@fourtytwo
Well, this is the absolute opposite of my base believe. For me the earth is neither unique nor special, it's just special for us because we live there.
I think with such a different base believe it's no surprise to come to different conclustions.
Belief is unwelcome (and across purposes) in knowledge/fact, most of all scientific. You are, of course, permitted to believe any fantasy you like - but the science is clear and undeniable; the earth is the only place like it and there is ONLY data attesting to this fact. There are weak statistical arguments that there may be other objects with similar size, but we have no idea what they are / how far away they are / or if they have anything in common with the earth (nor will we in the conceivable future). The belief you profess is most likely not your own (not organic), it was taught to you and many others through conditioning through rote under the guise of education. The anti-intellectual/anti-science worship of aliens and sci-fi is required in the religion of scientism.
I fully agree with this opinion.
Then why do you feel it is an opinion? It is a contemporarily and historically demonstrable fact.
Even knowing, that my way of thinking can lead me to a wrong direction sometimes, it's the only one I personally can rely on.
Yes, and often what we are taught to know is wrong. This is also an obvious contemporarily and historically demonstrable fact.
I read a lot about experiments related to flat water level.
Cool. However you should be aware that there is no experiment that has anything to do with the shape of the world. Experiment is not used in any way to determine the shape of physical objects in reality. People who talk (and are taught) about experiment this way, don't even know the proper definition - let alone other fundamentals of the scientific method.
This experiments are claimed by both (RE'er and FE'er) to proof their position.
Experiment has a rigorous and inflexible definition. It is scientific technical vernacular, and you are using it incorrectly (as were the people you encountered who claimed their mere measurements/observations were experiments). I agree that pointing to these measurements as proof of the shape of the entire world is deluded and indefensible.
Explanation is based on optical effects
It simply MUST be, otherwise it contradicts their religious worldviews. That presumptive/default/apologist "explaination" is one of the reasons that globe believers don't critically evaluate their beliefs, or conduct science to get to the bottom of the issue. They just stick their fingers in their ears and repeat the holy prayer mantra of "refraction" to keep the "bad data" at bay.
However, the natural law of water's surface always being flat at rest easily empirically proves that water does not and (due to its fundamental properties) cannot curve in the sustained convex manner that the globe requires. The belief that the water does curve (because it simply MUST in the minds of the devout) the way the globe model requires has never been confirmed/measured in empirical science even once in all of human history. It's not science, it's merely speculation as it always was. The natural law is inarguable, has stood unchallenged for centuries in hydrostatics, and can be demonstrated by anyone at any time. The belief in "curv-a-level" and bendy water are just religious dogmas misrepresented as "scientific fact" to children.