It turns out that rather than some unknown ancient marvel, it was a simple logical deduction that allowed Egyptians to transport the mammoth stones used to build the pyramids, according to a team of physicists from the University of Amsterdam.
The team hypothesized that the Egyptians dampened the sand along the routes they used for transporting the 2.5 ton stones, making the sand firmer and allowing their fairly rudimentary sleds to glide more easily across the terrain.
“Experiments revealed that the required pulling force decreased proportional to the stiffness of the sand,” the university said in a statement. “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 biggest difficulty in dragging or pushing a sled across sand is that the weight digs into the sand ahead of it, causing the sand to build up. At a certain point the build-up must be cleared away before the sled can proceed.
However, when sand gets wet, the water causes the grains of sand to bind together, increasing the stiffness and subsequently reducing the amount of force necessary to drag something across it.
“Everyone who has been to the beach will know that dry sand doesn’t make good sandcastles — the grains slump into a puddle when the bucket is lifted,” the team wrote in the study synopsis. “Adding water can solve this problem: the grains stick and the castle holds its shape.
“This is great for sandcastle building, and also, it turns out, for sand transportation.”
While it may seem simple, the Egyptians still had to figure out the correct amount of water to use, as too much or too little water significantly decreases the effectiveness, according to the scientists.