Condensed concepts

NOVA is a Science TV show on PBS in the USA.  This is a nice 12 minute segment on emergence, first shown in 2007. It focuses mostly on computing, origin of life, and has brief allusions to flocking. Readers in the USA can watch a higher quality of the video on the NOVA site.

In a Mott insulator the electrons are localised leading to local magnetic moments that weakly interact with one another via superexchange. This means there is a new low-energy scale associated with spin dynamics. But, at the level of Dynamical Mean-Field Theory (DMFT) there is no superexchange and the local frequency-dependent spin susceptibility is a delta function, as discussed here. In a Fermi liquid the charge and spin degrees of freedom are both delocalised and the energy scale for spin dynamics Es is defined by the Fermi energy (or coherence temperature). As the Mott insulator is approached Es becomes small, much less than the bare Fermi energy. Furthermore, Es is associated with “kinks” in the quasi-particle dispersion relations seen in Angle Resolved PhotoEmission Spectroscopy (ARPES) experiments on strongly correlated materials. This is discussed in this post  which features the graph below for zero temperature. However, in the bad metal state, it is not clear what the

The Economist has a good editorial Seize the day The fall in the price of oil and gas provides a once-in-a-generation opportunity to fix bad energy policies Governments need to do two main things. First, cut fuel subsidies. This is particularly important in the Majority world, as this favours the wealthy, who can afford to drive cars. Indonesia has just done this and used the saves to fund education and welfare. Second, cut subsidies that encourage oil and gas exploration and production, rather than renewables. There is also a 10 page special report Let there be light  Thanks to better technology and improved efficiency, energy is becoming cleaner and more plentiful The two most striking graphs are those below.

In a post last year A survival and sanity guide for new faculty I suggested that they should not apply for every grant possible or take on every prospective graduate student. I was asked to write something about what criteria might be used for making these decisions . Here, I will just focus on the grant issue. Hopefully, later I will discuss students. First, you should acknowledge that you do have a choice. Don't let pressure from others make you think you don't. Alternatives to not applying including waiting for a year, or putting in an application jointly with another colleague. This is a tricky and subjective issue for which there is no clear answer. Here, I will suggest some questions to ask yourself. Do I really need the grant? Do I actually need the money to do the research? Or do I need the grant for career reasons? If you are an experimentalist and have no ongoing funding to pay for supplies such as liquid helium then there is a very good reason to apply. On th

I wrote a post How (not) to break into a field . Some of those ideas where supported when I recently started reading Paul Krugman 's nice little book, The Self-Organizing Economy Early in the book he notes: the authors of articles and books on complexity almost never talk to serious economists or read what serious economists write; as a result, claims about the applicability of the new ideas to economics are usually coupled with statements about how economies work (and what economists know) that are so ill-informed as to make any economist who happens to encounter them dismiss the whole enterprise.  But it does not have to be that way. Unfortunately, you could replace "complexity" with quantum information theory and "economics" with chemistry, biology, or condensed matter physics. Or,  astrophysicists and cancer, ... physicists and the origin of life .... string theorists and condensed matter .... On the positive side, Krugman then discusses some nice

A number of proteins involve short strong hydrogen bonds [also known as low-barrier bonds] and there is considerable debate about how important or relevant they are for functionality.  A particularly interesting enzyme is KetoSteroid Isomerase (KSI) which features such bonds. Its structure and mechanism has recently been elucidated by some beautiful experiments using mutants near the active site. There is a nice paper Quantum delocalization of protons in the hydrogen-bond network of an enzyme active site Lu Wang, Stephen D. Fried, Steven G. Boxer, and Thomas E. Markland This is a combined experimental and theoretical study of isotope substitution effects where the protons are replaced with deuterium. This allows one to probe the effects of the zero-point motion of the protons in hydrogen bonds. You can see zero-point energy with a pH meter. The authors measure the change in the pKa [acidity] with H/D substitution of the different amino acid residues in the active site of KSI. S

Normally this blog attracts about 700 page views per day, according to blogspot.  However, yesterday it got 5000! I have no idea why. Presumably someone with a significant following Tweeted it. If you know the answer, please let me know, even if you are a robot! I have not seen a traffic increase like that this since I pointed out that  Greg Scholes' "quantum biology" paper in Nature involved fitting 20 data points to a curve with 17 parameters .

The Economist recently ran a report, entitled Exclusivity for everybody  with the subtitle "The modern luxury industry rests on a paradox, but is booming nonetheless." The paradox is that luxury/status brands such as Gucci, Cartier, Louis Vutton got their name because they were so exclusive [expensive]. But now they are mass produced and mass marketed to middle classes, even in the Majority World. I realised that this is just what the mother of luxury journals , Nature Publishing Group, has done too. Now everyone can have a Nature paper too!

