On the Writing Process

The problem I typically have when writing about technical topics is trying to include everything and to answer objections that seem vitally important to me but which don’t make much sense unless you’ve heard the debates inside my head. Removing that stuff has by now become a standard part of my revision process. My colleagues point it out, I feel a little hurt, then I grudgingly agree, and in a week or so I re-read my work and I don’t get why I thought that extra stuff was so important in the first place.

I’ve also noticed that the parts of an argument that people object to are often the bits that I thought were almost incidental, or that exist mostly in their head — they want to keep having the argument they’ve been having before. Trying to foresee how this will play out is hard, and it always helps to have input on that.

I count myself lucky to work with people who care about this kind of thing. I wish I’d had more training in my early years of physicist school — some harried lab reports and a single term paper don’t add up to much, honestly, given how much of our professional output is the written word.

My 2019 in Science

First, of course, there was the doubt and the pain.

But we’ve already covered that.

Let’s talk about the papers I managed to get out the door and into public view. In retrospect, the list is pleasingly not insubstantial:

There was also From Gender to Gleason, my review of Adam Becker’s book What is Real? (2018). By the time I was done, it was as lengthy as a paper, but the arXiv isn’t really a host for book reviews, so I just posted it here at Sunclipse and moved on.

Predator/prey or Perish

Looking at academic publishing from the perspective of Fully Automated Luxury Gay Space Communism is an interesting experience.

Consider, for example, the term predatory publisher for shady outfits that will accept anything for the right fee and put it on a website that calls itself a “journal”. Scummy behavior, right? But is it really “predatory”? What fraction, exactly, of their customers are being conned, and how many are walking into the deal with their eyes wide open? A used-car salesman might be a sleaze, but if you’re going to his dealership to pay cash for a getaway car, the relationship is more of a symbiosis.

I’m sure it’s convenient for the legacy institutions to present the situation as saintly scholars being exploited by deceptive newcomers. [cough]

Suppose the Web came to be, but there never were any respectable Open Access journals. No “Open Letter to Scientific Publishers” in 2001, so no Public Library of Science; no Budapest Initiative in 2002 or Berlin Declaration in 2003. Would the morass of “predatory” OA really look all that different? Perhaps not. Websites are cheap, calling yourself a journal is easy, and as we just noted, there’s a ready market.

But without the cover of PLOS and the like, would “predatory” OA have a veneer of respectability to offer its customers? Well, consider that paying to attend conferences is a thing that academia finds universally respectable. So, a “predator” could do what outfits like WASET do now: offer “conferences” with no standards, no dedicated space, perhaps not even a physical event. And if you’ve got a paper, great! For only a modest additional fee, it can go in the conference proceedings, which will conveniently be available online.

Quality is always the hard course of action. Legitimate OA journals were optional; only the pay-to-play racket was inevitable.

As We Would Not Actually think

There’s an aspect of Vannevar Bush’s “memex” that, I think, would still be difficult to achieve with current software, and that is its intensely personal character. The memex that his 1945 essay “As We May Think” imagined was to be “an enlarged intimate supplement to [the user’s] memory.”

A modern analogue would have to be something like a personal wiki, hybridized with a social-media platform. Every post you make is intended to be retrievable: cross-indexed, hyperlinked. Like, if every time you posted to your Mastodon instance, it was also added as a page to your own MediaWiki setup. And you could share pages from your MediaWiki with just a few clicks, sending any set of them you wish to another Mastodon user. Instead of just sharing a news story, you could pull up every news story you ever shared, along with whatever comments you made about them, and all the ways that you had decided to tag them.

It’s not beyond what software can do, but we don’t generally seem to have worked toward what Vannevar Bush had in mind. There wasn’t supposed to be just one Memex for everybody.

The bits and pieces are present, but there hasn’t been the drive to put them together in a way that makes the package readily usable. We have software for sharing personal records and observations (social media), and we have platforms for making association trails (e.g., Wikipedia, TV Tropes, etc.). But the Memex that VB envisioned was an individual possession that facilitated social exchanges. In slogan form: The memex was like building your own Wikipedia, with adjustable privacy settings, one blog or microblog post at a time.

