Ancient Egyptians had to pull massive statues and pyramid stones weighing 2.5 tons on large sleds across the desert -- without any modern mechanical device. Now, new research shows how adding a small amount of water to sand significantly reduces the sliding friction -- a clever trick that allowed the Egyptians to cut the number of workers needed by half.
Comment les Egyptiens ont-ils déplacé ces énormes blocs de pierre ? En les faisant glisser sur du sable mouillé ! CQFD.