Meme

So, it looks like I’m part of a blog-meme. I normally wouldn’t do this, but I have some time to kill what with all this flying I’m doing (visiting grad schools). So, here goes, slightly modified…

1. Link to the person who tagged you. Done.

2. List 7 a few random things currently on your mind.

• Where should I go for grad school? I have it narrowed down to a few institutions, each of which has its own particular strengths and weaknesses - in terms of the projects I’m very excited about, equipment/facilities, funding, location, the size of the groups, the intellectual culture, etc. The spreadsheet has them dead even to within uncertainty, which means that I’ll have to keep taking data…

• Some of the research groups I’m interested in joining are quite large. This is often cited as a disadvantage, since it could translate into less “face-time” with the advisor, although to be fair - isn’t the more relevant parameter the (postdoc + senior grad student)/new student ratio rather than the faculty/new student ratio?

• Research - just thinking through the details of a number of experiments and simulations that I’m working on. The annoying thing with all this traveling is that it really punches a hole in my productivity (as well as means I’ll be missing the first half of the APS March Meeting!); but then again, talking to all these fascinating people and finding out about all the cool work going on at these different places is invaluable.

• Another thing that traveling makes difficult is staying on top of the literature. I have several tens of papers waiting to be read, and while long flights are great for plowing through them, the rate at which the to-read list grows is impressive.

• I came across this interesting NYT book review on a recent book, Intern by Sandeep Jauhar. The gist is Scrubs-ian in nature - it’s the story of a medical intern trying to deal with the imperfections of day-to-day hospital culture, the meaning of life, etc. - but what really got me was his physics background (he has a Ph.D. from Berkeley) and the analogies he makes: “Life on the wards was like the plasmons I had studied in condensed matter physics… where individual electrons, moving randomly, coalesced into something greater than the sum of their parts. There was a sort of synchronized buzz. … In the midst of this collective excitation, I kept thinking, Why am I so lonely?” Alright, so it’s kind of a stretch, but still - it’s physics.

3. Tag more people at the end of your blog and link to theirs. I’ll suggest Rod, Sam and Travis.

4. Let the tagged people know by leaving a note on their site. Done.

A few thoughts

Clearly blogging has slowed down now that I’m back into the swing of research. Here are a few minor non-research things that have transpired…

Free coffee? While attempting to read a thesis by a professor here, I came across an interesting line in the acknowledgments in which he thanked “the labours of the coffee and tea pickers whose efforts kept me awake long enough to produce this document”. Here’s a thought: athletes and celebrities receive inordinate amounts of free stuff - and of course, money - to endorse certain products (I presume). Why can’t physicists and other scientists do the same? For example, if Red Bull or La Colombe ran full-page ads in Nature along the lines of “Ed Witten drinks Red Bull - do you?” or “Andrew Wiles: turning La Colombe coffee into theorems”, I’m sure their sales would increase significantly. (I venture that no other single demographic consumes more caffeine.) And of course, they could give the individual/individual’s department free coffee and/or funding in return. It’s a win-win situation.

De Gennes dies: There’s not much I can say that hasn’t already been said (see this NYT article, for example). I’ve had the pleasure of delving into two of his books, the seminal Physics of Liquid Crystals - note to self: learn more about the connections between superconductors and liquid crystals - and the perhaps lesser-known Petit Point: A Candid Portrait on the Aberrations of Science. The latter is a rather interesting book, with very short chapters describing fictional characters based on scientific individuals. The sole reviewer of the book on Amazon claims to be able to identify Benoit Mandelbrot, Brian Josephson and Bernd Matthias in the various characters; my own hunch is that the chapter on “Chazot” is autobiographical in nature (the last line, “…in the end, Chazot’s real vocation is perhaps to give talks to high school students”, pretty much gives it away).

Blog-related: Henry Cate of the Why Home School blog is kicking off a carnival of space, which is a great idea (don’t know what a blog carnival is? See here.) Here are the archives, here is this week’s carnival, here’s the announcement, and most importantly - here’s how to submit a post for inclusion. Go for it!

And, in other news, Arunn of n0noscience and Rod of Perfectly Reasonable Deviations have both tagged me as being a ‘thinking’ blogger, which is a wonderful honor. I’m supposed to link to five other blogs that make me think, but it’s tough; the best I can do is link to the list of blogs I follow when I can since they’re all interesting.

Information theory: Cover and Thomas’ Elements of Information Theory (2nd ed.) is a really, really good book. Sadly I haven’t been able to read as much of it as I’ve wanted to, but it’s been a fascinating fusion of mathematics, physics, and computer science.

Philosophia Naturalis #8

This post was delayed by a number of ridiculous technical mishaps, but issue number eight of Philosophia Naturalis - the physics blogosphere’s very own blog carnival - is finally here. There were a number of very interesting submissions spanning pretty much everything that is involved in physics and the practice of it, and so I’ve split them up accordingly. Enjoy!

