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...