FYI: How Long-Running Is the Longest-Running Lab Experiment?

Slow Flow... Is there actually anything that flows slower than this? WHo anyhow stares at their monitors watching tar drop (or not drop) And I thought watching paint dry was terrible. Just ridiculous....

As far as I know, C--, glass is also a fluid. Panes of glass made hundreds of years ago are measurably larger at the bottom than the top. So yes, there are slower fluids than this. While we can observe the affect of gravity on things like glass made hundreds of years ago, this is the longest 'lab experiment' that is under 'controled conditions'.

Myth that glass is a fluid.
I thought that too and did some internet research before posting.

The reason glass in old churches is thicker at the bottom, simply because it was real hard to make perfectly formed glass in the past. And if you have a plane of glass, it would be natural to mount the heavier thicker portion of glass at the bottom in the frame.

But, hey research it yourself.

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See life in all its beautiful colors, and
from different perspectives too!

Room temperature glass is solid, that is.

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See life in all its beautiful colors, and
from different perspectives too!

actually, glass behaves like a liquid because it does not have a definite crystalline structure, and glass is actually flowing down due to gravity

Space, I have read that. But honestly, if I'm puting in a window, I'm not going to weigh it to see which end weighs more, I'm just going to put it in. So surly there would be at least some panes left that were put in with the heavy side up, or even to the side, right?

Glass is definitely not a viscous liquid, it is a solid. Not having a defined crystalline structure doesn't make it a liquid, it makes it an amorphous solid. And there would naturally be way, way more examples of old glass panes where the thick side is on the bottom because any pane where the thick side is on the side or top would be more likely to fall or break, not to mention that people consciously tried to put the heavy side down.

A solid has a definite melting point, as do ice, lead, iron, etc. When you heat them there a is an abrupt transition from solid to liquid when you arrive to the melting point. A super viscous fluid, as glass, tar, sealing wax, softens progressively as you heat them, without an abrupt transition between a hard phase and a liquid one. As temperature is risen fluidity increases. If glass were to behave as a crystalline solid, the only way to use it, will be molding it, blowing glass will not be possible.

You must admire these spamer's persistence.
Copy & paste.

I've heard of glass described as both solid and liquid. My best anecdotal evidence of glass flowing is with whats called a Rotovap (I know Buchi makes them but not sure who else). These are made out of glass but a large portion of them sit at a 45 degree angle. The glass neck that attaches to the flask you are evaporating things out of will bend over time. And not even that much time. We had one in college that wasn't that old and the next wobbled like it was bent. However, it was straight when we got it. The only explanation we had was that the weight of flasks on the end has slowly warped it (that is when they weren't rotating) so the effect of gravity was compounded by the weight of the flasks. This, along with the lack of a crystaline structure and lack of defined melting point will always put glass in the liquid column for me.

svillav,
Don't metels get softer as you heat them? So are you saying that metels are liquid too?

Copy and paste? Done. I'll cite from an education resource, since it explains it far better than I could.

For those not willing to read it all, I'll summarize: Glass isn't a liquid, but it's not exactly a crystalline solid, either. In fact, it turns out, it's a glass (pow!) which has certain characteristics of both, but not viscosity (its molecules are rigidly bound).

"Some people claim that glass is actually a supercooled liquid because there is no first order phase transition as it cools. In fact, there is a second order transition between the supercooled liquid state and the glass state, so a distinction can still be drawn. The transition is not as dramatic as the phase change that takes you from liquid to crystalline solids. There is no discontinuous change of density and no latent heat of fusion. The transition can be detected as a marked change in the thermal expansivity and heat capacity of the material.

The temperature at which the glass transition takes place can vary according to how slowly the material cools. If it cools slowly it has longer to relax, the transition occurs at a lower temperature and the glass formed is more dense. If it cools very slowly it will crystallise, so there is a minimum limit to the glass transition temperature.

A liquid to crystal transition is a thermodynamic one; i.e. the crystal is energetically more favourable than the liquid when below the melting point. The glass transition is purely kinetic: i.e. the disordered glassy state does not have enough kinetic energy to overcome the potential energy barriers required for movement of the molecules past one another. The molecules of the glass take on a fixed but disordered arrangement. Glasses and supercooled liquids are both metastable phases rather than true thermodynamic phases like crystalline solids. In principle, a glass could undergo a spontaneous transition to a crystalline solid at any time. Sometimes old glass devitrifies in this way if it has impurities.

The situation at the level of molecular physics can be summarised by saying that there are three main types of molecular arrangement:

crystalline solids: molecules are ordered in a regular lattice
fluids: molecules are disordered and are not rigidly bound.
glasses: molecules are disordered but are rigidly bound. "

- http://math.ucr.edu/home/baez/physics/General/Glass/glass.html

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"Extraordinary claims require extraordinary evidence." - Carl Sagan

This is so simple and cool at the same time.
I'm glad this experiment was allowed to run its course. If someone had set up the same experiment with glass we would have our answer by now, wouldn't we?

Actually, killer, in this case every glass window in existence is an experiment. Given enough time, every glass window would eventually flow out of its frame, just like this tar pitch -- if it was a liquid.

In this case, it's not and it doesn't.

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"Extraordinary claims require extraordinary evidence." - Carl Sagan

Drip

.Drip

@tertertert “Panes of glass made hundreds of years ago are measurably larger at the bottom than the top.”

I was taught this in an engineering materials class 10 years ago. But it turned out to be a myth. The way they poured glass way back in day was to pour the hot glass in the center of a rotating table. They would spin the table so that the glass would spread out into a thin sheet. Of course, it is impossible to get a perfectly uniform thickness from this method. They would then cut the shape they needed out of the circle. As @Space pointed out, most people would install the glass with the thickest part at the bottom. However this was not always the case. There are windows installed from the same period that are thicker at the sides.

Besides, if 18th century glass was noticeably thicker at the bottom due to gravity, you would expect 15th century glass to be a puddle (or at least be significantly thicker at the bottom than the 18th century glass).

This and other myths are debunked here:
http://www.lhup.edu/~dsimanek/sciurban.htm

Wikipedia (Find: "Behavior of antique glass")
http://en.wikipedia.org/wiki/Glass

I was also taught that glass could be poured to form a perfect crystal. However the structure becomes more "glassy" over time as the atoms abandon their order and move to a disordered state. I believe this is the part of the lecture where the myth was introduced.

Bottom line is that while the atoms in glass do reorient themselves over time, they are not free to mingle (flow) like a liquid. Their neighbor will always be their neighbor, even if you distort the structure with applied force. Sorry, glass is a solid.

democedes,
I really like your choice of icons!!;)

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Science sees no further than what it can sense.
Religion sees beyond the senses.

Robert1234 Religion sees prejudice, pain, and mayhem. Religion is the greatest of all man's invented evils.

RJW Silly putty has the same quality of being fragile under impact and flowing under gravity.

Longest running lab experiment? P.72 Feb.2012 PopSci

Wrong.

"Michael Faraday. Physicist and experimental chemist (1791 - 1867) Made a small sealed glass vessel of Colloidal Gold. It has been kept till this day in the Museum at The Royal Institute in London, England. When the sealed glass vessel of Colloidal Gold is inspected to-day, utilizing a Tyndall-Faraday Ultramicroscope, the tiny particles of gold are still in suspended motion. The motion is a continual random scattering movement. These Colloidal Gold particles have been moving continuously without stopping for approximately 150 years. This is the nature of colloidal particles."

From: alchemistsworkshop.com/id5.html