Condensed concepts

Today is the first day of classes for the beginning of the academic year. I am back to a regular teaching load. Last year, I posted about the most discouraging thing about the first week of semester . In preparation for a busy semester, I took last week off work (my last two posts were automated) and visited my son who has just moved to Canberra (ironically where I grew up) and spent time with my wife backpacking in one of my favourite places , Kosciusko National Park. Some photos are below. This reminded me of the importance of vacations and down time , of the therapeutic value of the nature drug , and of turning off your email occasionally.  Blue lake A view of the Rams Head Range from the upper reaches of the Thredbo river above Dead Horse Gap. A brumby (wild horse) near Cascades Hut.

Previously I posted about how science has changed [it is much more interdisciplinary and computational] and undergraduate science education really needs to catch up. I endorsed a great course on Physical models of living systems that Phil Nelson teaches and has just published a text for. [He kindly sent me a complimentary copy recently.]. In the recent UQ review of the B.Sc . there was some discussion of whether there should be more interdisciplinary courses offered and even whether one or two might be compulsory. That got me thinking about what the best courses would be. Energy and the Environment David  MacKay at Cambridge has a book Sustainable energy: without the hot air Advanced instrumentation and precision measurement NMR, x-ray crystallography, laser spectroscopy, mass spectrometry, microscopy, ... This should not just introduce these methods as "black boxes" but also describe the underlying science and let students have hands on experience. Chemical biop

There are several trends this post addresses: declining success rates on grant applications due to decreasing funding and increasing numbers of applicants desires to provide more opportunities for young people, women, and minorities the desire of administrators to be seen to be providing more opportunities the increasingly large amount of time required to prepare grant applications the large amount of time and money spent processing, assessing and ranking grant applications So who should be allowed to apply for a specific grant or fellowship program? How rigorously will eligibility requirements be enforced?  Will there be allowance for "special cases"? First, it is important to acknowledge that any grant or fellowship program has certain eligibility criteria: type of institution, career stage, gender, nationality, number of grants already held, ... A few things I have been recently been involved in that I thought were good. Expressions of Interest. Pri

An enduring theme on this blog is that one should always consider "boring" explanations for "surprising" experimental results before invoking the exotica beloved and promoted by luxury journals. An example was the extremely large magnetoresistance materials. In most metals the magnetoresistance [change in electrical resistance with external magnetic field B] depends quadratically on the B. The past few years there have been a plethora of papers about linear magnetoresistance in topological insulators, iron pnictide superconductors, and Dirac semi-metals. I wrote  a post  which discusses the issue and also links to an earlier post that considers different theoretical explanations. Many of these papers, particularly those in the baby Natures, want to link the linear magnetoresistance to the Dirac cone and possibly the Berry geometric phase associated with it. However, there are some critical and constructive papers. For example, Magnetotransport of proton-irrad

Robert Socolow has an interesting career history. He started out in elementary particle theory, with a Ph.D at Harvard, a postdoc at Berkeley and was an Assistant Professor at Yale. He then made a transition to environmental and energy policy, joining the faculty in Mechanical and Aerospace Engineering at Princeton in 1971. There is an interesting letter he wrote to Steve Fels in 1969 that describes his transition in research interests. Two years ago Socolow gave a Homage to Frank von Hippel , a physicist who made a similar transition, focusing on nuclear policy and arms control . It is worth reading. Here are some comments Socolow made about physics. Physics is a special way of knowing, within science. Physics stresses simplification – incredibly useful when other fields place a much lower value on simplification. The physics approach shines a light on other sciences, provides accessibility for outsiders (the intelligent layman).    Although our cohort stopped working at the

Last week The Economist had a good article about how in organisations today there is so little time to  think and do "deep work". Instead people are too busy going to meetings! The article is stimulated by a Harvard Business Review cover article on "collaborative overload" and a new book, “Deep Work: Rules for Focused Success in a Distracted World”  by Cal Newport. Minor point. I think the article title, "The collaboration curse: The fashion for making employees collaborate has gone too far" is a misnomer (at least in terms of the way academics think about collaboration). I don't think most meetings are actually about collaboration, but rather discussing, deciding on, communicating, and implementing policies. But, I do think the pressure to collaborate, particularly across research groups, disciplines, departments, and institutions has gone too far. But, that is not the biggest problem... Here are a few relevant quotes from the article.

For someone to put the main points to a popular song! Yesterday I heard an interesting talk "Truths we must tell ourselves if we are to manage climate change" at UQ by Robert Socolow [aged 80!]. He is well known for a paper, Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies The paper considers Seven ways to reduce carbon emissions. Glenn Wolkenfeld has written corresponding lyrics to the tune of the classic Paul Simon song, 50 ways to leave your lover! Socolow has an interesting career history, having started out in theoretical physics, working on elementary particles. I will write more about that career transition later.