A Good Old-School Skeptic Rant

Today’s discovery:

The online store of Marie “does it spark joy” Kondo is the new SkyMall catalogue.

The $60 “French Market” totebag looks flammable, so if you do strike sparks, you might have to douse the flames with water from the Balance Gem Water Bottle ($98).

And $156 for a “small cheese knife”? That, my friends, is going beyond SkyMall. We can’t stop here — this is Williams-Sonoma country.

And, of course, there’s the section of the shop devoted to — ting ting! — crystals. A tuning fork and a lump of rose quartz, $75 if you please.

Goddamn pseudoscientific “healing energy” crap for wine moms. Not only does it leech the respectability of science, but by aiming for that suburban market, it loses any chance of emotional depth. Nobody actually feels meaning or satisfaction from a SkyMall chakra stone, because of course they don’t. It just sits there. It does a worse job of just sitting there than a potted plant. The best you can do is try to convince yourself otherwise so you don’t admit you blew $75 feeding an exploitative industry that you could have spent paying off schoolchildren’s lunch debt or helping someone make the rent.

As long as you’re trading in bunkum, why not up your game and sell something with real weight and history to it? You want some serious Goop? How about a kit for performing some fucking divination by entrails. Can’t find Mr. Right? Learn the secrets of the heart by going through the liver.

On Being a Quantum Physicist in Autumn 2019

(a friendly warning for police violence, transphobia and philosophy of physics)

The way I see it, the two big Why? questions about quantum mechanics are, first, why do we use the particular mathematical apparatus of quantum theory, as opposed to any alternative we might imagine? And second, why do we only find it necessary to work with the full perplexities of quantum physics some of the time? These two questions are related. In order to understand how imprecise measurements might wash out quantum weirdness, we need to characterize which features of quantum theory really are fundamentally weird. And this, in turn, requires separating deep principles from convenient conventions and illuminating the true core of the physics. My own research has focused on the first question, but the second is never too far from my mind.

Of course, I have a lot on my mind these days, but I don’t think I’m special in that regard.

If you ask me, a “quantum system” can be any part of nature that is subject to an agent’s inquiry. A “quantum measurement” is, in principle, any action that an agent takes upon a quantum system. The road between Boston’s City Hall and the Holocaust Memorial is a quantum system. When the police use their bicycles as battering rams against queer kids and street medics, running towards the trouble is a quantum measurement. Being threatened with pepper spray, while secoondhand exposure already stings the eye and throat, one human thrown to the pavement in the intersection in front of you while another arrest happens on the sidewalk just behind you, is an outcome of that measurement. Unsurprisingly, textbooks provide little guidance on casting that event into the algebraic formalism of density matrices, and in the moment, other types of expertise are more immediately useful.

I first encountered quantum physics in a serious way during the spring of my second year at university — 2003, that would have been. I did not particularly care about the conceptual or philosophical “foundations” of it until the summer of 2010. The interval in between encompassed six semesters of quantum mechanics and subjects dependent upon it, along with my first attempts to find a research problem in the area. Once my curiosity had been provoked, it took the better part of a year to find an “interpretation” of quantum mechanics that was at all satisfying, and longer than that to make the transition from “this is how a member of that school would answer that question” to “this is what I declare myself”. Part of that transition was my discovery that I could put my own stamp on the ideas: The concepts and the history provoked new mathematical questions, which I could approach with a background that nobody else had.

The interpretation I adopted was the QBism of Chris Fuchs and Rüdiger Schack, later joined by N. David Mermin.

QBism is

an interpretation of quantum mechanics in which the ideas of agent and experience are fundamental. A “quantum measurement” is an act that an agent performs on the external world. A “quantum state” is an agent’s encoding of her own personal expectations for what she might experience as a consequence of her actions. Moreover, each measurement outcome is a personal event, an experience specific to the agent who incites it. Subjective judgments thus comprise much of the quantum machinery, but the formalism of the theory establishes the standard to which agents should strive to hold their expectations, and that standard for the relations among beliefs is as objective as any other physical theory.

