Flat water will "have a certain degree of convexity".

"Does the above experiment proves the Earth is flat?" this seems to be too broad here (the answer is obviously "no" though). The other question seems on-topic, though I'm not sure how notable it really is. And even the users in the flat earth society forum don't believe it to be correct.

The page only describes what the person "Tom Bishop" says they did. No photographs, no names of witnesses, no external evidence. If I describe a trip in which I walked to the moon, that doesn't make it possible.

What does your initial checking shows? Perhaps reading on Wikipedia? en.wikipedia.org/wiki/Bedford_Level_experiment

On Wiki page you can read that 'atmospheric refraction causing an object below the horizon to be visible', however above experiment takes into the account refraction as well.

@kenorb -- The experiment says they take into account refraction, but according to my back-of-the-envelope calculations, in the brief description they've understated refraction by a factor of 10 or more.

@tim: I have removed that part. Even if the experiment result were true, and even if the calculations were correct, that would be a surprising anomaly to be explained, but not enough to overthrow the consilience of evidence of a round earth.

Also relevant are the many reproducible experiments that, under controlled conditions, show that the expected degree of curvature does occur when other high points are observed over long distances eg, fecore.org/project/laser-experiment

I also note that Tom Bishop calculates the distance between his two points using Google Earth, a tool that assumes (and works only if) the Earth is round.

@DJClayworth: As is appropriate for a exposing a contradiction with a theory's prediction.

A question about "Is the Earth round?" is "opinion based"? On a scientific skepticism site? :-)

@kenorb Please see the chat.

@DJClayworth "is the earth flat?" would totally make sense here. "Does this random claim disprove the earth is round?" is asking for opinions and relying on reversing the burden of proof.

So the question is easy to fix: (a) if we want to discuss whether the earth is round, let's ask about that. (b) if we want do discuss about some factual claim regarding the experiment, let's ask about that

At the moment the claim is not based on facts, just opinions. If flatearthers find this evidence compelling, good for them.

Regarding the answers being removed, it was two 7k users openly refuting the claim based on their own theory, so those are unsalvageable.

@Sklivvz I am sorry but that is misreading the post. Disregard the headline and look at the question: "Is above statement correct?". How can you say that is "opinion-based".

@Sklivvz *"it was two 7k users openly refuting the claim based on their own theory, so those are unsalvageable." No, not letting you slip on that; explain that statement. What is this supposed theory I am presenting.

@Sklivvz I had this discussion with @OddThinking last week, whether the headline is the question or not. We concluded that the headline is not the question. If the headline and the actual question in the body of the post can be interpreted differently, then the headline needs to be fixed. But the headline is not the question.

@Sklivvz You have moderated as if the headline is the question, but it is not. "Is above statement correct?" — referring to the small text quoted from tfes — is the actual question.

In my opinion, the question in the title needs to be fixed. A user might reasonably only take that and answer that, we've seen this happen numerous times, and then we need to act on those answers and that's more painful. So -- let's fix the title and clarify the question, then reopen.

Regarding the answers, they were both basically unreferenced and read as the author's opinion on the matter. So at the very least they need to be reworded so they present an authoritative third-party, shared conclusion, including reputable references and citations of them.

I personally think they are unsalvageable because I suspect they were written based on personal authority, and back-referencing those answers without a rewrite is often impossible.

There is massive problem with calculated expected water bulge height. What sketch actually represent is how tall should be something to be seen at same height at different distances. Actual water bulge height is difference between earth radius and height of triangle with observer, target and earth center as points. If calculated this come up with 27m or 89 feet. So more than 3x less than "expected" height.

*correction, "not the length of the sagitta."

@Murphy I re-read in light of your comments, and the first paragraphs mislead me into reading the rest in a different way. You are right, your answer is not theoretical and I've put it back. I just removed the parts I found misleading, I hope you don't mind.

@Murphy you are correct, I though text was saying water bulge is 300 feet, but now I see it is not.

I've improved the post, do you think it's acceptable now?

@Sklivvz If you are going to reopen Murphy's answer then I want mine reopened as well since we refer to the exact same thing: mirages caused by temperature stratification.

@kenorb You do not need to change the question because you are making the same wrong assumption that Bishop does: that light always moves in a straight line.

Well, you are both saying the same thing in a very small part of your answer

@kenorb You are essentially asking "Well, can we be sure that the water is not flattened just there?".

@Sklivvz So?

The rest is still your calculations, opinions etc.

@Sklivvz Half of my answer analyses the numbers and math of the original clam and actually validates those.

And that's theoretical

We are not a maths site, how do you expect our users to validate (or dispute) that part?

@Sklivvz No, it is using the numbers and assumptions that were put into the original claim.

@Sklivvz No apparently we are a lookup service for people that are too lazy to look up an answer themselves... because with that rule, and applying it that strict, all we are ever allowed to do is say "Yes the claim is true, because there is someone else that says it is true" or "No, because here is someone else that says it is false", or "Don't know... because we cannot find anyone else that says it is true or false".

With that interpretation we are not allowed to apply universally established scientific theories, or — apparently — even junior high-school maths!

I am not kidding: calculating the height of the bulge between two points on a sphere is junior high-school geometry. Want the formula? Angle a = distance / circumference * 360 degrees. Height of the bulge = (1- cosine (a / 2)) * (circumference / 2 / pi).

@Oddthinking Please, give us your opinion. Do you honestly think the "No theoretical answers" rule is doing a proper job if it results in this over and over? Is it really worth it, instead of rewording it to keep out speculation and still allow people to think and do maths?

@MichaelK We do have this conversation repeatedly here. The issue is that people think we are against maths. We are against the (often hidden) assumptions that maths is based on.

For example, the Earth is NOT a sphere. Making the assumption that it is a sphere needs some consideration that "(1- cosine (a / 2)) * (circumference / 2 / pi)" is not sufficient to address. For example, the assumption that water is always static and at sea-level isn't safe.

@Oddthinking So how do we adress assumptions? Because if we are going to be anal about that: there is no solution to "The Problem of Hard Solipsism".

@Oddthinking ...which in that case means that no question here can ever be answered unless we assume — for instance — that when we reference someone that 1) they exist and 2) have written that thing we reference. What assumptions can be considered self-evident and what assumptions do we have to declare?

@MichaelK Indeed, so we can't be that anal about it, while still giving us plenty of scope to be far more anal about it than the disaster area that is Yahoo! Answers.

@Oddthinking So now we have not just one but two issues: 1) When answering, how shall assumptions be dealt with? Which assumptions count as self-evident? 2) We are still locked out from using established scientific theories and maths as foundations for our answers, because of the "no theoretical answers" rule. In effect we are not allowed to assume for instance "gravity is real" and hinge any answer on that assumption. Because gravity is a theory.