Twenty two hundred years ago, Eratosthenes applied the scientific method to test his hypothesis of the earth’s shape. The idea came from an epiphany based on his study of a scroll in the world’s first library at Alexandria, Egypt in 240 BC. The scroll explained that at noon on the summer solstice the pillars in the city of Syene (now Aswan), Egypt cast no shadows and when looking down the city’s wells one’s head would block the perfect reflection of the sun below.
The phenomenon observed at noon on the Summer Solstice in Syene was unique; for at the same moment in Alexandria, more than five hundred miles away, pillars did cast shadows. Also, when looking at a well one did not see the full face of the sun reflected from the bottom of the well. How could the sun’s rays have such different impacts on a flat surface when observed at precisely the same time? Extraordinary and fanciful notions were advanced to explain the uniqueness of Syene and its special relationship to the sun on the Solstice.
Eratosthanes, on the other hand, reasoned that the rays of the sun at its zenith on the longest day of the year must be perpendicular to the earth. If the earth is flat these rays would fall such that at every well on earth the sun’s image could be seen reflected perfectly below. If the rays struck the earth differently at the same time when the only variable was distance; he realized, it may be that the earth is round.
Eratosthenes used his knowledge of geometry, mathematics and geography to test his hypothesis by calculating the circumference of the earth. He started by measuring the angle between the top of a pillar and the end of its shadow cast at noon on the Summer Solstice in Alexandria. He used a gnomon and found the angle: 7.2 degrees. Through his knowledge of geometry he understood that this angle is the alternate interior angle to the angles between Alexandria and Syene at the center of the earth. As such, he could calculate that the degrees between the two cities were 7.2 degrees.
If the earth is round, he reasoned, there are a total of 360 degrees. Using division, we discover that the distance between Alexandria and Syene represents 1/50 of the total distance around the earth. So we can multiply the distance between Syene and Alexandria by 50 to arrive at the circumference of the earth. Please see the process outlined below.
The distance between Syene and Alexandria is approximately 500 miles (800 kilometers) or to use the measurement of his time 5000 stadia. If we multiply 500 miles by 50 we get 25000 miles. Today scientists generally accept that the circumference of the earth is 24901 miles. The remarkable accuracy of Eratosthenes’ conclusion validates his process and assumptions. More importantly, he was able to shine the light of reasoning on the controversial question of the earth’s shape at a time when people were more likely to explain reality with sensational myths and fantastic legends.
The Baha’i Faith teaches the essential unity of science and religion, and sees both as reflections of true reality:
Any religious belief which is not conformable with scientific proof and investigation is superstition, for true science is reason and reality, and religion is essentially reality and pure reason; therefore, the two must correspond. – Abdu’l-Baha, The Promulgation of Universal Peace, p. 107.
In this series of articles, we will use the rigors of the scientific process to explore the truth of the Return of Christ. Specifically, we will consider the Biblical prophecies associated with the End Times and the inception of “the Kingdom of God on earth as it is in heaven.” The goal–to lend the rigor of reasoning to a question often confused with materialism, fancy and prejudice.