Another of Albert Einstein’s accomplishments, in conjunction with Hungarian physicist Leo Szilard, was the invention of a refrigerator that operates without electricity, or the environmentally damaging freons currently used in fridges.

Malcolm McCulloch, a scientist at Oxford University in Britain, is leading a team to revive development of the idea.

Einstein and Szilard’s idea avoids the need for freons. It uses ammonia, butane and water and takes advantage of the fact that liquids boil at lower temperatures when the air pressure around them is lower. ‘If you go to the top of Mount Everest, water boils at a much lower temperature than it does when you’re at sea level and that’s because the pressure is much lower up there,’ said McCulloch.