Monday, November 30, 2015

A student's questions about scientists responding to climate change

A first year undergraduate student who is deeply concerned about climate change asked me a number of questions by email and then came to my office to discuss them. Since I think they are excellent questions I thought I would post them here (with his permission) and give a brief version of my answers. I welcome readers to give their own answers.
I am interested in and passionate about climate change. At the moment, I'm considering my uni options - wondering what I can study to best equip me to help in the great, global effort to mitigate (I'm a bit less interested in adaptation) climate change. I have a couple of questions to ask of you.
1. How would you respond to each of the following, somewhat contradictory statements: 
- 'Climate change can be mitigated by developing and deploying renewable energy and energy efficiency technologies, without significantly impacting on our standard of living.' 
- 'Environmental crises, including climate change, require us to move away from a social and economic system based on consumerism and growth' .
First, I am no expert on this complex issue. An economist at UQ who is an expert is John Quiggin. But, my view is that with energy efficiency measures, renewable energy, and some modest lifestyle changes significant progress can be made towards mitigating climate change. On the other hand, I think there are compelling social  and political reasons why the world, particularly the Western world, would be better off if we moved away from this mindless and insatiable pursuit of consumerism and economic growth.

But, I really think the biggest obstacle to concerted and significant global action is a lack of political will and leadership. This is particularly driven by "fear mongering" from vested business and political interests who claim the first option is true. "If we don't burn more coal we will all end up back in the caves or at least riding bicycles..."
I don't think the biggest obstacle is missing technical and economic solutions. Of course, if someone can make a durable and reliable photovoltaic cell with 20 per cent efficiency, that costs 20 cents per square metre to manufacture, and with a lifetime of 20 years, it would "solve" the problem. But, I only foresee incremental advances in the next decade. The case of Gratzel cells is quite discouraging.
2. If the institutional ethos of the UQ science faculty were a person, how would he/she respond to the above statements? 
I think you would really encounter a range of views, probably reflecting a rang of political convictions. I would hope most staff would believe that climate change is real, a result of human activity, and a major issue to address. On the other hand, I am occasionally surprised and disappointed to meet scientists, who are skeptics, even though 97 per cent of climate scientists are not.

I think you would find that some would also claim we need lots more research money (especially for new technologies) to address these issues, but they are clouded by self interest.
3. What facets of science would you recommend that I study:  
- Earth science (better understanding of the climate system)
- Physics/Engineering (renewable energy technology) 
- Psychology (Why do people behave the way they do) 
- Ecology (how ecosystems respond to climate change and other pressures)
Given that I think the major obstacles are political I think that becoming a political activist you may have the biggest impact. Studying sociology and psychology may help design the most effective campaigns. But you do need to understand the technical issues.
On the other hand, you should consider what you are good at and enjoy. There is no point trying to put square pegs in round holes.
Hence, I think you should let your own interests and abilities be a consideration. But studying a mix of the above could be very helpful.
I am wondering if UQ has plans to develop a specific course, or even a program, devoted to climate change?
Not that I am aware of. There are significant postgraduate activities at The Global Change Institute and the Energy Initiative. There was recently a review of the Bachelor of Science. The possibility of some elective courses that are multi-disciplinary has been floated and climate change is one. However, my experience is that such courses become a can of worms once you get multiple departments involved. Everyone wants a piece of the pie, to do it their way, but are not willing to take responsibility, or to "force" their own students to take the course so it is viable. Hence, I doubt you will see the kind of course you are hoping for during your time here. Sorry.

I wish I had more discussions like this with students.

I welcome people to give their own answers.

Friday, November 27, 2015

I believe in irreproducible results

At UQ we just had an interesting colloquium from Signe Riemer-Sorensen about Dark matter emission - seeing the invisible. Central to the talk was the data below. Focus on the red data around 3.6 keV.

