alright,

Today I've been busy moving audio equipment from home to home, the reason being that to find the best audio solution - the set up is a constant evolution (Ala F1 car)

anyway, we got a four shelf stand, that houses four glass pieces, about 5/6th of an itch thick that holds the audio equipment on top, so these are pretty heavy duty pieces of glass. These pieces of glass slide into the metal frame to produce the stand.

Well, we took the glass pieces out of the frame to transport the shelf. Coming off the mountain road the top piece of glass shattered without any noticable (or no) damage to the other three pieces that were underneath the fourth piece. So, we were coming down to sea level from about 1600feet, this wasn't sudden. since the four pieces didnt make contact with anything else other than the other pieces of glass, it's got me wondering what affects physics and the law of gravity had on the fourth piece to shatter itself without any accord.

I'll be interested in each and every theory as to why the top piece of glass shattered without making contact with anything other than the third piece of glass that was underneath it?