Probing Pyramids to Identify Internal Structure

Menchaca comments: The account by Bogdan C. Maglich on unpublished details of the Chephren pyramid experiment by Luis Alvarez and coworkers ¹ provides fascinating insight into this pioneering application of high-energy physics to archaeology. The method used by Alvarez involves finding statistically significant differences between measured and simulated muon flows in a given direction. The necessary ignorance of a detailed density distribution inside the investigated volume requires an approximation. As Maglich implies, both we and the Alvarez group assumed that the internal pyramid density is constant. Also, we are aware ² of the limitations introduced, not only by uncertainties related to the internal density distribution, but also by uncertainties about the external shape description, among other factors.

In Teotihuacan we assume that the mean composition and density distribution are similar to those found inside a 200-meter-long horizontal tunnel excavated near the base of the Pyramid of the Sun last century. We sampled the pyramid filling along that tunnel. The study reveals that the Mexican monument, although fairly uniform, is more heterogeneous than the Egyptian pyramid seems to be as judged by the limestone walls of the tunnel leading to the Belzoni chamber, where the Alvarez team located its muon detector. The measured mean density in Teotihuacan turns out to be appreciably smaller than the density of rock. As Maglich correctly suggests, we do consider the conditions in which stony walls of a hypothetical hidden cavity would result in a compensated mean density that would cancel the sought-for signal. This and other considerations helped determine the limitations of our experiment. ²

In contrast with the Chephren case, archaeological excavations in the Pyramid of the Sun provide excellent calibration references. Finally, in the Egyptian case, we tend to agree with the private response Maglich says he received from Alvarez concerning the unlikely possibility that a cavity having a granite ceiling would result in mean density compensation in all directions. That would be particularly unlikely with internal structures as large and intricate as those found in the Cheops pyramid.