A hidden narrow void in the Great Pyramid of Giza has been found by scientists in a discovery that could finally reveal the secrets of the 4,500-year-old monument.
The void stretches for at least 30 metres (100ft) above the Grand Gallery, an ascending corridor that links the Queen’s chamber to the King’s in the heart of the pyramid.
It is not known why the void came into existence or if there are any valuable artefacts inside as it is definitely not accessible.
But it has similar dimensions to the Gallery, which is 50 metres (164ft) long, eight metres (26ft) high and around a metre (3.2ft) wide.
Researchers suggest it could be a ‘construction gap’, part of a trench that allowed workers to access the Grand Gallery and King’s Chamber while the rest of the pyramid was built.
The discovery was made after physicists took images of the inside of the pyramid using particles fired to Earth from space.
These cosmic particles enter the rock in a similar way to X-rays, only much deeper.
The collaborative effort, between archaeologists, historians and physicists, has been hailed as the biggest discovery inside the Giza landmark since the 19th century.
Made under the watch of the Pharaoh Khufu and completed in around 2550 BC, Egypt’s Great Pyramid, or the Pyramid of Giza, served as the world’s tallest man-made construction for thousands of years.
The structure, also known as Khufu’s Pyramid, is the sole survivor of the ancient Seven Wonders of the World.
How it was built has long been a bone of academic contention and there is no universal agreement about its creation.
Scientists say the latest discovery, published in the journal Nature, could help shed light on its construction.
To find out more about the pyramid, researchers from countries including France and Japan began a project to scan the structure in October 2015.
The scientists made the discovery using cosmic-ray imaging, recording the behavior of subatomic particles called muons that penetrate the rock.
Detectors were set up inside the pyramid, including in the so-called Queen’s Chamber.
This allowed the pyramid’s insides to be seen without physically disturbing it, as the results showed empty space differently from rock.
The presence of the space, dubbed the ScanPyramids Big Void, was confirmed using three different detection technologies over several months after first being spotted, the paper said.
The results were then analysed three times.
The ScanPyramids mission is made up of researchers from Egypt’s Ministry of Antiquities, the University of Cario, and the non-profit organisation the Heritage Innovation Preservation (HIP) Institute.
‘ScanPyramids Big Void is not a room or a chamber – we don’t know if it is horizontal or inclined if it is composed by one or several successive structures, but it’s big,’ report author Mehdi Tayoubi, president and co-founder of the HIP Institute, told MailOnline.
‘The Grand Gallery is an internal spectacular internal structure (47m long, 8m high) a kind of internal cathedral at the centre of the pyramid.
‘This Big Void, with same size characteristics as the Grand Gallery, could be successive chambers, a tunnel. Many hypotheses are possible.’
In spite of the breakthrough, the newly discovered structure has yet to be reached in person by any researcher.
Report author Mr Tayoubi said: ‘This structure is not accessible, we don’t see (that) people tried, if you look at the Grand Gallery, to access the void which is above.
‘So this void was hidden, I think, since the construction of the pyramid, it was not accessible.
‘We needed this technique – the right technique at the right time – to be able to identify it and discover it.’
He added they were ‘very confident’ the results were correct.
Because no one has physically seen inside the void, what it was built for remains a mystery.
Researchers claim the space could be on an incline, which means it could have been used to transport huge blocks into the centre of the pyramid and was then left, experts said.
‘This finding is very exciting, but I don’t think it’s likely to be some kind of secret chamber,’ Dr Kate Spence, an archaeologist at the University of Cambridge who was not involved in the study, told the Telegraph.
‘I think it is an inclined ramp that was used to transport huge blocks into the centre of the pyramid and then left. The orientation leads up to the huge granite roof struts at the top of the relieving chamber.
Researchers from the Egyptian Ministry of Antiquities’ scientific committee suggest it could be a ‘construction gap’ – part of a trench that allowed workers to access the Grand Gallery and King’s Chamber while the rest of the pyramid was built.
More simply, the void may have simply been left there to relieve weight from the Grand Gallery below.
The finding opens up the possibility that the void could be linked to other different and undiscovered structures within the pyramid, the study claimed.
More importantly, the authors said, it could provide a method by which scientists can finally start to piece together how the pyramid was built.
They added that the development ‘show how modern particle physics can shed new light on the world’s archaeological heritage’.
‘This was a study about physics, it was not about Egyptology – we are not claiming anything about interpretation for this void – we are just claiming that there is a void and that’s all,’ Mr Tayoubi said.
Muon detectors have previously been used to map out the inside of the Fukushima’s nuclear reactor in Japan and it is hoped they can be used to explore other archaeological sites.
The detectors work by using cosmic particles known as muons that have the power to penetrate deeply into most materials.
The subatomic particles require only a few special instruments because they rain down naturally from the atmosphere above.
Muons are created when the upper atmosphere reacts with cosmic rays, producing a shower of particles, some of which decay into muons.
The elementary particles, which weigh around 200 times more than electrons, can very easily pass through any structure, even large and thick rocks like mountains.
Researchers can use these tiny particles to measure the density of structures, just like X-rays pass through our bodies to visualize our skeleton.
The team’s finding has been a long time coming after months spent trying to find the elusive ‘void’.
The researchers began using muon technology, thermal scanning and 3D laser mapping to lay out the pyramid’s internal structure in 2015.
Scanners placed in the Great Pyramid’s grand descending corridor, as well as a tunnel near the north facing entrance dug out by medieval explorers, found a small structure above the structure’s entrance in 2016.
Thermal imaging of the pyramid confirmed a human-height, corridor-shaped void that ran parallel but above to the descending corridor.
Researchers realised this corridor, labelled the ScanPyramid Northfacing Corridor, must lead somewhere, and spent the following months using mapping technology to find where it led.
This has now led the team to find the new structure, which sits above the pyramid’s Grand Gallery.
Some archaeologists have pinned hopes on using the sophisticated technology to locate the burial place of the legendary queen Nefertiti.
The wife of King Akhenaten, who initiated a monotheistic cult in ancient Egypt, queen Nefertiti remains an enigma, best known for a bust depicting her that is now on exhibition in Berlin’s Neues Museum.
A British Egyptologist, Nicholas Reeves, believed her remains were hidden in a secret chamber in the tomb of Tutankhamun, in the southern Valley of the Kings.
In 2015, archaeologists scanned the tomb with radar hoping to find clues.
Both Reeves’s theory and the inconclusive results have been terminated by other Egyptologists.
One of them, former antiquities minister Zahi Hawass, said that an adept of the sun god Aton would never have been allowed to be buried in the Valley of the Kings.