“Science on Saturday” Goes to 11

This weekend I had the honour and privilege of being the first speaker for the 2019 Ronald E Hatcher Science on Saturday series of lectures held at, and organised by, Princeton’s PPL (Plasma Physics Laboratory).  I’ll let PPPL themselves explain what Science On Saturday is all about:

Science on Saturday is a series of lectures given by scientists, engineers, and other professionals involved in cutting-edge research. Held on Saturday mornings throughout winter, the lectures are geared toward high school students. The program draws more than 300 students, teachers, parents, and community members. Topics are selected from a variety of disciplines.

Named after the late Ronald E Hatcher, who ran and hosted the series for many years, Science on Saturday is a fun way to bring physics (and other lesser sciences) to the general public(s) and other scientists alike. I was bowled over by the enthusiasm and engagement of the audience, who braved a bracing Saturday morning to hear about the connections between Sabbath, Stryper, and Schrödinger.  (The free bagels and coffee before the talk were, I’m sure, not entirely incidental in attracting the audience. I certainly can vouch for the quality of the pre-lecture consumables.) The Q&A session at the end ran for over an hour, with many insightful questions from the audience, whose age range seemed to span ~ 9 to 90 years young!

A number of those who were in the audience e-mailed me after the talk to ask for a copy of the slides. I’ve uploaded them to SlideShare (sans videos, regrettably) to make them publicly available here:


Andrew Zwicker has been the energetic and entertaining host for Science on Saturday for, if I recall correctly, more years than he cares to remember. In parallel with his career in physics, Andrew has successfully forayed into politics, as outlined at his Wikipedia page. Before the lecture he told me about an exciting scheme to encourage more early career researchers into politics. I thoroughly understand the reticence of many scientists to get involved with the political sphere — my involvement with the Royal Society MP-Scientist pairing scheme a number of years ago was an eye-opener in terms of the mismatch that can exist between political and scientific mindsets — but we need to bite the bullet and dive in*, especially in an era when hard scientific evidence is so readily dismissed as “fake news”. (Apologies. Make that “FAKE NEWS” and add any number of exclamation marks to taste.)

On the day of my Science on Saturday lecture, a white supremacist march had been mooted to be held in Princeton (not the most likely of venues, it fortunately has to be said, for that type of hatemongering.) In the end, the basement dwellers never turned up — they claimed that it was a hoax. But the counter-protesters attended in their heart-warming hundreds…

I’d like to offer a very big thank you both to Andrew for the invitation to speak at “Science on Saturday” and to DeeDee Ortiz, the Program Manager for Science Education at PPPL, for organising the visit. A similarly massive thank you to Lori for all of her help and organisation, including providing the key musical “props” used during the lecture.

*Excuse the mixed metaphor. I love mixed metaphors. This, taken from Leon Lederman’s “The God Particle” as an example of writing by one of his PhD students, is my very favourite: “This field of physics is so virginal that no human eyeball has ever set foot in it.” (That quote tickles me so much that I use it as part of the introduction to the final year Politics, Perception, and Philosophy of Physics  module here at Nottingham.)

A graphic depiction of nanotech

Far back in the mists of time — well, towards the tail end of 2015 — I wrote a post for the Making Science Public (MSciP) blog on just why I had done a rather embarrassing U-turn regarding the “Pathways To Impact” [1] statement that is required for every grant proposal submitted to the UK research councils. You can read the full confession here but, in a nutshell, I was very happy to eat humble pie in this case: a grant application for which the Pathways… statement focused exclusively on public engagement (with nary a whiff of commercial appeal or application) was funded.

A major component of that particular Pathways To Impact statement is the commitment to produce a graphic novel stemming from our research. Over at MSciP, my colleague and friend Brigitte Nerlich has been tracking the development of the graphic novel in question, Open Day — the result of a collaboration between Brigitte, the Nottingham Nanoscience Group, and the exceptionally talented duo of Charli Vince and Shey Hargreaves. (I’ve got to stress that the collaboration is very uneven indeed, with Charli and Shey providing both 99% of the inspiration and 99% of the hard graft necessary to bring Open Day to fruition.)

If you want to find out more about how Charli brought Kim, Radhika, and the fluorescent feline below to life (and death…), take a look at the fascinating Open Day: Planning, Talking, and Inking over at Charli’s blog.


