Blogs / Cosmic Variance

In the Fall I’ll be starting teaching again, after a semester away on sabbatical and then enjoying teaching relief during my first semester at Penn. I’ll be teaching a course that I truly love, and that I’ve taught a number of times before - Mathematical Methods of Physics I, to a class of beginning graduate students, and some interested seniors.

The backbone of this course, as I teach it, is rather traditional, since the topics involved are things that form the basis of the toolbox that professional physicists need. From year to year I have added various extra topics (some differential geometry, some topology, some group theory, …), but I always cover

• Analysis of Complex Functions
• Exact and Approximate Evaluation of Sums and Integrals
• Exact and Approximate Solution of Ordinary Differential Equations
• Transform Calculus
• Sturm-Liouville Theory
• The Calculus of Variations

One challenge in a course like this is to maintain the connection with actual applications of the techniques one is covering. Since I was originally taught this material in a set of courses as a mathematics undergraduate, my own take on the material can be rather formal, and I have worked over the years to balance this out. However, as you might guess, my own examples are predominantly drawn from those areas of physics with which I am most familiar - for example, supersymmetry, and the restrictions that holomorphy places on superpotentials, is a nice illustration of the power of complex analysis.

But this course is supposed to provide a basis for all graduate students, including those with interests in other branches of theoretical physics or, indeed, experimental physics or observational astrophysics and cosmology. There are, of course, rather general things that one can do that should be of use to everyone, such as the use of Fourier and Laplace transforms in solving heat, diffusion, and other equations. And the calculus of variations appears everywhere already. There are also, incidentally, lots of cute things one can do in the opposite direction, like cooking up examples of oscillating systems in which the sum over all modes gives the total energy, which is easy to calculate another way, and using this to provide a way to compute infinite sums. Nevertheless, what I really yearn for are even more examples illustrating the use of some of the above topics from other branches of physics.

I could, of course, annoy my colleagues with this question, but I thought that opening it up to Cosmic Variance readers might provide some novel suggestions. So, if you have some unusual example, brief enough to be useful in a class, of the use of any of the above in any branch of physics (even particle physics and cosmology - there’s plenty I don’t know there also), I’d appreciate you filling me in in the comments.

And if any of my students-to-be are reading this - beware; it’s possible that good suggestions you see here, that don’t make it into class, may turn up on exams - who knows?

Via Dmitry Podolsky, a series of YouTube videos from Stanford encompassing an entire course by Lenny Susskind on general relativity. I didn’t look closely enough to figure out exactly what level the lectures are pitched at, but it looks like a fairly standard advanced-undergrad or beginning-grad introduction to the subject. (For which I could recommend an excellent textbook, if you’re interested.) This is the first lecture; there are more.

It’s fantastic that Stanford is giving this away. I don’t worry that it will replace the conventional university. The right distinction is not “people who would physically go to the lectures” vs. “people who will just watch the videos”; it’s between “people who can watch the videos” and “people who have no access to lectures like this.” And Susskind is a great lecturer.

All the signs are pointing to a major announcement by the University of California, possibly as early as tomorrow, in response to the large cuts in state funding in its next fiscal year, which begins July 1. The UC total budget of $19 billion includes core state funding which will be reduced from $3.3 to $2.8 billion, representing a 10% cut in state funding, which was 17% of the total university funding this year. On the table are furloughs, pay cuts, and staff reductions, some mix of which now seems inevitable.

The UC system has ten campuses, centrally administered from the UC Office of the President in Oakland. Earlier this spring the UCOP paved the way for legal authority to enact emergency measures in the face of fiscal emergencies such as this. Every department in the the entire system has been struggling to meet large budget reductions already, but the demise of the state ballot Propositions 1a and 1b meant that the reductions for the 2009/10 year were greater than hoped.

Then, on Friday, UC president Mark Yudof announced a 5% pay cut for senior management, down to the level of Vice Chancellors at each campus. It therefore seems rather likely that a general 5% reduction in some form is in the offing. The 23-campus California State University system faces a similar situation.

