Science Fair Project Encyclopedia
Great Pyramid of Giza
The Great Pyramid of Giza, (sometimes spelled Gizeh) is the oldest and last remaining of the Seven Wonders of the World and the most famous pyramid in the world. It is presumed to have served as the tomb of the Fourth dynasty Egyptian Pharaoh Khufu (also known under his Greek name Cheops), after whom it is often called "Khufu's pyramid."
Age and location
A few hundred metres southwest of Khufu's Great Pyramid lies the slightly smaller pyramid of Khafre, one of Khufu's successors who also built the Great Sphinx, and a few hundred metres further southwest is the pyramid of Menkaure, Khafre's successor, which is about half as tall. Khafre's pyramid appears the tallest on some photographs as it is somewhat steeper and built on higher terrain.
At construction the Great Pyramid was 280 Egyptian Old Royal Cubits tall (146 metre), but due to erosion and the theft of its topmost stone (the so-called pyramidion) its current height is approximately 137 m. As has been proven by papyrus documents, each side measured in Antiquity 440 Old Royal Cubits (230.5 m). Now each side has a length of approximately 227.5 m. The reduction in area and the current edgy appearance of the structure is due to theft of the polished triangular limestone block inserts which gave the pyramids a smooth-looking surface for most of the antiquity. The Great Pyramid covers more than 5 hectares at the base.
For four millennia it was the world's tallest building, not being surpassed until the 160-metre tall spire of Lincoln Cathedral was completed in around 1300. The accuracy of work is such that the four sides of the base have only a mean error of 15 mm in length and 12 seconds in angle from a perfect square. The sides of the square are aligned quite precisely in North-South and East-West directions. The sides of the pyramid rise at an angle of approximately 51°51′.
The pyramid was constructed of limestone, basalt, and granite stones from two to four tonnes in weight each, adding up to a total estimated weight of some 7 million tonnes, and a volume of 2,600,600 cubic metres. It is the largest Egyptian pyramid, but the Great Pyramid of Cholula in Mexico is larger in volume. When originally built, the pyramid had inset facing blocks of polished limestone, creating smooth sides; they have since fallen out, or been recycled for other building projects, leaving the underlying step-pyramid structure visible. Most of the limestone casing was removed by an Arab Sultan in 1356 in order to build mosques and fortresses in nearby Cairo.
The Great Pyramid differs in its internal arrangement from the other pyramids in the area. The greater number of passages and chambers, the high finish of parts of the work, and the accuracy of construction all distinguish it. The walls throughout the pyramid are predominantly bare and uninscribed. Three chambers are arranged centrally, on the vertical axis of the pyramid. The lowest chamber is cut in the bedrock upon which the pyramid was built; it is the largest of the three and appears to be unfinished, roughly cut in stone. The middle chamber or "queen's chamber" is the smallest, measuring approximately 5.74 by 5.23 metres, and 4.57 metres in height. Its eastern wall has a large angular doorway or niche, and two narrow shafts, about 20 centimeters wide, extending from the chamber to the outer surface of the pyramid, blocked by limestone "doors" at several points. Egyptologist Mark Lehner believes that the chamber was intended as a serdab—a structure found in several other Egyptian pyramids—and that the niche would have contained a statue of the king, but the true purpose of the chamber remains a mystery.
The uppermost chamber or "king's chamber," approximately 10.45 by 5.20 metres and 5.80 metres high, bears shafts similar to those in the middle chamber. It has an antechamber adjoining via a small doorway, and a flat ceiling composed of nine large granite blocks, separated by five small relief chambers. It contains a huge granite sarcophagus which must have been placed in it during construction; it is too large to pass through the tiny passageway of the burial chamber.
A descending passage leads from the entrance of the pyramid to the underground chamber. About half-way along, a second passage ascends towards the upper chambers. This again breaks into two corridors, one horizontal, leading to the 'queen' chamber, and the other still ascending, leading into the burial chamber. This final asscending corridor is a fantastic space with a height of aprox. 8 metres, which earned it a name of 'grand gallery'. The grand gallery leans next to the walls of the burial chambers, and is connected with it through a tiny, tight passageway.
This passageway once contained crude stone mechanisms for one-time release of huge granite blocks which sealed the entrance into the burial chamber. The grand gallery also contained some sort of mechanism for the release of a huge stone block which plugged the ascending passage. The entire upper part of the pyramid was thus sealed after the burial of the king. There was one secret passage that was not sealed, leading through the very rock upon which the pyramid was built, towards the descending passage and outside the pyramid, through which the last of the workers and funerary priests could escape after the burial of the king.
