11 November 1930: Einstein receives a patent for his fridge
On this day in 1930, Albert Einstein and Leó Szilárd were awarded a patent for their revolutionary 'Einstein refrigerator'.
Albert Einstein is perhaps best-known for his theory of relativity. But he and his former student, the Hungarian physicist Leo Szilard, also came up with a design for a fridge – the so-called Einstein refrigerator – for which they were awarded patent number US1781541 A on 11 November 1930.
Sadly, their fridge never really got going. But, over 80 years after its invention, the Einstein fridge may yet play an important role in helping to save the planet.
The problem with the Einstein fridge was that it was inefficient. That left the door open for horrible modern fridges in the 1950s, which require man-made gases that can play havoc with our atmosphere.
But the Einstein fridge had plenty going for it. It comprised just four components, none of which included moving parts. That meant it required less maintenance. It also didn't require electricity, just a heat source. And it was clean.
It worked on the principle that liquids boil at lower temperatures in areas of low pressure. Ammonia vapour was used to lower the pressure of a chamber containing butane. As the butane boiled off, it took energy with it and made the fridge cold.
In the last few years, Einstein and Szilard's design has been revisited. A team from Oxford University claimed to have quadrupled the efficiency of the Einstein fridge by playing around with different types of gases. And it's not before time.
As living standards have steadily risen in poorer parts of the world, sales of polluting fridges have soared. But it's hoped the Einstein fridge might yet do away with ozone-depleting fridges, particularly where a reliable power supply might be missing. The Oxford team, for example, used solar power.
So, who knows, it may not be too long before you have an Einstein fridge in your kitchen.