Overall, this is not that bad when you consider the fact that 235,000 California state workers will face a 14% pay reduction, and the the US economy as a whole is still shedding well over half a million jobs per month. But then, as the Chronicle of Higher Education asks, will higher education be the next bubble to burst?

It has become somewhat of a tradition here at CV to announce our newly-minted PhDs. It is thus with great pleasure that I congratulate Devdeep Sarkar on having earned his degree in Physics from the University of California, Irvine, co-advised by Asantha Cooray and myself. Devdeep has worked very hard over the past few years, producing a total of 7 papers:

A. G. Riess et al.; Astrophys. J. (2009; in press)
A Redetermination of the Hubble Constant with the Hubble Space Telescope from a Differential Distance Ladder

D. Sarkar et al.; Astrophys. J. Lett. 684 L13 (2008)
Implications of Two Type Ia Supernova Populations for Cosmological Measurements

A. Cooray, D. Sarkar, and P. Serra; Phys. Rev. D 77 123006 (2008)
Weak Lensing of the Primary CMB Bispectrum

D. Sarkar et al.; Phys. Rev. D 77 103515 (2008)
Cosmic Shear from Scalar-Induced Gravitational Waves

D. Sarkar et al.; Astrophys. J. 678 1 (2008)
Lensing and Supernovae: Quantifying the Bias on Dark Energy Equation of State

D. Sarkar et al.; Phys. Rev. Lett. 100 241302 (2008)
Beyond Two Dark Energy Parameters

D. Sarkar, H. Feldman, and R. Watkins; Mon. Not. R. Astron. Soc. 375 691 (2007)
Bulk flows from velocity field surveys: A Consistency Check

Much of Devdeep’s work has focused on gravitational lensing (of CMB and of supernovae), as well as a better way to analyze data to constrain dark energy (in redshift bins, instead of using arbitrary, poorly-motivated parameterizations). Next month Devdeep is fortunate to be starting a postdoc with Dragan Huterer at the MCTP at Michigan.

Congratulations to Dr. Sarkar on a well-earned piece of parchment!

Via Brad DeLong, an article by Kevin Carey in the Chronicle of Higher Education starts with the obvious — the internet is killing newspapers as we knew them — and asks whether the same will happen to universities.

Much of what’s happening was predicted in the mid-1990s, when the World Wide Web burst onto the public consciousness. But people were also saying a lot of retrospectively ludicrous Internet-related things — e.g., that the business cycle had been abolished, and that vast profits could be made selling pet food online. Newspapers emerged from the dot-com bubble relatively unscathed and probably felt pretty good about their future. Now it turns out that the Internet bomb was real — it just had a 15-year fuse.

Universities were also subject to a lot of fevered speculation back then. In 1997 the legendary management consultant Peter Drucker said, “Thirty years from now, the big university campuses will be relics…. Such totally uncontrollable expenditures, without any visible improvement in either the content or the quality of education, means that the system is rapidly becoming untenable.” Twelve years later, universities are bursting with customers, bigger, and (until recently) richer than ever before.

But universities have their own weak point, their own vulnerable cash cow: lower-division undergraduate education. The math is pretty simple: Multiply an institution’s average net tuition (plus any state subsidies) by the number of students (say, 200) in a freshman lecture course. Subtract whatever the beleaguered adjunct lecturer teaching the course is being paid. I don’t care what kind of confiscatory indirect-cost multiplier you care to add to that equation, the institution is making a lot of money — which is then used to pay for faculty scholarship, graduate education, administrative salaries, the football coach, and other expensive things that cost more than they bring in.

I’m not sure I buy it. Let’s think about what good purposes a college or university might serve. Off the top of my head, I can think of several:

1. Classroom-based education. Certainly important.
2. Extracurricular learning. This includes everything from “participating in actual academic research” to “serving on the school newspaper.”
3. Meeting different kinds of people. Not only do students get exposed to professors, and an academic way of thinking about problems, but they also meet other students, hopefully from a wide variety of backgrounds.
4. Establishing independence. For many people, going to college is the first time one lives away from home, and begins to establish an identity separate from one’s family.
5. Belonging to a community. From the university itself to numerous smaller subcultures within, college provides an opportunity to belong. As great as the Teaching Company is, it doesn’t have a basketball team in the Final Four.

