The ancient Egyptians who built the pyramids may have been able to move massive stone blocks across the desert by wetting the sand in front of a contraption built to pull the heavy objects, according to a new study. Physicists at the University of Amsterdam investigated the forces needed to pull weighty objects on a giant sled over desert sand, and discovered that dampening the sand in front of the primitive device reduces friction on the sled, making it easier to operate. The findings help answer one of the most enduring historical mysteries: how the Egyptians were able to accomplish the seemingly impossible task of constructing the famous pyramids. To make their discovery, the researchers picked up on clues from the ancient Egyptians themselves. A wall painting discovered in the ancient tomb of Djehutihotep, which dates back to about 1900 B.C., depicts 172 men hauling an immense statue using ropes attached to a sledge. In the drawing, a person can be seen standing on the front of the sledge, pouring water over the sand, said study lead author Daniel Bonn, a physics professor at the University of Amsterdam. more... NBC News.com.