Secrets of a lost world
Engineering technologies more at home on the factory floor are helping to solve some of history’s most enduring mysteries. Jon Excell reports.
Of the seven wonders of the ancient world, the Great Pyramid of Giza is the only one still standing. Built around 4,500 years ago to house the body of the fourth-dynasty Egyptian pharaoh Khufu (or Cheops), it stands testament to a lost world’s technical expertise.
The 146m-high prism of about two million giant limestone slabs, many of them weighing up to 70 tonnes, has been the subject of almost unequalled analysis throughout the ages but the great structure is yet to yield up its biggest secret: how it was built.
Numerous theories have been put forward. Some believe it was constructed using either a straight or spiral external ramp that was raised as the construction proceeded. Others have suggested the blocks were hauled into place using long levers. Some have even claimed extra-terrestrials had a hand in the design. All agree that most theories pose more questions than they answer.
Last month, however, in an announcement that has divided the academic community, French architect Jean-Pierre Houdin revealed a compelling new hypothesis that the Great Pyramid was built from the inside out. In an unusual departure from the archaeological techniques usually deployed by Egyptologists, he arrived at his theory with the help of engineering software typically used to design cars and aircraft.
Houdin believes that a smaller, long, straight ramp consisting of two carriageways was used to build up to the 43m mark of the pyramid (about 73 per cent of its volume). Then the frontal ramp was systematically dismantled and the blocks that formed it used to complete the upper part of the pyramid through a ramp that spirals around the inside of the structure. According to Houdin’s calculations, the volume of rock used in the external ramp would have been exactly the volume of rock required to construct the pyramid above the 43m mark.
To put his theory to the test, Houdin teamed up with industrial software giant Dassault Systemes, developer of a suite of software tools that are claimed to be behind the design of almost 70 per cent of the cars on the road.
Houdin began by building a 3D model of the pyramid, using CATIA CAD software. Until now, he said, everyone who has tried to explain the construction of the pyramids has worked in 2D. ‘I was able to see the pyramid from the inside, turn it up, down, left, right — and to see the connections between the work inside the pyramid, between the grand gallery and the King’s chamber, the corridors and the chambers.’
Perhaps the most remarkable aspect of Houdin’s work is the 5,000 hours that his multi-disciplinary team racked up developing a model that took into account every aspect of the pyramid’s construction. Everything was simulated in detail: building processes; manpower; materials; even the properties of the Nile mud and animal oil that ancient Egypt’s engineers used to lubricate their sled runners.
In what must be a first for archaeology, Houdin even visited strongman competitions in the south of France where he gathered data that he used to integrate human mannequins into his simulation.
Richard Breitner, a Dassault Systemes engineer who has been working with Houdin on the project, explained how by using Delmia, a software tool typically used to shave seconds off manufacturing processes, the simulation also made it possible to figure out exactly how long the construction of the pyramid took.
‘We discovered that it would be possible to build the pyramid in 20 years, which is compatible with the generally admitted reign duration for Khufu, thought to be around 30 years. It fits,’ he claimed.
Asked whether the team had considered applying its sophisticated techniques to the existing construction theories, Breitner was dismissive. ‘You don’t need to simulate the big central ramp theory to see that it won’t work,’ he said, claiming that simple calculations demonstrate that a slope moderate enough to allow workers to build the entire pyramid would not actually fit on the Giza Plateau.
He was equally scathing about the external ramp theory, claiming that the heavy stones would have caused it to collapse. As for the notion that machines were used, Breitner claimed the 51° faces of the pyramid would cause the stones’ centre of gravity to swing away from the cranes and make them collapse. ‘You don’t need CATIA to do that, just simple reasoning, ’ he asserted.
In the course of formulating their theory, Houdin’s team also decided to apply their techniques to another of the Khufu pyramid’s mysteries: the cause of a series of cracks in the first three ceilings of the King’s chamber. Breitner and Houdin’s awe at the perfectionism of the pyramid’s designers led them to question existing theories suggesting the cracks were simply the result of the ceilings being too heavy.
To solve the riddle, the team employed finite element analysis (FEA) software. This tool, more typically used to perform procedures such as virtual crash tests, was used to analyse a virtual model of the King’s chamber as each ceiling was put in place and to see if the structure would collapse under its own weight.
As each ceiling was added to the computer model, nothing happened. The ceilings even remained intact when the full weight of the remaining portion of the pyramid was added above the King’s chamber. However, when the team simulated a southern wall collapse, which they knew had happened, cracks appeared in the virtual pyramid that exactly matched those on the real structure.
This discovery, said Breitner, not only confirms that their models are accurate but also disproves the theory that the King’s chamber had collapsed during its construction.
The team believes this explanation could help confirm the construction theory, as it suspects the southern wall collapse may have been triggered when the external ramp, which would have been in place for about 14 years, was removed. This, said Breitner, could be the subject of a future simulation.
Houdin claims to have the backing of numerous Egyptologists and scientists and is now writing a book on his work with Long Island University Egyptology Prof Bob Briar.
However, not everyone is convinced. UCL Egyptologist Prof David Jeffreys described the internal spiral hypothesis as ‘far-fetched and horribly complicated’, while Oxford University’s Prof John Baines, declared he was ‘suspicious of any theory that seeks to explain only how the Great Pyramid was built’.
Houdin is undaunted and believes his theory is given greater credence by the discoveries of a team of French experts who visited the Great Pyramid in 1986 to look for hidden chambers using a technique known as microgravimetry. This technology can be used to measure the density of sub-surface features by detecting minute variations in gravity on the ground surface.
