Glass is a hard and crystalline material. When glass smashes, what is going on at a molecular level - what is actually being separated? What atomic forces have been overcome?

Peter Finan, Haworth, West Yorkshire

The photo (above, right) shows a pattern that has formed between the two panes of glass of a double-glazed sliding patio door. The pattern is on the inside of the inner pane, but the inside of the outer pane of the door carries a faint copy. It extends from the top of the glass to two-thirds of the way down and two-thirds of the way across from the right. The lock is on the left. The door faces north-west and gets intermittent sun. What caused it?

Colum Clarke, Bray, Wicklow, Ireland

My glasses go from clear to quite black in the cold, but don't work so well when it's hot.

I wear glasses to correct my long distance vision.  Without them anything more than a metre of so away is blurry.  I can see objects close to me clearly without my glasses. 

If I hold a mirror I can see the reflection of close objects (such as my face) clearly.  The reflection of distant objects is blurry. 

Why is this so?  To my way of thinking, I am focusing on the mirror which is within the range I see objects clearly.

Vandals regularly smash the windows of our local railway station, and they are equally regularly replaced with laminated glass consisting of two sheets with a flexible layer between.

When the windows break (see photo), the glass on the side the stone came from cracks in concentric circles, but the other layer cracks radially, together forming a spiderweb pattern. Why is this?

Hugh Young, Pukerua Bay, New Zealand

We recently had a new kitchen installed at home, included was a glass topped halogen hob. Soon after - and much to her disappointment - my mother split some sugar on the hot hob while making jam. As the manual said, the hob was allowed to cool off before cleaning; however when it came to cleaning off the hardened sugar globules they took some glass away with them, leaving a sprinkling of pits in the surface.

No abrasives were used in cleaning, just hob cleaner and a sponge, what happened?

Liam, age 11, Galway, Ireland

When I was very young I thought it was solid (at room temperature), then I read an encyclopedia in primary telling me that glass was actually liquid.  Apparently this is shown in very old buildings where the windows are thicker at the bottom. I then recently read an article saying that glass being a liquid is a common misconception. What state(s) is glass at room temperature?