Viswanathan K's Thoughts

In his book, A Splendid Exchange , William Bernstein says Columbus knew he shouldn’t even be trying to reach India by going west. After all: “The feasibility of the westward route depended on its being short.” While nobody had found a route by going west (and thus its length wasn’t known), simple maths told the tale. From the time of the Greeks, the earth’s circumference was known to be 25,000 miles. The eastward route from Lisbon to Malacca was 7,000 miles. Ergo, the westward route would be (at least) the difference of the two: 18,000 miles. Not only was this much longer, it was “incompatible with survival at sea” for the age.   So how did Columbus then convince his funders? He used the age-old technique of fudging the data. He took the least possible circumference of the earth and the maximum possible width of Eurasia. Lie often enough, and you start believing the lie yourself! It happened to Columbus: “So thick-skulled was the discoverer of the New World that not un...

In his book Cosmos , Carl Sagan described how a Greek named Eratosthenes calculated the size of the earth almost 2,200 years back. He started with the observation that at a certain time, the sun cast no shadow in Alexandria. He inferred that this meant the sun was directly overhead. He then wondered how it was possible that a stick could cast no shadow in one place while at the exact same time, it could cast a substantial shadow at some other place (Syene). These observations didn’t match a flat earth scenario. Instead: “The only possible answer, he saw, was that the surface of the Earth is curved.” Eratosthenes then applied maths to the problem: “For the observed difference in the shadow lengths, the distance between Alexandria and Syene had to be about seven degrees along the surface of the Earth.” He then asked a man to calculate the distance between Alexandria and Syene: it was 800 km. If seven degrees mapped to 800 km, how much does three sixty degrees (a circle) ma...