An international team of archaeologists, physicists and engineers has found a 100-foot (30 m) long space deep inside the Great Pyramid, or Khufu’s Pyramid, one of the oldest and largest monuments on Earth. A paper reporting this discovery is published in the journal Nature.
Built on the Giza Plateau in Egypt during the IV dynasty by the pharaoh Khufu (Cheops), the Great Pyramid is 458 feet (139 m) high and 755 feet (230 m) wide.
There are three known chambers, at different heights of the pyramid, which all lie in the north-south vertical plane: (i) subterranean chamber, (ii) Queen’s chamber, and (iii) King’s chamber. These chambers are connected by several corridors, the most notable one being the Grand Gallery.
The Queen’s chamber and the King’s chamber possess two ‘air shafts’ each, which were mapped by a series of robots between 1990 and 2010.
To better understand the internal structure of the Great Pyramid, a team of researchers from Japan, France, and Egypt imaged it using elementary subatomic particles called muons, which are by-products of cosmic rays that are only partially absorbed by stone.
“Muon particles originate from the interactions of cosmic rays with the atoms of Earth’s upper atmosphere, and they continuously reach the Earth with a speed near to that of light and a flux of around 10,000 per m2 per minute,” they explained.
“Similar to X-rays which can penetrate the body and allow bone imaging, these elementary particles, also called ‘heavy electrons,’ can go through hundreds of feet of stone before being absorbed.”
“Judiciously placed muon detectors — for example inside a pyramid, below a potential, unknown chamber — can then record particle tracks and discern cavities from denser regions in which some muons are absorbed or deflected.”
“The challenge of such measurements consists in building extremely precise detectors and in accumulating enough data to increase the contrast.”
Three complementary techniques of cosmic-ray muon imaging — nuclear emulsion films, scintillator hodoscopes, and micro-pattern gaseous detectors — were applied to investigate Great Pyramid’s inner structure.
“The known voids (King’s chamber and Grand Gallery) were observed as well as an unexpected big void, which fully demonstrates the ability of cosmic-ray muon radiography to image structures,” the scientists said.
According to the team, the center of the newly discovered void is located between 131 and 164 feet (40-50 m) from the floor of the Queen’s chamber.
Its length is more than 100 feet (30 m) and its cross section is comparable to that of the Grand Gallery.
“There are still many architectural hypotheses to consider; in particular, the big void could be made of one or several adjacent structures, and it could be inclined or horizontal. The detailed structure of the void should be further studied,” the researchers said.
“Overall, this discovery shows how the methods developed in particle physics can shed light on one of the most important heritage buildings, and it calls for more interdisciplinary collaborations to help understanding the pyramid and its construction process.”
Kunihiro Morishima et al. Discovery of a big void in Khufu’s Pyramid by observation of cosmic-ray muons. Nature, published online November 2, 2017; doi: 10.1038/nature24647
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