Quantum uncertainty and wave-particle duality

I have always felt that Heisenberg's Uncertainty Principle was a manifestation of wave-particle duality, rather than a simple consequence of the quantum randomness.  The principle is literally a theorem in Fourier Analysis rather than a theorem in probability theory.  Recent experimental results reported by Tim Wogan in Physics World seem to provide evidence for this interpretation.  The relationship between uncertainty and wave-particle duality is not as simple as I would have thought, but nonetheless seems to be a better way to interpret it than to merely attribute it to the inherently random nature of quantum phenomena.

More evidence of the pollution of the scientific literature

DTLR has often lamented the pollution of the scientific literature by papers with flawed methodology or reporting, including bad study designs (e.g., lack of randomization in preclinical comparative studies) or bad analyses.  The inclusion of such published but flawed research has an amplifying effect when it is included in meta-analyses and systematic reviews.

Now comes a pair of news articles, one in Science by Holly Else, and the latest from Nature by Richard van Noorden, reporting that the inclusion of fake papers has even further polluted the literature and undermined such systematic reviews and meta-analyses.  This is an indictment of the existing mechanisms to fund, peer-review, and publish scientific research. 

The DTLR blog was founded partly to provide discussion of the eroded quality of the scientific literature, but it seems in the decade since its existence, the problem has only gotten worse.  And the public cannot be asked to "trust" science until scientists themselves can trust what their colleagues are doing.

What is the point of trying to do scientific research, when even the most rigorous and careful scientists will see their work published alongside flawed or even completely faked "research"?  Why are society's resources being funneled into an enterprise that is increasingly becoming a charade instead of a genuine contribution to human knowledge?

This is a very discouraging way to bring 2024 to an end!

My reading in physics biographies

My last post mentioned that I read a biography of C.-S. Wu earlier this year.  This has been part of a larger effort to start reading the biographies of notable physicists, which I began in the summer of 2023, after watching Christopher Nolan's Oppenheimer film.  So far, here are the substantial biographies I've made it through, in chronological order:

• Robert Oppenheimer:  A Life Inside the Center, by Ray Monk (Doubleday, 2012).

• Galileo: Decisive Innovator, by Michael Sharratt (Blackwell, 1994).
  
• Einstein:  His Life and Universe, by Water Isaacson (Simon & Schuster, 2007).
• Jean D'Alembert:  Science and the Enlightenment, by Thomas L. Hankins (Oxford University Press, 1970).
• The Man Who Changed Everything:  The Life of James Clerk Maxwell, by Basil Mahon (Wiley, 2004).
• Madame Wu Chien-Shiung:  The First Lady of Physics Research, by Chiang Tsai-Chien (World Scientific, 2014).

In addition, I read the following short biographies, again in chronological order:

• Isaac Newton, by James Gleick (Pantheon, 2003).
  
• Michael Faraday:  A Very Short Introduction, by Frank James (Oxford University Press, 2010).

• Niels Bohr:  A Very Short Introduction, by J. L. Heilbron (Oxford University Press, 2020).

The Bohr book was the only one so far that I've been disappointed with.

In earlier years, I've read other biographies of physicists; the ones I can remember include:

• Degrees Kelvin:  A Tale of Genius and Invention, by David Lindley (Joseph Henry Press, 2004).
• True Genius:  The Life and Science of John Bardeen, The Only Winner of Two Nobel Prizes in Physics, by Vicki Daitch and Lillian Hoddeson (Joseph Henry Press, 2002). 

I've also read the autobiographies of Max Planck and physicist-turned-quant, Emanuel Derman.

Future ambitions include tackling substantial biographies of Planck, and more on Galileo, Newton, and Maxwell.   In addition I'd like to add biographies of Leonhard Euler, A.-L. Cauchy, Lord Rayleigh, J. W. Gibbs, Lise Meitner, R.P. Feynman, and P. W. Anderson.  And ultimately I'd like to include 20th century fluid dynamicists; there exist biographies of Ludwig Prandtl, G. I. Taylor, and James Lighthill, and an autobiography of Theodore von Karman, though realistically I may only get to Prandtl and Taylor.  (I have read Iris Chang's Thread of the Silkworm, on H.S. Tsien, which I would strongly recommend.)

 

Chien-Shiung Wu

This month's issue of Physics Today features Chinese-American nuclear physicist Chien-Shiung Wu on its cover:

I was delighted to see this cover.  The article by Kam, Zhang, and Feng inside discusses Wu's "trailblazing experiments in particle physics".  Best known is her experiment confirming parity violation, which earned the theorists who proposed it, C. N. Yang and T. D. Lee, a Nobel Prize in 1957.  Many (including Yang himself) have commented that Wu should have been a co-recipient of that prize.

