In 1905, 11-year-old Frank Epperson accidentally invented the Popsicle. He left a mixture of powdered soda, water, and a stirring stick in a cup on his porch overnight. Because it was an unusually cold night in San Francisco, the mixture froze solid around the stick. Epperson pulled it out and licked it, realizing he had created a portable frozen treat. He originally named it the 'Epsicle.' Years later, his children began calling them 'Pop's 'sicles,' leading him to patent the name 'Popsicle' in 1923. During the Great Depression, the company introduced the twin-stick Popsicle for five cents, allowing two children to share one treat for a nickel. The physics of the treat involves the 'freeze-concentration' of sugar and flavor toward the center as it freezes from the outside in.