Scientists map unexplored corridor of Egypt’s Great Pyramid using cosmic rays

The Great Pyramid of Giza, the largest of Egypt’s famous monuments, has stood proudly for around 4,500 years. But the 2 million blocks that make up the tomb and the fortress were not impenetrable. Looters stole the structure of its ancient treasures thousands of years ago, and scientists have probed its interiors either by studying its hallways or with more advanced measurement techniques like thermal scanners.

The structure still holds many secrets, but since 2015 an international team of scientists, the ScanPyramids team, has been using subatomic particles to probe the unknowns of the monument. In 2017 they revealed a huge void – creatively dubbed the Big Void – located above the Pyramid Gallery, although the purpose of this void remains unknown.

In a study published Thursday in the journal Nature Communications, the team characterizes the structure of this corridor by taking advantage of the cosmic rays that constantly crash into Earth.

Cosmic ray muons, a subatomic particle considered one of the most basic building blocks of the universe, pass through the Earth’s atmosphere and sometimes collide with solid matter on the ground. The density and thickness of a given object determines how the muon is absorbed by the object – and it is measurable.

Two teams installed seven detectors inside two corridors of the pyramid over a three-year period, from 2016 to 2019, capable of capturing these muons. The direction in which these muons collide with the detector is useful in determining the material they passed through before being detected. This is how the team was able to first discover the North Face Corridor and then characterize its characteristics.

Their measurements show that the North Face Corridor sits about 2.6 feet behind the North Face Chevron, an interesting structure just above the modern public entrance to the pyramid with a currently unknown role. The hallway itself is likely 27 feet in length and shaped like a pipe and extends horizontally to the ground. It also appears to have a larger cross-section than the other corridors of the Great Pyramid and, at least by this measurement, it seems unlikely to connect to the Great Void previously detected by the ScanPyramids team.

It’s a particularly intriguing find because the North Face Chevron was once hidden behind the outer layer of casing stones on the pyramid. Why hide these rafters? What were they for? Why is there a corridor behind them?

It seems that each time scientists probe the Great Pyramid’s hidden pathways and seemingly empty spaces, they find more questions.