Last year Physics Today had an interesting article Psychological insights for improved physics teaching Lauren Aguilar, Greg Walton and Carl Wieman It generated a lot of letters in last months issue. I think it raises some issues that are not thought or talked about enough. Here, I just want to suggest that psychology does play a role in research seminars and conference seminars too. Speakers and their messages are not just judged on their scientific merits. In particular, our views are sometimes influenced by our emotions, positive or negative. Over the past year I think I have heard talks that have evoked in me responses such as negative- boredom, confusion, frustration, anger, feeling inadequate, .... positive- excitement, intellectual stimulation, curiousity, feeling clever, .... The former can come from talks that are obscure, too technical, poorly prepared, patronising, or full of hype... I have to confess, that as much a I try to be objective, I think my negative

Yes. The whole process of applying for [and mostly not getting] funding can be very frustrating. Generally, I am empathetic to colleagues who share their disappointments with me. However, there are two situations I am not particularly sympathetic too. Professor A is well funded and applies for an extra grant and does not get it. Professor B's grant application is successful but does not receive the full requested amount. I am even less sympathetic when A or B's spouse complains to me about this. These decisions need to be considered in a broader context. Funding agencies do have limited budgets and they need to consider what is going to be for institutions and a country in the long term. Consider the following vignettes of different faculty. John Smith is 45 and holds multiple grants. He has 3 postdocs and 11 Ph.D students. He publishes in luxury journals. Sue Jones has been an assistant professor for 3 years and has one Ph.D student, funded with start up funds.

The "cartoon" below appeared at CERN. I learnt about it from a commenter on Peter Woit's excellent blog, Not even wrong. Note, "The problem of condensed matter: they still don't get it".

To succeed you need to be at the right place at the right time. In my last post I discussed how in his book Outliers , Malcolm Gladwell presented some fascinating cases of how in certain fields those who were successful were all born within a few years of each other. For example, consider the list of 75 most wealthy people in history. 14 of them are Americans born between 1831-1840. The most successful computer entrepreneurs were born between 1953 and 1956. So I thought I would do a little "experiment" to see if anything like this happened in theoretical physics. In the twenty years after World War Two, a revolution in quantum many-body theory occurred. People applied new methods of quantum field theory to problems in solid state physics and nuclear physics. In principle any scientist between the ages of 25 and 65 could have been involved in that revolution. But, were they? Without thinking too much I wrote down the first twelve names that came to mind.  The list is bel

Everyone in my family just finished reading Outliers: the Story of Success by Malcolm Gladwell. I highly recommend it. Gladwell is a gifted writer and tells a great story. The book has led to some lively family discussions. Gladwell takes a diverse set of social science research and weaves it together into a coherent, compelling, and fascinating tale. In the process he debunks several popular myths about what makes some individuals extremely successful and others not. It certainly contradicts the mantra, particularly in the USA, that "you can be anything you want to be.... just dream it.... work hard ... pull yourself up by your bootstraps...  and it will happen..." Aside: In the book "success" is implicitly defined narrowly as professional success and public acclaim.  I would prefer a much broader definition. Personally, I think you can be "successful" in that sense and be a "failure" as a human being. Some of the ideas that Gladwell prom

In most cases it is because they simply don't have the option of continuing. However, now it seems some are leaving because of disillusionment. Doug Natelson has a thoughtful (and depressing) post Long odds: and how we spend our time . He discusses how he is currently writing three grant proposals that have an approximately 5 per cent chance of success, and raises the question of whether this is really a good use of his time? I would clearly say no. But he and many people in the US system are trapped. Personally I don't apply for anything with a success rate of less than 10 per cent. But in Australia we have the "luxury" that there are programs with a success rate of slightly less than 20 per cent. But, the main point of this post is to highlight two comments on Doug's post from postdocs who just left academic science because of disillusionment. I think their concerns are justified (and alarming) and I have no answer for them. This is why (or rather one

Best Wishes for the New Year! In the past, at the end of each year I have listed my most popular [i.e. most viewed] posts of the year. Unfortunately, on blogspot it is now difficult to figure that out. So, here I list ten of the more popular posts I thought were significant/satisfying. Is the mobility of protons in water high? Are there quantum limits to transport coefficients? Slow spin dynamics in the bad Hund's metal Seeking definitive signatures of quantum criticality How 5 years of blogging has changed me My paper submission strategy A survival and sanity guide for new faculty Latest talk on mental health for scientists Is publishing debatable conclusions now encouraged? An empirical potential to benchmark computational chemistry for hydrogen bonding? It is particularly satisfying to me that half of these posts are about deep scientific issues, not just my rants about luxury journals, metrics, neoliberalism, quantum biology, .... Thanks again to my r

Put yourself in the shoes of a search committee member. They will receive 100 plus applications. Most committee members are not in the same field as you. They are going to quickly skim your cover letter.  You need to be clear. You need to get their attention.  You need to give them some reason to believe that might want to have you as their colleague. Here are a few general suggestions. Below I list sites with more specific recommendations. 1. You are applying for a faculty position, not another postdoc. It should be clear that you have a plan to establish an independent research program, an interest in teaching, an interest in advising graduate students, and a plan to get funding. The more specific the better. 2. A good way to indicate an interest in teaching and in the specific department is to suggest specific courses, both graduate and undergraduate, that you should teach. 3. List a few people in the department who you might collaborate with [especially theorists w