[1] Follow that link and you’ll see that the research councils’ primary criterion is “research excellence”. Of course it is.

A Patter of Podcasts*

* Following extensive research — the best part of three whole minutes on Google — there shockingly appears not to be a collective noun for podcasts. Henceforth, I’m using “patter”. Given at least one OED definition of the word, I think it fits.

I’ve been very fortunate — if I were a religious man, I’d say “blessed” — to have had the support of not only the fantastic marketing team at Ben Bella (including, in particular, Lindsay Marshall) but a number of colleagues and friends when it comes to “plugging” that book I’ve recently written.

I don’t want to turn Symptoms… into a series of adverts for ‘Uncertainty to 11′ — and I won’t. Promise. I’ve got a stack of non-book-related posts coming up if I can ever find time — but I’ve done a series of podcasts and interviews recently that I’ve enjoyed so much I wanted to say a public thank you to all those involved (including Lindsay for setting up and coordinating the majority.) I’ve already blogged about The Aussie Pink Floyd pinkcast and The Death Hangout, and there are a few other podcasts to be uploaded/broadcast in future that I’ll blog about (briefly) in due course, but for now…

The Unmade Podcast

Unmade…” is the brainchild of Brady Haran, with whom I’ve worked just a little over the last decade or so, and Tim Hein. The premise is that they chat about ideas for podcasts that might get made, but probably never will. Occasionally, they invite a guest or two on to join in the conversation and come up with their own ideas for podcast themes. Not only did Brady and Tim let me do that — although, as I noted in the podcast, I can’t claim credit for all of the suggestions I made — but they very kindly let me waffle on at length about that bloody book…


Although the Ikonokast podcast with Greg Laden and his co-host Mike Haubrich started off on that Spinal Tap-inspired theme, we diverged from there quite quickly and chatted about a much broader variety of academic (and non-academic) concerns than just the metal-quantum interface…

Coincidentally, that piece of metal that opens up the Ikonokast conversation (and closes the Unmade podcast) is something called The Root Of All Things that I recorded a while ago as background music for a video. I’m hoping to find time to expand this short piece, with the help of a few musician (and scientist-cum-musician) friends, to a full-blown nano-themed sci-fi metal track over the course of the next year or so. (After all, there’s EPSRC funding to do so.) For now, however, that piece has found its place as backing music for some of Pete McPartlan’s wonderfully quirky animations and art…

The Quantum Podcast

height_90_width_90_15817639_1066803776798865_1271 The Uncertainty Principle and Metal

Maria, the host, is a second year undergraduate physics student who explains a variety of topics covered in her degree via her podcast. We had a fun time discussing everything from Devin Townsend to string theory and the state-of-the-art in theoretical physics. The latter is a theme I’m going to return to very soon here at Symptoms… (and elsewhere) in the context of Sabine Hossenfelder‘s impassioned, sharp, and brilliant critique of the state of 21st century physics, “Lost In Math“. If you have any interest at all in physics, you owe it to yourself to go get Hossenfelder’s book.


I spent most of this podcast trying to stop laughing. Byrne and Wade, your genial hosts, are both very funny guys. Unfortunately, when tasked, I failed spectacularly to come up with a musician joke on the spot. Usually I fall back on one of the drummer classics — “How can you tell a drummer’s at the door? The knocking speeds up” — but it was clearly too early in the morning and/or insufficient caffeine had been imbibed.

A big thank-you to Brady, Tim, Greg, Mike, Maria, Byrne, and Wade for the invitation to join them for a natter.

100% Genuine Universe Splitter

For the one-time, knock-down price of $1.99, you too can have your own Universe Splitter™. On your iPhone. In one universe or another…


Be mindful of the small-print at that website, though:  “*According to prevailing quantum theory. Universes cannot contact each other. Not responsible for user’s actions.”

[Hat-tip to Adam Sweetman for alerting me to this important new technological breakthrough. Thanks, Adam. Now I need never dither again…]

We’re flattered, but enough of the physics envy. It’s embarrassing us all.

