Flat Earth is a subject I love pondering. This thread will be used for posting Flat Earth anecdotes I come across, and also for you to post your own proofs. Debunking is fine too; I’m not for or against the theory I just think it’s fun and interesting.
Is the earth a flat disk?
Imagine that we are in an ice age here on earth. Lake Superior has frozen over. I don't have any satellites or aircraft that can travel high above the earth so that I can look down and see whether the surface is flat or curved. Is there an experiment can I ran that could answer the question?
Yes, several. Here's one such experiment: Aircraft and satellites may not have survived the onset of the ice age but by God my Zamboni did. I get on my Zamboni to carve and smooth out an ice rink several feet wide and a million feet long. Perfect NHL quality flat-as-glass ice. I've also laid out a million foot long perfectly straight stripe with a hash mark at zero feet another hash mark at one million feet and minor hash marks every ten feet along the line.
I construct a wagon with four wheels, one at each corner. They support a 5th wheel in the center of the wagon. The 5th wheel juts down from the wagon and the tire rests on the ice. The wheel has a radius of 1.59 feet therefore a circumference of 10 feet. At the bottom edge of the tire I put a mark that signifies bottom dead center (BDC). At the center of the wheel on the edge of the hub I place a red mark. I put my wagon in place so that the BDC mark is precisely on the zero hash mark. Then I start moving my wagon along the line. I go in a perfectly straight line and there is zero skidding of the wheel on the ice.
How many 360 degree revolutions of the 10 foot circumference wheel along the one million foot long line in the ice will it take for the CENTER red mark on the wheel hub to travel one million feet? Will it take 100,000 revolutions (1,000,000 feet/10 feet per revolution)? Will it take more than 100,000 revolutions? Will it take fewer than 100,000 revolutions?
The answer is, "It depends."
What does it depend on? It depends on whether the surface is flat, positively or negatively curved. If the surface is absolutely flat (flat earth) then it will take exactly 100,000 revolutions for the center to travel one million feet. If it is negatively curved, as if moving along a curve from the inside of a circle it will take more because the center of the 5th wheel is traveling along a smaller radius curve than the edge of the 5th wheel. If the curve is positive then it will take fewer revolutions because the red mark at the center is traveling along a larger radius curve than the edge of the 5th wheel.
It's not a "gotcha!" or a trick. It's about the fact that two objects that are offset stacked above a line only travel the same distance along the line if they move in a straight, flat line. If they travel along a curved path they don't travel the same distance because the radius of the curve they are following is not the same. A car traveling along a straight road from LA to NY will not travel the same distance as a satellite in orbit 19,000 miles above the earth in order to get LA and then NY straight down below. If both the car and the satellite travel the same distance the satellite is not in orbit thus it isn't, by definition, a satellite.
So, if you discover that the red mark at the center of the wheel travels 1 million feet before the BDC travels one million feet you are living on a positively curved surface. Circles, ellipses, spheres and oblate ellipsoids are examples of closed positively curved surfaces.