Cool Experiments
Motivated by some recent quantum optics work recording the birth and death of microwave photons in a superconducting resonant cavity by a French group, Chad Orzel has proclaimed this to be “the golden age of experimental quantum optics”. And indeed, it seems to be: two other such experiments include this study of the Hanbury-Brown-Twiss effect, and this more recent realization of the delayed-choice experiment first proposed by John Wheeler in 1978. A closely related experiment is that of the ‘quantum eraser’ proposed by Scully and Drühl in 1981, and this post does an excellent job of summarizing the general principles.

On the opposite end of the size spectrum, Cosmic Variance recently hosted a very interesting discussion on some analysis of cosmic microwave background radiation data from WMAP (NASA’s much-publicized effort to very accurately measure the temperature of the CMB).

Interesting Theory
As tends to be the case, most posts were of a more theoretical bent. The mapping of the E₈ Lie group recently received a good deal of press, including a rather vague article in the New York Times (the gist of which was something along the lines of “a bunch of mathematicians did something really complicated involving a pretty picture, and apparently it has profound implications but we’re not exactly sure what.”) Mark Chu-Carroll and John Baez have taken a different approach, recently posting about the actual math involved and the whole point of the project. And speaking of recent math-y work that has received a good deal of press, these two posts report on this paper by Peter Lu and Paul Steinhardt (who used to be at Penn!) on signatures of quasicrystalline Penrose tilings in medieval Islamic architecture.

Penrose is an excellent segway into two posts by Scott Aaronson. The first poses the question: “what’s the connection between a black hole having an event horizon and its having a singularity? In other words, once you’ve clumped enough stuff together that light can’t escape, why have you also clumped enough together to create a singularity?” (This is related to the Penrose-Hawking theorems of general relativity). The second (or rather, the subsequent comments) deals with possible connections between the brain and quantum computers, something Roger Penrose has discussed in a good deal of depth. (Matt Leifer has a similar post, asking the question: “if quantum computers are more efficient than classical ones then why didn’t our brains evolve to take advantage of quantum information processing?“)

There’s more out there, too: see, for example, this post discussing the much-storied Bayesian theorem and connections to Bell’s inequalities, or this post on ‘biophysical economics’, an economic theory rooted in biological and physical realities first put forth in the 20’s. Something that struck me as being particularly interesting was this post on the use of evolutionary algorithms in lattice QCD simulations. Meanwhile, Ponder Stibbons has been plowing through Huw Price’s book (Time’s Arrow and Archimedes’ Point) on some of the more philosophical questions of physics, with posts on Price’s objection to dynamical explanations of entropy increase (”they can never account for the asymmetry in our observations unless they themselves have asymmetric assumptions”) and a modern-day version of Olbers’ paradox.

And of course, a good deal of very interesting physics (albeit of a different sort) goes into fields of inquiry that some would consider unconventional, like geophysics. These two posts dealing with earthquakes and volcanoes touch on this to a certain extent. The latter is particularly interesting, looking into the various possible triggers for volcanoes (and drawing connections between large earthquakes and volcanic eruptions, motivated by a fictional account of Charles Darwin’s journey on The Beagle).

The Culture of Physics
Speaking of geophysics, Jennifer Oullette has written about a talk at the recent APS March Meeting on large-scale pattern formation in geological systems, citing some work by Meredith Betterton (who gave a talk here at Penn on an unrelated subject recently) on the creation of artificial spiky ice formations. (March Meeting is an event when thousands of physicists get together and tell each other about what they’re working on - held, incidentally enough, in March.) A number of people have posted about various events at March Meeting; see, for example, this other post by Jennifer Oullette, this post by Travis Hime, and this one by Doug Natelson - or see the PhysicsWeb blog.

Having huge meetings and partying like rock stars isn’t everything, though. Among other things, the physics community (just like any other) has its share of scandals, politics, marketplace tactics, things of that sort. Sabine Hossenfelder, for example, has recently blogged about the problems of treating the scientific community as a marketplace, while Julianne Dalcanton’s post on physics’ “cult of genius” definitely touched a nerve among readers. Meanwhile, Clifford Johnson has shared his views on recent events regarding an imprisoned theoretical physics grad student. (And of course, there’s the media aspect of things: John Conway recently picked up on his two previous posts on the search for the Higgs boson to blog about the unexpected media response.)

Communicating Physics
Tommaso Dorigo recently posted about some of the problems associated with the way physicists communicate things to laypeople, dealing specifically with an example from high energy physics (what is a lower limit at 95% confidence level, anyway?). At the end of the day, the physics blogosphere’s rather good with this kind of thing. For example, ‘basic concepts’ posts (like the ones mentioned in this excellent post, or this one - part of a series - on special relativity) do an excellent job. And hey, communicating physics is kind of the whole point of this blog carnival, in a sense. I think that’s where I’ll end things - hopefully it’s been interesting. Thanks to everyone who submitted either their posts or someone else’s.