Feel free to add your own. We can argue whether online learning can be effective in replacing the first of these — after all, hearing a recorded lecture is not the same as hearing it live. But it would appear very difficult to replace the others. The four years one spends at college are often the most formative (and perhaps the most enjoyable) years of one’s life. It’s not clear, of course, how much people are willing to pay for those other purposes, as important as they may be.

On the other hand, there is a long-established bargain at big research universities that could conceivably come unraveled at the hands of the internet. Namely: it is research and scholarship that attracts the faculty and establishes the academic reputation of a school, but it is teaching that brings in students and tuition dollars. This is not an arrangement based entirely on avarice; the top research schools bring in a lot more money from grants and gifts than they do from student tuitions. But it reflects a deep philosophical split, that might signal an underlying instability: from within academia, the purpose of the university is seen as the production of new scholarship; from outside academia, the purpose of universities is seen as the teaching of students.

In the case of newspapers, the internet made it harder to tightly bundle straightforward news with advertising and sections of the paper any one reader might not be interested in. In the case of universities, will the internet make it harder to bundle teaching and research? Quick, name the largest private university in the U.S. The answer is the University of Phoenix, founded in 1976, where 95% of faculty are part-time and the large majority of teaching happens completely online.

It could happen that more education-providing corporations (one hesitates to call them “universities”) could develop better ways to provide online classroom educations to a large number of students who are interested in the first purpose listed above but are unwilling to pay for the second. If that model catches on, it will cause dramatic upheaval in the economy of traditional universities. And, much as I love the internet, that would be too bad.

Wednesday was a big day in the physics department at Penn, as we held the annual Henry Primakoff lecture. Primakoff was the first Donner Professor of Physics at Penn, and served on the faculty from 1960 onwards. He was best known for his eponymous effect, which, among other things, describes the production of neutral pseudoscalar mesons by the interaction of a photon with a virtual photon in the Coulomb field of a heavy nucleus. (Intrigued to know more about Primakoff, I came across this touching memoir by the late Peter Rosen, who had worked with him.)

Since T.D. Lee’s inaugural lecture in 1985, a string of outstanding physicists have delivered the Primakoff lecture. But I was extremely lucky that, in my first year here, the honor fell to a cosmologist - Jim Peebles. Jim was nice enough to give an astrophysics seminar yesterday afternoon (on “The Cosmology of Small-Scale Structure”), and then, after an hour break, to give his Primakoff lecture, titled “Finding the Big Bang”.

Popular-level lectures these days often focus on some of the more recent developments in the field, and the reasons they are so exciting. Certainly quite a few of my own public lectures take this approach. But Jim took a different tack, focusing instead on the sequence of events through which the big bang theory became accepted. He gave a wonderful historical account of the discovery of cosmic expansion, and a more personal description of the most important later discoveries; of the microwave background radiation (CMB) and the abundances of the light elements (Big Bang nucleosynthesis - BBN). Jim himself was around for a great deal of this important history (Indeed, it was Jim’s advisor, Bob Dicke, who set David Wilkinson looking for the CMB, only to be serendipitously scooped by Arno Penzias and Bob Wilson), and his take on how the various discoveries were made, and who played the important roles taught me quite a few details that I hadn’t realized. I don’t think I can do real justice to his account, but fortunately I don’t have to, since all will be described in an upcoming book, edited by Jim, with Bruce Partridge and Lyman Page, coming out at the end of next month. I’m sure we’ll write about it here.

That evening, I turned up for the dinner to celebrate the Primakoff lecture to find out that I was the second person to arrive, the first being Mildred Cohn Primakoff. Being new to Penn, I didn’t know that Mildred was around, and it was a wonderful surprise to meet her. Ms. Primakoff was born in 1913, and became a successful female scientist at a time when that was far less common than today, becoming the Benjamin Rush Professor of Physiological Chemistry at Penn, and receiving the National Medal of Science. They must have made quite a remarkable couple!

The astro community virtually shut down a couple of weeks ago. Didn’t you notice?

