Physics: Peering into the Pyramids

To protect them against enemies and intruders after death, Egypt's pharaohs were entombed with their treasures in cleverly concealed chambers deep with in their monumental pyramids. Most of these royal burial vaults have long since been discovered and looted, but some archaeologists suspect that others still lie undisturbed behind tons of lime stone and granite blocks. Egypt's pyramids may soon yield their remaining secrets. In a speech before the American Physical Society last week, University of California Physicist Luis Alvarez reported that his ingeniously conceived project to peer into the pyramids with cosmic rays is about to get under way.

Some time in March, in a chamber 400 feet below the tip of the Great Pyramid of Cheops, Egyptian and American scientists will set up a spark chamber to detect a component of cos mic rays called muons. Actually sub atomic particles traveling close to the speed of light, some of the muons will be energetic enough to penetrate the dense structure of the pyramid and pass through the spark chamber, a device consisting of two horizontal pairs of oppositely charged metal plates. Be cause the muon leaves a wake of ionized gas, which conducts electricity, a spark will jump between each pair of plates along the path of the particle.

Patient Computer. The relative locations of the two sparks, which determine the direction from which the particle came, will be noted electronically and stored on magnetic tapes. Every evening, the tapes will be sent to Cairo's Ein Shams University. There they will be fed into a computer that will calculate and memorize the point at which each recorded muon penetrated the surface of the pyramid. Because cavities within the pyramid offer less resistance to speeding muons than does solid stone, a greater number of muons will penetrate to the spark chamber along paths that take them through corridors and burial chambers. The computer will thus remember that certain well-defined areas of the pyramid's surface were penetrated by more recorded muons than the remaining surface area.

After patiently accumulating the muon data for two months—the time necessary to get statistically valid readings—the computer will spew it all out into a cathode-ray oscilloscope. On the screen of the oscilloscope, the data will be converted into images resembling X-ray plates, one for each face of the pyramid. Chambers and corridors within the pyramid will show up as dark areas on one or more of the faces—defined by the surplus of recorded muons that penetrated these areas.

The two-dimensional oscilloscope images, like X rays, will show the presence of cavities but will not indicate how deep within the pyramid they are.

To pinpoint their location, the scientists will move the spark chamber 35 feet away to another point within the pyramid and repeat the muon-recording process. The resulting images, combined stereoscopically with the originals, will precisely locate the hidden chambers.