The authors go on to make the case that Wu's late 1949 experiment, which they say was "the first conclusive verification of photon entanglement", may also have been Nobel-worthy, given the 2022 Nobel Prize awarded to Aspect, Clauser, and Zeilinger for their work on photon entanglement and the violation of Bell's inequalities".  However, during Wu's lifetime (and well beyond, until quantum information science emerged as a viable discipline in the last decade or two) this field of physics was considered peripheral.  It is only now, in retrospect, that the importance of the work of Wu and others is being fully acknowledged.  Perhaps most unjust of all, John Stuart Bell himself should be recognized as a physicist who should have (but didn't) receive a Nobel Prize.

Earlier this year, I read a biography of Wu by Chiang Tsai-Chien, Madame Wu Chien-Shiung:  The First Lady of Physics Research (World Scientific, 2014), so Wu has been on my mind recently.  I previously blogged about her when the US Postal Service issued a stamp in her honor in 2021, and more recently in my post about the APS March Meeting in Las Vegas last year, where I attended a talk by Michelle Frank about Wu.  Frank has called attention to Wu's work on quantum entanglement in a Scientific American article in April of that year.  Wu's granddaughter, Jada Yuan, published a lovely article about her grandma in the Washington Post in 2021.  The online biographies of Frank and Yuan suggest that they are both at work on biographies of C.-S. Wu.  I think both books would be most welcome.  The Chiang biography, despite its many strengths, leaves much to be desired, and Wu deserves a more substantial biography.  She should be considered one of the titans of 20th century experimental physics.

 

Fluid Dynamics in Salt Lake City

I have blogged previously about attending the Joint Mathematics Meeting in San Diego (2018) for the first (and so far only) time, and the APS March Meeting in Las Vegas (2023), my fourth time attending that meeting.  I don't typically blog about the conferences I attend, but it behooves me to post today about one more, the APS Division of Fluid Dynamics annual meeting, which took place last week (Nov. 24-26) in Salt Lake City.  This is because fluid dynamics has been a central part of my scientific career, as well as a cornerstone of this blog.  Indeed, the Salt Lake City meeting was my sixth DFD.  My previous five have all been after I left graduate school:

• 2003:  Meadowlands, NJ.
• 2005:  Chicago, IL
• 2009:  Minneapolis, MN
• 2012:  San Diego, CA
• 2014:  San Francisco, CA

As can be seen, I had not attended DFD in exactly a decade.  Partly this is because I decided at the 2014 meeting that the APS March Meeting was probably of greater interest to me than a conference specialized in fluid mechanics, especially since the March Meeting had plenty of fluids sessions itself.  However, the March Meeting tends to be attended by physicists who do fluids; while DFD is dominated by engineers, applied mathematicians, and various Earth & planetary scientists who do fluids -- a much better representative group of this discipline. However I have found in my latter years that my interests in fluid mechanics tends towards historical, pedagogical, and foundational issues, rather than the cutting edge of research, which is what DFD showcases.  Nonetheless, attending DFD once a decade, while attending the March Meeting more often, may be quite appropriate in order to nourish my intellectual interests in physics and fluid mechanics.

Anyhow, this year's DFD was held at the Salt Palace convention center in downtown Salt Lake City.

The West Temple entrance to the Salt Palace Convention Center

I arrived on Saturday evening Nov. 23 to pick up my badge, but through a different entrance where a cheer-leading competition was taking place!  There was glitter all over the carpet, and children practicing their routines in the hallway.  I ran into a colleague in the hallway who must have seen my utterly bewildered expression, and he kindly directed me towards the DFD registration area.  Here is a shot of that part of the convention center at a calmer moment.

The DFD registration area at the Salt Palace Convention Center, as seen from near the West Temple entrance.

The meeting got going promptly at 8am Sunday morning, while the evening reception ran well into the night.  I don't think I headed back to my hotel until around 9pm that night, despite having forgotten that I had been given two free drink tickets for the reception.  (Thus I never used those tickets.)  The second morning session on Sunday featured a new "Interact" poster session, which began with one-minute flash talks by each poster presenter, followed by time for the audience to speak with the poster presenters one-on-one.  I attended the session on Rayleigh-Benard convection, which was graced by two top figures in the field:  Robert Ecke and K. R. Sreenivasan.  Unfortunately the latter's poster consisted of printouts of a recent paper published in the Journal of Fluid Mechanics, and the author did not stay very long, as I'm sure he had other people's posters in other sessions that he wanted to see.  Logistically, the flash talk portion of the session was difficult to execute gracefully, despite everyone's best efforts.  I'm not sure if this was much of an improvement over a regular poster session.