Apart from accessible chambers and corridors, the Great Pyramid also holds inaccessible spaces. The so-called 'air shafts' are canals which run through the stone mass of the pyramid at certain angles, connecting the burial chamber of the king with the north and south face of the pyramid outside. Why these were planned and built is not known, although they were certainly not 'air' or 'ventilation' shafts. It is possible that they had a symbolic meaning, allowing the soul of the deceased king to travel to the stars in the north and south sky, which were important in Egyptian religion and mythology.
Another interesting feature of the Great Pyramid are the so-called 'relieving chambers'. This is an ingenious system raised over the king's burial chamber, constructed to relieve vertical and horizontal loads. The relatively thin wall between the burial chamber and the grand gallery likely could not absorb all of the horizontal pressure from the granite roof of the chamber. Thus, the granite roof had to be raised above the level of grand gallery. However, this created another problem, since now the walls of the burial chamber would be more than 8 meters high, and thus very unstable. Thus, huge granite slabs were placed horizontally as stabilisers between the walls, one above another. The empty spaces between granite slabs today are called 'relieving' chambers, though they were never meant to be accessed; and were not until the 19th century, when they were opened by dynamite. This, turned out to be an incredibly valuable discovery. Since the 'relieving chambers' were never meant to be accessed, the stone blocks on their walls were not prepared and laid as carefully as those in the accessible interior of the pyramid. Thus, graffiti of the pyramid workers were found inscribed on some of the blocks, mentioning the names of the worker crews which built the pyramid (or at least placed these particular stones), and the year of rule and the name of the pharaoh who had the pyramid built: Khufu. The Great Pyramid is otherwise completely empty of any inscriptions or hieroglyphs whatsoever. This is the only evidence which proves that pharaoh Hor Medjedu Khnum Khufu had the Great Pyramid built, and that this is, in fact, the legendary king which Herodotus calls Kheops.
Many varied estimates have been made regarding the labor force needed to construct the Great Pyramid. Herodotus, the Greek historian in the 5th century BC, estimated that construction may have required the labor of 100,000 slaves for 30 years. Polish architect Wieslaw Kozinski believed that it took as many as 25 men to transport a 1.5-ton stone block; based on this, he estimated the workforce to be 300,000 men on the construction site, with an additional 60,000 off-site. 19th century Egyptologist William Flinders Petrie proposed that the labor force was largely composed not of slaves but of the rural Egyptian population, working during periods when the Nile river was flooded and agricultural activity suspended. Egyptologist Miroslav Verner posited that the labor was organized into a hierarchy, consisting of two gangs of 1000 men, divided into five zaa or phyle of 200 men each, which may have been further divided according to the skills of the workers.
Some research suggests alternate estimates to the aforementioned labor size. For instance, mathematician Kurk Mendelssohn calculated that the labor force may have been 50,000 men at most, while Ludwig Borchardt and Louis Croon placed the number at 36,000. According to Verner, a labor force of no more than 30,000 was needed in the Great Pyramid's construction.
Herodotus speculated that the stone blocks used in the Great Pyramid's construction were maneuvered into place by raising them up a succession of short wooden scaffolds. Another possibility proposed by the ancient scholar Diodorus Siculus was that the giant blocks were dragged along a system of ramps to the necessary height. More recently, Mark Lehner speculated that a spiralling ramp, beginning in the stone quarry to the southeast and continuing around the exterior of the pyramid, may have been used. In Lehner's model, the stone blocks may have been drawn on sleds lubricated by water.
The most precisely cut stone blocks were reserved for the outside. Once in place their corners were smoothened to give an almost shiny outer appearance of the pyramid.
The idea of using roller to move stone blocks with rollers were made popular in Hollywood movies, but as of today, there are no historical records to demonstrate how ground transportation was done.
The technical mastery demonstrated by the pyramids may be as much a credit to ancient Egypt's alchemists as its engineers. In a radical departure from traditional egyptological thought, some scientists have postulated that the pyramids were not built out of cut stones, but rather poured in place, in the form of concrete. Ancient Egyptians are known to have used both lime and gypsum in this manner, and it would account for a number of discrepancies in the generally accepted theories, such as the distance of the pyramids from the nearest matching stone quarries (15 miles) and the precision with which the blocks were fitted together. This method would also dramatically redistribute and reduce labor in comparison with manual stonemasonry. Fossils within the limestone blocks are jumbled, which is consistent with the reconstitution that would occur after the process of breaking down the limestone for use as a binding agent.