This has stimulated more than 100 theory papers!
This reminds me of the faster than speed of light neutrinos and the 17 keV neutrino, 500 GeV particles seen by the Fermi gamma ray telescope, BICEP2 "evidence" for cosmic inflation, ....

The above data is discussed in detail here.

I don't want to just pick on my astrophysics and high energy physics colleagues as this happens in condensed matter and chemistry too... remember cold fusion... think about periodic reports of room temperature superconductors!

The painful reality is that cutting edge science is hard. One can be incredibly careful about noise, subtracting background signals, statistical analysis, sample preparation, .... but in the end there is Murphy's law .... things do go wrong .... and crap happens...

Skepticism and caution should always be the default reaction; all the more so the greater the possible significance or surprise of the "observed" result.

I believe in irreproducible results.

Thursday, November 26, 2015

How the 80-20 rule may be undermining university quality

I recently learned about the Pareto principle, which according to Wikipedia

"(also known as the 80–20 rule, the law of the vital few, and the principle of factor sparsity) states that, for many events, roughly 80% of the effects come from 20% of the causes."

For example, if you are supervising a team of employees, 80% of your time will be spent in dealing with 20% of them, probably the mostly poorly performing or most vocal.

This past year I have had a minor administrative role, as a "Research Committee" chair. Probably 80% of the time, involves co-ordinating, supporting, and assessing grant funding applications, both internal and external to the university. Most of these grant programs have success rates at the 10-20% level. Virtually none of my time is actually spent on initiatives to help improve the quality or quantity of research done by the bulk of faculty members.

My experience has also made me more aware of what people in senior management appear to spend their time doing and what gets their interest and attention. Increasingly, it seems to be focussed on "high status" activities associated with "esteem measures" such as "prestigious" grants and fellowships, and of course, publication in luxury journals. The issue is well illustrated with a story about some researchers who were making a pitch for a new supercomputer centre.

University VP (Research): Will this help you get a Nature paper?

Researcher: Probably not, but it will help other researchers at the university publish a hundred other papers.

The problem is again that little attention or resources are directed to most of the research that is going on.

Tuesday, November 24, 2015

Postdoc available to work with me on strongly correlated electrons

UQ has just advertised for a new postdoc to work with me on a project, "The bad metallic state in quantum materials", funded by the Australian Research Council.
The position is for 2 years and 9 months.
Applications close on 31 January, 2016.

The official advertisement and job description is here and contains a link to a portal through which a formal application should be made.

Looking at the "bad metals" label on the blog will give a flavour of some of the problems I am interested in.

Looking at the "career advice" label will give some flavour of my philosophy and expectations of working together.

Monday, November 23, 2015

Quantum critical spin dynamics of a magnetic impurity in a semiconductor

There is an interesting paper
Quantum critical dynamics of a magnetic impurity in a semiconducting host
Nagamalleswararao Dasari, Swagata Acharya, A. Taraphder, Juana Moreno, Mark Jarrell, N. S. Vidhyadhiraja

The key physics of the Kondo model is the formation of a spin singlet state between the impurity spin and the spins of the electrons in the conduction band. We say, the impurity spin is “screened” by the spins in the conduction band.
The "screening" electrons involved span from the Fermi energy up to some higher energy.
The relevant energy scale is the Kondo temperature which depends in a non-analytic way on the density of states (DOS) at the Fermi energy, and is roughly the binding energy of the spin singlet.
As the DOS goes to zero the Kondo temperature goes to zero.

But, what if there is an energy gap at the Fermi energy, as in a semiconductor?
One might expect that the Kondo effect disappears and the local moment is no longer screened.
Specifically, is there a critical non-zero value of the energy gap below which the Kondo effect survives and one observes at Fermi liquid?
How about if the temperature is larger than the energy gap but less than the Kondo temperature?
Then perhaps the electrons that are thermally excited into the conduction band can screen the impurity spin.

