How is glass a liquid, if it looks and feels like a solid?

Doesn’t quite answer your question, but http://atlasobscura.com/place/pitch-drop-experiment

@Rarebear That is interesting.

@Rarebear: I love being amazed by the ingenuity of some people. Thanks for that fascinating link.

It’s not. Wiki says,
Glass is not a high-viscosity liquid at room temperature: it is an amorphous solid, although it does have some chemical properties normally associated with liquids. Panes of stained glass windows often have thicker glass at the bottom than at the top, and this has been cited as an example of the slow flow of glass over centuries. However, this unevenness is due to the window manufacturing processes used in earlier eras, which produced glass panes that were unevenly thick at the time of their installation. Normally the thick end of glass would be installed at the bottom of the frame, but it is also common to find old windows where the thicker end has been installed to the sides or the top. In fact, the lead frames of the windows are less viscous than the panes, and if glass was indeed a slow moving liquid, the panes would warp at a higher degree.

Here is a live webcam of the pitch drop experiment
mms://drop.physics.uq.edu.au/PitchDropLive or http://tinyurl.com/2uchkcg

When “glass” is super heated it becomes molten or “fluid” as in capable of flowing. 2,700 or so deg F will get you there.

Just as water can be a liquid, solid,(ice) or gas (water vapor); other substances may be in different forms depending on their temperature. This may be a simple minded answer, but there I am.

Glass is amazing. So is concrete. We take both for granted, but we really shouldn’t.

Here’s some reading about glass.

http://dwb4.unl.edu/Chem/CHEM869A/CHEM869ALinks/www.ualberta.ca/~bderksen/florin.html

here is the conclusion of the piece for those who don’t want to read it all:

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.

Here’s a great link about glass too.

http://expertvoices.nsdl.org/sciencegeekgirl/2009/03/17/is-glass-liquid-no-but-it-is-complicated/

it’s still a liquid in that it will flow, although VerySlowly. If you’ve been in a very old house with its original windows there are characteristic bulging rdges at the bottom from a century of creep.

@dabbler No. It is true that many old windows are thicker at the bottom than at the top, but it’s not because glass flowed over time and puddled at the bottom. Old windows were made by spinning the molten glass and then cutting it into panes, resulting in glass that was thicker at one end than the other. In fact, later observations noted that some ancient glass is thicker at the top than at the bottom. It just depends on how the window was placed.

If you’ve been in a very old house with its original windows there are characteristic bulging rdges at the bottom from a century of creep.

I was going to mention that, too. But @cazzie‘s expertvoices link says not.

“Old windows were made by spinning the molten glass and then cutting it into panes, resulting in glass that was thicker at one end than the other.”