Peter Fulde [who turns 80 in 2 months!] has a nice informative 2 page Commentary Wavefunction-based electronic structure calculations for solids . For electronic structure calculation there are two distinct alternative methods (formulations): those based on Density Functional Theory (DFT) and wave function based approaches. Fulde directly addresses an "objection" to the latter raised by Walter Kohn in his Nobel Prize Lecture.  He suggested that for more than one thousand electrons a many-body wave function is not "scientifically legitimate" because it suffers from the the "exponential wall" problem. (i) It cannot be calculated with sufficient accuracy. (ii) It cannot be represented numerically sufficiently well that it can be stored and later retrieved. Fulde states The exponential wall problem is avoided when we characterize the many-electron wavefunction not by a vector  ψ ( r 1 σ 1 , ... ,  r N σ N ) in Hilbert space but instead by a vector 

Nature Physics has an editorial The Rise of Quantum Materials . In a refreshing change for the Nature Publishing Group, it is devoid of hype. The editorial nicely gives the scientific background to the sociological observation:   As it has become clear that the study of emergent properties is no longer restricted to strongly correlated electron systems, a new, broader description has become necessary. And the term that seems to be gaining currency on departmental websites and research programmes is quantum materials.   [Indeed, I just got a grant with a title "The bad metallic state in quantum materials"] My only minor comment is that the editorial does not quite explain why "quantum" is appropriate nomenclature. I would say that is because on some level they have macroscopic properties [e.g. quantised magnetic flux in superconducting vortices and quantised Hall resistance] that are quantum mechanical in sense that they involve Planck's constant. This i

I find it interesting to listen to the introductions that different seminar speakers get. Sometimes the introduction tells you more about the host than the speaker. Introductions I don't like may include: "Sarah has published lots of Nature and Science papers." Mention of the h-index or number of citations. Mention of amounts of grant money. "John has done important work in quantum biology". "The speaker needs no introduction (so I won't give one)". I have heard this many times but I did not really know the speaker. A live dialogue between the host and speaker about the details. e.g., "When did you get your Ph.D with me? So how long have you been at Sydney now?" "When I Googled him this is what I found out ...." Recitation from an old university web page. For a few years I sometimes got introduced as someone who does research on the "electrical conductivity of DNA". I finally discovered that this wa

No, we should redouble our efforts! Over past few years some scientists, particularly string theorists, have suggested that we should give up on the idea of falsifiability  as a criterion for deciding whether or not to accept or reject a specific scientific theory. (A good theory is one that one can perform a specific experiment, whose outcome may lead to the rejection of the theory). For example, in 2014 in answer to the question, "What scientific idea is due for retirement?" Sean Carroll's answer was Falsifiability.  He uses this to justify string theory and the multiverse. First, I think several important points need to be conceded and acknowledged. 1. There are subtle philosophical issues associated with falsifiability. Popper did not have the last word! 2. In practise, rarely will a theory get rejected just because there is experimental data that is inconsistent with it. Sometimes the data will get rejected. Other times the theory will get modified. 3. In

For Christmas (two years ago) my sister-in-law gave me a copy of Ava Helen Pauling: Partner, Activist, Visionary by Mina Carson , a historian at Oregon State University, which is home to the Linus Pauling archives.  I read it then but it has taken me a while to get around to writing this post. Aside: There are many personal dimensions to this gift choice. My sister-in-law and her family live in Corvallis, and their younger daughter attends Linus Pauling Middle School. Of course, they knew about my great admiration of Pauling. But also, the author has been in a book club with my sister-in-law. I enjoyed reading the book and it gave me a different perspective on Pauling's life. Although, some of the more intimate details in the book I would rather not have known about... The author nicely highlights how Ava Helen was really the driving force behind Linus' political activism, which ultimately led to his second Nobel Prize (in Peace) for the Partial Nuclear Test Ban Tre

Normally we associate spin-orbit coupling with degenerate atomic orbitals (or energy bands) associated with d- or f-orbitals. However, in solid state physics a quite distinct type of spin-orbit coupling can occur and has attracted a lot of interest over the past decade. In a seminal 2005 paper  [which took 12 months for PRL to publish!] Kane and Mele proposed that in graphene a spin quantum Hall effect could occur due to spin-orbit coupling. Moreover, this paper proposed that this state was a topological insulator, starting a whole industry. I want to just focus on the spin-orbit coupling term in the Hamiltonian that is the first step in their argument. This term arises because there are two carbon atoms per primitive unit cell in the crystal lattice. [A and B sub lattice]. It does not have local inversion symmetry. How large is Delta_so ? Kane and Mele estimated, based on a crude argument, that is was about 1.2 Kelvin. But, then they gave a renormalisation group argument,