That’s how we put it in the FAQ. Any physicist who is weird enough to endorse an interpretation of quantum mechanics will naturally get inquiries about it. Many of these, we get often enough that we try to compile good answers together into a nicely portable package — with the proviso that the quantum is a project, and some answers are not final because if physics were easy, we’d be done by now.

There’s a question which seems particularly suited to answering in the blog format, though: “Why don’t you believe in the Many Worlds Interpretation?”
Continue reading On Being a Quantum Physicist in Autumn 2019


Mathematics was always my worst subject at school, right up until I went to college. I’ve heard a similar story from other physicists. I don’t know how useful my speculation about it will be to anybody else, but I think this is the reason why.

The kind of mistake I was prone to making, and the flaws in the way mathematics was taught, meshed perfectly. Carelessness cost more in math than in anything else, on the whole. If I was writing a history essay and I happened to swap Elba and St. Helena, I might only get docked a couple points out of a hundred, or perhaps none at all if the teacher had too many papers to grade. But if I wandered away from my pre-algebra homework, and upon my return my garishly awful handwriting had turned absolute-value bars into ordinary parentheses, my calculations would be completely off from that point onward. Nor did any of my teachers pick up on my problem — “Blake, you’ve got to be more careful!” — which makes me suspect that they weren’t much better at identifying what went wrong for other students, either.

In history and to a large extent in science, I was able to get by all through middle and high school with what I had learned out of books and documentaries on my own. (I was extraordinarily lucky to have a family that already had plenty of books around, and the means and the sense to provide me with more as I packed their contents into my brains.) I don’t think I had to learn anything in school that came across as wholly new. Everything was at most an elaboration of a topic I had already seen, something I’d grasped from a Larry Gonick cartoon guide, let’s say, done up with a few more details that might just have been included for the sake of having homework problems to assign. Algebra and geometry and trig and calculus, though, came closer to asking for a genuine production on my part.

Techniques of checking one’s work, which might have helped me to become a bit more generally competent, were either not taught or not motivated. “Plug your value of $x$ back in and check” might have been the last step of a few algebra exercises, but only because it was part of the rubric, devised to add another thing that could be graded.

The weird thing is that I had a sense of the importance of the mathematics, of the motivation for it. I knew why Kepler had cared about sines and cosines — to hear the music of the spheres, to turn comets from signs of dread into those of wonder. Exponentials tracked the explosion of populations and the decay of radioisotopes, each ominous in its own way. The subject offered wonders of pure thought and marvels of application. At the time, schoolwork merely seemed disconnected from those treasures which I saw in secondhand outline. Now, in retrospect, it appears almost a parody of them.

Concerning Wigner’s Former Roommate

I attended a workshop on the mini-genre of Extended Wigner’s Friend “paradoxes” but did not think that I’d write much on the topic myself. And, indeed, the comment I eventually produced is mostly bibliography.

B. C. Stacey, “On QBism and Assumption (Q)” [arXiv:1907.03805].

I correct two misapprehensions, one historical and one conceptual, in the recent literature on extensions of the Wigner’s Friend thought-experiment. Perhaps fittingly, both concern the accurate description of some quantum physicists’ beliefs by others.

Also available via SciRate.

On Reconstructing the Quantum

It’s manifesto time! “Quantum Theory as Symmetry Broken by Vitality” [arXiv:1907.02432].

I summarize a research program that aims to reconstruct quantum theory from a fundamental physical principle that, while a quantum system has no intrinsic hidden variables, it can be understood using a reference measurement. This program reduces the physical question of why the quantum formalism is empirically successful to the mathematical question of why complete sets of equiangular lines appear to exist in complex vector spaces when they do not exist in real ones. My primary goal is to clarify motivations, rather than to present a closed book of numbered theorems, and consequently the discussion is more in the manner of a colloquium than a PRL.

Also available via SciRate.

New Paper Dance

Another solo-author outing by me: “Invariant Off-Diagonality: SICs as Equicoherent Quantum States” [arXiv:1906.05637].

