i think this explains pretty good:
https://www.lhup.edu/~dsimanek/hollow/morrow.htm
should read the whole paper it is very informative!
Quote
Inverting the rectilineator section top/bottom doesn't help either, for the structure will still sag in the same sense, with ends drooping. Could this be the systematic error that accounts for the results? With the materials used in the rectilineator, the sag can't be very large. But a sag of only 0.000003 degree in each section, multiplied by the 1045 sections in a four mile length, gives a cumulative error of 0.003 degree. That would be about the latitude difference between the endpoints of the survey. Such a small error was far too small to be measured or detected in just one, or even a string of a few, rectilineator sections.
This is a subtle source of systematic error. The preliminary tests of the rectilineator were done with only a few of those sections they had (four). The systematic error for these would be far beneath detection level during those tests. An individual section's cross arms might deviate from parallelism in one of two directions, or might, by sheer accident be nearly parallel for one orientation of the rectilinator. If it deviated in one direction, then when the section was inverted, the deviation would flip in the other direction and still be such as to cause the ends to bend downward. Even if by pure accident the first few rectilineator sections were aligned exactly parallel, the procedure of "recycling" sections and inverting them would ensure a systematic error from that point onward of about the same amount over the entire length of the survey.
This is a subtle source of systematic error. The preliminary tests of the rectilineator were done with only a few of those sections they had (four). The systematic error for these would be far beneath detection level during those tests. An individual section's cross arms might deviate from parallelism in one of two directions, or might, by sheer accident be nearly parallel for one orientation of the rectilinator. If it deviated in one direction, then when the section was inverted, the deviation would flip in the other direction and still be such as to cause the ends to bend downward. Even if by pure accident the first few rectilineator sections were aligned exactly parallel, the procedure of "recycling" sections and inverting them would ensure a systematic error from that point onward of about the same amount over the entire length of the survey.
https://www.lhup.edu/~dsimanek/hollow/morrow.htm
should read the whole paper it is very informative!
Interesting piece of information but it's overly pessimistic, almost as if it is trying too hard to discourage people from conducting this experiment. If there is a risk of unavoidable systematic error then results should vary. Some experiments should give a result according to which the Earth is convex. Some may even tell us that the Earth is flat. However, it will always be possible to determine the truth by using the Monte Carlo method. You may get it wrong once but after enough attempts the true curvature of the Earth must start showing up.
I think I am starting to get it why this experiment hasn't been conducted again. It's because of what I just said. Until this experiment has been carried out just once it is plausible to say that the results must not be trusted due to a potential cumulative error. However, if more and more people were to conduct this same experiment, we could start applying probability theory on the results and thereby statistically find out the truth.
edit:
LOL I didn't notice at first who the author of that writing is --- Donald E. Simanek
(picture of a true shit-scientist above)
This guy was paid to debunk results of the original rectilineator experiment. He's not a scientist, he's a fucking investigative journalist. I should have known.
edit 2:
This guy Donald E. Simanek is clearly delusional, look at what he has written:
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Today men have walked on the Moon, and the "illusion" idea doesn't survive, unless, like the modern flat-earthers, we assume that the entire space program is a giant conspiracy to deny the truth, faked on a Hollywood sound stage with clever special effects.
He honestly believes that NASA is telling the truth and hasn't faked anything. This guy cannot be taken seriously. I would be willing to accept scepticism from a person without an expectation bias but this Donald guy is full of it. He is whining about the rectilineator guys to have an expectation bias but he himself has a humongous expectation bias in a sense that he expects earth to be convex and NASA to be telling the truth. His writings cannot be taken seriously for that reason alone. Like seriously guys, look at the irony ---- sceptic thinks he has debunked a conspiracy theory by accusing his opposition of having an expectation bias, while the sceptic himself has an even greater expectation bias favouring his own theory.