Historical story

Scientists scan Cheops pyramid with muons and find hidden space

A sensational find in Egypt:the 139 meter high pyramid of Cheops appears to contain a still unknown space. Several scientific teams made the discovery by screening the stone structure with muons, particles that continuously bombard the earth.

The elongated space would be at least thirty meters long and about the diameter of the so-called great gallery that lies below, which is one to two meters wide and almost nine meters high. The scientists involved are in the dark about the precise shape and content of the space. The research method used is not precise enough for that.

The find is the result of research conducted by three teams of Japanese and French scientists over the past few years. They started working with muon entomography. A method somewhat similar to the way a CT scanner creates a three-dimensional image of a patient based on X-rays.

However, the researchers did not use X-rays but muons, particles that arise in large numbers in the atmosphere and pass through matter relatively easily. In the 1960s the pyramid of Khafre was also investigated in this way, no new cavities were found. Success can now be reported at the Cheops pyramid, which is next to it. The discovery of the new space is this week in the scientific journal Nature published.

An explanation of the technique used to screen pyramids.

Patient

The "patient" in the scientists' scanner was the largest pyramid in Egypt, with a (current) height of 139 meters and a base of 230 meters. The colossus was built under the authority of Pharaoh Cheops (aka Khufu), who probably lived in the 25 e or 26 e century BC.

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With such a large and massive structure, X-ray scans are of little use, the radiation simply does not get through. The solution is muons, particles that are formed when high-energy cosmic particles reach the earth and collide with the atmosphere. Matter allows a large part but not all of the muons to pass through, so scientists could use it as a measure of the amount of rock between their detectors and the atmosphere.

In fact, the scientists were looking for clues about the pyramid's construction method. They placed muon detectors at various strategic places outside and inside the pyramid, including the King's Chamber. These are a kind of photographic plates that record traces of muons as the particles shoot through them. The measurements (which took months) uncovered not only the known spaces, but also a new elongated space that lies above the gallery. Incidentally, it can also be several small rooms, the detection method is currently not sensitive enough to determine the precise shape of the room.

Temper expectations

Is it now time to call Indiana Jones and explore the new space(s)? For the time being, no attempts are being made to visit the space. In a next step, the scientists hope to obtain a more precise map of the cavity, also based on muon tomography.

As fun as it is to speculate about the spectacular content or intriguing function of the new space, archaeologists and historians temper expectations. It could well be a recess left by the pyramid's builders to relieve pressure on the space below. But whichever way you look, the 4,500-year-old pyramid will keep researchers busy for years to come.