Every ten years the entire Astronomy and Astrophysics community gets together to decide what to do next. We take stock, and plan out the next decade. Committees are formed, white papers are written, town halls are attended, and at the end of a long process a report is issued, with a ranked list of the priorities of the community. This Decadal Survey helps decide which telescopes are built and which space missions fly, and sets the direction for the major advances of the field in the coming years. I think this process is fairly unique among academic disciplines; a field self-consciously trying to come up with a formal plan for the future. Of course, it can be quite contentious, but at the end the bulk of the community gets behind what is decided, and everyone goes forward from there. The hope is that this process expresses the will of the community, and therefore will impact which projects are pursued and funded (as opposed to leaving it up to politicians and other non-astronomers). In addition, it’s a chance for everyone to get together and learn what’s happening across the field, and see what directions things are moving in.

We are now in the midst of Astro2010, the current decadal review. A panel has been formed, chaired by Roger Blandford. A large portion of the astro community was out-of-commission in mid February, as everyone frantically finished up their science white papers. Over 320 were submitted, all of which will eventually become public on the NRC website (yours truly contributed to four, having to do with coordinated gravitational-wave and electromagnetic observations, gamma-ray bursts, and rapid-cadence surveys.). If you’re impatient, you can take a look at a subset of the white papers on the arXiv. The Panel is now soliciting white papers on the State of the Profession and on Technology Development, as well as on specific mission proposals. Anyone is welcome to submit. If you have particularly strong opinions, and feel your voice must be heard, there will also be a series of Town Hall meetings over the next few months.

The survey should be completed in about a year, with a document summarizing the directions the field is likely to go in for the next decade. The titles of the science white papers makes for interesting reading in its own right. They show the tremendous breadth of the community, ranging from planets to cosmology, and from magnetic fields to first light.

Like a lot of folks in the science biz, I’ve been wondering about the outcome of the science spending in the stimulus package. The econ crowd argues that an effective stimulus should be both fast acting and temporary. Common sense also dictates that the spending should be something that will eventually either reduce spending in the future, or grow the GDP.

There’s much speculation that some fraction of the NSF and NIH spending will go towards funding recent proposals that were very highly ranked, but fell just below the funding cutoff. Given how ridiculously oversubscribed the individual investigator grant programs are, there will be no lack of worthwhile projects to fund. On the other hand, these types of grants are not necessarily fast acting. Notifications take a while to process, and by the time the funding becomes secure, job “season” for academics would be well over, causing a significant delay before personnel could be hired and money spent.

However, I think there is a pretty obvious use for some of the money that better targets the goals of the stimulus package — fund postdocs directly. In astronomy, there are a number of high prestige fellowships that are awarded to postdocs through the NSF or NASA. These awards offer postdocs complete freedom to direct their own research programs, a high degree of flexibility as to where they go, and a modest budget to support their research. Thus, instead of spending 2-3 years performing labor for a senior PI, the postdocs can develop new lines of research.

I see a lot of benefit to this idea, and not too many drawbacks:

First, postdocs are typically at a very productive stage of their careers. They’ve learned tons of useful tricks in grad school, but are not yet bogged down by teaching, grant writing, and sitting on endless committees. Scientifically, postdocs are a lot of science bang for the buck.

Second, of all of us on the science track, postdocs are possibly getting slammed the hardest. Faculty searches are getting cancelled left and right, so we have an academic generation of highly trained scientists with nowhere to go. In the past, many of these people have successfully transitioned into industry (thus moving the benefits of past investment in their training back into the private sector), but these days that’s not much of an option either. Giving the most promising of these folks a way to tread water for a few years might keep more of them in the scientific pipeline long enough to transfer into a stable position which made use of their skills.

Third, independent postdoctoral fellowships allow one to develop skills that one needs to make a longer term scientific career work — namely, the ability to choose your own scientific questions and then plan and execute your approach. Instead, if the stimulus package gets funneled to postdocs solely through PI grants, then a significant fraction of postdocs are primarily going to learn additional skills in “doing what their advisor suggested”. (While ideally there’s mentoring to support grant-supported postdocs, that doesn’t always occur.) Moreover, the PI has a responsibility to the granting agency to deliver the products supported by the original grant, and cannot legally support the postdoc working on topics that are unrelated, no matter how cool and clever they are. Developing one’s scientific judgement, and prioritizing one’s effort are skills that transcend the particular needs of academic science — thus, even if these postdocs do not eventually wind up on an academic track, the skills they acquire during a truly independent phase would be of huge benefit in the private sector.

