[cctalk] Re: AI? Really?

On Fri, 24 Jan 2025, Frank Leonhardt via cctalk wrote: A simple home experiment: Find two points, such a hill/mountain-tops that are visible from each other, but 10 or 20 miles, at least apart east/west.. Set up a vertical tube or slot. When the sun is directly overhead, tell the other person, and see how long it takes before the sun is directly overhead at the other location. if you don't want to use cellphones, since that would not have been available in the past, use smoke signals. I found about a minute to go 15 or 20 miles. 15 or 20 miles in a minute is about 1000 miles an hour. Since the sun's cycle is 24 hours, that would mean that it travels 24,000 miles in a day. And therefore, the circumference of the earth is about 24,000 miles. If you make up some jigs for measuring, and average the readings over a few days, you can get a fairly accurate estimate of the circumference of the earth. Divide by PI if you want the diameter. With visual signaling, instead of cellphones, you might lose a little accuracy, but it was well within the reach of technology for thousands of years. And, it would was close enough to make it obvious that if you want to sail west from europe to the indies, you are going to run out of supplies long before you get there! Unless you are dumb lucky, and happen to bump into some land on the way. Columbus had a bad idea that the earth was MUCH smaller, so he thought that he could make it. He did not prove that the earth is round; that would have to wait for Magellan. And, except for "flat-earthers", educated people knew that the earth was round, and even had a reasonable estimate of how large.