Hall C, where many of the plenary events, including the awards session, took place.

After lunch, the awards session took place in Hall C, presided over by this year's DFD chair, Peko Hosoi of MIT.  The reception, which was not a full scale banquet, took place in the exhibit hall (Hall A) at 7pm.

Entrance to Hall A, the exhibit area.

In the previous 5 DFD meetings, the reception included a real banquet.  Most memorable for me were the receptions for the 2003 and 2012 DFD meetings.  In 2003, the reception was held at Tavern on the Green, in Central Park of New York City.  Buses were provided to take us there.  I recall having conversations with Stephen W. Morris and (more briefly) Troy Shinbrot there.  At dinner I was seated with a professor and his wife, of Eastern European origin, whose names I cannot recall.  I remember the conversation turning toward the professor's son, who had pursued a non-lucrative career in avant-garde film-making.  Alas, the good professor appears to have been incredibly disappointed with his son's career choice.  He seemed to praise my contrasting choice to pursue a scientific career, albeit not one centered in academia, and not even closely related to fluid dynamics.  At the 2012 DFD reception, I befriended a French post-doc, and after dinner we went for a long walk along the marina, almost reaching the U.S.S. Midway, before turning back.  The post-doc had once worked for a technology start up, but their product, while technically quite innovative, provided only a marginal practical improvement over its existing competitors, and customers found it difficult to justify the cost (not just financial, but in requiring specialized training) to use the product.  It was a sound lesson in scientific entrepreneurship.  Eventually I began peppering him with questions about French politics and culture (this was the era of the presidencies of Monsieurs Sarkozy and Hollande).

Alas at this year's reception, I didn't have any interesting conversations at all.  I have also noticed across several conferences that I've attended this year that there are fewer exhibitors, especially book exhibitors.  Here, only SIAM and Cambridge University Press were purveying books (the latter was also promoting the Journal of Fluid Mechanics), while AIP Publishing and APS' Physical Review Fluids were hawking their journals.  I placed an order for two books with SIAM, and picked up a book (60% discount with reservation if picked up on site) from Cambridge, Joseph Powers' Mechanics of Fluids, which look to be very promising.  After returning home I placed an additional order for more Cambridge books, using the meeting 30% discount code.  I've felt for over a decade that they are the lead publisher in fluid mechanics, and I am pleased that they have not yet abandoned the conference circuit, though they may be feeling less and less competition these days.  JFM was celebrating its 1000th volume, and a commemorative brochure was distributed at the conference, which I think will be a lovely keepsake.  However, unlike the previous DFDs I've attended, there was no brochure prepared regarding the Gallery of Fluid Motion entrees.

Monday morning I mainly attended the Education and Outreach session, which featured many talks on in-class lab demos as well as alternatives to traditional textbooks.  I then attended the Fluids Education lunch, which was not clearly described ahead of time.  It turned out to be a panel discussion with lunch provided.  The table I sat at was not very talkative at all, so it wasn't a very social event, unlike the various mixers featured at other conferences I've attended this year.  Monday afternoon featured a poster session.  I zeroed in on one poster that was closely related to my graduate work from over 20 years ago, and while initially the presenters were absent, two of the authors eventually turned up, and I was able to talk to them.  There were also at least two rather controversial posters, which I will not discuss here, as they do not deserve any further attention.  (I am told that an ethics complaint was filed with APS regarding one of them.)

That evening, attendees were invited to visit the Leonardo Museum, a few blocks away, which currently has a major exhibit on flight, as well as smaller exhibits on AI, water, and a special exhibit related to the meeting, the Traveling Gallery of Fluid Motion (TGFM).  This is the second year of the TGFM, and this year's exhibit is titled "Spiraling Upwards".  For an additional $15, we could attend a private reception welcoming the TGFM, where the artists (one was a real artist, the others were DFD researchers) each gave a few words about their works.

The Leonardo Museum in Salt Lake City.

The Leonardo Museum was quite an appropriate venue for this event, as Leonardo DaVinci, its namesake, was a keen observer of fluid motion, and he rediscovered what we call the hydraulic continuity equation, a precursor of the mass balance principle in modern fluid dynamics.

