ScanPyramids is an international research project, launched in October 2015 by Cairo University's Faculty of Engineering and the French HIP Institute (Heritage Innovation Preservation), that uses non-invasive physics, chiefly cosmic-ray muon imaging, to look inside the pyramids of Giza without drilling or moving a single block. Its two headline results are the "Big Void", a space at least 30 metres long above the Grand Gallery of Khufu's pyramid published in Nature in November 2017, and the North Face Corridor, a short sealed passage behind the chevron blocks above the original entrance published in March 2023.
Why it matters: the Great Pyramid has been explored, tunnelled into and measured for more than a thousand years, yet the Big Void was, in its discoverers' words, the first major inner structure found in it since the nineteenth century. The finds have attracted heavy speculation, so it is worth being precise about what was measured, what was not, and where interpretation begins. For the wider context, see the Ancient Egypt topic hub.
What is the ScanPyramids project?
ScanPyramids is a scanning mission run under the authority of Egypt's Ministry of Antiquities, coordinated by Cairo University and the HIP Institute, with particle-physics teams from Japan and France supplying the detectors. Nagoya University contributed nuclear emulsion films, Japan's High Energy Accelerator Research Organization (KEK) contributed scintillator hodoscopes, and France's Alternative Energies and Atomic Energy Commission (CEA) contributed gas-detector muon telescopes built on Micromegas technology. Alongside muography, the project used infrared thermography on the outer faces and 3D simulation to compare detector data with the known architecture. The guiding rule is non-destruction: no new holes, no removed stones.
How does muon imaging work?
Muon imaging, or muography, works like a passive X-ray that uses particles from space instead of a machine. When cosmic rays, mostly high-energy protons, strike the upper atmosphere, they produce showers of secondary particles, among them muons. Muons, heavy cousins of the electron, reach the ground continuously, roughly one per square centimetre per minute at sea level.
Muons can pass through tens of metres of rock, but dense material stops a share of them. The more stone a muon has to cross along a given line of sight, the fewer arrive at a detector from that direction. A detector placed inside or beside a structure therefore records a "shadow" of the mass above and around it. If there is an empty space somewhere along a line of sight, less stone stands in the way, and the detector counts more muons from that direction than the model of the solid structure predicts. That excess is the signal of a cavity.
The method is slow, since detectors must sit in place for weeks or months to collect enough counts, but placing them at different points lets researchers triangulate where a void sits and roughly how large it is, with no drilling and no radiation source. For an earlier look at how the project began, see the 4biddenknowledge report on researchers using cosmic-ray technology to scan the Great Pyramid.
Who first used muons on a pyramid?
The idea is older than ScanPyramids. In the 1960s the American physicist Luis Alvarez, winner of the 1968 Nobel Prize in Physics, led a joint American and Egyptian team that placed spark-chamber detectors in the Belzoni Chamber, the only known room inside the pyramid of Khafre (Chephren) at Giza. The work was briefly interrupted by the 1967 Arab-Israeli war and resumed afterwards. The results appeared in Science in February 1970 under the title "Search for Hidden Chambers in the Pyramids".
Alvarez's team found no hidden chambers in the portion of Khafre's pyramid that their detectors covered, which the paper put at about 19 per cent of the volume. The survey proved that the technique worked, and it remained the reference point for half a century until ScanPyramids revived the idea with far more sensitive, portable detectors.
What is the Big Void?
The Big Void is a large empty space inside the Great Pyramid of Khufu, located above the Grand Gallery, with a cross-section similar to the Gallery's and a length of at least 30 metres. It was reported by Kunihiro Morishima and colleagues in "Discovery of a big void in Khufu's Pyramid by observation of cosmic-ray muons", published online in Nature on 2 November 2017.
The result was credible to physicists because of how it was cross-checked. It was first seen with nuclear emulsion films installed in the Queen's Chamber, then confirmed with scintillator hodoscopes in the same chamber and with gas detectors placed outside the pyramid. All three, analysed separately, pointed to the same excess of muons from the same region above the Grand Gallery.