A couple of days ago in the Guardian, Timothy Garton Ash highlighted how economics has been dangerously led astray by the baseless assumption that it’s a “hard” science like physics: When economists ignore the human factor, we all pay the price. It’s a convincing and compelling argument, and Garton Ash’s admonition of economists aspiring to the “status, certainty and predictability of physics” should be on the required reading list for all those who study and teach the dismal science.

This misplaced aspiration to reduce exceptionally complex, human issues to simplistic mathematical models, and to adopt the methodology and mindset of the physicist when it’s far from appropriate, is, however, widespread. Physics envy extends well beyond the confines of economics: the green-eyed monster is hardly a stranger in other social sciences. I’m not about to revisit the science wars  — nor am I about to loftily suggest that physics (and, more generally, the physical sciences) is purer-than-pure when it comes to peer review or its ability to sniff out a hoax — but Garton Ash’s article appeared just as I had finished reading a very recent, highly lauded, and exceptionally frustrating example of the misapplication of physics concepts in social science. It seems that, twenty years on from Sokal’s hoax, the social sciences still too often remain in thrall to their physical counterparts.

I can’t quite remember where I first read about Alexander Wendt‘s book, “Quantum Mind and Social Science: Unifying Physical and Social Ontology” but I suspect it was via Twitter (before I retired my account). It’s published by Cambridge University Press (so it’s got their imprimatur of adademic quality), and the reviews at their website are glowing: “a book of speculative grand theorising that is sadly lacking in the social sciences today”; “For most social scientists, all that Wendt takes us through will be a revelation. Wendt’s discussion of this material is just fabulous,”; “The author takes a courageous stance on a number of deep and difficult issues in philosophy of mind.”

Despite the title, I tried to give Wendt’s book the benefit of the doubt. I really did. And, to be fair, at times he does a fairly good job of outlining the history, the underpinnings, and the philosophical ramifications of quantum physics, including such challenging aspects as Bell’s inequalities, the EPR paradox, and entanglement. But there’s this right at the start of the book (p.3):

In this book I explore the possibility that this foundational assumption of social science [that we live in a world of classical physics] is a mistake, by re-reading social science “through the quantum”. More specifically, I argue that human beings and therefore social life exhibit quantum coherence — in effect that we are walking wave functions. I intend the argument not as as an analogy of metaphor, but as a realist claim about what people really are“. (Emphasis mine).


Just no.

This, the central theme of Wendt’s book (which runs to 293 pages excluding references), is demonstrably incorrect. We are not phase-coherent wavefunctions. Phase coherent interference of quantum mechanical pathways is the bedrock of quantum physics. As Feynman put it in the context of the double slit experiment: “We choose to examine a phenomenon which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery.

If we were indeed walking wavefunctions then all of those quantum mechanical effects that we see at the single particle level would apply to our macroscopic world. And they clearly don’t. One of the very first concepts that physics undergrads (or, indeed, physics A-level students) encounter in their study of quantum mechanics is the de Broglie wavelength. There’s an exceptionally  simple relationship between the quantum mechanical wavelength of a particle/object (λ) and its momentum (p) which goes like this:

λ = h/p

where is Planck’s constant. (Apologies to the physicists who may be reading. You might want to skip forward a bit. There’s a ranty bit towards the end). For a typical human at typical walking speeds, that wavelength is not just negligibly small, it’s utterly beyond negligibly small. I’ll leave you to do the sums. (I’ll note in passing that “de Broglie wavelength” is not an entry in the index of Wendt’s book).

If we were walking wavefunctions of the type Wendt proposes then we would see the same type of interference effects in our everyday life that happen at the single particle level. We would diffract when we walk through doorways. We would be able to tunnel through walls without expending any energy. That blasted cat would indeed be simultaneously dead and alive.

(Edit 07/02/16:: I should clarify that even if humans were phase-coherent wavefunctions, and all other physics remained the same, the probability for tunnelling through a wall would still be unimaginably tiny. However, it’s clear from Wendt’s arguments that all other physics wouldn’t remain the same…)

But we don’t, and it isn’t. And the reason we don’t is exceptionally simple: we live in a world of classical physics. Wendt disputes this: “It has long been assumed that quantum effects wash out statistically, leaving the decohered world described by classical physics as an adequate approximation of macroscopic reality“.  But it’s not an assumption — it’s demonstrably the case that quantum effects “wash out statistically” as the system size/degrees of freedom/temperature increase. A vast amount of experimental data (coupled with an extremely well-developed mathematical framework) clearly shows this. No assumption necessary — there’s oodles of exceptionally strong evidence that demonstrates that human beings do not behave like quantum particles.