I attended additional sessions on Tuesday, though I took a long lunch break to enjoy pho at a busy downtown eatery called Tamarind, which I highly recommend!

I've been away from physics and fluid mechanics for over two decades, so unlike conferences in my current field, where I constantly run into people I know, I am very much an outsider at the March Meeting and DFD conferences.  Indeed, I met only 3 people that I knew from before at this year's DFD, though I intend to reach out to a few others whom I met there and have some professional interests with.

The 2024 Nobel Prizes in science

DTLR cannot resist opining on this year's Nobel science prizes laureates, especially when several of the non-physics laureates have physics connections, while one of the physics laureates does not.

One of the two laureates for physiology or medicine is Gary Ruvkun, whose bachelor's and Ph.D. degrees are in biophysics.  One of the three laureates for chemistry, David Baker, had done a postdoc in biophysics.  He currently has an adjunct appointment in the physics department at his university, along with four other departments aside from his home department.  A second chemistry laureate, John Jumper, had done a bachelor's degree in physics and math, and a master's in theoretical condensed matter physics, before earning a second master's and a Ph.D. both in theoretical chemistry.

It is perhaps also notable that David Baker's father was a physicist and his mother was a geophysicist.  One of the physics laureates, John Hopfield, also had two physicist parents.  

Artificial intelligence was the center of this year's physics and chemistry awards.  Two of the three chemistry laureates were awarded for AI-based protein structure prediction, for their work with AlphaFold, which is owned by Google's parent company, Alphabet.  There is little doubt that this achievement belongs to biological chemistry.  I was pleased to see a share of the award go to employees of a private sector company instead of a university, not something that happens often nowadays.

The physics prize, however, has been extremely controversial, in many cases sparking outrage and cynicism, among both physicists and non-physicists.

Let's start with the laureates themselves before discussing their achievements.  A number of commentators, including some who should know better (e.g., Sabine Hossenfelder) falsely claim that the award was not given to physicists, but to computer scientists.  This is only half true.  One of the laureates, Geoffrey Hinton, is not a physicist, by either education or employment.  He is a cognitive scientist and computer scientist.  (Apparently he is also a direct descendent of George Boole!)  The other, John Hopfield, has superb physics bona fides.  His education was in physics, he was a Buckley Prize winner for his contributions to condensed matter physics, and he is probably the greatest living biological physicist today.  It is true that he is also considered a neuroscientist and a molecular biologist.  In fact, his last academic position before retirement was on the Princeton University molecular biology faculty.  He is a titan of both physics and interdisciplinary science, though the Nobel committee focused on his work on Hopfield Networks, a model of associative memory based on statistical physics (specifically, spin glasses).  He has served as President of the APS.

Unlike many, I celebrate Hopfield's Nobel award.  Geoffrey Hinton is really the puzzle here.  The Nobel committee zeroed in on his stochastic versions of Hopfield Networks, which are called Boltzmann machines.  However, his contributions to neural networks go well beyond that:  he introduced the backpropagation algorithm and later was one of the founders of deep learning methodology.  He is just as much a titan in the neural net community as Hopfield is in the biological physics community.

The history of neural networks is long, and boasts key contributions by a number of individuals.  While Hinton in undoubtedly a key figure in this history, others have also been recognized (including by the Turing award).  Perhaps the key point for the Nobel committee was Hinton's use of statistical physics ideas for the Boltzmann machine. 

There is no doubt that neural networks are used in physics, as in so many other fields of science and engineering.  There is also no doubt that ideas from physics have influenced neural network technology, and machine learning more generally.  But are Hopfield Networks and Boltzmann machines worthy of a Nobel Prize in physics?  This is a question that was hotly debated in the days after the awards were announced.  It seems though, the debate has been lopsided, at least in the sources I've read, with few commentators being willing to defend the Nobel commitee's choice this year.  This award was a huge surprise to nearly everyone who follows the Nobel Prize news every October, including me.  I was even more shocked when the host of the Physics World podcast admitted he had never heard of John Hopfield until the announcement of the prize.

The American Physical Society, in its official new release, decided to get behind the award, but notably emphasized Hopfield as a longtime member of the APS community.  This could be read as a veiled critique of Hinton's award; as far as I know, Hinton's one contribution to the physics literature is a co-authored paper that was published in a physics conference proceedings.

In principle there are several APS units that might choose to celebrate the award to either Hopfield or both Hopfield and Hinton:  the Division of Biological Physics, the Division on Computational Physics, the Topical Group on Statistical and Nonlinear Physics, the Topical Group on Data Science, and the Forum on Industrial and Applied Physics.  However, I have seen and heard of few who have actually embraced this year's award.

