Flat earth conspiracy types seem to have a few things in common. All arguments start with a vague understanding of an idea and then they become twisted into a strange nonsensical rationalization of misguided observation. Bad Science results.
Generally the observation itself is incorrect and the initial premise is flawed from the get go.
A typical FE starting premise might be.. “The earth is flat because the horizon is not curved”
My response to this might be. “How curved should you expect it to be?”
If you don’t know what your looking for you won’t know when you have found it.
The bigger a planet gets the less curve will be detected. You need to use a bit of trig but its very easy to work it out. There are a couple of variables that need to be set before you can get the correct answer. Apart from the radius of the planet size your standing on, you need…
First – what is you viewing height? The farther you are from the surface the farther the horizon appears and the more curve you can see. Standing on a floating raft in the ocean, your view point might be only 5 feet above the water surface.
Secondly – over what “width” are you trying to measure the curve. Let’s assume we will take a picture of the horizon and then measure the curve with a ruler placed on a monitor. A telephoto camera lens has a small field of view and a wide angle lens has, well, a “wide angle” of view. The wider the view the more curve will be captured in the photo. If we then display our image on a 16″ wide video monitor we should be able to measure the curve.
Now, not wanting to get bogged down in math details, I’ll just give you a couple of results that I worked out on a simple spreadsheet.
Given a Viewing height of 5.0 feet and an iPhone camera lens of 63 degrees… results in a Horizon distance of 2.75 miles and an expected curve on the monitor 0.003″ That’s 3/1000 of an inch on each side. Not measurable.
Lets try something from a higher vantage point like looking out of an aircraft window from 42,000 ft. Same camera and the horizon is now 250 miles away and the curve in the picture should be about 1/4″. Remember that’s a 1/4″ on a 16″ wide desktop monitor not on a 3″ camera display. This is at least measurable but you will need a an oceanic flight, a window seat, and no clouds or haze in order to capture the horizon curve.
So go do it! or just look at Google Earth.