N. David Mermin and me
There is nothing I am more proud of than Mermin's appreciation of my work
N. David Mermin is Horace White Professor of Physics Emeritus at Cornell University (Ithaca, NY). Having obtained his Ph.D. in Physics in 1961 from Harvard, he is known throughout the scientific world as co-author of Solid State Physics and for his thirty “Reference Frame” columns in Physics Today (published between 1988 and 2009), which engaged a broad audience in a very humorous and relatable way. In 2016 these were published, along with several longer essays, in Why Quark Rhymes with Pork, and Other Scientific Diversions (Cambridge University Press). Mermin was awarded the first Julius Edgar Lilienfeld Prize of the American Physical Society “for outstanding contributions to physics” in 1989, and is a member of the American Philosophical Society, the U.S. National Academy of Sciences, and the American Academy of Arts and Sciences.
The following is a short excerpt from an interview conducted by David Zierler, which took place in April 2020.
M: My current view of the problems in quantum foundations is that they arise from a failure to understand the nature of scientific knowledge. Now, no practicing physicist worries about the nature of scientific knowledge. It’s the kind of thing that philosophers should worry about, but even they don’t worry enough about it.
… at the moment, I’m under the illusion that I understand quantum mechanics, which may well stay with me for the rest of my life. I’m already 85!
Z: Is that a humble way of saying that possibly no one understands quantum mechanics?
M: I would say that at the moment, I and a few close friends understand quantum mechanics, [laughs] and we’re trying to explain it to the rest of the world. And we’re making a small amount of progress.
Z: Who would you include among this small circle of friends?
M: Chris Fuchs, who is a physicist at UMass-Boston; Ruediger Schack, who is a mathematician at Royal Holloway college in London; possibly Ulrich Mohrhoff [emphasis added by Yours Truly], who writes about physics from the Pondicherry Ashram in India; a few of Chris’s students, postdocs, and collaborators. Hans Christian von Baeyer recently wrote a whole book about it. That’s about it. …there’s so much noise in this area. There’s so much talk, so much nonsense, that it’s very hard to sound a fanfare and say, “This is it. Listen.” Nobody really reads anybody else’s papers anymore…. People are too busy writing papers to read other papers. So am I, although I’ve pretty much stopped writing for the past couple of years.
In 1998 Mermin published an article in American Journal of Physics titled “What is quantum mechanics trying to tell us?,” in which he presented the “Ithaca interpretation” of quantum mechanics. The name is a variation on the “Copenhagen interpretation” of quantum mechanics, which at the time was still regarded as the orthodox interpretation. In 2000 I published an article presenting the “Pondicherry interpretation” of quantum mechanics in the same journal. It was titled “What quantum mechanics is trying to tell us.” Prior to publication I emailed the manuscript to Mermin, who wrote back:
All I can say so far is that it is clear that in Section I you understand the IIQM better than any reader I have had so far and have elegantly identified its weaknesses. I have to read more to decide whether I think the PIQM does better. You write so gracefully that that I’m not without hope. I catch myself admiring isolated sentences.
A couple of hours later I got a second email:
Having just told you that it would take me a while, I found I couldn’t put the paper down, so I’ve been through it once, and here are some reactions.
It is charming. Often I think that is all one can ask from an interpretation of quantum mechanics. (Most of the specimens in the cabinet [of curious interpretations] are not.)
And a few days later:
… it gave me much pleasure to be so intelligently … criticized.
Fast forward to April 2014. I am participating in a Workshop at the Centre for Quantum Technologies (National University of Singapore) to honor Berge Englert on the occasion of his 60th birthday. Ruediger Schack gives a presentation on QBism, which is a way of thinking about science that Mermin now considers to be “as big a break with 20th century ways of thinking about science as Cubism was with 19th century ways of thinking about art.” I was shocked to learn that Mermin was on board. He had just published a Comment in Nature with the (to me, then, infuriating) title “QBism puts the scientist back into science.” I can, however, take solace in the fact that Mermin’s first exposure to QBism was not very different, reacting as he did to Chris Fuchs’ insistence that quantum mechanics is a “single-user theory” (i.e., about “Me, me, me!”) by hurling the s-word (i.e., solipsism) at him.
My chief objection was then (and still is) that QBists tend to play fast and loose with such expressions as “the world,” “the external world,” or “the objective world.” Sometimes they refer to something that induces experiences in us, othertimes they refer to something that we construct, through a collaborative human effort, on the basis of our private experiences. Uncritically identifying these two things tends to produce no end of ambiguity if not inconsistency.
In his anthology The Unity of Nature, which I read in the 1980s, the physicist and philosopher Carl Friedrich von Weizsäcker wrote: “Those who really want to understand contemporary physics, will find it useful, even indispensable at a certain stage, to think through Kant's theory of science.” While I did so, and while I was much impressed by Kant’s epistemology, at the time I felt (quite wrongly) that it was undermined by quantum mechanics. Kant once wrote that “it was the recollection of David Hume that many years ago first interrupted my dogmatic slumber.” Similarly I might say that it was QBism which interrupted my own dogmatic slumber.
