ARCHAEOLOGY / Great Pyramid hides a great secret: New evidence has boosted Egyptologists' hopes for the discovery of a hidden chamber, says David Keys

A NEW in-depth study of evidence recently obtained from inside Egypt's largest pyramid has increased the probability that an unknown secret chamber exists deep within the pyramid's structure.

The story began early last year when a German scientific team used a miniature robot equipped with a video camera to penetrate previously unexplored parts of the pyramid. At the end of an 65m- long and 20cm-wide passageway, the robot discovered what appeared to be a stone door with metal handles.

On this, however, the world of Egyptology was divided as to whether it was indeed a door, and as to whether or not a hidden chamber might lie behind it.

A detailed analysis of all the structural and architectural evidence has recently been completed, and substantially strengthens the case for the existence of a secret chamber.

The scientist who ran the robot exploration of the pyramid, Rudolf Gantenbrink, concedes that although the case for a chamber is not yet proven, the evidence from a technical point of view 'appears to suggest that a cavity is more likely to exist than not'.

Mr Gantenbrink, an engineer and robotics expert who has spent six years studying the structure of the pyramids, has now carried out a detailed investigation of the video material obtained by the robot inside the Great Pyramid.

There are 14 pieces of evidence pointing towards the existence of a secret chamber, and none pointing in a contrary direction. This is the first time that the evidence which the robot obtained inside the pyramid has ever been published.

There is good evidence for the sort of structural stress that a chamber would cause. The robot found heavy damage (figure 1) four metres in front of the stone 'door'. Stress within the fabric of the pyramid may have resulted in a small section of the floor disintegrating. It was the heaviest damage found in the 180 metres of passageways which Gantenbrink's robot has so far explored.

The only other cases of similar damage in the Pyramid are to be found adjacent to the other two chambers - the King's Chamber and the Queen's Chamber - caused by structural stress associated with the chambers.

There is also evidence that the architect of the Great Pyramid deliberately included a special structural feature (figure 2) in an area of the pyramid near to the door, specifically designed to cope with the extra stress that would be caused by a chamber. The interfaces between nearly all the stone blocks (which make up the walls of the pyramid's four miniature passageways) are perpendicular to their respective passageway floors.

The only exceptions to this rule are three vertical interfaces - one near the King's Chamber, one near the Queen's Chamber and one near the stone door in an adjacent passageway. In the first two cases the vertical interfaces were included to cope with stresses caused by the two chambers. There is no obvious reason for such a stress-relieving device in the vicinity of the door, unless a previously undetected chamber lies in that area.

The section of passageway immediately in front of the door appears to be made of very fine white limestone (figure 3). The only other examples are blocks near to the two known chambers.

The three metres of passageway floor in front of the door bear saw marks (figure 4). Virtually all the other stonework in the Great Pyramid was cut using hammers and chisels, with the exception of the masonry used to construct the two chambers and external masonry.

The alleged door has sharp edges, while nearly all the other stone blocks used to construct the passageways have rounded edges. The only other exception is where the passageway enters the King's Chamber.

The door itself is a stone slab (figure 5), with what appear to be two copper handles, each inserted into a hole drilled in the slab's upper front face. The handles could be functional or merely symbolic.

All the stone blocks used in the construction of 180 metres of passageways so far explored by the robot are bonded together using mortar. However, the stone door has no mortar - an indication that it was designed to move.

This stone door is slightly wider than the passageway itself, and fits into a perpendicular recess inset into each wall. The robot was able to video one of these recesses because the door has a small triangular gap at one corner through which it could be seen. Detailed viewing of the recess has revealed the highest quality of stone masonry (figure 6) so far discovered.

The door itself appears to be taller than the passageway. This fact - plus the existence of the wall recesses - suggests that it may have been some sort of sliding door capable of being opened only through upward movement. The robot shone a 5mm laser beam underneath the door, as it is not resting on the floor.

The last 70cm section of the passageway before the door has polished faces (figure 7) - unique in the pyramid's passageway complex.

Evidence obtained by the video camera suggests that the masonry of whatever structure or void lies behind the door is not composed of the ordinary yellow limestone from which most of the pyramid is made.

For 92 per cent of its length, the floor of the passageway is covered with fine sand which has seeped out over the millennia from between the blocks of stone used in the passageway's construction.

Only in the four metres in front of the door is there a complete absence of such sand (figure 8). Given the existence of the triangular gap in the door, this absence of fine sand may indicate that whatever lies behind the door is not made of the normal yellow limestone pyramid masonry.

What may be evidence of organic material beyond the door is a quantity of granular black material (figure 9) between the upper left side of the door and the wall of the passageway. It is possible that this could be organic dust from decaying wood or textiles beyond the door. Black dust was found many years ago in the King's Chamber.

In the upper southern passageway is a mysterious and unique series of niches (figure 10) arranged in the passageway walls at a point immediately above the end section of the lower passageway. Their function is at present unknown.

Although all the evidence points towards there being a chamber behind the stone door, there can be no proof without further investigation. Mr Gantenbrink has recently developed a special system for detecting cavities, and he believes that if it is applied within the pyramid, it would be possible to discover whether or not a chamber really does exist.

Once the existence of such a chamber has been confirmed, it would be relatively easy to discover what it contains. A fibre-optic lens could probably be inserted by the robot into any chamber through the triangular gap in the door. Alternatively, the door itself could be opened by sliding it upwards.

Mr Gantenbrink has already designed systems to carry out these functions. However, whether he will ever get the chance to put his plans into action is now in the balance.

Egypt's Supreme Council for Archaeology (formerly the Egyptian Antiquities Department) has refused to allow him to continue his research work within the pyramid. Examining evidence relating to the structural aspects of the pyramid is a subject needing engineering expertise.

But suggesting what might lie within a previously undiscovered chamber is strictly a matter for Egyptologists. Some believe that the passageways were built as shafts through which the soul of the dead pharaoh could travel to the sky.

For the time being, Mr Gantenbrink remains cautiously optimistic about the possibility of a chamber being discovered. 'Whether or not a chamber exists behind the slab of stone cannot be determined for certain from the state of the exploration at present,' he says.

'There are no technical factors or other evidence which exclude the possibility of such a cavity behind the slab of stone. The result of the investigation still remains nevertheless uncertain,' says Mr Gantenbrink. 'A credible final result cannot be reached through premature interpretations, but only through further factual and objective research.'

(Photograph and graphics omitted)