CV Gap Years

Every year I get asked to write letters for the evaluation of faculty at other institutions for tenure and/or promotion. My typical thought process on being asked to write a letter for someone I don't know well is: "OK, I've heard of that person/read their papers/seen them at conferences. Sure, I'll write a letter." Then I note the due date and send off a quick e-mail agreeing to write the letter. Most often the request arrives in the summer and I write the letters in summer or early fall. [If you click on the 'tenure' label in the frame on the right -- perhaps after scrolling down a bit -- you will see my previous comments on writing tenure letters.]



When it gets to be time to study in detail the materials relevant to the evaluation -- for example: CV, selected publications -- in many recent cases I have dealt with (recent = past 5 years) -- there have been complications. Example complications: unexplained gaps in the publication record (at least, unexplained to outside reviewers), lack of advisees and lack of publications with advisees, and/or few to no grants (and no research proposals pending with the individual as PI). In a recent example, I was asked to comment specifically on publication quality and quantity, grants, and other research aspects, but I found this difficult owing to some of these complications.



I can think of 'good' explanations for all of those complications. A gap in publications could be related to a massive time commitment setting up a lab and preparing new classes; it could also be related to personal issues that would not trigger an official extension of the probationary period and that would not be explained in a cover letter to external letter writers. Lack of advisees could be caused by unsuccessful attempts at advising students who quit or failed for reasons completely unrelated to the advising ability or practices of the faculty member. And we all know that it is difficult to get grants these days (although we still have to try, so a lack of pending research proposals is troubling).



The host institution is of course aware of all these issues, knows the context, and will likely do what it wants about them -- ignore them completely and focus on the individual's potential or treat them as fatal flaws that justify denial of tenure/promotion -- no matter what my letter says. And there are other significant factors (teaching ability) that are typically not known by outside letter-writers who are asked to comment on scholarship.



Sometimes I think that these letters are just a necessary formality and there is nothing useful that I can say in my letter. It's not constructive to think about that while working on one of these letters, so I try to think about how -- as a faculty member reading other people's letters for colleagues -- I find some letters to be quite useful. These letters can be useful not so much for whether the individual thinks the candidate should or should not be tenured and/or promoted but for the perspective they provide about the person's body of work.



So I try to focus on that aspect of my letters. After (re)reading some of the candidate's publications and thinking about their ideas and work and trajectory, I try to express what I think about that person's scholarship and their impact on the field. (I have written before about how I do not like to do comparisons with others in the field and I do not like to answer the question of whether someone would get tenure at my institution.) Writing in detail about the candidate's research may or may not be of interest to faculty and administrators but I think it's the best contribution I can make to the process, more so than any detailed comments about the data in the CV.

Lights On Pipes - Which One Heats The Most?

We also deal with elementary stuff here.

The people at the Frostbite Theater at JLab has another video out. This time, they show an experiment on which pipes heats the most when shined with light.

The results is not surprising. But what is surprising is why the white pipe heats up faster initially. So, anyone wants to enter a Science Fair to study why this is so, especially when Steve is way too old to enter?

Zz.

LIGO Gets Ready

Not sure how long this article will be available without a subscription, but in case you missed this article on LIGO in last week's issue of Nature, this is a good one to keep.

De Rosa, a physicist at Louisiana State University in Baton Rouge, knows he has a long night ahead of him. He and half a dozen other scientists and engineers are trying to achieve 'full lock' on a major upgrade to the detector — to gain complete control over the infrared laser beams that race up and down two 4-kilometre tunnels at the heart of the facility. By precisely controlling the path of the lasers and measuring their journey in exquisite detail, the LIGO team hopes to observe the distinctive oscillations produced by a passing gravitational wave: a subtle ripple in space-time predicted nearly a century ago by Albert Einstein, but never observed directly.

It's a daunting task, with instrument of such precision, that so many things can contribute to the "noise" being detected. We will just have to wait and see if we will get to detect such gravitational waves anytime soon.

Zz.

Big Mystery in the Perseus Cluster

The news about the x-ray emission line seen in the Perseus cluster that can't be explained (yet) by current physics.

The preprint that this video is based on can be found here.

Zz.

Quantum Criticality Experimentally Confirmed

A new experimental result has confirmed quantitatively the presence of a quantum critical point.

The researchers experimentally confirmed the predicted linear evolution of the gap with the magnetic field, which allowed them to pinpoint the location of the quantum critical point. At the critical field, the observable is expected to display a power-law temperature dependence, another hallmark of quantum criticality, with a characteristic power of -3/4 in this case—precisely what they observed. Even more, a rigorous experimental analysis allowed them to estimate the prefactor to this behavior, which they found to correspond nicely to the theoretically predicted one. And finally, they observed this behavior to persist to as high a temperature as almost half of the exchange coupling, which sets the global energy scale of the problem. This answers an essential question about how far away from the absolute zero temperature quantum criticality reaches or how measurable it really is. The experiment constitutes the first quantitative confirmation of the quantum critical behavior predicted by any of the few existing theories.