While the French team did not find what they were looking for, they did uncover an unusual anomaly: a strange, low-density spiral structure rising through the inside of the pyramid. ‘When I put my drawings next to their drawings it was very strange that it was the same design,’ said Houdin.
He now hopes to use a range of similar, non-destructive techniques to verify his theory. He has joined up with microgravimetry experts at French engineering consultant SAFEGE, and has been working with UK defence specialist Thaleson the use of radar technology.
He also hopes to use powerful thermal cameras to detect tiny differences in temperature over the face of the pyramid, claiming the presence of an internal ramp will leave a thermal signature courtesy of the cooling voids behind certain blocks. The advantage of this technique, he said, is that you do not even have to be close to the pyramid to use it.
While all these techniques have been used individually before, Houdin believes this will be the first time they have been used together as a package and will be key to verifying his theory.
But cutting through the red tape is likely to be a laborious process. Prof Zahi Hawass, the eccentric under-secretary of state for the Giza monuments, keeps a tight hold on the keys to Egypt’s antiquities. Houdin is confident he will get the chance to put his theories to the ultimate test but accepts he’s in it for the long haul.
While Houdin waits to be granted permission, scientists in the UK are preparing to use similar techniques to try to solve another ancient mystery: the location of Ithaca as described in Homer’s Odyssey. Dated between 800-600BC, the Odyssey is one of the oldest texts in Western literature. The story centres on the Greek hero Odysseus and his journey home to Ithaca after the fall of Troy.
The location of the island of Ithaca described in the story has baffled researchers for almost 3,000 years. Homer’s descriptions bear little resemblance to the modern island of Ithaca, which lies west of the Greek mainland next to the island of Kefalonia, and many scholars have speculated that he had little knowledge of the area.
However, in 2003 a group of UK academics proposed a radical alternative: that this confusion has occurred not because of geographical errors by the poet but because of geological changes in the landscape that have occurred in the last 3,000 years.
The team has proposed that the ancient island of Ithaca described by Homer is, in fact, now the western peninsula of Kefalonia and that dramatic geological events in the past 2,000 years led to the formation of a land bridge in an area now known as the Thalia valley.
Last month, the team announced it had joined up with Dutch geophysical prospecting company Fugro. Now, led by Edinburgh University geologist Prof John Underhill, the group is preparing to visit Kefalonia to use Fugro’s technology to search for a buried sea channel consistent with their hypothesis.
Steve Thomson, Fugro’s director of airborne survey, said that initial tests are likely to be carried out from the air. The group will begin by building an accurate terrain map of the existing surface using a high-resolution light detection and ranging (Lidar) system.
This airborne mapping technique, which uses a laser to measure the distance between the aircraft and the ground, is popular in the oil and gas industry. Thomson said Fugro has also used the system to map and measure drooping powerlines to help reduce the loss of energy into the ground.
He also expects to use airborne electromagnetic mapping technology to get an overall impression of the near surface structure of the ground and determine the types of material in place where the channel might have been.
After this, the group will begin using land-based techniques that provide even higher resolution images of the sub-surface geology. ‘This will give us the opportunity to get a really robust 3D image of the sub-surface in the key areas. We have the opportunity to get a good idea of where a buried channel might run underneath that landslide and rockfall debris,’ said Underhill.
Thomson explained that this detailed image of the area in question will enable the group to drill a series of boreholes that will be used to take samples of rock and carry out downhole geophysics, where different sensors will be used to determine what sort of structures are evident in the vicinity of the holes.
Underhill is excited about the opportunities offered by this range of technologies. ‘We will be able to see in the samples whether the age information is compatible and consistent with there being a marine channel in the past 3,000 years in that position,’ he said. ‘None of that would have been possible or feasible without the techniques that can now be employed.’
While the techniques offer the best possible hope of solving the mystery, the project also presents Fugro — a company that typically develops exclusive solutions for oil and gas companies — with a rare opportunity to showcase its expertise. ‘It’s not often that we can go into an area, do the investigation and show that information to people,’ said Thomson.
For Underhill, the blend of technology and antiquity is an irresistible formula. ‘From an archaeological and classical Greek scholarship point of view, there’s a big prize and a long unsolved conundrum there that people have wondered about for 2,000 years or more.
‘The geology itself isn’t something that’s earth shattering but when you add it to the classical Greek scholarship, then it really does take on a life of its own,’ he said.
Sidebar: How technology solved more historical riddles
Archaeologists used space-based imaging technology to locate the lost city of Ubar in 1992. The fabled Arabian trading post — described by Lawrence of Arabia as the Atlantis of the sands — was, according to legend, swallowed up by the desert in AD100.
The researchers found the city by tracing ancient desert roads detected in pictures taken from space. These tracks, which were identified as old caravan routes, led a team of archaeologists to a remote area in southern Oman, where excavations uncovered a large octagonal fortress.
They also uncovered artefacts from around the world, which led them to conclude they had indeed uncovered the long-lost settlement.
More recently, scientists and researchers used modern scanning techniques to discover the secret of a mysterious device found in a Roman shipwreck. The purpose of the so-called Antikythera mechanism, found off the Greek island of the same name in 1902, has baffled scientists since its discovery.
Last year members of the Anglo-Greek team probed the 2,000-year-old machine using a range of advanced imaging techniques and discovered that it was, in fact, an ancient analogue computer designed to model and display astronomical cycles.