Tuesday, November 25, 2014

Writing style, "grand visions", and impact

It's hard for me to believe that over eight years (!) have passed since I wrote this.  Recently I've been thinking about this again.  When writing proposals, it's clearly important to articulate a Big Picture vision - why are you working on a problem, where does that problem fit in the scheme of things, and what would the consequences be if you achieved your goals?  Some people's writing styles tilt more in this direction (e.g., our team is smart and highly accomplished, and we have a grand vision of a world set free by room temperature superconductors - this path will lead us there) and others lean more toward the concrete (e.g., our team is smart and highly accomplished, and we've thought carefully about an important problem - here is what we are going to do in some detail, what the challenges are, and what it will mean).  I tend to lean toward the latter.  It's not that I lack a grand vision - I'd just rather underpromise and overperform.  Still, it's clear that this doesn't always pay dividends.  (Of course, the best of all possible worlds is to promise a grand vision and actually achieve it, but that's extremely rare.)

Sunday, November 16, 2014

Beautiful mechanical design, + excellent outreach

Yesterday I came across this video series, put up by "EngineerGuy" Bill Hammack.   It shows a mechanical analog computer originally designed by Michelson for building up Fourier series (sums of sinusoids) of up to twenty integer multiples of a fundamental frequency.   Moreover, you could use this machine to go backwards, and mechanically do Fourier decomposition of periodic waveforms.  It's really wonderful.  I would love to have one to use as a teaching tool, and I'm sure some enterprising person will figure out how to 3d print all the relevant parts (except the springs and cables), or perhaps build one out of Lego.

I also wanted to point out Hammack's other videos.  This is great outreach - really accessible, clear, well-produced content.

Friday, November 14, 2014

Chapter epigraphs from my book

Because of the vagaries of British copyright law and their lack of the concept of "fair use", I am not allowed to use clever little quotes to start the chapters of my nano textbook unless I have explicit permission from the person or their estate.  Rather than chasing those, I've sacrificed the quotes (with one exception, which I won't reveal here - you'll have to buy the book).  However, on my blog I'm free to display these quotes, so here they are.

• "I would like to describe a field, in which little has been done, but in which an enormous amount can be done in principle. This field is not quite the same as the others in that it will not tell us much of fundamental physics (in the sense of, “What are the strange particles?”) but it is more like solid-state physics in the sense that it might tell us much of great interest about the strange phenomena that occur in complex situations. Furthermore, a point that is most important is that it would have an enormous number of technical applications. What I want to talk about is the problem of manipulating and controlling things on a small scale."  - Richard Feynman, "There's Plenty of Room at the Bottom" lecture, Engineering and Science 23, 22 (1960)
• "More is different." - Phil Anderson, Science 177, 393 (1972).
• "Solid state I don’t like, even though I started it." - Wolfgang Pauli, from AIP's oral history project
• "How do we write small? ... We have no standard technique to do this now, but let me argue that it’s not as difficult as it first appears to be." - Richard Feynman, "There's Plenty of Room at the Bottom" lecture, Engineering and Science 23, 22 (1960)
• "God made solids, but surfaces were the work of the devil." - Wolfgang Pauli,  quoted in Growth, Dissolution, and Pattern Formation in Geosystems (1999) by Bjørn Jamtveit and Paul Meakin, p. 291.
• "The importance of the infinitely little is incalculable." - Dr. Joseph Bell, 1892 introduction to Arthur Conan Doyle's A Study in Scarlet
• "Magnetism, as you recall from physics class, is a powerful force that causes certain items to be attracted to refrigerators." - Dave Barry, 1997
• "If I were creating the world I wouldn’t mess about with butterflies and daffodils. I would have started with lasers, eight o’clock, Day One!" - Evil, Time Bandits
• "Make big money!  Be a Quantum Mechanic!" - Tom Weller, Science Made Stupid (1985).
• "I am an old man now, and when I die and go to Heaven there are two matters on which I hope for enlightement. One is quantum electrodynamics and the other is the turbulent motion of fluids. And about the former I am rather more optimistic." - Horace Lamb, 1932 address to the British Association for the Advancement of Science, as cited in Eames, I., and J. B. Flor. "New developments in understanding interfacial processes in turbulent flows." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369.1937 (2011): 702-705
• "Almost all aspects of life are engineered at the molecular level, and without understanding molecules we can only have a very sketchy understanding of life itself." - Francis Crick, What Mad Pursuit: A Personal View of Scientific Discovery (1988), p. 61
• "Be a scientist, save the world!" - Rick Smalley

Thursday, November 06, 2014

Refereeing redux.

"I would like to see a post addressing how to handle a paper sent back by the editor for another round of reviews. Of particular interest to me: what do you do if you notice errors that escaped notice (or weren't present) in the original manuscript? What if the authors answered your issues well in the response letter, but didn't include those modifications in the manuscript? What advice would you have if the authors have clearly done the experiments and theory well, and the results are worth publishing, but the writing/figures are still not at a publishable level following their revisions?"