Since 2014 I have written several papers attempting to integrate the two approaches, some published, some under consideration, and most of them available at the preprint arXiv at Cornell. One off-shoot of this effort was the realization that Niels Bohr had come tantalizingly close to adopting a QBist stance. This led to the publication of a paper in Quantum Studies: Mathematics and Foundations.1 What follows is from the referee report which, as it turned out, was written by Mermin:
This is an important contribution to the philosophy/interpretation of quantum mechanics. It should be published, and may turn out to be of historic importance. It clarifies the many writings of Niels Bohr on the subject. It explains why Bohr’s views have been misunderstood and distorted over the past nine decades. It provides a much-needed exposition of how Bohr’s views are closely related to the writings of Immanuel Kant. And it argues that the relatively recent interpretation of quantum mechanics called QBism is basically an elucidation of Bohr, despite assertions to the contrary by most QBists. And it does all this, comprehensibly and convincingly, in a little over eight pages!
Two general remarks before I turn to detailed suggestions:
1. I started taking QBism seriously seven years ago. It is still very much a minority point of view. I would expect the understanding of QBism to grow if access were available to the views expressed here by Mohrhoff, especially his badly needed clarification of the position held long ago by Niels Bohr. So my enthusiasm for this paper is not disinterested. On the other hand, Mohrhoff argues that QBism is not, as I had thought, the final answer to the interpretive puzzle discovered nine decades down the road, but merely a reformulation of the badly understood solution that was offered repeatedly by Bohr over his final three and a half decades. My enthusiasm is not just for having my own views advertised, but also for having them criticized and perhaps corrected.
2. The paper is related to two very long papers Mohrhoff has posted on arXiv earlier this year: arXiv:1905.07118 (37 pages) and arXiv:1907.11405 (42 pages). I cannot stress strongly enough how important it has been for me to read this 8-page overview of those treatises. I expect now to understand the arXiv essays very much better when I reread them. I would urge the author to add references to those lengthy unpublished essays for readers wanting to learn more about the subject. I also urge you to allow him to cite them, even though they are not journal references. They are easily downloaded from arXiv.org.
When, in May 2020, I submitted another 36-page paper titled “A QBist Ontology” to arXiv.org, I received the following response:
Dear arXiv user,
arXiv is intended as a forum for professional members of the scientific community to communicate their formal research results. In order for our moderators to consider your submission, please provide the following information:
1. Do you have a conventional publication record? In what field? Please provide us with a current list of publications.
2. What is the precise nature of your institutional affiliation?
For more about arXiv moderation please see …
Regards,
arXiv moderation
By then I had posted some 36 preprints on arXiv, many of which were subsequently published in peer-reviewed journals—information that was readily available to the arXiv moderators. I duly replied with a list of 22 published papers including my quantum mechanics textbook (now in 2nd edition). I also quoted from the above review by Mermin, and I copied my reply to him. Soon thereafter I almost simultaneously received two emails, one from arXiv moderation and one from Mermin to the moderators (cc’d to me). The first went like this:
Dear arXiv user,
Our moderators determined that your submission is on a topic not covered by arXiv. As a result, we have removed this submission…
Regards,
arXiv moderation
In his email, Mermin made some flattering remarks about the importance of my work and his interest in it. This did not change their decision. I forwarded their final decision letter to Mermin, who then wrote to a friend of his who is currently on arXiv.org’s Scientific Advisory Board. The paper was subsequently posted.
To understand what has happened here, one needs to know that my QBism-inspired attempt to integrate the realistic and transcendental approaches to science points inexorably in the direction of a primarily idealistic ontology. The paper contains quotations from Sri Aurobindo as well as two sections on the philosophy of the Upanishads, which was endorsed by Schrödinger. Those moderators obviously weren’t ready for that.
Today (June 6, 2021) I am happy to add that the paper, after several revisions, has been accepted for publication in Foundations of Science.2
And they probably haven’t read Whitehead either! Might not even know who he was. If he were alive today, he would be banned from publishing at “arXiv”, banned from crossing the Atlantic on a ferry boat and banned from teaching at Harvard. It would be considered detrimental to common order. No one would implore him to carry on, to move, to create. At the end of the day, it took the best minds of a generation 60 years to prove him “wrong” on an interpretative subject, and all the rest has been passed over like a monumental and beautiful wave on a bamboo raft.
Anyway, coming back to your doctrina elegans, what Mermin said is just a reflection of a common perception. You have a impeccable style. You can be read. My feeling back in the day was probably the same as that of everyone who has ever paid you any level of attention. We can tolerate anything from a philosophical mind, we can disagree with the argument, with the form and the conclusions, but we cannot tolerate a mind that cannot be read; yours is a joy to follow. You are as good a scientific writer as Bill Starbuck (and that’s where the spectrum ends effectively). In fact, both of you are on the same boat.
I cannot say anything about QBism, because I haven’t read a word about it (yet), but my first impression from what you say here is this: haven’t we said all that already before? This feels like my sleepy commute. I’m getting off here, even though I thought I already got off on the previous station, and they both look rather similar.
As of one interpretation or another being more preferred I cannot vouch one way or the other, but you not being read in the future, that is a non-event. Doesn’t matter what the referee community thinks. Humanity will (and are) losing good sense, but we will never lose style.
Yours,
A