A scientific study called "Scan Pyramids" ushered in November 2015 has revealed that the ancient Great Pyramid of Giza built as a tomb for the pharaoh Khufu, has some mysterious cavity or void inside, triggering an unprecedented interest among experts.

The thermal mapping of Great Pyramid of Giza included four masterpieces of the Fourth Dynasty (2575-2465): on the site of Dahshur, about 15 kilometers south of Saqqara.

The second one is the South pyramid, called the Bent, and third one is the North pyramid, called the Red, both built by Snefru (2575 - 2551). The fourth one is about 20 kilometers from Cairo. The pyramids of Khufu and Khafre were built by the son and grand-son of Snefru.

"Such a big void can't be an accident," stressed Mehdi Tayoubi, president of the non-profit Heritage Innovation Preservation Institute in Paris, who led the research.

Built with an estimated 2.3 million stone blocks and standing 140 meters tall and 230 meters wide, the Great Pyramid is an engineering marvel, built for Khufu, who died in 2566 B.C.

Using cosmic rays, subatomic particles from above, the new team of physicists found a previously unknown void within the pyramid by obtaining its imaging with more powerful particles called muons. Tens of thousands of muons scan each square meter of Earth. Unlike electrons which pierce a few centimeters, muons are 207 times as massive and travel through hundreds of meters of stone before being absorbed.

Though muon imaging was undertaken in the late 1960s, no anamolies were found. And 30 years ago, when EDF foundation detected a density anomaly in the form of a spiral in Khufu, it led to seek more scientific imaging of the pyramids without causing any material destruction.

In November 2015, using the techniques developed in Japan by the teams of KEK (High Energy Accelerator research Organization) and Nagoya University, a muon radiography centre was set up in Cairo to get concrete results.

The current experiment has revealed the presence of three known large cavities: the queen's and king's chambers, and a long corridor that connects them, known as the grand gallery. Surprisingly, they spotted a new void area above the grand gallery, which is mysterious.

The new cavity measuring 8 meters high, 2 meters wide and about 30 meters long — like a cathedral, rising 20 meters above the ground in the pyramid's core has become the major focus now triggering new interest in the study of pyramids by particle scientists, let alone archaeologists till recently.

Archaeologist Mark Lehner, director of Ancient Egypt Research Associates in Boston, who was not part of the current research team, said:"It's not the ideal place to contain a body." Perhaps, it could be a symbolic void meant to be a passage for the pharaoh's soul to heavens, Tayoubi explains.

Zahi Hawass, an Egyptologist who chaired the panel to review the latest project, rules out the possibility that the cavity could be a "secret room." He suggested that it could be part of the construction strategy to relieve the weight of the stone blocks above the grand gallery and to save it from collapse, and to protect the core chamber.

Mehdi Tayoubi is hopeful that their findings, published in Nature, would prepare the path for future scientific research missions.