Just to put the right physics to work here, allow me to explain that angela's Pyrex dish did not explode, exactly. It did suffer the fate of most tempered glass products when the temper layer is scratched deep enough or overly stressed, or a combination of the two -- like the case w/ Gordon's window. In angela's case there was no real external force present, just the internal stresses caused by the tempering and a mild thermal stress due to hash browns (?). In Gordon's case there was an external force (the sudden momentum change required of the bird due to its encounter w/ such a larger momentum already in progress, namley Gordon's fat a---, er, I mean Gordon's humgous truck). In each case the transformation of the glass into so many small bits is caused by the release of the high tensile and compressive stresses imposed on the wall of the glass during tempering. These high compressive stresses on the outside are balanced by high tensile stresses in the glass wall interior. Glass is VERY strong in compression, but much weaker in tension. All is hunky dory so long as the outer layer compression does not exceed the glass's limit (which is very high) or the layer is scratched, causing a stress concentration. If you get to that point the built-up internal stresses just run to completion in every direction releasing all that built-up strain energy, and the result is all those little pieces. The strain energy is turned into all that extra surface. This is not an explosive event, as there is no gas pressure or other form of energy available to push the glass particles away, so they just slump down. The crack propagation does take place very fast and will make a nice noise, as all have attested to. I believe you could be standing right next to angelas dish when if boke, and aside from being scared sh--less by the sudden noise, no danger would be present. The particles do not fly away. The many small granules of glass are felt to be much less dangerous than the few larger pices one would get with untempered glass, which will fail at lower loads and does so by forming only a few much larger pieces. In each case, BTW, the broken edges are just as sharp, but the small bits of tempered glass fragments are not big heavy daggers, and this is to the good. In the case of auto glass, safety is compounded by gluing two such tempered layers together w/ a very thin plastic film that holds all the wee tiny fragments together, more or less, should a fracture occur.
As for the white Corning ware, which as noted is a form of Pyroceram, this material is a fine grain ceramic and not amorphous glass. Pyroceram has a rather high tensile strength to begin with. It is not tempered. If it is loaded to failure, say by dropping it, it will fracture, but generally into a few large pieces, vs. the mirriad (?) small fragments you see in tempered glass failures. Turns out this material is used in the nose cones of rockets, and if heated fast enough (WAY faster that anything possible is a regular oven), it can build up enough stress throughout its wall that it will fracture into a lot of small pieces.
That's it kids; class dismissed.
