Scientists develop 'unbreakable' glass almost as tough as steel

There used to be an issue where people's head would go through a window but the glass wouldn't entirely shatter, so the rest of the body wouldn't go through. A deadly broken window collar

Source: took the same tech class 2 years in a row, and watched some documentary on car safety _4 times_ each year. Yay for American middle school

Laminated glass remains in one solid mass held together by the plastic sheet in the middle, while tempered glass explodes into tiny pieces that are sharp but not overly harmful. Ordinary annealed glass breaks into long, dagger-like pieces that are dangerously sharp, which is why it's tempered or laminated into safety glass.

So the windshield is meant not to break apart, because it's laminated rather than tempered. The polymer lining between the lites of glass prevents it from scattering and causes it to be quite impact resistant. [1] Conversely, you'd really hate to have tempered glass as your windshield, if it broke the entire thing would just pop into tiny pieces that would get into your eyes. If a rock hit hard enough to break a hypothetical tempered windshield, the parts that didn't pop would be filled with cracks and impossible to see through due to being white from being filled with tiny cracks, though you could just bat them out of the way as any parts were partially intact would simply crumble when moved.

The side windows are tempered, incidentally. If you've ever broken a side window, you know what I mean about the whole thing just exploding. [2] If you manage to pop it, the entire window will just fall apart easily, which might be good if you had to leave from the window of a car. It can cause small cuts and scratches and such, but it's not terribly dangerous unless it gets in your eyes, even if, say, a sheet of 3mm, 33 1/4 x 73 1/4 inch glass breaks while you're holding it. [3] It's no fun, but when you compare it to the fact that annealed glass accidents have been fatal, it's not so bad. [4] Yes, I used to work for a glass factory, so when I say that I've seen hundreds of tons of broken glass, the word 'tons' should be understood in the literal, 2,000 lbs sense of the word.

[1] Source: Determined empirically by beating on damaged pieces of it with a shovel, when said pieces wouldn't fit into the dumpster. Or you can read this, whatever: http://sem-proceedings.com/10f/sem.org-IMPLAST-2010-SEM-Fall...

[2] See also: https://www.youtube.com/watch?v=xPwaq_6aXbo This normally happens only if hit from the corner or an edge, but it can happen just randomly. We usually saw this in winter, but only a few times a year, meaning there was at most about a 1 in 10,000 chance of spontaneous breakage in my experience and probably significantly less based on the average daily volume numbers I remember. When there's something containing the edge of tempered, it sometimes just takes on a white, broken look due to all the cracks, but crumbles to the touch. It tends to just disintegrate like in the video most of the time, though.

[3] Source: Direct, personal experience on multiple occasions for that very size and many others. This is an every-day kind of thing and causes no injury to someone with proper safety gear.

[4] Source: I'm directly aware of at least one such accident where someone was found dead after having their neck cut when attempting to dispose of a cracked sheet. I also provided first aid to someone who could've lost a hand to injury.

Fiction becoming reality. I thought "transparent aluminum" was just completely made-up nonsense when I saw the movie. Whodda thunk!

Almost every material known to man will break/crack/shatter/do-something if you rapidly cool it from an elevated temperature.