IFL Science
Inside the Great Pyramid Of Giza, there is a massive void. The room, sealed when the pyramid was completed some 4,500 years ago, is of unknown purpose, though some have speculated it could be a secret burial chamber of the pharaoh Khufu, who ordered the pyramid to be built.
In 2017, a team known as ScanPyramids scanned the Great Pyramid of Giza using muon tomography. Muon particles are negatively-charged particles produced by cosmic rays which collide with atoms in the Earth’s upper atmosphere at around 10,000 per square meter per minute.