In a discussion with a friend he noted that the colour magenta is not a real colour. I have also heard of this and you can read more on that on Mentalfloss.
I would like to know if a word or phrase exists to express the mass agreement of people which runs counter to scientific analysis or technical correctness. Yes, magenta is not a real wave length but I can reach an understanding with a layman on what magenta is.
If context is about an event or occurrence, urban myth would be a good fit.
- The phrase urban myth – is quite new. Curiously, an urban myth does not usually have anything to do with the city: it is simply “a story about an unusual event or occurrence that many people believe is true but that is not true.” An example would be the tale that Elvis Presley is still alive after spending decades in a witness protection program. The phrase urban myth has been used to describe such hoaxes since at least 1971. MW see also "urban legend"
"legend" and "myth" also convey "mass agreement of people" but not necessarily "which runs counter to scientific analysis or technical correctness."
Folk is the term used for naive understanding in different fields of study, e.g., folk etymology and folk philosophy.
folk (adj.)
Of or relating to the common people or to the study of the common people
folk sociology m-w
Folk Physics / Naïve Physics
Folk Physics
A term for people spontaneously understanding the workings of the physical world. Contrary to scientific physics, folk physics is based on immediate human understanding of the nature of physical objects and intuitive human prediction of physical events in nature. It can be seen as a naïve or common sense approach to human environment. Human interaction with the physical environment is normally based on habits and practical understanding that are very different from the theoretical approach of scientific physics. Thus, insights gained by folk physics are often characterized as contrary to those of scientific physics, and are therefore deemed wrong and misleading with respect to a scientific understanding of the physical world. A. Runehov and L. Oviedo (eds.) Encyclopedia of Sciences and Religion
Naïve physics or folk physics is the untrained human perception of basic physical phenomena. In the field of artificial intelligence the study of naïve physics is a part of the effort to formalize the common knowledge of human beings.
Many ideas of folk physics are simplifications, misunderstandings, or misperceptions of well-understood phenomena, incapable of giving useful predictions of detailed experiments, or simply are contradicted by more thorough observations. They may sometimes be true, be true in certain limited cases, be true as a good first approximation to a more complex effect, or predict the same effect but misunderstand the underlying mechanism.
Naïve physics can also be defined as an intuitive understanding all humans have about objects in the physical world. Certain notions of the physical world may be innate. Wiki
J. Peter and J. Garvin; Folk Physics, Pre-science, and Demarcations of Science (2017)
Of course magenta is "real" in that it's perceived as a color, regardless of the mechanism.
This may be slightly off the mark of what you're looking for, but there's the well-publicized "Mandela Effect", a category of "false memory," in which a mass opinion is not merely slightly inaccurate but fully convinced of something patently false, especially as regards the record of their memories.