Moreover, we spend a great deal of time in undergraduate lectures teaching students to take the appropriate limit so that a quantum problem reduces to the classical situation (or a relativistic problem reduces to a classical scenario). One illuminating example is the case of Planck’s formula for the average energy per mode of blackbody radiation (to which Wendt refers on p.44 of his book) — this reduces to the classical formula (which is simply kT) in the appropriate limit(s). It is beyond misleading to suggest that it is only an “assumption” that quantum effects are washed out in the macroscopic world. There’s enough quantum woo out there from the likes of Deepak Chopra without accomplished academics such as Wendt (and prestigious academic publishers such as Cambridge University Press) adding to it.

Social science is important – it provides key insights into human behaviour and addresses questions that are beyond the scope of the physical sciences. I enjoy interacting and collaborating with my colleagues in social science both at Nottingham and elsewhere and gain a great deal from our discussions. But I’ll be brutally honest. I know for a fact that there are many in the “hard” sciences (and elsewhere) who would argue that the funding of social science is a waste of money and that it could be much better spent elsewhere. Misappropriating ideas from quantum mechanics in an attempt to ride on the coat-tails of the (highly successful) intellectual framework underpinning physics does social science no favours at all.

We physicists still don’t understand what the vast majority of the universe is made up of. So don’t envy us — pity us. And try to follow xkcd’s advice the next time you see “quantum” used outside a physics context…

When scientists help to sell pseudoscience: The many worlds of woo

…or, as Peter Coles suggested, The Empirical Strikes Back

Until a couple of weeks ago, I was blissfully unaware that there was a secret out there that had the potential to change my life forever. I could do anything, be anything, get anything I so desired… if I only knew The Secret. Despite my hitherto abject ignorance, it’s not a particularly well-kept secret: millions know about it — and its universal law of attraction guiding ‘principle’ — largely due to Oprah Winfrey’s glowing and gushing endorsement.

Nor is The Secret anything new. The film which first gave it away was released nearly a decade ago. Like the best memes, however, its rate of infection continues to grow. Googling “The Law of Attraction” gives millions upon millions of hits, and counting.

I found out about The Secret via Tim Brownson and Olivier Larvor, both mentioned in my previous post, and with whom I had a fun and expletive-fuelled discussion for their Raw Voices podcast last Friday. We chatted about the regular claim made by ‘Law of Attraction’ gurus — who make a nice little earner out of selling their ‘expertise’ — that quantum physics is at the heart of The Secret.  (I’ll add a link to the podcast when it becomes available. Edit 31/08/2015. The podcast is here.)

So what is The Secret? Well, it’s nothing more than the idea that if you think positive thoughts, good things will happen to you. The rather vile converse tenet is also part of The Secret: anything bad that happens to you is simply because you’re not thinking enough good thoughts. The law of attraction is just another way of expressing The Secret: if you think those good thoughts and click your heels together three times, you’ll attract good stuff to you. (Quite whether it’s an inverse square law has not yet been ascertained.)

Where does the quantum physics come in? I’ll let Rhonda Byrne, author of The Secret, enlighten you by way of a few quotes from her book:

The law of attraction is the law of creation. Quantum physicists tell us that the entire Universe emerged from thought.

Your thoughts determine your frequency, and your feelings tell you immediately what frequency you are on.

The law of attraction is a law of nature. It is as impartial and impersonal as the law of gravity is.

How it will happen, how the Universe will bring it to you, is not your concern or job. Allow the Universe to do it for you.

The Universe offers all things to all people through the law of attraction.

It’s easy and cathartic, of course, to rant about the anti-scientific nature of this type of delusional woo and to bemoan the extent to which our culture celebrates irrationality and “mysticism”. As Toby Young pointed out in an article celebrating the end of Oprah Winfrey’s chat show,

Above all, it is Oprah’s incontinent sentimentality that I find so objectionable, the elevation of ersatz emotion over any critical thought. For Oprah, the only test of veracity worth the name is whether something “feels” true, as though our initial emotional response to something – whether a prospective lover, a spiritual belief system or a political leader – is a more reliable guide than a careful sifting of the evidence.

