ScanPyramids mission

ScanPyramids project

ScanPyramids mission

ScanPyramids mission

ScanPyramids project

ScanPyramids mission

ScanPyramids mission

Though the Great Pyramid at Giza in Egypt is one of the ancient world's biggest and most elaborate monuments, we still know very little about how it was constructed. We also don't know how many chambers are hidden inside it. Now, an international research team has identified what appears to be a large empty space or void above the pyramid's famed "Grand Gallery." The scientists report in the journal Nature that they used a cutting-edge technique for detecting cosmic radiation to make their discovery.

The Pharaoh Khufu (2509-2483 BCE) ordered the Great Pyramid to be built at Giza roughly 4,500 years ago. The structure remained sealed until 820 CE, when the Caliph al-Ma'mun broke open one of its walls and discovered three chambers inside, arranged vertically. These chambers are connected by the "Grand Gallery," a large corridor. Since that time, many have tried to find additional rooms and failed. Part of the problem is that we have no remaining plans for the pyramid's design, so it's impossible to know where to look. Plus, archaeologists today can't explore the pyramid using invasive techniques that might damage the structure. So explorers have to get creative. That's why Heritage Innovation Preservation Institute's (HIP) Mendhi Tayoubi organized a team of engineers and physicists who would use cosmic radiation to map the interior of the pyramid to look for empty spaces.

Specifically, the team used three different techniques for collecting muons, byproducts of cosmic rays produced naturally in Earth's atmosphere that can penetrate thick rock. Muography works a lot like x-ray photography. A chemically treated film captures the pattern of muons as they pass through the rock, giving us a picture of what's inside. When muons hit solid objects like bricks, their paths are slightly diverted. But when they pass through empty space, like the "void" that the researchers discovered, their paths remain straight.

To get a muograph of the pyramid, the researchers collected muon traces using nuclear emulsion films and scintillator hodoscopes set up in the queen's chamber at the base of the pyramid; they also used gas detectors outside. Next, they used specialized software to analyze the trajectories of the muon trails. After intensive study and comparing results from the three different muon-gathering tests, the team confirmed that there is a void space—perhaps a chamber or corridor—above the Grand Gallery. It appears to be about the size of the Grand Gallery, too, roughly 30 meters long, and is located about 15 to 17 meters above the surface of the ground.

Last year, the same team used muography to detect a void space shaped like a corridor behind a chevron-shaped structure on the pyramid's northern wall. Tayoubi said he and the team have wondered whether this corridor might be connected to the new void they discovered.

The scientists were ultimately convinced that they had found a genuine empty space after they checked their work by using muography to capture images of the Grand Gallery. The pattern created by the void of the Grand Gallery matched the pattern created by the unidentified void above it. Now they had strong evidence that the muography technique worked on known empty spaces. This strengthened their confidence that the void they identified was not an artifact or error.

Many mysteries remain. Tayoubi said that the team still isn't sure of the orientation of the void space. It might be at an angle, or it might be parallel to the ground. There is also no way to know whether it's an empty space that serves some kind of structural function or a tomb full of treasures. Though the team has made several advances in muography just during the two years of their investigation, University of South France physicist Sébastien Procureur said there are hard limits to the resolution on muographs. We will likely never be able to identify smaller objects in the space, if there are any.

Currently, there is no non-invasive way to reach this void in the Great Pyramid. The team said that they hope future generations of scientists will be able to explore it, perhaps by drilling a hole and sending in tiny drones to photograph the space. Right now, however, we don't have the technology to do that. It might be easier to start by exploring the void space they identified on the pyramid's northern wall, because we know that it is relatively close to the surface of the structure.

The team now awaits analysis from archaeologists and Egyptologists as to what this chamber might mean. HIP engineer Hany Helal, who worked with the team, said the group deliberately chose not to work with Egyptologists "in order not to be biased." He added, "We are scientists and engineers and technicians... we are sure about [this void] from a scientific point of view. We are confident that this void exists. What does it mean, why is it there, what is the purpose of it? We have to have an international discussion about that to know what it could be."

We do know it's unlike structures archaeologists have found in other pyramids. In addition, this open space isn't a room whose entrances were lost over time as the pyramid aged. Tayoubi confirmed that the void area had to have been hidden at the time the monument was built. "It’s not a false start, where they tried something and abandoned it. The engineering and design of this structure was carefully planned," he said. "It's not an irregularity of construction. We leave the door open to discuss this with Egyptologists."

Nature, 2017. DOI: 10.1038/nature24647

Listing image by ScanPyramids mission