The above fundamental questions are relevant to understanding magnetic semiconductors. They can be addressed by studying the gapped single impurity Anderson model. A number of numerical and analytical studies over the years have produced different answers to the above questions. The current paper gives definitive answers based on state-of-the art Quantum Monte Carlo calculations.

The phase diagram is shown below, with temperature versus the energy gap, delta.
Both are scaled by the Kondo temperature in the absence of the gap. LM denotes an unscreened local moment and GFL a Generalised Fermi Liquid.
The phase diagram is universal in the sense that it is independent of U in the Kondo regime (for large U) and the only relevant energy scale is the Kondo temperature (not the band width or the hybridisation energy).
It is not at all obvious (at least to me) that the universality of the delta=0 case has to extend to the non-zero delta case. But it does.

One sees that the critical value of the energy gap is zero.
Furthermore, above some non-zero temperature, of the order of a fraction of Kondo temperature and about one half of delta, a Generalised Fermi liquid forms where the local moment is completely screened.
The authors also show that the dynamic spin susceptibility associated the spin of impurity exhibits “quantum critical scaling” in the sense that it depends only on omega/T where T is the temperature and omega is the frequency.

Hopefully the paper will stimulate some experiments, either in quantum dots or in semiconductors, to observe this fascinating physics.

Friday, November 20, 2015

Fulfilling the bureaucratic minimum

There is no doubt that universities and research institutions are becoming more bureaucratic. This is arguably from the increased demand for accountability and from the rise of the managerial class. This means more paperwork, more boring meetings, and more rules and regulations. How do we cope?
Let me first give two extreme responses and suggest an alternative.
John and Joan could be faculty, postdocs, or graduate students.

1. John is focussed on research and teaching. Afterall that is the mission of the university not all this bureacractic nonsense. Any emails from administrators are deleted. In fact he has placed a “block sender” on some. He never responds to requests to complete on line surveys, fire safety training, or annual reports. He does not attend departmental meetings. If forced to attend meetings he brings his laptop and catches up on email.
Deadlines for reports, drafts of grant applications, and exam papers are missed. The only way he will complete an administrative task, even after several email requests, is if someone comes and knocks on his door. Sometimes he tells secretaries, administrators, or colleagues if they want the task done they should do it for him. The only tasks he does actually complete are done at the last minute.
John is not “well liked” either by colleagues or local administrators.

2. Joan is the opposite of John. She is a very conscientiousness member of the community. She reads all the admin emails (including the attachments) carefully, actively participates in all the meetings, updates all the databases, and writes carefully crafted reports. She completes all the tasks in a timely manner. Sometimes she agonises about the content and wording of her reports and gets colleagues to give her feedback on drafts. She gives managers detailed and constructive feedback about a range of their iniatives and issues.

Both extremes present problems.
Basically, John is selfish because he leaves others to cover for him, on some tasks that one just cannot avoid doing.
On the other hand, Joan is wasting a lot of her time, that could arguably be better spent on teaching or research (or on non-work pursuits!). She is also “enabling” the propogators of bureacratic nonsense.

Somehow we need to find a balance between John and Joan. Let me suggest a simple question to decide what to do and what not to do.
If I don’t complete this task (or at least complete it in a timely manner) is it going to inconvenience someone else (because they will have to do it or keep bugging me to do it)?
Fulfilling this bureacratic minimum leaves significant room for tuning out a lot of the noise, deleting a lot of email, skipping some meetings, and quickly completing reports by "box ticking" and cutting and pasting.

Wednesday, November 18, 2015

Emergent quantum matter at JNU

Today I am giving a seminar on Emergent Quantum Matter in the School of Physical Sciences at JNU. My host is Brijesh Kumar. Here are the slides.

Last time I gave this talk, someone asked the tricky and controversial question "Is ferromagnetism an example of spontaneously broken symmetry?" Peierls said yes. Anderson says no. I previously discussed their exchange here.

Aside. One thing I  enjoy about JNU is the very large posters that student political activists have placed on buildings. Many contain challenging quotations that are worth considering, such as this one.