DIY: Testing Earth's curvature. Clear assumptions, proposition of two experiment.

Is it convex or concave ?
This thread is not a joke. I count on normal and essential discussion :slight_smile:

Is the above true ? Is there really a bulge in the middle of the lake due to its convexity ? The Polish guy proved there isn’t…
Proposition of two experiments:

  • based on optical zooming (you can use a camera, camcorder, binoculars, telescope, etc.)
  • would need a strong enough laser. If you don’t have one you can even use long enough tape or rope.

Instruction here:

Why use shortened URLs inside internet?

Sounds about right. I’ve heard it as 8 inches of curvature over 1 mile which would work out to an 8 inch bulge spanning 2 miles.

Not sure that you can actually notice that small amount standing on shore with your eyeballs ~5 feet above the ground and waves and stuff but the effect is there.

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I’ve observed this effect on Lake Tahoe. It’s definitely real, regardless of what the OP thinks.

He made pictures of the opposing shore (link in first post) with camcorder placed 50 cm above water surface. The visibility range for this height is 2,5 km. The shore is 5,65 km away though.

Far more likely to do with atmospheric distortion (e.g. “mirage”) than concave lake surface. It’s not at all unusual to be able to see things that are theoretically below the horizon because of atmospheric effects.

But the camera is placed…below the calculable convexity for 5,65 km which is 62 cm.

Aren’t you making Twoflower’s point?

Nope. Think about it. It’s about the physical barrier (supposed bulge in the middle of the lake due to convexity) that should block the view but it doesn’t. The laser experiment proposed in the article I gave a link to would be surely much more spectacular and leave no doubts. But that will be hard to perform…I mean, who’s got a laser like that ?

It’s also not unusual to see doubled, upside-down ships (or other objects) under some conditions (I have), and these conditions are only applicable very close to the water surface and at sufficient distances, exactly where this test is done. If you are testing for concavity or convexity, it is necessary to eliminate or compensate for these effects.

But that is exactly the point. Atmospheric effects distort the light from the observed objects, making them visible, even though they would be out of view if the light traveled in a straight line. So the effect you’ve described is either caused but this common, easily observed phenomenon, or else by a totally-against-the-known-laws-of-physics concave curvature of the lake surface. You decide.

karol, are you aware that light (even laser light) may not travel in a straight line under certain conditions? And this experiment is flawed if that happens?

Again, because I don’t think you read the article at all :slight_smile:

There is supposedly a bulge in the middle of the lake or any other water reservoir and it can be easily calculated. This bulge is supposed to block the view of the opposing shore. But it does not. We can see reflection of the shore on the water surface.

Now imagine that the laser beam below is a really long tape or rope. If you tied it to one shore at the height of 20 cm and went in a boat to the other shore that is 7 km away (calculable convexity in the middle of such lake is 98 cm) what should happen to the rope ? It should…sink.
Instead, the distance between the rope and the water surface will…rise till we reach the middle of the lake and then it will…decrease.
Same with laser, it will either hit the water instead of the reader or it will hit the reader because of the…concavity.

You’re still insisting that the light beam will remain perfectly straight, despite atmospheric effects that are well known and which will bend the light beam. That assumption is utterly incorrect.

Atmospheric refraction

You still don’t seem to understand but there’s another point. There’s no so called downward refraction :slight_smile:
Watch this in your free time: captions and annotations.

You guys are really persistent about this. Kudos, fighting ignorance and all.

As for Ms. Karol, well done. You’ve proven that the earth is convex, and that we all live on a rotating wheel space station. Moon thing, spaceships, all that are hoaxes. Good job, we can all sleep easy now.

(might want to up the dose a little)

A few points:

1.) This was experimentally tested in Norfolk England, first resulting in a finding that the earth was flat (!). More careful measurements later proved the earth convex (whew!) The effect of atmospheric refraction on the results has been noted:

2.) Cyrus Teed (“Koresh”) and his Koershans backed a similar experiment by Ulysses Grant Morrow in 1896 along the Illinois Drainage Canal, which proved the earth concave, just as Teed believed. Critics blamed atmospheric refraction. (Same cite. see also Martin Gardner’s Fads and Fallcies in the Name of Science. Alsi The Big Book of Weirdos)

3.) In Hal Clements science fiction classic Mission of Gravity, the Mesklinites, living on a high-gravity planet, are convinced that they live in a bowl-shaped environment. They know it isn’t flat, because they’ve worked out the geometry. But it looks like a concave surface to them, because in their case, atmospheric refraction is severe.

In “Project: Genius” by William Hayes, a high school student attempts this kind of experiment, and at first, discovers that the Earth is flat, before realizing the need to correct for refraction.