This is regrettable.  I think Hopfield is deserving of the honor in the sense that James Peebles was in 2019 - a kind of lifetime career recognition.  I'm not ready to render an opinion on Geoffrey Hinton's Nobel Prize in Physics.  We need to take a step back from the knee-jerk, immediate, and highly emotional reactions.  I'm hoping some thoughtful commentators will, in the coming year, weigh in with well considered opinions.  As a physicist who has worked in machine learning (there are now many, many of us), I may choose to view this award as recognition of those working in this interdisciplinary space who actually use physics ideas, regardless of our formal education or employment in physics.

Peer Review Week 2024

Apparently we are ending this year's "Peer Review Week".  Many publishers are celebrating the work of their peer reviewers, who are typically unpaid volunteers that support the review of articles submitted to academic journals, grants proposals submitted to funding agencies, and occasionally papers submitted for presentation at conferences.

For those of us who work in non-academic institutions, like private sector or government organizations, there is often a parallel internal peer review process for employees, before they are allowed to submit to an external journal or conference.  There are notable differences between this internal peer review process and the academic reviews I refer to above; the rest of this post will focus solely on the academic sector review.

Peer review has taken a great deal of criticism in recent years.  I personally am sympathetic to the view of Adam Mastroianni, who argues that no peer review is better than (at least conventional) peer review.  Post-publication peer review (such as on PubPeer) is, for me, a preferred way for a community to assess the merits of a scientific publication.  Peer review, as conventionally practiced, does not do what it claims to do, confer an imprimatur of quality and approval upon a scientific publication.  There is no limit to the stories of terrible papers published in top journals that contain almost blindingly obvious flaws, along with excellent papers that were repeatedly rejected by outstanding journals.  A defender of peer review may argue that surely the false positive and false negative error rates must be low.  It is impossible to verify such a claim because the peer review process is shrounded in anonymity, and publishers are reluctant to release any data regarding the performance of peer review at their journals.

I don't see anything of value that pre-publication peer review actually create that cannot be duplicated, in a better way, using post-publication peer review.

A thought-provoking podcast given by Dr. Mastroianni can be found at Econtalk (along with a reference to his substack article on the topic).  I won't rehearse all his criticisms here - he does it more eloquently than I could.

One issue not addressed by him is the inclusion of ad hominem attacks on the authors of manuscripts in reviewer reports.  The U.K.'s Institute of Physics Publishing (IOPP) released last week a campaign against such unprofessional comments in peer review.  This podcast is an extremely interesting discussion of the topic, and the proactive ways IOPP is using to address it.  IOPP also rates each review they receive, and is now willing to share this feedback with reviewers who request it.  It's about time someone reviewed the reviewers!  (I may well decide to take the peer review training course offered by IOPP if time allows.)

I've been on both sides of peer review on many occasions.  I've had experiences where the peer review process clearly improved my manuscript, and I've had experiences where the process clearly degraded the manuscript, that is, the published version is notably worse than the original, in my not-so-humble opinion.  I've experienced a few cases where reviewers of my work have signed their reviews, i.e., revealed their identities; most of the time they are anonymous, but in a handful of cases, I believed I could guess who some of them are.  

I've also heard from others who've had their ideas stolen by peer reviewers!

On the other hand, in my highly biased opinion, every peer review I have performed for others has resulted in improvements in their manuscripts.  It is notable that every article I have ever peer reviewed has eventually been accepted for publication.  On the other hand, I've never signed a review, so I've always been anonymous to the authors I've reviewed.

Finally, in a handful of cases I've posted non-anonymous post-publicaton peer reviews on PubPeer. And sometimes when I wonder about the legitimacy of a published paper, I'll check up on it in PubPeer.  I advise readers to do the same.

Hacking Google Scholar

Finally, we enjoyed (but were dismayed by) the account given on Reese Richardson's blog about how Google Scholar can be "hacked".  Phony papers are uploaded onto ResearchGate, to boost citations to one's own (possibly equally fraudulent) papers.  There are companies offering to carry out such a citation-boosting campaign for paying customers, but Richardson shows how easily one can do it oneself.  However after he wrote about it, Google Scholar removed the fraudulent citations to the work of "Larry Richardson" (a cat), without necessarily implementing a global solution to the problem.

Predatory conferences: an expose!

