Hidden Chamber found in Great Pyramid using Cosmic Rays

How sub-atomic particle detectors are enabling archaeologists to peer inside ancient structures as never before

Archaeologists have uncovered a mysterious chamber deep within the Great Pyramid of Giza, using a cutting-edge imaging technique based on the detection of subatomic particles created by cosmic rays. Dubbed the ScanPyramids Big Void, after the name of the project that discovered it, the cavity is approximately 30m long and 3m high and is situated above the Grand Gallery, a large corridor that connects the two largest of the iconic structure’s three main chambers. The Great Pyramid, also known as Khufu’s Pyramid, was built during the reign of Pharaoh Khufu, who reigned from 2509 to 2483 BC. Constructed from limestone and granite blocks, and rising to 139 metres, it is the oldest and largest of the Giza pyramids and one of the most impressive structures to survive from the ancient world.

Despite years of extensive research, there is no consensus on how exactly the monument was constructed. As yet, the precise structure and role of the newly-discovered void remain unknown, but the findings may pave the way for further studies that could help researchers to understand the pyramid and its construction process. “No important internal structures have been found in the Pyramid since 820 AD, when the Calife Al Mamun dug a tunnel and penetrated inside, revealing most of the structure we know today,” said Prof Mehdi Tayoubi from Cairo University. “Finding something as important, in terms of size, as the Grand Gallery is an important breakthrough.”

The void was discovered using sensors tuned to detect muons (particles that are created when high energy cosmic rays slam into molecules in the upper atmosphere). To see through the Great Pyramid, the researchers used a technique developed in high-energy particle physics: they tracked particles called muons, which are produced when cosmic rays strike atoms in the upper atmosphere. Around 10,000 muons rain down on each square metre of Earth’s surface every minute. Sensitive muon detectors have been developed for use in particle accelerators, but they have also been used in the past decade or so to determine the inner structures of volcanoes and to study the damaged nuclear reactor at Fukushima, Japan.

By piecing together data from several different locations, the team were able to form a three dimensional image of the pyramid’s internal structure. “Our discovery is the first demonstration of the potential of cosmic ray imaging to gather new information in archaeology,” said Nagoya University’s Kunihiro Morishima from Japan. “The Big Void has not been touched by anyone since the building of the pyramid 4,500 years ago, so, if there are some artefacts inside the big void, they should be very important for understanding ancient Egypt.” The team now plans to take further scans of the Big Void, in order to determine its shape and structure in more detail.

Researchers placed muons detectors inside and outside the pyramid to find out whether theories of a hidden space in the Great Pyramid were true.

What's so special about the Pyramid?

Whereas other pyramids from this period sit above underground burial chambers, Khufu’s Pyramid contains several large rooms inside the body of the structure itself. These include the King’s chamber, which still holds a stone sarcophagus, the smaller Queen’s chamber and a sloping passageway known as the Grand Gallery. Many enthusiasts have wondered since the 19th century whether there might be more hidden chambers inside the pyramid, or even whether the king’s real burial chamber is yet to be found!