Prince Rupert's drop

The prince Rupert's drop is a truly amazing thing.When molten glass hits cold water, its outer surface cools rapidly and shrinks as it solidifies. Since the center is still fluid, it can flow to adjust to the outer shell’s smaller size. As that center eventually cools and solidifies, it also shrinks, but now the outer shell is already solid and can’t change its shape to accommodate the smaller core. The result of this is a high amount of internal pressure, as the inside pulls the outside from all directions the glass is set to release a lot of energy. If you break the thin glass at the tail, a chain reaction travels like a shock wave through the drop. As each section breaks, it releases enough energy to break the next section, and so on, shattering the whole drop in less than a millisecond. At the same time The glass can be extremely strong aswell glass breaks when tiny scratches pull apart and spread into fractures. Since the surface is compressed by internal stress, scratches can’t grow, and the glass is very difficult to break.