Also in this week's Nature, an investigation of predatory conferences!  Journalist Christine Ro actually attended one.  Her observations are eye opening.

I get spam emails from these conferences on a weekly basis.  I've never been tempted to attend one.  I tend to go to conferences sponsored by professional societies that I know fairly well, or other established conference series.  However, as the article shows, many do not have the luxury of being as picky as I am.  Predatory conferences are basically rip-offs, of both the attendees and those who evaluate their CVs.

DTLR hereby denounces predatory conferences, and urges scientists to boycott these sham events.

More Earth Science

The June issue of Physics Today featured an interesting article by Gayen and Klocker, "Deep Convection Drives Oceanic Overturning", pointing to the inadequacy of the classical Rayleigh-Benard model of ocean convection.  This reinforces my questioning of the sincerity of those who study small aspect ratio thermal convection, when they make claims that their research is somehow relevant to real convection in planetary or stellar environments.

This month's Eos has a really nice summary of the flaws of the Colorado River Compact, by Ge et al.  Although I don't live in the Colorado River catchment, I am not far away, and this is a case study of the inevitably ugly collision of science and politics.

Speaking of which, this week Nature has a news article by Jeff Tollefson on a whistle-blower at the U.S. Geological Survey.  Unfortunately, any government bureau is necessarily politically accountable, and this leads to unavoidable clashes betweeen scientific "experts" and political authorities.  Formal whistleblower protections codified in federal law have little or no actual value in the real world. though federal employees are forced to take annual trainings on them.  It is a colossal deceit.

An Antarctic expedition

I would also like to strongly recommend a delightful article by a journalist (Sofia Moutinho) who joined a scientific expedition to Antarctica, described in the June issue of Eos.  As someone who does not routinely do field work, this piece was an intriguing glimpse at the intense tempo of operations, and extreme conditions, for such an expedition.

The debunking of superluminal neutrinos

The July issue of Significance includes an article in its "Bad Stats" series by Robert Matthews about the claim made in 2011 by experimental physicists in San Grasso, Italy, of detecting faster-than-light neutrinos from CERN.  This was the story of the OPERA experiment (Oscillation Project with Emulsion-tRacking Apparatus).  Among the literature cited by Matthews is a very good write-up on the episode by Chad Orzel, in the MIT Ptess Reader.  This article originally appeared in a 2020 book, Pseudoscience, published by MIT Press.  Orzel's piece is probably the best non-technical summary and post-mortem of the incident that I've run across - a keeper.  DTLR recommends it!

Happy Birthday, APS!

May 20 was the 125th birthday of the American Physical Society (APS).  Founded in 1899 at Columbia University, and later taking over publication of the Physical Review (founded in 1893 at Cornell University) in 1913, the society has expanded both its core early functions (conferences and journal publications) as well as added many other programs in the last century and a quarter.

I joined the APS around 1997, and its Centennial Meeting in Atlanta (1999) was the first national scientific conference I ever attended, and the first one I ever gave a talk at.  That year, the March and April meetings were combined into a grand extravaganza, with (if I recall right) well over 10,000 attendees.  I remember following (by coincidence) at least one Nobel Laureate down an escalator (J. Friedman) and recognizing others in the hallways or meeting rooms.  I presented again at the 2002 March Meeting in Indianapolis, though my findings were shot down by a very prominent scientist in the audience.  That was the second and final time I presented at an APS conference, though in later years I've attended "for fun" on my own time on several occasions, including last year.  I have also attended a number of APS section meetings, as well as the Division of Fluid Dynamics annual meetings.  I once published in an APS journal (Physical Review E), but that was during the end of my time in graduate school.

Since I have not been a practicing physicist for over two decades, I have not been an active APS member, but I am a Life Member of the parent organization and a number of its individual units.  Indeed, I have been an APS member for just over 20% of APS's own lifetime, and just over 50% of my own lifetime!  Many Happy Returns, APS!

Physics Today and fluid mechanics

Back in December, I discussed a couple recent items in Physics Today of great relevance to fluid mechanics.  I remarked that we don't get to see fluid mechanics on the cover of PT very often.  Well, lo and behold, the last couple months have proven me delightfully wrong!  The cover of the April issue featured "Fluid Dynamics of Dry Salt Lakes", referring to a "quick study" article by Beaume, Goehring, and Lasser.  It discusses a theory of groundwater convection as a possible explanation of polygonal patterns on dry lake beds ("salt polygons").  The very next month, the cover features "A Shocking Start to Stars", referring to a piece by Ceccarelli and Codella, on the role of shock waves in the interstallar medium, especially in star formation, and even in synthesizing certain precursor molecules of life itself.

