An important issue in science is what’s right and what’s wrong. Another is who gets credit for what. The former issue is scientific while the second is social. It matters little to the progress of science who discovers what. It matters a lot to the people who do it. We like to get credit where due.
Nowadays, Fritz Zwicky is often credited with the discovery of dark matter for his work on clusters of galaxies in the 1930s. Indeed, in his somewhat retrospective 1971 Catalogue of Selected Compact Galaxies and of Post-Eruptive Galaxies (CSCGPEG), he claims credit for discovering clusters themselves, which were
discovered by me but contested by masses of unbelievers, [who asserted] that there exist no bona fide clusters of stable or stationary clusters of galaxies.Zwicky, CSCGPEG
Were Zwicky alive today, a case could be made that he deserves the Nobel Prize in physics for the discovery of dark matter. However, Zwicky was not the first or only person to infer the existence of dark matter early on. Jan Oort was concerned that dark mass was necessary to explain the accelerations of stars perpendicular to the plane of the Milky Way as early as 1932. Where Zwicky’s discrepancy was huge, over a factor of 100, Oort’s was a more modest factor of 2. Oort was taken seriously at the time while Zwicky was largely ignored.
The reasons for this difference in response are many and varied. I wasn’t around at the time, so I will refrain from speculating too much. But in many ways, this divide reflects the difference in cultures between physics and astronomy. Oort was thoroughly empirical and immaculately detailed in his observational work and conservative in its interpretation, deeply impressing his fellow astronomers. Zwicky was an outsider and self-described lone wolf, and may have come across as a wild-eyed crackpot. That he had good reason for that didn’t alter the perception. That he is now posthumously recognized as having been basically correct does nothing to aid him personally, only our memory of him.
Nowadays, nearly every physicist I hear talk about the subject credits Zwicky with the discovery of dark matter. When I mention Oort, most have never heard of him, and they rarely seem prepared to share the credit. This is how history gets rewritten, by oversimplification and omission: Oort goes unmentioned in the education of physicists, the omission gets promulgated by those who never heard of him, then it becomes fact since an omission so glaring cannot possibly be correct. I’m doing that myself here by omitting mention of Opik and perhaps others I haven’t heard of myself.
Zwicky got that treatment in real time, leading to some of the best published rants in all of science. I’ll let him speak for himself, quoting from the CSCGPEG. One of his great resentments was his exclusion from premiere observational facilities:
I myself was allowed the use of the 100-inch telescope only in 1948, after I was fifty years of age, and of the 200-inch telescope on Palomar Mountain only after I was 54 years old, although I had built and successfully operated the 18-inch Schmidt telescope in 1936, and had been professor of physics and of astrophysics at the California Institute of Technology since 1927 and 1942 respectively.Zwicky, in the introduction to the CSCGPEG
For reference, I have observed many hundreds of nights at various observatories. Only a handful of those nights have been in my fifties. Observing is mostly a young person’s occupation.
I do not know why Zwicky was excluded. Perhaps there is a book on the subject; there should be. Maybe it was personal, as he clearly suspects. Applying for telescope time can be highly competitive, even within one’s own institution, which hardly matters if it crossed departmental lines. Perhaps his proposals lacked grounding in the expectations of the field, or some intangible quality that made them less persuasive than those of his colleagues. Maybe he simply didn’t share their scientific language, a perpetual problem I see at the interface between physics and astronomy. Perhaps all these things contributed.
More amusing if inappropriate are his ad hominem attacks on individuals:
a shining example of a most deluded individual we need only quote the high pope of American Astronomy, one Henry Norris Russell…Zwicky, CSCGPEG
or his more generalized condemnation of the entire field:
Today’s sycophants and plain thieves seem to be free, in American Astronomy in particular, to appropriate discoveries and inventions made by lone wolves and non-conformists, for whom there is never any appeal to the hierarchies and for whom even the public Press is closed, because of censoring committees within the scientific institutions.Zwicky, CSCGPEG
or indeed, of human nature:
we note that again and again scientists and technical specialists arrive at stagnation points where they think they know it all.Zwicky, CSCGPEG, emphasis his.
He’s not wrong.
I have heard Zwicky described as a “spherical bastard”: a bastard viewed from any angle. You can see why from these quotes. But you can also see why he might have felt this way. The CSCGPEG was published about 35 years after his pioneering work on clusters of galaxies. That’s a career-lifetime lacking recognition for what would now be consider Nobel prize worthy work. Dark matter would come to prominence in the following decade, by which time he was dead.
I have also heard that “spherical bastard” was a phrase invented by Zwicky to apply to others. I don’t know who was the bigger bastard, and I am reluctant to attribute his lack of popularity in his own day to his personality. The testimony I am aware of is mostly from those who disagreed with him, and may themselves have been spherical bastards. Indeed, I strongly suspect those who sing his praises most loudly now would have been among his greatest detractors had they been contemporaries.
I know from my own experience that people are lousy at distinguishing between a scientific hypothesis that they don’t like and the person who advocates it. Often they are willing and eager to attribute a difference in scientific judgement to a failure of character: “He disagrees with me, therefore he is a bastard.” Trash talk by mediocre wannabes is common, and slander works wonders to run down a reputation. I imagine Zwicky was a victim of this human failing.
Of course, the correctness of a scientific hypothesis has nothing to do with how likeable its proponents might be. Indeed, a true scientist has an obligation to speak the facts, even if they are unpopular, as Zwicky reminded us with a quote of his own in the preface to the CSCGPEG:
The more things change, the more they stay the same.