Made under the watch of the Pharaoh Khufu and completed in around 2550 BC, the Great Pyramid, also known as Khufu's Pyramid, served as the world's tallest man-made construction for thousands of years. Scientists say the particles penetrate any material that made them the flawless tool to X-ray the pyramid with. They include a lengthy passage called the Grand Gallery, which leads to the Queen's Chamber and the King's Chamber.
"There are many voids in the pyramid because of construction reasons", said Zahi Hawass, an Egyptologist and former Egyptian minister of antiquities and director of excavations at Giza, Saqqara, Bahariya Oasis and the Valley of the Kings, told LiveScience.
It is located above a tall, cathedral-like room known as the Grand Gallery, and this newly found space is comparable in size - about 100 feet long, according to a report in the journal Nature.
At present, neither the particle physicists nor the world's Egyptologists have any idea just what goal the Big Void filled, nor what artefacts, if any, maybe sealed inside it.
"In order to understand how Khufu was built, we need to understand the internal structure".
Using sensitive detectors that identify changes in speed, these muons can accurately give us an image of empty spaces in buildings. "On the other hand, as an architectural discovery, something we didn't know about the interior of the Great Pyramid, it's absolutely big news".
Muon detection has improved significantly since it was developed in the 1960s, so Tayoubi and his colleagues were able to use three advanced muon-detection techniques-nuclear-emulsion films, hodoscopes, and ardon gas-based detection.
"The first reaction was a lot of excitement, but then we knew that it would take us a long, long time, that we needed to be very patient in this scientific process", says Tayoubi.
"In order to construct the Grand Gallery, you had to have a hollow, or a big void in order to access it - you can not build it without such a space", he said. "I don't know what it could be".
He's interested in whether small robots might somehow enter this space through tiny cracks or holes and provide more information. "So any new contribution is always a welcome addition to our knowledge".