However, I was personally most enthralled by another piece that also appeared in the May issue by meteorologist Tim Palmer, "The real butterfly effect and maggoty applies".  The title seems to have been taken from two earlier efforts, one coauthored by Palmer in 2019 on the real butterfly effect (published in Nonlinearity), and the other a 2002 PT Reference Frame article by Sir Michael Berry on singular limits.  Both these papers seem to have had a strong influence on this article, which mainly deals with weather predictibility, and more generally the predictability of nonlinear systems, including the limits of artificial intelligence-based prediction.  The article is very good, informative, and very readable.  I'd come across the singular limit concept in discussions of aerodynamic lift, where viscosity is the parameter that when taken to exactly zero (and not just a limit approaching zero) results in the impossibility of lift.  Reading Palmer's piece, and then Berry's, has helped me understand that there are other such examples in physics.

Another howler from Science Magazine

In my last post, I scolded the editor-in-chief of Science, Holden Thorp, for an op-ed, though I largely agreed with his conclusion.  It didn't take long for him to provoke the DTLR hornet's nest again, and this time I can't say I agree with him.  The April 11 issue features another op-ed by him, titled "Teach Philosophy of Science".  He points out the risk of the erosion of public trust in science, pointing specifically to survey results indicating that 92% of Americans "felt it important that scientists show they are 'open to changing their minds based on new evidence,' which is of course what they must do," Thorp writes.  He claims that the "history of science is a powerful narrative of this culture of self-correction" and laments that "Resetting the public's understanding of how science works will be a big job."  His proposed solution is to teach philosophy of science to undergraduate science majors!

I regard that proposed solution as a non-sequitur.  Using Thorp's own argument, I say it is the history, not the philosophy of science that should be taught.  To be honest though, when I was a young student, I was interested in history, but not the history of science.  I was busy learning the science itself.  I am much more receptive to history of science now, for the reasons Thorp suggests.  I have not found philosophy of science to be insightful or to help me think about doing science.  Earlier this year I finished reading A Philospher Looks at Science, by Nancy Cartwright.  While I admire her support for the views of Kay and King's Radical Uncertainty, her book hardly made a dent on my way of thinking about science, and how to do science, whereas Kay and King helped me substantially clarify my thinking on probability models applied to the real world.

Returning to Thorp, the bigger problem in his argument is that somehow the public will trust science more if only they understood better how scientists change their views and "self-correct".  Unfortunately the history of science has plenty of examples of abject failures as well as successes.  Consider the wholly unnecesssary resistance to such figures as Ignaz Semmelweiss (who contributed to the germ theory of disease), Dan Shechtman (discoverer of quasicrystals), and Katalin Kariko (mRNA pioneer).  Consider also the crisis of non-reproducible research that I mentioned in my last post.  Science won't self-correct if no one bothers doing the self-correcting.  There are no financial or professional incentives either to reproduce others' work, nor to do one's own work with sufficient care and sound methodology to ensure it will withstand the test of time.

At its most cynical, science is merely a self-propagating exercise in securing endless piles of grant money for "research" of limited value and interest, as noted in this recent video by Sabine Hossenfelder, who points out that it is public tax money that fuels the seemingly joyless cycle of beg, spend, and publish.  If the public saw science this way, rather than in the romanticized way Thorp imagines, would they really trust scientists enough to allow their taxes to be spent as such?  Personally I would not, and I am a scientist!

I assert that the number one thing scientists can do to increase public trust in science is to reform their own house.  Only then will they deserve public support and trust.

Digression.  I last wrote about Sabine Hossenfelder nine years ago this month.  Although in that post I largely disagreed with her on one particular topic, I've since come to admire her devastingly blunt contrarian views on physics research.  For some time, I was also a financial supporter of hers on Patreon, though I am not longer financially able to support any of the deserving people I admire on Patreon.

Science Magazine colossal hypocrisy

I could not believe my eyes when I opened the Feb. 2 issue of Science to the editorial page.  The featured op-ed, as frequently is the case, is by the current editor-in-chief, Holden Thorp, and is entitled "Earning Respect and Trust".  He discussed the Science family of journals' editorial staffs, and the lack of respect they sometimes encounter by authors of submitted manuscripts.  He rightfully defends these staffers, and insists that they be respected by lab scientists.  I wholly agree with these sentiments.  It is his method of argument that I strongly reject.

