In 212 BC, a Roman fleet was besieging the city of Syracuse (in Greece) when suddenly numerous mirrors reflecting sunlight appeared on the city walls, setting the ships ablaze. The Greek scientist Archimedes utilized the effect of concave mirrors to focus light on a single point, incinerating the enemy.
Ancient peoples used concave mirrors for various purposes, primarily in magical practices. Concave mirrors create a light field that does not cast shadows at their focal point. Sorcerers and magicians believed that at the focal point of a concave mirror is concentrated an invisible source of bioenergy, and if someone looked directly into that focal point, they would be granted the ability of clairvoyance.
In several cultures, there is a tradition of calling back the spirits of the deceased using bowls or concave bronze basins with smooth, mirror-like interiors—essentially a form of concave mirror. In 1950, in a deep cave in Epirus, western Greece, archaeologist Sotir Dakar discovered a large bronze pot, with a polished interior, dating back approximately 3,000 years. Strangely, when someone looked closely into the pot, they could see mystical and bizarre images, particularly noting that each individual saw different images, and even the same person viewed different images at different times.
These images depicted scenes or figures from a time long ago. Based on the curvature of the pot’s base, it was determined that the focal point of this curvature was precisely at the center of the pot’s mouth. Unfortunately, shortly after its discovery, this pot was stolen from the storage of a museum in Greece, and since then, its fate remains unknown.
In some cultures, prophets used concave mirrors for divination. Indian shamans often used gold-plated concave mirrors, although some preferred those made of pure iron. Pure iron, with a purity of 99.999%, never rusts; when polished, it achieves a superb shine and is referred to as the “Mirror of King Solomon“, highly valued among practitioners of divination. Ancient Russians also used concave mirrors in the form of bronze or ceramic basins to predict love fortunes for those seeking partners.
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| The Nazca Plain with millions of straight, intersecting lines. |
There are also ancient concave mirrors whose purposes remain a mystery to this day. For example, many mirrors have been found near the Nazca geometric garden in Peru. These mirrors, about half a meter in diameter and slightly curved, are made from an alloy of gold, silver, and copper, with a very smooth interior. Due to their slight curvature, the mirrors have a focal length of several kilometers. Because of their highly polished surface, they reflect sunlight intensely, allowing the reflected light to be seen clearly at the focal point, even from miles away. The ancient Inca natives’ use of these mirrors remains unclear. Based on their ability to project light over long distances, it can be speculated that they served as signaling tools. They may also have been used to establish straight lines (the Nazca Plain features millions of intersecting lines, each extending tens to hundreds of kilometers but entirely straight).
Many scientific inventions have originated from concave mirrors. The English scientist Roger Bacon (1214-1294) possessed what were known as “encyclopedic” concave mirrors. His contemporaries regarded him as a “great sorcerer“, but from a modern perspective, he was a diligent experimenter, dedicated to uncovering the mysteries of nature. Not only was Bacon a natural philosopher, but he was also a “philosopher of all things“, engaging in nearly every field of both natural and social sciences. He created two remarkable concave mirrors for teaching at the University of Oxford. With the first mirror, one could light a candle at any time of day by placing the candle’s flame precisely at the mirror’s focal point. The second mirror allowed users to see the scenery of any location on Earth if their eyes were positioned correctly at a certain distance from the mirror; if the mirror was tilted and the viewer adjusted their position accordingly, they would see a different scene. It was as if the entire landscape on the Earth’s surface was reflected onto a mirror in the upper atmosphere, then reflected back into Bacon’s wondrous mirror. The first mirror faced opposition from faculty members who complained that students spent all day focusing on lighting candles instead of studying books and conducting other experiments. The second mirror was accused by the church of being a “heretical” object. As a result, both mirrors were destroyed, and Bacon lost his teaching privileges.
Due to the complications from this incident, many of Bacon’s documents, writings, and records were burned. However, what remains today indicates that he was the first to predict the invention of the microscope, telescope, automobile engine, and aircraft. Hundreds of years before Berthold Schwarz created gunpowder, Bacon documented the chemical composition and principle of operation of a substance that could ignite similar to gunpowder later on. It was also through Bacon’s optical experiments that eyeglasses were invented in 1287. Bacon’s writings also suggest that he envisioned the structure of cells and understood that the process of conception involved the union of sperm and egg. Additionally, Bacon grasped the origins of a form of energy that is many times more potent than atomic energy!
How did Bacon acquire such extensive knowledge, living in the 13th century, centuries before leading scientists like Giordano Bruno, Galileo Galilei, Leonardo da Vinci, Isaac Newton, and Albert Einstein, whose inventions later became the foundation of human knowledge? Scientists believe it was because he developed special scientific instruments or received such tools from some mysterious source. One of these special instruments was the concave mirror. In the surviving records of Bacon, there is a document indicating that he “saw through a concave mirror a spiral-shaped star located between the constellations Pegasus, Andromeda, and Cassiopeia.” Remarkably, 400 years later, in the 17th century, European astronomers discovered the Andromeda spiral nebula in exactly that location using powerful telescopes.
Why do concave mirrors possess such extraordinary abilities? No one has been able to fully explain this, but generally speaking, like flat mirrors, concave mirrors reflect both visible and invisible energy, even the subtle radiations emitted by the human body, but concave mirrors can enhance these forms of energy. Particularly, only concave mirrors can create a focal point—the convergence point of all reflected rays. This is the crux of what is considered the mysterious and miraculous capabilities of concave mirrors.
In 1667, scientists at the Florence Academy of Sciences conducted an experiment by directing a concave mirror toward a large block of ice located at a considerable distance, and the measurements showed that the temperature at the mirror’s focal point was significantly lower than the surrounding air temperature. The scholars concluded that cold objects emit cold radiation, similar to how hot objects emit thermal radiation. Today, we know that there is no such thing as “cold radiation.” Based on the laws of thermodynamics, modern science has shown that it is not “cold rays” converging at the focal point of the concave mirror; rather, it is the heat at that point that tends to escape into the surrounding environment. Thus, concave mirrors possess not only the characteristics of a receiving antenna but also of a transmitting antenna. Today, radio and television transmitting antennas are parabolic (dish-shaped) for this reason.
(Source: Pravda)
