ant world...i was just a kid.. anyway i went away for a week came back and they were all dead but anyway thats another story. Yea but i love watching how ants and insects work.... remembering all the hundreds and thousands of tunnels and communities that lie beneith our feet. Its like in london... the thought that below you is a series of tunnels transporting people from place to place is ascary.... :S
I was going to say the same thing ... large structures echoed in smaller structures in infinite iterations, like fern leaves. It's beautiful. Order from chaos. The way a muddy patch of ground can look like a mountainous landscape or a trickle of dog pee can look like the river Nile. OK maybe not the last one...
MACROCOSMIC ECHO FRACTALS ACROSS THE MICROSCOPIC ENTROPY BRIDGES.. that's the name of the flag i made, y'know, the cosmic yak one i'll be taking to beautiful days ~