This elevation of what “feels true” above cold, hard, impersonal evidence is, of course, why Oprah was such a fan of “The Secret”. Nonetheless, a central credo of Byrne’s books — and of the extremely lucrative legions of woo they have inspired — is that the “law of attraction” is grounded in science. This claim lends The Secret an air of credibility by effectively exploiting the classic argument from authority fallacy: if quantum physicists say there’s something in it, then Byrne must be onto something. (There’s a fascinating type of cognitive dissonance at play here, however, in that when scientists deign to criticise The Secret they’re of course told by Byrne’s acolytes that science doesn’t know everything).

It’s always fun for us scientists to get on our high horse and loudly berate Byrne, Deepak Chopra, Robert Lanza, and the many and varied other purveyors of woo for their lack of understanding of science, and of quantum physics in particular.

But we’re a big part of the problem.

Compare Byrne’s claim,

The law of attraction is the law of creation. Quantum physicists tell us that the entire Universe emerged from thought. 


“[T]he atoms or elementary particles themselves are not real; they form a world of potentialities or possibilities rather than one of things or facts.” Werner Heisenberg

“In the beginning there were only probabilities. The universe could only come into existence if someone observed it. It does not matter that the observers turned up several billion years later. The universe exists because we are aware of it.” Martin Rees (from The Anthropic Universe, New Scientist (August 1987))

We now know that the moon is demonstrably not there when nobody looks. N. David Mermin (The Journal of Philosophy 78, 397 (1981))

“It was not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to consciousness.”  Eugene Wigner

We have reversed the usual classical notion that the independent ‘elementary parts’ of the world are the fundamental reality, and that the various systems are merely particular contingent forms and arrangements of these parts. Rather, we say that inseparable quantum interconnectedness of the whole universe is the fundamental reality…  (David Bohm, quoted in The Tao Of Physics, Fritjof Capra (1975))

Can we really blame Byrne, Chopra, et al. for promoting the idea that we’re all part of one interconnected universe, whose structure/reality we influence with our thoughts, when not only popular science books/magazines, but the scientific literature, are awash with statements like those above? After all, the preceding list of quotes is from a set of highly respected physicists who have made huge contributions to our understanding of the universe. Moreover, when we lesser scientists speak about quantum physics to the wider public(s) we’ll often quote those luminaries and talk up the more ‘fantastical’ elements of the theory.

I suspect that there are physicists who would immediately baulk at my use of “fantastical” and would point out that we live in a world that is essentially quantum. I beg to differ. The world around us is indeed the result of literally countless quantum events. But the quantum weirdness is washed out precisely because of the uncountable and uncontrollable combinations of those unthinkably large numbers of quantum events.

We live in a world of classical physics. While this, on the face of it, is a statement of the bleeding obvious, those of us involved in communicating science need to be a little more upfront about it.  Yes, of course quantum theory is the jewel in the crown of science (at least from this lowly “squalid state” physicist’s perspective), underpinning the structure and behaviour of all matter. And, yes, there are of course fascinating, unsettling (to some more than others), and complicated connections between information theory and quantum theory at the most fundamental level. For what it’s worth, I’m of the opinion that there’s a lot to be said for Anton Zeilinger‘s interpretation of the “message of the quantum“:

…the distinction between reality and our knowledge of reality, between reality and information, cannot be made. There is no way to refer to reality without using the information we have about it.

…but we have to realise that for the macroscopic systems all around us every day, there are immeasurably many ways that information can ‘leak out’. Everything around us — the walls of my office, the trees I can see through my window, the pizza I had for lunch, the nitrogen and oxygen molecules in the air I’m breathing — is an “observer”. Consciousness not required. That long-suffering and infuriating feline is observed long before the box is opened.

Debates regarding the ontological vs epistemological aspects of the wavefunction (and its associated ‘collapse’, if you subscribe to the Copenhagen interpretation) continue to rage. This, by Matt Leifer, is by far the best review I’ve read on the question of the ontic vs epistemic nature of the wavefunction. I enthusiastically recommend Leifer’s paper for key insights into the “state of the nation” when it comes to the fundamental interpretations of quantum mechanics. (His blog posts are also well worth reading).

