A Simple Trick May Have Helped the Egyptians Build the Pyramids

No ancient aliens needed: A little bit of water reduces friction when dragging a sled over sand

The Great Sphinx and the pyramids of Giza (Egypt). Ca. 1845. Lithography by David Roberts. adoc-photos/Corbis

When you consider the great constructions of the ancient world, from the Hanging Garden of Babylon to the Colossus of Rhodes and the Great Pyramid of Giza, it's hard to imagine how such stunning structures came to be. The tools and technology at hand were, compared to today, staggeringly primitive. Just trying to imagine how ancient Egyptians built the pyramids is so difficult that some people have turned to more, er, creative interpretations.

In a new study lead by Daniel Bonn, a team of physicists worked out how Egyptians may have made the daunting task of dragging massive stone blocks through the desert less challenging than it seems. The trick, says the American Physical Society in a synopsis of the study, is water:

Bonn et al. tested the sliding friction of dry and wet sand when a weighted sled was pulled across the surface. As water was added, both the force needed to pull the sled and the friction coefficient were found to decrease below that of the dry sand, before increasing at higher water contents.

Stone blocks would have been pulled on sleds by large teams of people. By slightly wetting the sand in advance of the sled, the scientists say, it would have drastically reduced the drag and prevented the stone blocks from digging into the sand.

The physicists' study was about the way sand changes when wet, but the connection to the ancient Egyptians wasn't totally pulled out of left field. In their study the authors point to an image, a painting from the tomb of Djehutihotep dated to around 1880 B.C., that showed a large group of people using a rope to pull a sled carrying a giant figure. At the front of the sled a person is seeing pouring something on the ground just ahead of the sled.

A wall painting from the tomb of Djehutihotep.
A wall painting from the tomb of Djehutihotep Bonn et al. / Physical Review Letters

H/T Times of Israel

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