My answers are probably what you'd guess.  I try hard to identify possible errors the first time through refereeing a paper.  If I spot something on the second round that I'd missed, I try to be clear about this by writing something like "Also, on this pass through the paper, I had the realization that [blah blah] - my apologies for not catching this on the first round, but I think it's important that this issue be addressed."  Again, I try hard not to miss things on the first pass, since I know how annoying it is from the author side to be hit with apparently new objections that could have been addressed in the first revisions.

I've definitely had cases where the authors wrote a great response and then made almost no changes to the manuscript.  In this situation, I usually say, "The response letter was very convincing/clarifying regarding these points, and I think it is important that these issues are discussed in the manuscript itself."  I would then, in the "comments to the editor" part of the report, re-emphasize this, in the hopes that the editor will push the authors about it.

If the manuscript contains good science but is written at an unpublishable level (rare, but not unheard of), I try to point this out diplomatically (e.g., "The science here is very interesting and deserving of publication, but I strongly recommend that the presentation be revamped substantially.  I think swapping the order of the figures would make the story much clearer.").  Again, to the editors, I might make more specific recommendations (e.g., "This manuscript absolutely needs to be closely edited by a native speaker of English" if it's full of truly poor grammar).

The basic strategy I follow is to try to evaluate the science and offer as useful and constructive feedback as possible (given that I can't spend tons of time on each refereeing assignment), in the kind of professional and courteous tone I'd like to read in reports on my own work.

Tuesday, November 04, 2014

"What happened to PRL?"

A commenter wrote the following:  "About PRL, I do have a concrete question. You've been around for some time, I am new in the business. Can you explain what happened to it? Twenty years ago it used to be the journal to publish in, now it is an afterthought."

Physical Review Letters remains a premier place to publish high impact physics results in letter-format (that is, typically 4-ish page papers with around 4 figures).   I think that the recently arrived editor in chief Pierre Meystre is working hard to revitalize PRL as a "destination journal" for physics results, where you know that the primary audience comprises physicists.

That being said, the origins of some of PRL's (possible) loss of cachet are immediately obvious.  Twenty years ago, Nature and Science were not as highly regarded within the physics community as places to publish.  Nature Publishing Group did not have all of its various progeny (Nature Physics, Nature Materials, Nature Nanotechnology, Nature Photonics being the four most relevant here).  Likewise, the American Chemical Society's journal offerings used to be a lot less friendly to physicists.  Now there are Nano Lett., ACS Nano, ACS Photonics, ACS Applied Materials and Interfaces.   It's a far more competitive journal marketplace, and the Phys Rev journals have been slow to innovate.  Furthermore, I think there is a broad perception that PRL's refereeing can be long, arduous, contentious, and distressingly random.  Some of the competing journals somehow are able to be rapid and on-target in terms of the expertise of the referees.  If you have a hot result, and you think that refereeing at PRL is highly likely to take a long time and require a protracted fight with referees, other alternatives have room to make inroads.

Somehow PRL needs to improve its reviewing reputation in terms of accuracy and timeliness.   That, I think, would be the best way to be more competitive.  That, and a re-design of their webpage redesign, which is neither particularly attractive or functional.

Sunday, November 02, 2014

What are skyrmions?

Skyrmions are described somewhat impenetrably here on wikipedia, and they are rather difficult beasts to summarize briefly, but I'll give it a go.  There are a number of physical systems with internal degrees of freedom that can be described mathematically by some kind of vector field.  For example, in a magnetically ordered system, this could be the local magnetization, and we can imagine assigning a little vector $\mathbf{m}$ (that you can think of as a little arrow that points in some direction) at every point in the system.  The local orientation of the vector $\mathbf{m}$ depends on position $\mathbf{r}$, and there is some energy cost for having the orientation of $\mathbf{m}$ vary between neighboring locations.   In this scenario, the lowest energy situation would be to have the direction of $\mathbf{m}$ be uniform in space.

Now, there are some configurations of $\mathbf{m}(\mathbf{r})$ that would be energetically extremely expensive, such as having $\mathbf{m}$ at one point be oppositely directed to that at the neighboring sites.  Relatively low energy configurations can be found by spreading out the changes in $\mathbf{m}$ so that they are gradual with position.  Some of these are topologically equivalent to each other, but some configurations of $\mathbf{m}$ are really topologically distinct, like a vortex pattern.  Examples of these topological excitations are shown here.   With a lone vortex, you can't trivially deform the local orientations to get rid of the vortex.  However, if you combine a vortex with an antivortex, it is possible to annihilate both.

Skyrmions (in ferromagnetis) are one kind of topological excitation of a system like this.  They are topologically nontrivial "spin textures", and in real magnetic systems they can be detected through techniques such as magnetic resonance.   It's worth noting that there are other topological defects that are possible (domain walls that can be soliton-like; defects called "cosmic strings" if they are defects in the structure of spacetime, or "line defects" if they are in nematic liquid crystals; monopoles (all arrows pointing outward from a central point) sometimes called "hedgehogs"; and other textures like the boojum (a monopole pinned to the surface of a system; relevant in liquid crystals and in superfluid 3He)).  With regard to the last of these, I highly recommend reading this article, which further cemented David Mermin as a physics and science communication idol of mine.