John Stewart Bell, whose contributions to quantum theory have been lauded — although not by some — as “the most profound discovery in science“, was rather scathing about what he called the FAPP (“for all practical purposes”) principle. This was, in effect, his equivalent of the “shut up and calculate” dictum (traditionally attributed to Feynman but possibly (probably?) originally due to David Mermin) . He made arguments both against FAPP and in support of treating all of the universe on an equal quantum mechanical footing in his classic Against Measurement article back in 1990:

Is it not good to know what follows from what, even if it is not really necessary FAPP?

In the beginning natural philosophers tried to understand the world around them. Trying to do that they hit upon the great idea of contriving artificially simple situations in which the number of factors involved is reduced to a minimum. Divide and conquer. Experimental science was born. But experiment is a tool. The aim remains: to understand the world. To restrict quantum mechanics to be exclusively about piddling laboratory operations is to betray the great enterprise. A serious formulation will not exclude the big world outside the laboratory.

But there’s no getting away from the fact that “the big world outside the laboratorydoes behave very differently from those “piddling laboratory operations” designed to test the fundamentals of quantum mechanics. In the headlong rush of excitement brought about by the inherent weirdness/counter-intuitiveness of quantum mechanics we too often gloss over this when explaining quantum mechanics to a non-scientific audience (or to a scientific audience unfamiliar with the minutiae of quantum physics). Put bluntly, it doesn’t matter how many times you attempt to repeat the double slit experiment at a macroscopic scale by firing marbles at a couple of slots cut in a piece of cardboard — you’re not going to see the appearance of an interference pattern.

While physicists and philosophers continue to debate the reasons for this lack of “quantumness” on macroscopic scales — including the extent to which decoherence explains the loss of the interference pattern — the empirical observation is simply this: coherent interference, the bedrock of quantum weirdness, is not realised for macroscopic objects in the everyday world.

Zeilinger, Arndt and co-workers (including, at one time, my colleague now here at Nottingham, Lucia Hackermüller) have carried out elegant — or what are perhaps better described as heroic — experiments with ever-larger quantum objects to show that interference effects are possible even for molecules as large as 6 nm in size with a mass of 6910 atomic mass units. In a particularly impressive piece of work whose results were published in 2012, Juffman and co-workers imaged the molecule-by-molecule build up of a quantum interference pattern for two types of phthalocyanine molecule, namely PcH2 (C32H18N8, 58 atoms with a mass of 514 amu), and its larger fluorinated counterpart F24PcH2 (C48H26F24N8O8,F24PcH2, 114 atoms, mass 1298 amu). Here’s a video of the formation of a molecular interference pattern a molecule at a time:

…and here’s a comparison of the interference patterns formed by (a) the smaller and (b) larger molecules.


Despite the remarkable level of experimental control achieved by Juffman et al., the visibility of the interference pattern for the larger molecule is much weaker due to the contribution of an incoherent background arising from the size of the source of the molecules and the molecular velocity distribution. 1298 amu is about 22 orders of magnitude smaller than the mass of a marble. (You can add another three orders of magnitude for the mass of the average human being). When decoherence is an issue for particles which are 1298 amu in size and contained in an exceptionally well-controlled experimental environment, it’s clear just why coherent quantum interference isn’t a feature of the macroscopic world.

This simple absence of quantum interference for everyday objects is enough, by itself, to entirely debunk the claims of Byrne, Chopra, Lanza and other woo-meisters. When was the last time they diffracted when walking through a doorway?

It’s no Secret: we live in a classical world.

Before I stumble to the end of this long-winded post, I want to tackle — as briefly as possible — two other frustrating aspects of quantum woo that, again, we physicists have perhaps not always done enough to counter. The first is the idea of the “holistic” interconnected universe, as described by Bohm in that quote above: “…inseparable quantum interconnectedness of the whole universe is the fundamental reality…”.

In one technical, and entirely unmeasurable, sense, as you read this your electrons are indeed entangled with mine. And they’re entangled with those of every animal, mineral, and vegetable on the planet. And with those of any small, blue, furry alien species yet to be discovered. As I’ve discussed in a previous post, this coupling arises in quantum theory because, in essence, there’s no such thing as complete, perfect confinement of an electron (or any other particle).