Finally, the postdoc applications are ready to go. Committees have met and made prioritized lists for this most recent round of awards, and my past experience suggests that they could probably double the number of awards before having any substantive concern that the money was going to someone who was not yet ready for full scientific independence. The money could then be out there stimulating those postdocs by the fall, but would be over in 3 years — fast acting and temporary, just like it’s supposed to be. If more stimulus is needed next year, they can just increase the number of awards a second time (preferably opening it up to people who are more than three years past their PhD, which is a current limitation on some of the programs).

The main drawbacks I can see are (1) that it takes money out of the hands of PI’s who have a proven track record of making smart scientific judgements and (2) that it adds to the overpopulation of postdocs compared to faculty positions. With regard to the first, there is nothing that says that PI’s can’t lure these independent postdocs to their project (especially if the agencies keep rules in place to keep all the postdocs from bunching up at one or two particularly attractive institutions). If you are doing interesting things, and have a good record for mentoring, some of these people will be more than happy to collaborate with you. Moreover, in many fields postdocs need access to infrastructure that only PIs have (lab space, big fancy science toys, large data sets, etc), in which case the postdocs would be likely to affiliate themselves closely with PIs anyways.

As for the second concern, I’m not quite sure where I come down on the issue. I’ve always thought it was a mistake for people to see a tenure-track faculty position as the only acceptable outcome of PhD level training, and by giving people scientific independence at an early stage of their career, you’re offering them a chance to develop skills they’d need for anything they’d do in the future. These people are stuck in a holding pattern anyways, and it makes more sense to me to let them do their best work while they’re looking for a place to land.

It’s been a bit of a hectic week. Last Monday I took the train (can’t tell you how happy I am whenever I avoid flying these days) to Washington DC, for a couple of days of government work, finishing up quite late on Wednesday. The next morning I flew from DC to Vancouver (you can’t always avoid it), where on Friday I delivered the departmental colloquium at Simon Fraser University. My friend, and former postdoc, Levon Pogosian is a Professor there, and I spent a very stimulating couple of days discussing physics with him and his colleague Andrei Frolov. Everyone is always telling me how beautiful Vancouver is, but on my previous visits there has been nothing but rain and cloud, and I haven’t seen anything of the area’s natural assets. This time however, it was fifty degrees and sunny, without a cloud in the sky for the entire visit, and I was just blown away by the breathtaking scenery entirely surrounding the city. Completely gorgeous! I also managed to squeeze in a wonderful dinner with friend, UBC Professor and blogger, Moshe Rozali.

On Saturday morning I was up bright and early to fly back to Philadelphia, arriving late on Saturday, in time for a quick dinner and sleep before the firefighter and I had to drive up to Syracuse for some personal business that was going to take 25 minutes, but needed us to be there in person. We completed that this morning, and then I rented a car and drove immediately back to Philadelphia.

After a week like that, I’d normally think about taking a day off before driving back, but in this case that wasn’t an option because tomorrow is a big day for us here at Penn. You may recall me mentioning that the university was setting up a new Center for Particle Cosmology. Well, tomorrow is our launch event! The first part is a panel discussion, with program

The Center for Particle Cosmology presents Of Telescopes and Microscopes
A Panel Discussion and Q&A

Tuesday, February 24, 2009
4:30 – 5:30 p.m.
Bodek Lounge, Houston Hall
3417 Spruce Street

The study of the microscopically small and the unimaginably large are no longer distinct realms of inquiry. In the first of a series of events hosted by the Center for Particle Cosmology, leading experts will consider what insights modern observations might provide into phenomena such as dark matter, dark energy and the physics of the early universe.