Some of those who have examined the Great Pyramid have made speculations regarding the numerical significance of the dimensions, angles, and ratios present in the structure.
One popular assertion is that the ratio of the pyramid's perimeter to its height times two ( P / ( 2 × H ) ) gives a close approximation of the mathematical value π; that is, the height is to the perimeter as the radius is to the circumference of a circle. This characteristic is determined by the linear slope of one of the pyramid's sides; any pyramid with a slope of arctan ( 4 / π ), or approximately 51°51′14″, will have this characteristic.
The sides of the Great Pyramid have this approximate slope; it is peculiar in this respect, as it more closely expresses this slope than any other surviving Egyptian pyramid. William Flinders Petrie determined the weighted mean angle of the north face of the Great Pyramid to be 51°50′40″, within 35 arcseconds, or about 0.01 degrees, of an exact expression of π. Colonel Howard-Vyse, in 1837, discovered two intact and in situ casing stones, from which he determined the slope to be between 51°50′ and 51°52′15.5″, while Charles Piazzi Smyth, Astronomer Royal of Scotland, in 1865 estimated the overall angle to be 51°51′14″, based on measurements of several surviving casing stone fragments and the angle of the pyramid itself. Whether the Great Pyramid's builders intended for the structure to express π is unknown.
Additionally, Smyth claimed that the measurements he obtained from the Great Pyramid indicate a unit of length, the pyramid inch , equivalent to roughly 1.01 British inches, that could have been the standard of measurement by the pyramid's architects. From this he extrapolated a number of other measurements, including the pyramid pint, the sacred cubit, and the pyramid scale of temperature. Applying these to the dimensions of the structure, he inferred the existence of expressions of the polar diameter and mean density of the Earth, the length of a solar day, the distance from the Earth to the Sun, and the precession of the equinoxes.
Although Smyth's derivations are frequently regarded by skeptics as having no scientific merit and of being merely an artificial device for attributing numerical significance to the Great Pyramid's dimensions, please see also Moscow and Rhind Mathematical Papyri.
Paranormal and prophetical allegations
As a structure of impressive construction and mystery, the great pyramid has attracted the attention of occultists (as have many other aspects of ancient Egyptian culture). The great pyramid and the Sphinx are often alleged to have been built with mysterious ancient forces rather than human labor and/or by Atlanteans, extraterrestrials, or other mysterious creators.
It has also been alleged that the dimensions and details of the Great Pyramid, properly interpreted, provide prophecies of events in modern times. This theory was first proposed in the 1800s by John Taylor , who believed the pyramid had actually been constructed by the biblical Noah. Charles Piazzi Smyth later elaborated on this theory in his book Our Inheritance in the Great Pyramid. No scientific evidence has been found to support these allegations to date. Edgar Cayce was apparently sympathetic to the idea, though his convoluted language makes it difficult to be certain.
- List of Egypt-related topics
- Measures and Mathematics
- Giza Archives Project Museum of Fine Art Boston's repository for archaeological records dealing with MFA excavations at Giza
- A Picture Tour of The Great Pyramid at the Great Pyramid of Giza Research Association.
- PBS's NOVA Pyramids
- Wall, John, "The Wrong Question (or: The Myth of the Mystery of the Missing Messages)". In the Hall of Maat.
- World-Mysteries.com - Mystic Places : The Great Pyramid
- Guardian's Pyramids of Egypt
- Ottar Vendel's Age of the Pyramids
- Composition of Giza Plateau
- Secret chamber may hold key to mystery of the Great Pyramid (The Guardian, August 30, 2004.)
- Amateur archaeologists track lost tomb of Cheops (Australian Broadcasting Corporation, August 30, 2004.)
- Pyramid Construction: Ancient ramp leading to the Great Pyramid discovered, but only of maximal height approximately 100 feet. Pyramid's original height was 481 feet. Also, the heaviest stone blocks were discovered to have holes bored on opposite sides, indicating the use of cranes to raise and precisely position them.
- Pyramid construction theory
- Joseph Davidovits' Ari-Kat Geopolymer theory of pyramid construction
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