Re: glass

I can't see that anyone would bother trying. Estimates for the viscosity of soda glass are around 10^20 poise whereas lead is around 10^10. ISTR some medieval plumbing has sagged under its own weight.

Corning Glass museum has a nice explanation:

I rested a house brick on top of a light bulb for over five years and there was no deformation in that time.

Tim

When I were younger, Victorian houses wit heavily sagged lead plumbing were common.

NT

It has to be many centuries old. So, churches and cathedrals.

Urban myth, in those days flat glass was always produced by spinning a disk, so it is always tapered. And glass-makers set the thick edge at the bottom for stability, there is also a prism effect directing light more downwards.

The physicist in me would still like to see it measured, rather than estimated. Glass rod with optical flats on each end. Rest on two supports on an optical bench with a decent weight in the middle. Multiple beam interferometry. Maybe try to formulate a "low viscosity" composition?

Nice thought, but no.

I never dug it.

It was always there. Presumably since before te addjacent field was equipped with land drains that dump into an active drain (in the fen use of the term) at te bottom of hte garden.

Field run off via that is impressive after a storm

No, the process of vitrification below the glass transition temperature makes it a solid.

Or if you stick it down for a while with old fuel rods in the hard water tank

For similar purposes we had a small quarry that apart from the odd amount for our own requirements like a stone wall fell into disuse circa 1913 ,very useful over decades to dispose of awkward stuff though some of it like the horse drawn cart and various other interesting bits could be sold now rather than dumped. Despite our efforts most of the quarry remains and the tip bit is well covered with soil

Been in different hands for a while now but doesn?t seem to have changed much.

GH

yep. Probably the best place to dump glass is in the sea where it will turn back into sand quite rapidly.

As long as all the little fish aren't at risk of cutting themselves on the sharp edges of broken glass ;-)

I presume glass is a resource that is always recycled if possible rather than being dumped (landfill, sea, etc).

Since it involves atoms moving past each other, I would expect the ones in glass to have to go through crystalline positions, which would be more stable, which is what happened in the case of the lens you mentioned, and is seen in some items of Roman glass.

That just gives me an empty page.

Glass isn't crystalline, it's amorphous.

See e.g.

There is some value in clear container glass for recycling. Coloured glass (especially green), has little or no value for recycling, and is often used as ballast or as an aggregate in building road sub bases etc.

It doesn?t actually. We still get plenty turning up from the days when it was a fad to put messages into bottles and toss them in the sea.

That?s my point. It?s amorphous but made of something that has a stable crystalline form. So if it were creeping, the rearrangement of atoms would cause it to form crystals.

What about vitroceramic hobs?

vitroceramic: 1.A heat-resistant material created by crystallizing glass in controlled conditions. (Wiktionary)

Much depends on the chemical composition of the glass as to whether it will form a crystalline phase if given the appropriate heat treatment. Many 'glass-ceramics' contain lithium, especially those used on cooking hobs. They have a low coefficient of thermal expansion, so tend not to crack when exposed to big temperature gradients. The mirrors of giant astronomical are also made of glass-ceramic with a low coefficient of thermal expansion, so that they don't distort when subject to temperature variations, day to night, for example.

See also