Don't mess with the Pyramids, people take it personnally

When Michel Barsoum came in town to present his latest findings I was not expecting that it would have any relevancy to an items of my research interest. His presentation was about the process involved in the construction of the Pyramids.

Michel Barsoum and his colleagues have found some evidence that parts of the Great Pyramids of Giza were built using an early form of concrete, debunking an age old myth that they were built using only cut limestone blocks.

The amount of resistance that goes with this theory is pretty impressive. For an idea of the fierceness of the debate, one can read the comments of this blog. As far as I can tell his main interest in the theory stands in the discovery of low cost concrete materials to be used in poor countries. The pyramid story, while interesting on its own right, is clearly setting the stage for more advances in our understanding low cost construction materials.

During the presentation, Michel Barsoum mentioned that if his theory holds, i.e. the upper part of the pyramids are made of concrete, then it is very likely to the top part of the pyramid still hold millions of liters of water. That water would be the reason early electromagnetic measurements were negative.

It so happens that there are other methods that can be used to find out if there is water in rocks:

• Neutron Thermalization is one of them. In neutron transport, it is very well known that neutrons slow down very fast when in contact with water. This is the mechanism at the heart of Pressurized or Boiling Water Reactors (PWR / BWR) in use in most nuclear reactors. So when we try to find water on the Moon or Mars, neutrons are generated and scattered through rocks. Detection on how they have been slowed down (this is called thermalization) is key to understand the medium of interest. The idea is that neutrons decelerate to low speed (thermal) very fast when they scatter with hydrogen (because they have about of the same mass). Hydrogen is generally an indicator of water. Neutrons can either be galactic neutrons (very high energy GeV range) or produced by man-made generators (14 MeV) (like in the oil business). In either case the scattering down is so rapid that you don't have any population of neutrons in the intermediate range (epithermal). The technique was used during the Clementine mission to find water on the south pole of the Moon.
• Another possibility of detecting water is with infra-red. One can take a look at satellite data that have IR sensors such the Hyperion hyperspectral camera on board EO-1. The spectral bands include wavelength in the IR range. One shot of the pyramids can be seen on the side of this paragraph (but if one wants a better one, one can task the satellite for $750 by going through the USGS interface.)

When asked, at the end of his presentation, why he felt there was so much resistance for a new explanation ( an explanation that is very persuasive as it includes photos taken at the Pyramids and other artifacts at the Louvres in France) his answer was sort of funny. Most kids, all over the world, are taught about the pyramids and how they were built with enormous blocks of stones. People take it personally when you tell them that this childhood explanation has holes and can be better explained with a simpler and more elegant solution.