Mysterious void in the heart of the Great Pyramid of Giza

SCANPYRAMIDS 3D representation of the inside of the pyramid, highlighting the newly discovered void (the white dots)SCANPYRAMIDS

A huge empty space found inside the Khufu pyramid in Egypt is helping researchers better understand how the monument was built (Nature, November 2). The Great Pyramid of Giza, as it is also known, was built from blocks of limestone and granite some 4,500 years ago, under the rule of Pharaoh Khufu. At more than 140 meters (m) high, it is the oldest of the seven wonders of the ancient world. The Khufu pyramid differs from others in that it has several chambers inside, including the King’s Chamber, where a stone sarcophagus was found, and the Queen’s Chamber. Discovered in the nineteenth century, these galleries have been extensively studied by archeologists and experts have continued to wonder whether there are other hidden chambers in the structure. To investigate this mystery, a group of researchers coordinated by Japanese physicist Kunihiro Morishima, from the Nagoya University, Japan, used a technique that involves detecting muons—particles similar to electrons, but with about 200 times the mass. These particles travel at close to the speed of light. As they reach the surface of the Earth and pass through objects, they lose energy and disintegrate, being partially absorbed by the rocks. In practice, they can be used like a kind of X-ray for large objects or structures. At the end of 2015, the researchers installed muon detectors in the pyramid and recorded the particles that passed through it. When analyzing the data, they identified a high volume of muons in the center of the monument, suggesting that there is a void at least 30 m long above the Grand Gallery, a sloped corridor linking the King’s and Queen’s Chambers. This is the first major inner structure discovered in the pyramid since the nineteenth century, but it is not yet known whether the space is a chamber, or a compartment constructed by the builders to relieve the weight of other stone chambers and prevent collapses.