Mysteries of pyramids in Egypt

Shrouded in rumors and legends, the pyramids at Giza, Egypt are the last remaining of the Seven Wonders of the Ancient World. Since the early days of Western exploration of the sites, elaborate booby traps and vast stores of golden treasures have birthed stories of curses, unexplained deaths and injuries. While archeologists understand why the pyramids were constructed, many questions about their history, composition and structure remain unsolved.

Who Built the Pyramids?

Many movies, books and other works of historical fiction centering around life in ancient Egypt -- particularly the oft reimagined biblical story of Moses -- depict the pyramid builders as slaves. Although it has been documented that ancient Egyptians employed slaves or servants, modern archeological research shows that Egyptian workers actually constructed the pyramids.Villages and remains of pyramid workers have shed light not only on the ethnicity and sex of the workers, but also on the amenities available to workers. Workers' villages included not only craftsmen relating to the pyramid's construction but also cooks, bakers, priests and medicine men.

When Were They Built?

Though the pyramids are one of the most recognizable symbols of the ancient Egyptian pharaohs, these immense, complex tombs were only built during distinct portions of the ancient Egyptian civilization. The first known pyramid, the Step Pyramid of Djoser, has been dated to around 2630 B.C during the third dynasty, and most of the larger pyramids, including the Pyramids of Giza, were constructed shortly after, with the Great Pyramid being built around 2530 B.C. After this initial burst of building, pyramid construction stopped entirely at the end of the sixth dynasty, around 2200 B.C. During the 12th to 14th dynasties, between 2000 B.C. and 1700 B.C., pyramid building experienced a brief renaissance, though the results were not as monumental as the earlier period.

How Were They Built?

One of the enduring mysteries of the pyramids centers around how they were constructed. The fact that they have endured for more than 4,000 years is testament enough to their sound construction, but archeologists and structural engineers also marvel at the precise sizing of the individual blocks. Archaeologist believe the limestone blocks were quarried and shaped using copper chisels, the hardest metal known to the Egyptians at that time. While films often depict thousands of workers carrying or pulling the limestone blocks, which weigh an average of 2.5 tons, the blocks were typically floated from the quarry sites to the construction locations during the frequent Nile River floods.

What Are They Made Of?

For centuries of Egyptology scholars, the physical composition of the pyramids had never been questioned. Elements that shouldn't be present in limestone or occur naturally at the site were dismissed as remnants of renovation efforts. As structural science and analytical tools advanced, archeologists began to notice compositional anomalies in the pyramids that were increasingly difficult to reconcile. In 2006, Michel Barsoum, a materials engineering professor at Drexel University, undertook extensive chemical and X-ray analysis of both external and internal sections of the pyramid stones. His results that some portions of the pyramids are actually made from concrete, not stone are slowly upending the popular image of large groups of workers painstakingly pushing the stone blocks up the sides of the pyramids.

In recent months, experts have been searching for hidden chambers located within the Egyptian pyramids, as well as for additional insight into how these amazing structures could have been built. Organized by the Faculty of Engineering of Cairo and the Paris-based Heritage Innovation Preservation Institute, the Operation Scan the Pyramids project aims to conduct in-depth examinations of the pyramids using non-invasive methods such as thermal imaging and muon radiography, a Japanese technique that has been used to peek inside active volcanoes as well as the nuclear reactors of Fukushima.

Last week, an initial infrared temperature scan of the famous tomb belonging to the pharaoh Tutankhamen, better known as King Tut, turned up promising results: a temperature difference in the tomb’s northern wall, which may indicate a hidden cavity behind the wall’s surface. Their work follows up on claims made earlier this year by Egyptologist Nicholas Reeve of the University of Arizona, who proposed that ultra high-resolution images of Tut’s tomb showed hidden doorways leading to previously unexplored burial chambers, possibly including the final resting place of the legendary Queen Nefertiti, who was married to Tut’s father.

Now, Egypt’s Antiquities Ministry has announced that a thermal scan of the three ancient pyramids built on the Giza plateau, some 20 km from Cairo, during the 4th dynasty (between 2613-2494 B.C.), has identified some intriguing anomalies. In particular, a scan of the largest of the three pyramids—known locally as Khufu and internationally as Cheops, but often referred to simply as the Great Pyramid—revealed higher temperatures in three of the stones at the bottom of the eastern wall. Though the authorities cannot say definitively what this anomaly means, they speculate that such differences in temperature could indicate empty areas inside the structure, internal air currents or the use of different building materials.

An international team—including scientists and architects from Egypt, Canada, Japan and France—conducted the thermal scanning at different times of the day and night. They focused particularly on sunrise, when the sun heats the limestone of the pyramids from the outside, and on sunset, when the structures were cooling down. In the case of the Khufu pyramid, they found that while much of the wall heats up and cools down uniformly (with a typical difference of only 0.1 to 0.5 degrees Celsius between adjacent stones), a three-stone spot on the eastern wall acted differently. When compared with surrounding stones, this area showed a difference in temperature of 11 degrees Fahrenheit (6 degrees Celsius), appearing as a bloom of red on the thermal scans.

By the time Operation Scan the Pyramids concludes, at the end of 2016, researchers will have scanned the Great Pyramid and the second-largest of the Giza pyramids, built for Khufu’s son Khafre, as well as the Bent Pyramid and the Red Pyramid, both built at Dahshur (about 15 km south of Saqqara) by Snefru, Khufu’s father and the founder of the 4th Dynasty. The goal of the scanning project is to find more anomalies, each of which will provide another clue for Egyptologists to investigate in their attempts to solve the enduring mysteries of the pyramids.

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