You Never Knew Albert Einstein Invented This Genius Appliance

Albert Einstein was arguably the most famous scientist of all time, so highly-esteemed that his name has become a synonym for genius. Einstein was responsible for several major breakthroughs in physics, but while he gained world fame for the laws and theories he laid out, he wasn't well known for inventions. However, Einstein did tackle technology on the side, showing particular interest in one unlikely device: the refrigerator.

Refrigerators first entered home use in the early-1900s, and although electronic refrigerators were a major improvement beyond old ice boxes, early iterations had a major issue: they often leaked toxic gas. Refrigerators work by circulating a chemical called a refrigerant through a series of tubes. The refrigerant begins as a liquid and then evaporates as it circulates, carrying heat away. Just as the evaporation of sweat cools your skin down, the evaporation of refrigerant cools your food down. The gas moves through a coil on the back of the fridge, releasing the heat (that's why the back of your fridge is hot) before entering a compressor, which exerts pressure to convert it back into a liquid and start the cycle again.

In 1926, Einstein read a newspaper story about a Berlin family who had suffocated in their sleep after their refrigerator malfunctioned and released toxic refrigerant gasses. He became determined to find a safer technology, but he wouldn't go it alone. He phoned up his colleague Leo Szilard, who had a knack for gadgets, and they went on to create something truly remarkable.

To thwart the danger of refrigerators leaking toxic gasses into people's homes, Einstein and Szilard zeroed in on one specific component of the technology: the compressor. Tasked with the vital role of turning gaseous refrigerants back into liquids, the compressor is both the starting and finishing line of the refrigeration cycle, but as Einstein noted, the seals used in compressors could break from the immense pressure they generated. This led to refrigerant gases, which at the time were either ammonia, sulfur dioxide, or methyl chloride, to escape the machine.

Einstein and Szilard resolved to fix this deadly problem by eliminating the mechanical compressor entirely and creating what is known as an absorption refrigerator. Absorption refrigerators take advantage of the fact that a liquid's boiling point drops as pressure drops, using an evaporator flask filled with liquid butane, which evaporates when a vapor is introduced above it. Most importantly, Einstein and Szilard replaced the old mechanical pump used in gas compressors with an electromagnetic pump. The pump worked by using an electromagnetic field to move a sample of liquid metal (specifically a potassium-sodium alloy) through a cylinder, creating the effect of a piston without the need for a motor. The Einstein-Szilard pump wasn't quite as efficient as a mechanical pump, but it had no moving parts and no seals that could be broken, meaning nothing could leak out of it. It was a brilliant concept, and yet, it became one of Einstein's rare career flops.

Einstein and Szilard filed for patents on their refrigerator in Germany, the United Kingdom, and the United States, ultimately securing U.S. Patent No. 1,781,541 in 1930. However, the fridge never made it to market. The design had some shortcomings — it wasn't energy efficient and the constant formation and collapse of tiny bubbles within the liquid metal was apparently quite unpleasant to the ears — but their biggest obstacles were external.

The inventors' progress was disrupted by the dual crises of the Great Depression and the rise of the Nazi Party in Germany. Both Einstein and Szilard were Jewish, as well as ardent pacifists, and ultimately, they both fled Germany in the early 1930s. After WWII had ended, they never revived the project because, in the meantime, another invention had supplanted them.

Einstein was hardly the first person to notice that toxic refrigerants leaking into homes was a problem, but while he attempted to fix the problem by changing the pump system, others took a different approach: changing the refrigerants themselves. In 1930, the American chemist Thomas Midgley introduced the world to chlorofluorocarbons (CFCs), sold under the brand name Freon. Freon wasn't deadly like ammonia and sulfur dioxide, and it soon became the standard for refrigerators.

At the end of the 20th century, decades after Einstein's death, it was discovered that CFCs damage the ozone layer. Freon was later banned, but even then, we just switched to using different refrigerants, and the Einstein-Szilard fridge remains a curiosity of the past.