But this predicted coupling between electrons in two human beings in the same room, let alone on different sides of the globe, is so mind-bogglingly tiny — smaller than the smallest thing ever, and then some — that it has zero influence on anything we measure or could ever hope to measure. FAPP, there is no coupling at all (and that’s why we can treat the Pauli exclusion principle for electrons in a particular atom without ever having to worry about all the other atoms in the universe).

Here I disagree fundamentally with Bell in that I’m soundly of the opinion that the distinction between “practice” and “principle” is absolutely key to the science we can do and, in particular, how we explain that science to various audiences. It therefore impinges directly on the questions about the nature of reality we can address. That’s because I’m a cynical old experimentalist who has too often seen beautiful theoretical predictions (from that most powerful of tools in the condensed matter theorist’s toolbox, density functional theory) shot down in flames because of an ugly experimental result. Thus begins a process of rehabilitating and tweaking the theoretical methods: “Oh, we just need to use a different functional…The exchange-correlation term isn’t quite cutting it…The dispersion interactions aren’t accounted for…There’s an issue due to basis set superposition we need to address…“.

That type of feedback between experimental measurement (or observation) and theoretical calculation is absolutely central to science. I was therefore gobsmacked by claims last year that we’re supposedly entering a world of “post-empirical science“,  and was very happy to see those claims promptly and elegantly rebutted by Sabine Hossenfelder. If there’s anything that will help promote the further rise of outlandish woo, it’s a move by scientists towards the idea that claims about the nature of the universe don’t need to be supported by observation, data, or evidence; that the “internal consistency” or elegance of a theory is good enough for it to be accepted. Beauty is merely in the eye of the beholder.

If it disagrees with experiment, it’s wrong. In that simple statement is the key to science. It doesn’t make any difference how beautiful your guess is, it doesn’t matter how smart you are who made the guess, or what his name is… If it disagrees with experiment, it’s wrong. That’s all there is to it.

That was Feynman, of course, on the scientific method. Lest we forget.

Coupled with this rather hubristic notion of “post-empirical” science is the related troublesome confusion, as highlighted by Peter Coles, between the map and the territory. A mathematical model is exactly that — a model. We will further bolster the “woo age” movement if we start mistaking a mathematical model, i.e. the map, with the territory of reality. So, for example, while I can entirely appreciate just why Sean Carroll and others are rather wedded to the many-worlds interpretation (MWI) of quantum mechanics, claims that the MWI is “probably correct“, for reasons including that it has the smallest number of postulates compared to any other breed of QM, leave me cold. Why is the most accurate theory necessarily the most elegant or the most “compact” in its postulates? I seem to hear the distant sound of bongos being beaten in frustration…

Similarly, there’s an argument justifying the “reality” of the many worlds of the MWI that goes something along the lines of — if you’ll excuse the paraphrasing of Mr. Adams — “Hilbert space is big. Very big. You just won’t believe how vastly, hugely, mind-bogglingly big it is.”. But an infinite dimensional Hilbert space is a mathematical construct. And a state in that infinite dimensional Hilbert space, or, indeed, in any finite dimensional Hilbert space we might consider, is not a physical entity. It’s a model. As Eric Scerri memorably pointed out over fifteen years ago in the context of claims that electron orbitals had been experimentally observed, a state in Hilbert space is about as real as the Cartesian x,y,z axes we use to model problems in classical physics. (This is not to say that I don’t see some of the attractions of the MWI over the traditional Copenhagen approach; Carroll does an impressive job of laying out the MWI’s virtues. Nonetheless, I remain unconvinced by Carroll’s stance on the issue of testability and share Chad Orzel’s agnosticism regarding the various ontic vs epistemic interpretations of quantum mechanics.)

What really matters when it comes to stemming the steady flow of woo, however, is that none of this quantum weirdness has any influence at all on how we live our lives. When we communicate science to a diverse audience we need to spend a little less time exploiting the “Wow. Quantum. Physics.” factor — and I’m certainly hardly blameless here — and explain carefully why classical physics holds sway in the world around us.

If we don’t, we could very well be adding our own small quantum of woo to the spread of pseudoscience.