 Scientists Say They've Found Hidden Space In Great Pyramid Of Giza 
 
 Enlarge this image toggle caption ScanPyramids mission ScanPyramids mission 
 
 The Great Pyramid of Giza has been probed with the tools of modern particle physics by scientists who say they have discovered a huge, secret space hidden within its ancient walls. Indeed, the team that made the find reports that it is the first significant internal structure found within the Great Pyramid since the 19th century. ScanPyramids has already detected a smaller void on the northern face 
 
 The new cavity is perhaps 30m long and several metres in height 
 
 All three muon technologies sense the same feature in the same place 
 
 Khufu famously contains three large interior chambers and a series of passageways, the most striking of which is the 47m-long, 8m-high Grand Gallery. 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. "What we are doing is trying to understand the internal structure of the pyramids and how this pyramid has been built," he told reporters. “We know that this big void has the same characteristics as the grand gallery,” said Mehdi Tayoubi at the HIP Institute in Paris, a non-profit organisation that draws on new technology to study and preserve cultural heritage. Read more 
 
 Also known as Khufu’s Pyramid, or the Pyramid of Cheops, the Great Pyramid was built in the 4th dynasty by the pharaoh Khufu, who reigned from 2509 to 2483 BC. The monument rises 140 metres above the Giza Plateau and has three chambers known from previous explorations: a subterranean one at the base of the pyramid, the Queen’s chamber at the centre, and the King’s chamber above. These particles rain down and lose energy as they pass through materials — like the thick stones of the pyramid — and that makes them slow down and decay. Image copyright SCANPYRAMIDS Image caption The newly found void is directly above the Grand Gallery 
 
 The ScanPyramids team is being very careful not to describe the cavity as a "chamber". "What we are sure about is that this big void is there; that it is impressive; and that it was not expected as far as I know by any sort of theory." "It could be a kind of space that the builders left to protect the very narrow roof of the Grand Gallery from the weight of the pyramid," he told the BBC's Science In Action programme. Jean-Baptiste Mouret, from the French national institute for computer science and applied mathematics (Inria), said the team had an idea how to do it, but that the Egyptian authorities would first have to approve it. The question now arises as to how the void should be investigated further. “The muons can’t tell us about chambers, form, size, or any possible objects, so it’s far too early to speculate. Enlarge this image toggle caption Amr Nabil/AP Amr Nabil/AP 
 
 "The romantic interpretation and what everyone wants to hear is that this is a hidden room and the king's body is inside or there's grave goods we didn't know about or we're going to learn more about history ... and none of that is responsible speculation at the moment," cautions Peter Der Manuelian, an Egyptologist at Harvard University who was not part of the research team.
– It's not every day that what is essentially nothingness would be major news, but today is that day: Scientists announced in Nature that after two years of study, they've identified a roughly 100-foot-long void in Egypt's Great Pyramid of Giza—built around 2500 BC, it's the most ancient of the seven wonders of the ancient world, notes the Guardian. It's the first discovery of a new structure in the monument since the 19th century, and it came by using muography, which can pick up on changes in density within rock. What was found, the BBC reports, isn't being called a "chamber," and it explains why: Also known as Khufu's Pyramid, the structure contains voids that are believed to have been incorporated to bolster the structural integrity of the pyramid. While three muon technologies confirmed its existence, "we don't know whether this big void is horizontal or inclined ... [or] made by one structure or several successive structures," says Mehdi Tayoubi. It sits above the pyramid's "most striking" chamber, the Grand Gallery, a corridor that links the Queen's and King's chambers. An archaeologist who reviewed the work says it's possible the void was intended to "protect the very narrow roof" of the gallery, though others contend that for the cavity to effectively have that function, it would need to be smaller. The Guardian notes the pharaoh Khufu's mummy is missing, but a Harvard Egyptologist tells NPR the idea that the cavity is "a hidden room and the king's body is inside ... none of that is responsible speculation at the moment." The team next hopes to get approval to drill a 1.2-inch hole that a robot could fit into. (The world's largest pyramid was mistaken as a mountain.)