However it is unclear whether the void is a chamber or a corridor, or whether it played any more than a structural role in the pyramid’s construction. Scientists discovered the void using sensors that detect particles known as muons, which rain down on Earth when cosmic rays slam into atoms in the upper atmosphere. The muons travel at close to the speed of light and behave much like x-rays when they meet objects.
To pinpoint the cavity, scientists from Nagoya University in Japan, and KEK, the country’s high energy physics lab, installed muon-detecting photographic plates and electronic muon detectors around the Queen’s chamber. At the same time, researchers from CEA, France’s energy research organisation, trained “muon telescopes” on the pyramid from the outside. The Great Pyramid was built in the 4th dynasty by the pharaoh Khufu, who reigned from 2509 to 2483 BC. The monument rises 140 meters above the Giza Plateau and has three chambers known from previous explorations. Peter Der Manuelian, professor of Egyptology and director of the Harvard Semitic Museum, said the discovery was “potentially a major contribution to our knowledge about the Great Pyramid.”