Price Rupert's droplet is a fascinating phenomenon of glass physics that has intrigued scientists for centuries. It is a glass bead with a bulbous head and a thin tail, formed by dripping molten glass into cold water. The rapid cooling creates a state of high compressive stress on the surface and high tensile stress in the interior of the droplet. This makes the head very resistant to mechanical damage, but also very sensitive to any crack initiation in the tail. If the tail is slightly damaged, the droplet explodes into fine powder due to a chain reaction of crack propagation.
The origin of the name Prince Rupert's droplet comes from Prince Rupert of the Rhine, who brought some of these glass drops to England in 1660 and presented them to King Charles II as a curiosity. However, the drops were already known to Dutch glassmakers before that and may have been discovered even earlier by other cultures. The drops have been studied by many scientists, including Robert Hooke and Isaac Newton, who tried to explain their peculiar properties.
Modern techniques such as high-speed photography and polarimetry have revealed more details about the stress distribution and fracture dynamics of Prince Rupert's droplets. The drops have also inspired applications such as toughened glass and novel materials with tunable mechanical properties.