Throughout history, people have looked upon the ancient pyramids of Egypt and scratched their heads, wondering how all those giants blocks of stone were moved across the desert and stacked up high. Physicists from the University of Amsterdam and the Foundation for Fundamental Research on Matter believe they have an answer as to how those stones were moved.
The first part of the equation is that stones and statues were placed on sledges and pulled across the sand. If you've ever walked on a beach barefoot, you know it's slowgoing when you're in dry sand, but much easier when you're walking on wet sand. The physicists say the correct amount of dampness in the sand halves the amount of pulling force required to move a sledge with a honking huge stone on it.
To test the idea, the scientists created a lab model of how it would work, using a small version of a sledge pulled across a tray of sand. They measured the amount of pulling force needed to move the sledge as well as the stiffness of the sand.
"Capillary bridges arise when water is added to the sand. These are small water droplets that bind the sand grains together. In the presence of the correct quantity of water, wet desert sand is about twice as stiff as dry sand. A sledge glides far more easily over firm desert sand simply because the sand does not pile up in front of the sledge as it does in the case of dry sand," the report reads.
The results were published this week in the journal Physical Review Letters with the title "Sliding Friction on Wet and Dry Sand."
This theory isn't just a case of scientists coming up with creative solutions long after the fact. A wall painting found in the tomb of ancient Egyptian ruler Djehutihotep depicts Egyptians pulling a sledge laden with a massive statue on board. One of the people in the painting leans over the front of the sledge, pouring what appears to be water onto the ground ahead.
Of the many theories related to the movement of large stones and statues in ancient Egypt, this approach appears to be a pretty solid one. It probably won't dissuade enthusiastic alien theorists from their beliefs, though.