What the paper does not say is just as important. The authors wrote that there is currently no information about the intended purpose of the void. Speaking to National Geographic at the time, Mehdi Tayoubi of the HIP Institute said the team did not know whether it was horizontal or inclined, or whether it was made of one structure or several successive structures. The researchers deliberately avoided the word "chamber". Muography reveals a lack of mass, not what fills the space or what it looks like inside, and nobody has seen into the Big Void.
For how this fits the construction debate, including the long-running theories about internal ramps and relieving spaces, see how the Great Pyramid of Giza was built.
How did Egyptologists react?
Zahi Hawass, the former Egyptian antiquities minister, dismissed the announcement in press coverage at the time, saying "This paper offers nothing to Egyptology. Zero." Peter Der Manuelian of Harvard, by contrast, was reported as calling the result potentially a major contribution to knowledge about the Great Pyramid.
Both reactions can be true at once. The physics is robust: three detector types agree that something less dense than solid masonry sits above the Grand Gallery. The archaeology is open: until the shape is resolved or the space is seen, its function is unknown.
What is the North Face Corridor?
The North Face Corridor is a sealed, empty passage roughly 9 metres long sitting directly behind the large chevron (gabled) blocks above the pyramid's original north entrance. Its characterisation was published by Sébastien Procureur, Kunihiro Morishima and colleagues in Nature Communications on 2 March 2023, in a paper titled "Precise characterization of a corridor-shaped structure in Khufu's Pyramid by observation of cosmic-ray muons".
Using nuclear emulsion films and CEA's Micromegas telescopes, the two independent analyses measured its length at 9.06 and 9.23 metres. The cross-section is about 2 by 2 metres, the floor sits roughly 20 metres above ground level, the structure is essentially horizontal, and it lies above the Descending Corridor.
On the same day, Mostafa Waziri, then secretary-general of Egypt's Supreme Council of Antiquities, announced the result at the pyramid itself. The team had pushed a 6-millimetre Japanese endoscope through a small joint between the stones, and the camera showed an empty corridor. Waziri suggested it was likely built to redistribute the weight of the pyramid, either around the main entrance or around another chamber or space not yet found. That remains a hypothesis. The 4biddenknowledge archive covered the announcement in cosmic rays chart the course of a concealed passage.
What the scans have not found
The scans have not found a burial, a treasure or a way into either space; much of the confusion comes from headlines that stretched the results.
The corridor is not the Big Void. The North Face Corridor sits low on the north face, behind the entrance chevrons; the Big Void sits much higher and deeper in the core, above the Grand Gallery. Some outlets conflated them in 2023. They are separate features, and any link between them has not been demonstrated.
Neither is a treasure room or a burial chamber. No objects, inscriptions or remains have been detected, and muography cannot detect them.
Nothing has been entered. The corridor has been seen only through an endoscope; the Big Void has not been seen at all. Its shape, whether one space or several, sloping or level, is unresolved.
The 2025 "underground city" claims about Khafre's pyramid are a separate story. Those claims came from a different team using satellite radar analysis, not ScanPyramids, and were contested by radar specialists and Egyptologists. The companion piece on Billy Carson and the Khafre radar claims covers them, and the Hall of Records explainer sets out what scans of the Sphinx area have and have not shown.
The project has not stopped at Khufu. In late 2025 a team from Cairo University and the Technical University of Munich, working within ScanPyramids, reported in NDT & E International that ground-penetrating radar, ultrasonic testing and electrical resistivity tomography had detected two small anomalies, consistent with air-filled voids, directly behind the polished granite casing on the east face of Menkaure's pyramid. They measure roughly 1 by 1.5 metres and 0.9 by 0.7 metres. The study set out to test the independent researcher Stijn van den Hoven's 2019 suggestion that the east face might hide a second entrance. The authors did not claim to have found one; they left the interpretation to Egyptologists. It remains a hypothesis, not a confirmed entrance. Visitors who want to see where all of this sits on the ground can start with the Giza Plateau visitor's guide.
