Ever since the discovery of the first pyramid, scientists have pondered over how ancient Egyptians built these monumental structures that are visible even from space. Though there are some theories about the construction technique, the question that was always left unanswered is how workers were able to lug the giant limestone bricks that weighed as much as 2.5 tons, from the quarry to the pyramid sites that were located hundreds of miles away.

While dragging them over rudimentary sleds was the obvious answer, it would have required superhuman strength against the friction of the desert sand. Turns out that the workers did have some assistance . . . from ordinary water! What is even more amazing is that the answer to the puzzle has been right in front of Egyptologists for many years, thanks to a wall painting inside the tomb of ancient Egyptian nomarch, Djehutihotep.

The artwork that depicts a Pharaoh being dragged by a large contingent of workers, has one significant detail that had so far been misinterpreted - A man pouring water in front of the sled the Pharaoh is being dragged upon.

Egyptologists had always thought that the man was performing some kind of purification ritual. However, some scientists now believe that the water was being poured for a totally different reason - to help pull the sled across the sand.

This revelation was made on April 29th in the journal Physical Review Letters, by researchers from the University of Amsterdam and the Foundation for Fundamental Research on Matter.

The team led by Daniel Bonn from the University of Amsterdam arrived at this conclusion after conducting extensive testing in their laboratory, by sliding a weighted tray across both dry and damp sand mixed with varying amounts of water. In dry sand, heaps formed in front of the sled as it was dragged along, slowing it down dramatically.

However as water was added, it made the sand more rigid, helping reduce both the force needed to pull the sled and the friction against it. That's because the water helps form capillary bridges between the sand particles, causing them to stick together like glue. What was interesting was that the force required to pull the sled reduced in proportion to the stiffness of the sand - And it was not a small amount either, but as much as 50% which meant that half-as many workers were needed to move the heavy bricks.

But, there was a tipping point - After the moisture exceeded a certain amount, the stiffness started to decrease and the capillary bridges, melt away, causing the sand to clump up around the sled once again. According to researchers, the perfect balance appears to be when the volume of the water is between 2-5%, the volume of sand - a proportion ancient Egyptians seemed to have mastered perfectly. Now if we could only find a painting that would tell us how the smart workers constructed these impressive structures without access to modern mechanics, life would be perfect!

Resources: independent.co.uk,iflscience.com