Nice! Not surprisingly (at least, not to me), the clearest confirmation of this exotic quantum phenomenon is first found in a condensed matter system.

A few background reading for those who want to have more info on quantum criticality can be found here and here.

Zz.

Room for Improvement

Student comments on my teaching of a particular course:



Great professor!

I have enjoyed this class!

I liked the readings.

This course required too much previous knowledge.

Professor very helpful with homework.

Homework very useful for class.

Well-constructed lectures.

Very organized lectures.

She speaks very clearly.

She answered my homework questions.

She provided images and charts to supplement the subject matter.

The in-class exercises were helpful.

I liked the practice exercises we did in groups during lecture.

I liked that she asked questions during class and this helped deepen my understanding of concepts.

Useful supplementary material to help us understand lecture material.

She explained the topics completely in class. Didn't use a textbook as a crutch.

It was great that lecture and lab material were well coordinated.

She was always ready to answer questions.

She was always willing to help with any questions.

She provided the subject matter very clearly.

The last project was too much work for this level of class.

Lecture presentations very clear.

I liked the in-class exercises.

You should improve your teaching methods.



Note that almost all of the comments are in the 3rd person (except for the last one), as if the students were writing to someone else about me, rather than writing to me with feedback. I don't know if it matters in terms of type and level of feedback whether the student is imaging an unknown audience or speaking directly to me (?). At evaluation time, I give a little talk to the class about the importance of this feedback and how it is used by instructors and the department/college/university, but I think there is still general confusion among students about what exactly the purpose of these evaluations is and who reads them and whether anyone cares what they think.



These are overall nice comments, and unfortunately also rather classic in that the criticisms are too vague to help me understand what the specific complaints are.



The last comment, despite being too vague to be useful in any specific way, is absolutely right. Despite being deep into my mid-career years, I don't want my teaching to fossilize. I want to improve. In recent years I have attended teaching workshops and gotten some ideas from those. When I team-teach, a faculty colleague is in the classroom with me, so I get some peer feedback. And last term, I jettisoned the too-long and too-detailed textbook and provided focused readings, including some that I wrote myself. That seems to have worked quite well (or at least no one said they missed having a textbook), so perhaps that counts as an improvement. I would also like to do some new things involving e-learning and have been to some workshops and meetings about that.



I am thinking about teaching because I was just looking at my evaluations, though mostly I am enjoying having lots of uninterrupted time for research. This week I even managed to submit a manuscript on which I am primary author. It's been about two years since I've been able to do that (and I don't mean to imply that I did it alone -- an excellent colleague was essential to the completion of this paper).



As I was finishing the paper (and a related grant proposal) recently, it occurred to me that I could create a new teaching module based on this work and incorporate it into the class for which I just received teaching evaluations (not, of course, as extra work but replacing some older material). Probably more than any major change in teaching style, a realistic way that I can improve my teaching is to find good ways to incorporate new material -- specifically, integrating New Science with Classic Science, so that students learn the fundamental stuff without which they are incomplete as scientists and people and yet are also exposed to new things that help them see where the field is at (including being exposed to unresolved questions that might inspire them).



Anyway, it's been a busy summer so far. My father recently asked me if my husband "also has the summer off" and I was actually quite calm about it this time. Have you had a similar conversation with anyone yet this summer? Parents? Neighbors? Friends? Students? Assuming that you do in fact work in the summer even if you are not teaching, did you (1) smile serenely and let them continue to exist in ignorance; (2) correct them (a) calmly, (b) not calmly; or (3) lapse into stony silence (if having a conversation) or send a glaring emoticon (if in e-contact)? (or other..).

Topological Insulators

In case you missed it and are interested in this area, this is a review article, which happens to be a chapter in a book, on "Topological Insulators, Topological Crystalline Insulators, and Topological Kondo Insulators". This is not meant for non-experts because it reviews the current understanding of this family of material.

Zz.

Quantum Physics In Your Daily Lives

I initially thought that this Newsweek article was reporting something new that had been discovered in quantum mechanics that had some serious applications. But it turns out that it was more of an article that quite clearly described all the practical advances that came out of QM.

At the most basic, almost everything we do is grounded in quantum physics—matter (all of it) is a collection of quantum particles, while light, electricity and magnetism are all quantum phenomena. At the next level are the quantum technologies we humans built without being aware of the physics that made them possible. When Swan and Edison produced electric lightbulbs, they didn’t know that light generated from a heated filament is a quantum process—they ended up implicitly drawing on quantum physics without even knowing it.