Billy Carson's reading
Billy Carson's work on the Great Pyramid does not centre on the muon data, and this article does not attribute any view of the Big Void or the North Face Corridor to him. His interest lies elsewhere in the building and beneath it.
In his reading, summarised in the Great Pyramid explainer, the Great Pyramid is a repository of encoded advanced knowledge that dynastic Egypt inherited or restored rather than invented, and possibly a device with a function beyond that of a tomb. Carson points to the pyramid's mathematical relationships, its precise orientation and its placement in the landscape, and he connects its origin to Thoth through the Emerald Tablets, which he treats as a memory of that origin. Mainstream Egyptology dates the pyramid to Khufu's reign in the Fourth Dynasty and regards the Doreal Emerald Tablets as a twentieth-century text, so readers should weigh both. Carson also gives particular weight to the King's Chamber, which he frames as a space connected with consciousness and pineal activation.
His most specific claims about hidden spaces at Giza concern what lies beneath the plateau. On the 2025 Khafre radar story, Carson argues that the reported underground structures match descriptions he published in his Compendium of the Emerald Tablets and represent ancient technology rather than empty caverns. That is his interpretation of a contested, non-ScanPyramids claim; the companion article sets out both his argument and the criticism of it.
Watch, read and go deeper
Billy Carson's teachings on Egypt, the Great Pyramid and the mystery-school tradition are collected in the 4BK TV series Egyptian Mystery School. The construction explainer and the Khafre radar companion linked above carry the engineering debate and Carson's own position on hidden structures beneath Giza. Everything on the subject is gathered on the Ancient Egypt topic hub.
Frequently asked questions
Did ScanPyramids find a hidden chamber in the Great Pyramid?
ScanPyramids found two previously unknown empty spaces in Khufu's pyramid: the Big Void above the Grand Gallery (2017) and the North Face Corridor behind the entrance chevrons (2023). The researchers avoid the word "chamber" because muography shows only missing mass, not purpose or contents. The corridor has been viewed by endoscope and is empty; the Big Void has not been seen.
How big is the Big Void?
The 2017 Nature paper describes it as at least 30 metres long, with a cross-section similar to that of the Grand Gallery. Its exact shape, orientation and whether it is one space or several are still unknown.
Is the North Face Corridor the same as the Big Void?
No. The North Face Corridor is about 9 metres long and sits behind the chevron blocks above the original north entrance, around 20 metres above ground. The Big Void lies much higher in the pyramid, above the Grand Gallery. No connection between the two has been shown.
How do muons see through stone?
Muons are produced when cosmic rays hit the upper atmosphere, and they reach the ground continuously. Stone absorbs some of them, so a detector counts fewer muons through dense masonry and more through empty space. A direction with an unexpected excess of muons indicates a cavity, much like a shadow on an X-ray in reverse.
Is ScanPyramids connected to the 2025 Khafre "underground city" claims?
No. The Khafre underground claims came from a separate group using satellite radar analysis and were disputed by specialists. ScanPyramids results appear in peer-reviewed journals and concern spaces inside the pyramids, not beneath the plateau.
Sources and further reading
- Morishima, K. et al., "Discovery of a big void in Khufu's Pyramid by observation of cosmic-ray muons", Nature 552 (2017).
- Procureur, S., Morishima, K. et al., "Precise characterization of a corridor-shaped structure in Khufu's Pyramid by observation of cosmic-ray muons", Nature Communications 14 (2023).
- Alvarez, L. W. et al., "Search for Hidden Chambers in the Pyramids", Science 167 (1970).
- Helal, K., Elkarmoty, M. et al., "Detection of two anomalies behind the Eastern face of the Menkaure Pyramid using a combination of non-destructive testing techniques", NDT & E International 155 (2025).
- Mark Lehner, The Complete Pyramids (Thames & Hudson).
- National Geographic, coverage of the Big Void announcement, November 2017.