Coherence, treated as a resource in quantum information theory, is a basis-dependent quantity. Looking for states that have constant coherence under canonical changes of basis yields highly symmetric structures in state space. For the case of a qubit, we find an easy construction of qubit SICs (Symmetric Informationally Complete POVMs). SICs in dimension 3 and 8 are also shown to be equicoherent.

Also available via SciRate.

It Is a Heartbreakingly Lovely Spring Day

When I was a prickly atheist teenager, I did not appreciate the Battle Hymn of the Republic. After all, it was one of the bad guys’ songs in Inherit the Wind, wasn’t it? Much later, I realized — oh, it was written by an abolitionist in 1861. She was thirsty to see the fields watered with slaveowner blood. OK then. More terrible swift sword, please.

When I was a prickly atheist teenager, I was rather confident that the people who put “evolution is just a theory” stickers in all our biology books would be Good Germans if given the chance.

Turns out? I was right.

If I had foreseen that organized atheism would descend into sexism and xenophobia, then I would give myself credit. Yes, pretty much as soon as I met a convention-ful of skeptics, I found myself ill at ease with the blithe acceptance of economic injustice, and vaguely surprised by how easily the cogs of critical thinking were disengaged once the conversation moved beyond “UFOs, aspirin commercials, and 35,000-year-old channelees”. I should have been more upset, and sooner.

When I was a university student, I wrote a sestina in the voice of Persephone, mourning her life, with the trick ending that she’s a goth girl and wishes she had eaten more of the pomegranate seeds so that she could groove on the underworld for a longer fraction of the year. This may be indicative of my type of indulgence then.

When I was a university student, I began a novel. Like any youngster who has just discovered layering and allusion — anagrams with doctorates — I went full in, under the spell of Pale Fire and Appel’s Annotated Lolita and elective courses on hypertext fiction. I am sure the result would in many places embarrass me now, though at least I am still fond of this sample. I doubt I had the stylistic control to make all of my attempts at subversion be more than recapitulations. In retrospect, one character seems, within the strictures of a “romance” subplot, to be discovering their own asexuality. A better writer would have done more with that. And the motives of my off-screen villains now feel a bit too armchair, too intellectualized, when simple misogynist fury would suffice.

Also, I underplayed climate change, treating it as a diegetic justification for a mild surrealism, a reason for the world to be reshaped — under a spell, again, this time of Borges’ “Death and the Compass”.

You see, I finished that novel in 2008, when plenty was wrong with the world, but matters were sufficiently good for sufficiently many that it felt we could make things right, if we only worked hard.

When I was younger, I found that “Holy Writ” was habitually obscure, frequently cruel and almost always in need of an editor. Now, as we are poised to inherit the heated wind, I would add that the best reason to know the story of Abraham nearly sacrificing Isaac is to appreciate the twist ending that Wilfred Owen gave it:

But the old man would not so, but slew his son,
And half the seed of Europe, one by one.

From Gender to Gleason

… or, The Case of Adam Becker’s What Is Real? (2018).

It is easy to argue that the founders of quantum mechanics made statements which are opaque and confusing. It is fair to say that their philosophical takes on the subject are not infrequently unsatisfying. We can all use reminders that human flaws and passions are a part of physics. So, it would be nice to have a popular book on these themes, one that makes no vital omissions, represents its sources accurately and lives up to its own ideals.

Sadly, we’re still waiting.

Full review (PDF).

In Re “CopenHagen” and “COLLAPSE”

I was having an e-mail conversation the other day with a friend from olden days — another MIT student who made it out with a physics degree the same year I did — and that led me to set down some thoughts about history and terminology that may be useful to share here.

My primary claim is the following:

We should really expunge the term “the Copenhagen interpretation” from our vocabularies.

What Bohr thought was not what Heisenberg thought, nor was it what Pauli thought; there was no single unified “Copenhagen interpretation” worthy of the name. Indeed, the term does not enter the written literature until the 1950s, and that was mostly due to Heisenberg acting like he and Bohr were more in agreement back in the 1920s than they actually had been.