Funny Journal Content

1. A candidate for the funniest journal title/paper graphic…
Here’s a cute paper: rolling a single molecular at the atomic scale. The authors look at C₄₄H₂₄, a molecule possessing two triptyene ‘wheels’ (with three ‘paddles’, each) and thus two intramolecular degrees of freedom when adsorbed on a metal surface (the independent rotation of each wheel), and push it along with an STM tip. Interestingly, the STM current is a good indicater of what kind of motion the molecule is undergoing (’rolling’ versus ‘hopping’). What I find most amusing is that the molecule was previously used to construct a ‘molecular wheelbarrow’, a result which was published in Tetrahedron Letters - probably the funniest journal title I’ve come across - and includes the following priceless graphic:

2. Can a biologist fix a radio? Or, what one scientist learned while studying apoptosis
Speaking of funny papers, this paper by Yuri Lazebnick (via Structure+Strangeness) is great. Here’s an excerpt, dealing with the question of how would a biologist fix a radio, knowing only that it is a box meant to play music?

How would we begin? First, we would secure funds to obtain a large supply of identical functioning radios in order to dissect and compare them to the one that is broken. We would eventually find how to open the radios and will find objects of various shape, color, and size. We would describe and classify them into families according to their appearance. We would describe a family of square metal objects, a family of round brightly colored objects with two legs, round-shaped objects with three legs and so on. Because the objects would vary in color, we will investigate whether changing the colors affects the radio’s performance. Although changing the colors would have only attenuating effects (the music is still playing but a trained ear of some people can discern some distortion), this approach will produce many publications and result in a lively debate.

3. Formation of a nematic fluid at high fields in Sr₃Ru₂O₇:
I had quite a lengthy post on electronic liquid crystals in 2-dimensional electron gases (e.g. GaAs/AlGaAs heterostructures) a while back, and briefly noted that:

Scientists in Europe have measured a large magnetoresistive anisotropy in the correlated electron oxide strontium ruthenate (Sr₃Ru₂O₇) near the ‘metamagnetic quantum critical point’, indicating the formation of a new quantum nematic phase. This is strikingly similar to the tranport anisotropy in 2DEGs I’ve been talking about… in particular, both show strong sensitivity to disorder - and the authors claim that the formation of this phase is tuned by the divergence in the quasiparticle effective mass near this critical point. One can only wonder what other kinds of systems could yield such behavior as well.

This European work is now one of the feature papers for the online Journal Club for Condensed Matter Physics, with a far more in-depth (yet very readable) commentary by Catherine Kallin of McMaster University in Canada.

Ideas in Condensed Matter Physics

Doug Natelson has a post soliciting suggestions for the most powerful idea in condensed matter physics, putting out the Hohenberg-Kohn-Sham theorem/method underlying DFT as being a good candidate. Others have suggested Bloch’s theorem, Anderson’s paper on localization, Laughlin’s paper on the Fractional Quantum Hall Effect, Onsager’s solution of the 2D Ising model, Landau’s papers on Fermi liquids, BCS theory, “and whatever the most appropriate Bethe ansatz paper is”.

I need to learn way more condensed matter physics in order to say anything constructive, although I do feel that another on the list could be Philip Anderson’s “More is Different: Broken symmetry and the nature of the hierarchichal structure of science“, which arguably set the tone for the principle (paradigm?) of emergence in complex systems (and perhaps unwillingly led to a good deal of philosophy and/or pseudoscience, too). Perhaps one of the most-quoted passages from the paper - that I’ve seen, at any rate - is the following:

The ability to reduce everything to simple fundamental laws does not imply the ability to start from those laws and reconstruct the universe… The constructionist hypothesis breaks down when confronted with the twin difficulties of scale and complexity. At each level of complexity entirely new properties appear. Psychology is not applied biology, nor is biology applied chemistry. We can now see that the whole becomes not merely more, but very different from the sum of its parts.

Anyway, the post reminded me of a paper I came across a long time ago in Rev. Mod. Phys. by W. Kohn (of Hohenberg-Kohn-Sham, as mentioned above) in 1999 that basically attempts to document the evolution of condensed matter physics. Here’s an excerpt:

It is perhaps interesting to look at the history of condensed matter physics from the viewpoint of T. S. Kuhn… [who] sees scientific history as a succession of (1) periods of ‘‘normal’’ science, governed by serviceable scientific paradigms, followed by (2) transitional, troubled periods in which existing paradigms are found to be seriously wanting, which in turn lead to (3) ‘‘scientific revolutions,’’ i.e., the establishment of new paradigms, which may or may not be accompanied by the rejection of the old ones.

Such a linear view seems applicable to the whole field of CMP for some of the broadest revolutions, which directly or indirectly affected a large fraction of the field:

• x-ray diagnostics yielding crystal structures (1910s);
• achievement of low temperatures allowing the observation of calmed condensed matter (1900s);
• quantum mechanics, (1920s);
• the band-structure paradigm (1920s, 1930s);
• nuclear and electron spin magnetic-resonance diagnostics (1940s and 50s);
• neutron elastic and inelastic diagnostics (1950s);
• many-body electron theories (beginning in the 1930s, with major revolutionary steps in the 1950s and 60s);
• electronic computer-assisted theory and experiments (1960s-);
• soft matter (1960s-);
• and nanoscience (1980s-).

I like it - clearly this is very broad, but it’s a very good summary of how the field has evolved into what it is today.