Archaeologists have long suspected that there are hidden chambers inside the Great Pyramid of Giza — one of the “Seven Wonders of the Ancient World.” But only recently was the possibility confirmed by science. Recently, researchers with the ScanPyramids project confirmed that there is a “plane-sized” void in the middle of the 5,000-year-old structure. This is the first discovery of its kind to be made since the 19th century.

The research began two years ago when a team of scientists announced that they would use particle physics to try and scan deep into the Great Pyramid of Giza — also known as the Pyramid of Khufu — without disrupting its outside. Their plan was to image internal structures that are inaccessible to researchers. What they found was stranger than anyone could have predicted.

Credit: ScanPyramids Project

Thanks to their efforts, we now know that there is a massive internal void inside the Great Pyramid that is at least 30 meters (100 feet) long. Needless to say, scientists are baffled by the discovery.

“This is a premier,” said Mehdi Tayoubi, a co-founder of the ScanPyramids project. “It could be composed of one or several structures… maybe it could be another Grand Gallery. It could be a chamber, it could be a lot of things.”

“It was hidden, I think, since the construction of the pyramid,” he added.

Credit: ScanPyramids Project

The team used cosmic-ray imaging to record the behavior of muons — subatomic particles. When muons rain down from earth’s atmosphere, they are absorbed or deflected by harder objects which slows them down. By applying particle physics, the researchers were able to study the particles’ trajectories and determine what parts of the pyramid are stone — and which are open space. Their paper was peer-reviewed before appearing in the journal Nature.

Tayoubi explained that the group was determined to investigate the pyramid with non-destructive analytical techniques. When the high-tech method worked, everyone was blown away. He said,

“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.”

Credit: ScanPyramids Project

He continued,

“The good news is the void is there. Now we are sure that there is a void. We know that this void is big. I don’t know what it could be. I think it’s now time for Egyptologists and specialists in ancient Egypt architecture to collaborate with us, to provide us with some hypotheses.”

The ScanPyramids team is hoping small robots can be used to enter the space through tiny cracks or holes and provide more information.

Credit: ScanPyramids Project

Said Peter Der Manuelian, an Egyptologist at Harvard University who was not part of the research team:

“That’s the good thing about the muon project, there’s absolutely no damage to the pyramid at all. I hope that, in collaboration with the Egyptian antiquities authorities, further exploration will be set in motion. The study of the pyramids has been going on for an awful long time. So any new contribution is always a welcome addition to our knowledge.”

h/t The Independent, NPR