Pyramid riddle solved? Amsterdam scientists say so

Physicists from the Foundation for Fundamental Research on Matter (FOM) and researchers from the University of Amsterdam think they may have solved how ancient Egyptians transported heavy stones to construct Pyramids.  According to their research, supervised by FOM group leader professor Daniel Bonn, and published online on the 29th of April in Physical Review Letters, the stones were moved by sledge, and the sand over which the sledge moved was likely moistened. Ancient Egyptians built pyramids with these huge slabs of stone, which were pulled across the desert by workers. Research from the University of Amsterdam now reveals that ancient Egyptians probably used water to decrease the amount of force needed to pull the giant stones. "Experiments have demonstrated that the correct amount of dampness in the sand halves the pulling force required", the press release from the FOM Foundation states. In order to test this theory, the physicists had a laboratory version of the ancient Egyptian sledge placed in a tray of sand. They then calculated the ratio between the stiffness of the sand and the relevant pulling force to determine how much water needed to be added to the sand.

The experiments revealed that the stiffness of the sand was directly proportional to the amount of pulling force needed to move the stones across with the sledge. According to the FOM Foundation, 'capillary bridges' come up when water is added to the sand, small water droplets that bind the sand grains together, reducing friction and allowing for easier movement of the sledge as the sand would be more compacted. FOM Foundation states that there is even clear proof that the ancient Egyptians knew about this trick. "A wall painting in the tomb of Djehutihotep clearly shows a person standing on the front of the pulled sledge and pouring water over the sand just in front of it." The research could also prove helpful in our contemporary understanding of 'granular material' like sand, asphalt, concrete and coal. The data might help optimize transport and processing of granular material which, according to FOM Foundation "at present accounts for about ten percent of the worldwide energy consumption."