"[A team of eight researchers led by Daniel Bonn] placed a laboratory version of an Egyptian sledge in a bin of sand that had been dried in the oven. Then they threw down some water, and measured the grains’ stiffness."<p>Surely the way to test this theory isn't to make a model of a sledge, and bake some wet sand in an oven in your lab in Amsterdam! Go to Cairo, build a wooden sledge, get some water and fifty men for an hour and see whether one can sledge two tons across wet sand. I quite fancy testing it out myself. Perhaps I could run a Kickstarter to build a pyramid.