Edward Craven Walker, a British accountant, invented the lava lamp in the early 1960s. He was inspired by a homemade egg timer crafted from a cocktail shaker and filled with alien-looking liquids that he saw bubbling away on a stovetop in a pub. Walker was determined to create his own version that used a lightbulb as the heat source. For the prototype, he used an old Orange Squash beverage bottle and two mutually insoluble liquids. While the exact recipe is proprietary, we know that one of the liquids is water-based and the other is wax-based and includes the solvent carbon tetrachloride, which adds weight to the otherwise buoyant wax-based material. So how does his design work? The lightbulb heat source at the bottom of the lamp liquifies the waxy blob, and as it expands, its density decreases, so it rises. At the top of the lamp, it cools off, congeals, and sinks back down again. The process repeats over and over, creating a fascinating visual spectacle. Walker formed a company, Crestworth Ltd., and began manufacturing and selling his “Astro Lamps.” (In 1965, he sold the U.S. manufacturing rights to Lava Lite.) Interestingly, lava lamps were originally intended to be somewhat staid — they were even advertised in the American Bar Association Journal. However, perhaps due to their mesmerizing, calming visual displays and ability to set a certain type of low-key mood, they quickly became associated with “grooviness.” As tastes changed in the late 1970s, the lava lamp craze came to an end. But when the Austin Powers movies debuted in the late 1990s, lava lamps became popular once again. While they are no longer as popular as they once were, lava lamps have not disappeared by any means. In fact, original owners still order replacement bulbs and plenty of new units are still sold through a variety of retailers, including Target and Walmart.