Panelists Include:
Vijay Balasubramanian, Associate Professor of Physics and Astronomy
Bhuvnesh Jain, Associate Professor of Physics and Astronomy
Janna Levin, Assistant Professor of Physics and Astronomy (Barnard College of Columbia University) and author of A Madman Dreams of Turing Machines, winner of the 2007 PEN/Robert Bingham Fellowship for Writers
Mark Trodden, Professor of Physics and Astronomy

Moderated By:
Gino Segre, Emeritus Professor of Physics and Astronomy and author of Faust in Copenhagen: A Struggle for the Soul of Physics

Introduction By:
Tom Lubensky, Chair of the Department of Physics and Astronomy

Sponsored by the Center for Particle Cosmology and the School of Arts and Sciences.

This is then followed by:

Guests are invited to mingle with Center faculty who will be happy to answer questions and talk about their research. As part of the reception, attendees will also enjoy multimedia presentations by:

Mark Devlin, Professor of Physics and Astronomy and a principal investigator of BLAST (the “Balloon-borne Large-Aperture Submillimeter Telescope”)

Evelyn Thomson, Assistant Professor of Physics and Astronomy and a member of the ATLAS collaboration, a particle physics experiment at the Large Hadron Collider at CERN

Refreshments will be served.

which we expect to go on until around 7pm. Well, we’ll see about that “leading experts” stuff, but I’m hoping it’ll be a lot of fun. And with Gino and Janna involved, how could it not be? After all, if Janna can handle Stephen Colbert, and Gino can hold his own in the New York Times, they should be OK with us.

If you’re in the Philadelphia area you’re welcome to attend - you just need to register. This has taken up quite some time over the last two weeks, and so on Wednesday it’s back to work finishing a couple of papers that are begging for final edits.

I just got back from Pittsburgh, a city famous for honoring football players along with Fathers of our country. Apparently they recently won some sort of sporting contest, so the citizens were generally in good spirits.

I was visiting to Center for the Philosophy of Science at the University of Pittsburgh, to speak in their annual lecture series. The Center, along with the Department of History and Philosophy of Science, help make Pittsburgh one of the world’s leading institutions for studying philosophy of science.

The Center is also a remarkably friendly place, and I had a great time during my visit. The highlight, predictably, was lunch with some of the graduate students, where we got to let our hair down and talk about big ideas concerning time and causality and determinism. (Almost all professional academics start out fascinated by big ideas, but the interest is gradually beaten out of them along the way by the demands of professionalism and career advancement. Grad school is probably the peak combination of background knowledge and willingness to confront the hard problems.) I also got to chat with Adolf Grünbaum, whose declamations concerning the Primordial Existential Question had impressed me a year and a half ago. And I got to meet some fellow bloggers in the flesh — the formidable Cosma Shalizi, who helped me understand how to augment the principle of indifference with conditionalizing over the past hypothesis, and Bryan Roberts of Soul Physics, who was one of the aforementioned grad students.

But if I’m really honest, my favorite part of the trip was probably the building. The Center for the Philosophy of Science is housed in the Cathedral of Learning, a looming structure on the University’s campus — the second-tallest academic building in the world, after one at Moscow State University. Despite my lack of religious sympathies, I love cathedrals — the looming structures, swooping curves, open spaces, all designed to elicit a certain emotional response going far beyond their direct practical purpose. (Not that different from the best casinos in Vegas, really.) And I love learning! So the Cathedral of Learning is pretty much the perfect building.

And it really does work as a building. What everyone points to are the many Nationality Rooms scattered throughout the building — a series of 27 spaces decorated in the style of various different countries, often with the input (and financial assistance) of the respective governments, which work as display pieces but are also functioning classrooms. (I was told that prospective students are sometimes convinced to come to Pittsburgh by a visit to the room corresponding to their personal heritage.) But what I liked was the immense Commons Room (pictured), with impossibly high ceilings, which is just a place where people can sit down and read and talk and think. Such places are very precious, and the world should have a lot more of them.

If Wikipedia is to be believed, the Cathedral grew out of a vision of Chancellor John Gabbert Bowman in the 1920’s. He insisted that the Commons Room be built on the principles of true Gothic architecture, with self-supporting arches. When told that these things cost money, he replied:

“You cannot build a great University with fraud in it.”

I’m not sure if that’s strictly true, but it’s an honorable principle to strive towards.