Let's look, for example, at a few sentences in the third paragraph, line by line.  First,

If anything, the challenges that science is experiencing now are not due to a lack of success in the laboratory.

That is manifestly false.  The crisis of non-reproducible research, documented for nearly 20 years now, with almost no widespread progress on reform, has been a frequent topic of discussion on DTLR, and even in the news section of Science itself.  Two of the cornerstone enablers of this crisis have been poor methodology, both in the lab and in the data analysis.  I have specifically called out previous AAAS CEO Rush Holt's similar denials that it is exactly the core activity of scientific research that is rotten; for example:  here, here, here, and here.  I won't rehash those arguments.  Holt's retirement from AAAS, the year after my posts, was greatly welcomed.  However. Holden Thorp has now revived what I will call the Holt Myth.

Next,

The notion that lab work is the only purposeful endeavor in science is obtuse and is an example of precisely what leads to the view that scientists are intellectual elites who do not value the contributions or abilities of anyone except themselves and the small group they deign to recognize as their peers.  Every time this academic hauteur is revealed to the public, confidence is lost for a simple reason--scientists like these are not inspiring the people's trust.

Now, I completely agree with this criticism!  However, he uses the term "top journal" earlier in the paragraph, not quite saying, but seemingly implying, that his journal is among the top ones.  In many fields Science certainly is considered among the top journals (e.g., see here), and he is part of the very elite he seems to be complaining about.  Authors who aim to publish in such elite journals, where novelty is prized over reproducibility, are incentivized to be sloppy and fast, rather than careful and slow.  The motto of DTLR is "Garbage In, Gospel Out":  Thorp's journal could be exhibit A of this phenomenon.  Perhaps Science and its editors should themselves take a humility pill before lecturing the rest of us on the harms of elitism.

 

 

Aerodynamic lift

It is natural to expect anyone who claims to be a physicist to be able to give a simple, intuitive explanation of aerodynamic lift, using basic principles of classical mechanics.  Unfortunately, most of the time a physicist's such explanation is misleading, over-simplified, or just plain wrong.  One of the most important reasons for this is that there is no such simple, intuitive explanation.  I recently stumbled upon a reference to this excellent 2020 Scientific American article by Ed Regis, that outlines the two main competing explanations (Bernoulli's theorem vs. Newton's third law).  However, others such as the Coanda effect, have been proposed, and are not mentioned in the article.  Nonetheless Regis' article resonated with me because he seems to give a balanced discussion while debunking some of the clearly incorrect variants of these arguments.  He also spoke with two people whose insights I regard as essential, namely, John D. Anderson and Doug McLean.  Anderson is the author of a number of widely used textbooks on relevant topics, such as Introduction to Flight, Fundamentals of Aerodynamics, Modern Compressible Flow, Computational Fluid Dynamics: The Basics with Applications, and A History of Aerodynamics.  (I own three of these books.)  McLean is a retired Boeing engineer, and author of Understanding Aerodynamics, which I recently acquired.

I became interested in the competing intuitive explanations for aerodynamic lift during my time in graduate school, in the late 1990s.  At the time I was involved in atmospheric science research.  One of the professors I worked with informed the members of his lab that Prof. Anderson had been invited to visit our university; and moreover (knowing of my interest in this topic) my professor had invited Anderson to visit our lab for a discussion on it.  It was certainly an honor, and I and at least one other student in the group asked Prof. Anderson to sign our textbooks during his visit.  At the time, I was very partial to the Newton's third law version of the explanation (and still am, though I recognize it as woefully incomplete).  Anderson struck a more neutral tone, stating that both the Bernoulli principle and Newton's second law were at work in lifting an airfoil.  Neither of them was "wrong" per se.  That discussion over 20 years ago seems compatible with the views he gives in Regis' piece.

I won't discuss the officially accepted explanations, formulated in the early 20th century, given by Kutta and Zhukovsky, for 2-dimensional flow, and by Prandtl, Lanchester, and Prandtl's students (notably Blasius) for 3-dimensional flow, here.  However I note that Falkovich (Fluid Mechanics, 2/e, Cambridge University Press, 2018) points to the importance of viscosity in these formulations.  A purely inviscid flow "produces no lift" (p. 56).  He continues, "Without friction-caused separation [of the boundary layer], birds and planes would not be able to fly."  Neither the Bernoulli principle (which is strictly only true for inviscid flows) nor the Newton's third law explanation makes any reference to boundary layer separation and nonzero circulation around the airfoil.  As Anderson says in the Regis article, there just isn't a "one-liner" explanation of aerodynamic lift.