For Bohr, the “collapse of the wavefunction” (or the “reduction of the wave packet”, or whatever you wish to call it) was not a singular concept tacked on to the dynamics, but an essential part of what the quantum theory meant. He considered any description of an experiment as necessarily beginning and ending in “classical language”. So, for him, there was no problem with ending up with a measurement outcome that is just a classical fact: You introduce “classical information” when you specify the problem, so you end up with “classical information” as a result. “Collapse” is not a matter of the Hamiltonian changing stochastically or anything like that, as caricatures of Bohr would have it, but instead, it’s a question of what writing a Hamiltonian means. For example, suppose you are writing the Schrödinger equation for an electron in a potential well. The potential function $V(x)$ that you choose depends upon your experimental arrangement — the voltages you put on your capacitor plates, etc. In the Bohrian view, the description of how you arrange your laboratory apparatus is in “classical language”, or perhaps he’d say “ordinary language, suitably amended by the concepts of classical physics”. Getting a classical fact at your detector is just the necessary flipside of starting with a classical account of your source.

(Yes, Bohr was the kind of guy who would choose the yin-yang symbol as his coat of arms.)

To me, the clearest expression of all this from the man himself is a lecture titled “The causality problem in atomic physics”, given in Warsaw in 1938 and published in the proceedings, New Theories in Physics, the following year. This conference is notable for several reasons, among them the fact that Hans Kramers, speaking both for himself and on behalf of Heisenberg, suggested that quantum mechanics could break down at high energies. More than a decade after what we today consider the establishment of the quantum theory, the pioneers of it did not all trust it in their bones; we tend to forget that nowadays.

As to how Heisenberg disagreed with Bohr, and what all this has to do with decoherence, I refer to Camilleri and Schlosshauer.

Do I find the Bohrian position that I outlined above satisfactory? No, I do not. Perhaps the most important reason why, the reason that emotionally cuts the most deeply, is rather like the concern which Rudolf Haag raised while debating Bohr in the early 1950s:

I tried to argue that we did not understand the status of the superposition principle. Why are pure states described as [rays] in a complex linear space? Approximation or deep principle? Niels Bohr did not understand why I should worry about this. Aage Bohr tried to explain to his father that I hoped to get inspiration about the direction for the development of the theory by analyzing the existing formal structure. Niels Bohr retorted: “But this is very foolish. There is no inspiration besides the results of the experiments.” I guess he did not mean that so absolutely but he was just annoyed. […] Five years later I met Niels Bohr in Princeton at a dinner in the house of Eugene Wigner. When I drove him afterwards to his hotel I apologized for my precocious behaviour in Copenhagen. He just waved it away saying: “We all have our opinions.”

Why rays? Why complex linear space? I want to know too.

The Mills of Institutional Review Boards

Back in 2017, nominal intellectuals Peter Boghossian and James Lindsay proved that they were willing to invest a lot of energy in lying. Not content to rest on those laurels, they joined with Helen Pluckrose and soon redoubled their efforts. I didn’t have much to say about their “Grievance Studies” brouhaha when that story broke last fall, apart from the observation that the Bogdanov brothers had a better success rate — six out of six bullshit papers accepted! — and I’m still waiting for Steven Pinker to call the whole of physics a heap of postmodern rubbish.

(He won’t; he’s too busy appropriating its respectability.)

Today, I learned that Boghossian’s institutional review board found that his actions in the “Grievance Studies” hoax constitute research misconduct.

EDIT TO ADD: Further commentary on the ethics of academic hoaxes.

Sporadic SICs and exceptional Lie algebras

A while back, I had a bit of a sprawling conversation about certain geometrical oddities over multiple threads at the n-Category Café. I finally got organized enough to gather these notes together, incorporating edits for clarity and recording one construction I haven’t found written in the literature anywhere.

Sometimes, mathematical oddities crowd in upon one another, and the exceptions to one classification scheme reveal themselves as fellow-travelers with the exceptions to a quite different taxonomy.

UPDATE (30 March 2019): Thanks to a kind offer by John Baez, we’re going through this material step-by-step over at a blog with a community, the n-Category Café:

  • Part 1: Definitions and preliminaries
  • Part 2: Qutrits and E6
  • Part 3: The Hoggar lines, E7 and E8

"no matter how gifted, you alone cannot change the world"