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It only takes a few minutes analyzing a smartphone to realize the pervasiveness of quantum technology. To start, quantum physics is required to construct any solid-state electronics—every chip inside your iPhone is packed full of quantum devices like transistors and has to be designed to encompass the peculiar quantum behavior of electrons. On top of that, your phone has a computer, display, touch interface, digital camera, light-emitting diode and global positioning system receiver—each developed as a result of our understanding of the field.

As I've always tried to convey, physics is more than just the LHC and string theory. It is also your iPhone, your MRI, your GPS, etc. A lot of people often hear about the exotic properties and consequences of QM without realizing that it works, and that they are using it! So this is a good article to give anyone who is ignorant about this.

Zz.

Many-Body Quantum Fluctuations In Residual Resistivity Of Metals

As a condensed matter physicist by training, the issue of charge transport in matter has always been a topic that I encounter often, especially when I was doing my postdoc many, many years ago. While the physics of charge transport in metals, under "ordinary" situations, can be adequately described by the Drude model, resulting in, for example, the beloved Ohm's Law, there are many other situations where such a simplistic model just doesn't work. And in those situations, that is where the physics gets very interesting and can be quite complicated.

The factors that influences charge transport in matter depends very much on how a charge carrier scatters. So the scattering rate determines the properties of resistivity/conductivity, etc. In a metal, there several types of scattering: electron-phonon scattering, electron-impurity scattering, and electron-electron scattering.[1] The dominant term that has a strong temperature dependence is the electron-phonon scattering, which is the primary mechanism that determines the resistivity of a metal. The electron-electron scattering has a weaker temperature dependence, while the electron-impurity scattering is mostly temperature independent.

What this means is that, as we lower the temperature, at some point, the electron-phonon scattering "freezes out", and no electron-phonon scattering contributes to the resistivity. The resistivity will then be a function of predominantly the electron-electron contribution. As the temperature approaches 0 K, one will notice indication that the resistivity will not be zero. This is the residual resistivity, whereby even at 0 K, there will still be a net resistivity of the material that is due to electron-impurity scattering. Note that this "impurity" need not be foreign atoms that are not part of the material. It can also be crystal defects and deformation that interrupts the long-range order of the crystal structure of the metals. The charge carriers can scatter off these defects as well.

That is how we were taught in solid state courses. we often deal with charge transport using the Boltzmann transport equation, and treating this within the Drude model The full quantum mechanical treatment, via the Kubo formulation, is a BEAST, and often unsolvable.

But now, along comes a new theoretical treatment of charge transport in metals, using DFT, that arrived at a rather unexpected result.[2] The new treatment showed that there is a strong contribution to the electron-impurity scattering due to the electron-electron many-body effects. The electron-impurity scattering is not as simple as we thought. They showed how well this new explanation matches the residual resistivity measured for aluminum.

This is another example where, something that we know very well and for a long time, can often reveal new physics and information when it is examined at the very edge of the boundary of our knowledge. We subject many of our ideas to the extreme case (in this case, very close to 0K) to see how well they work in those situations. It is one of the ways we expand the boundary of our knowledge.

Zz.

[1] see http://ift.tt/1iVYHyU

[2] http://ift.tt/1iVYGei

Deborah Jin Awarded IoP's Newton Medal

The UK's Institute of Physics has awarded JILA's Deborah Jin with this years Isaac Newton Medal, which is the IoP's most prestigious award.

In 1999 Jin and her then PhD student Brian DeMarco were the first researchers to cool a gas of fermionic atoms so low that the effects of quantum degeneracy could be observed. This phenomenon underpins the properties of electrons in solid materials, and the ability to create and control ultracold "Fermi gases" has since provided important insights into superconductivity and other electronic effects in materials. Working with Cindy Regal and Markus Greiner at JILA, Jin later created the first fermionic condensate in 2003, by cooling a gas of potassium atoms to nanokelvin temperatures.

I've always said that she deserves a Nobel Prize in physics for this work. It is also about time that a woman wins this after several deserving ones had been overlooked.


Zz.

Prove Man-Made Climate Change Isn't Real And Win $30,000

This is the put-up-or-shut-up challenge, very much like James Randi's challenge to prove the existence of supernatural phenomenon.

A physicist has put up $30,000 of his own money to challenge global-warming skeptics to unequivocally show him evidence that man-made global warming doesn't exist.

Dr Keating -- a professor of physics for over 20 years and author of Undeniable: Dialogues on Global Warming -- is offering a grand prize of $30,000 of his own money to anyone who, using the scientific method, can disprove the existence of man-made climate change. In addition, he is offering a smaller prize of $1000 to anyone who can provide any valid scientific evidence against man-made climate change.

You can read his official statement of the challenge on Keating's blog.

Now, this is NOT to say that he is looking for proof of warming due to anthropic causes. There's a difference here. He's looking for FALSIFICATION of the claim, i.e. evidence that such a claim of human origins for global warming isn't valid.

Also note that he is not a fly-by-night physicist moonlighting as a climate expert. So you'd better be good at this, because he is!

Zz.