The Pyramids of Giza, the last remaining of the seven wonders of the ancient world, are among the most popular tourist destinations in the world.
Built more than 4000 years ago, the pyramids stand as a great and massive architecture marvel. The miracle of the pyramids is in their construction engineering, and its challenge to the laws of physics, at a time when the current technologies did not exist.
Defying Gravity
Dr. Mohamed Farag, associate professor of physics, said that it is nearly impossible to build a pyramid like Khufu today. The Great Pyramid of Giza, named after King Khufu, consists of over 2 million blocks of stone of various sizes, ranging from 2 to 15 tons, and some of which, like those in the king’s room, could reach 70 tons.
Lifting stones of this size manually is impossible because it challenges the laws of gravity, Dr. Farag explained. According to Isaac Newton, every object with “mass” attracts everything else with mass. So the Earth, like any other planet, attracts all objects to its surface. The bigger the mass of the object, the stronger the attraction force it experiences from a planet.
This attraction force is defined as “weight.” Weight varies depending on the planet because each planet has its own gravity. The effort made to move or lift a stone is called “work.”
The greater the weight of the object, the more work is required. And the farther the distance, the more effort you need to exert. Therefore, to move an object, you need to apply a force that causes it to move a certain distance. This is the basic definition of work.
If you apply a force to an object but it doesn’t move, then no work is done. And if the force acting on an object from all directions is zero, the object will remain stationary, according to Dr. Farag.
Another factor is potential energy. It is the stored energy in an object due to its elevated position. Dr. Farag explained that gravity is the reason behind potential energy.
This energy is stored due to the object’s mass and its height above the ground. The higher the object, the more potential energy it has. If you want to lift a stone, you need to expend more work and store more potential energy at each height.
Without modern levers machines, it is hard to imagine how people at that time managed to overcome these hurdles, Dr. Farag said.
Moving Stones
The second obstacle is transporting these large stones, whether from the Pyramid Plateau itself or from granite quarries near Aswan.
According to physics, the settling mass on a surface must have equilibrium between forces in both vertical and horizontal axis. In vertical direction, the mass is pressing on the surface by a weight force pointed normal to the surface. The surface acts on the mass in the opposite direction with normal force.
In horizontal direction, pulling is trying to move the mass while the surface roughness affecting the mass by a force called “friction” in the opposite direction of the movement of the mass. If the friction is equal to the pulling force, it will settle on the surface. However, if the normal force is less than the weight, it will sink into the surface underneath.
So, you need pulleys, carriers, or scaffolds that can lift 70 tons and bear this weight without crushing or denting, Dr. Farag explained. Nowadays, we can use steel iron to make wheels that can lift huge weight. But in the age of pyramids, iron had not been discovered yet.
Cutting Stones
Another mystery outlined by Dr. Farag is the technique of cutting stones. If you want to cut a stone, you have two options, he said. Either to break it with a tool like a hammer, but this will give it an irregular shape and may cause an irreparable damage. And if it is cut, you will need to smooth it to make its surface even.
This requires massive effort for every stone, and will probably not produce well-polished stones.
The second option is to use a tool capable of scratching and cutting the stone. But we need to know its hardness based on the Mohs scale of mineral hardness.
The German geologist and mineralogist Friedrich Mohs, introduced a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material.
According to this scale, diamond (10) is the hardest material, while granite is (6-7). This means diamond can cut granite if it is used as a cutting tool.
Dr. Farag pointed out that pyramids, as many scientists believe, were built in the Bronze Age. Bronze is a mix of tin and copper, with hardness (3) on Mohs scale. So no way it could cut granite.
Some theories suggest they used Diorite rock (6-7 on Mohs scale), but the question is how did they make such tools? Dr. Farag wondered.
Mysterious Technology
According to Dr. Farag, all of the above suggest that ancient Egyptians had some kind of technology that enabled them to perfectly cut and polish stones to be used in pyramids or obelisks, for example. Furthermore, they had lever system that could handle large stones, lifting and arranging them in this precise manner.
“However, until we find an artifact or papyrus that explains how this pyramid was built in a scientifically convincing way, all these will remain speculations and attempts to understand how these people created this wonderful miracle,” he added.
