In his time, Zwicky was regarded as an eccentric person so his theory was not taken seriously by other astronomers. They assume that Zwicky created a new form of a matter because the force of gravity he calculated did not match the observations. Zwicky's research was forgotten by many people until in the late 1970s an astronomer named Vera Rubin discovered a strange rotational galaxy.

That was the same way they killed all those that said the earth is round, because the common mind thought it is flat. True facts will surely surface from the waters of fallacy. Nicely written @whalhesa