Blogs / Cosmic Variance

As we recently noted, Stephen Hawking has stepped down from the Lucasian Chair at Cambridge. The chair didn’t stay empty for long. It has been announced that Michael Green will become the new Lucasian Professor. Green is one of the pioneers of string theory, and is already at Cambridge. I’m not sure he even switches offices, or chairs for that matter.

Hawking did seminal work in general relativity. He proved a number of singularity theorems (with Roger Penrose). He wrote The Large Scale Structure of Spacetime (with George Ellis). John Wheeler conjectured that quiescent black holes have “no hair” (i.e., all black holes look identical, being distinguished only by mass, charge, and angular momentum), and Hawking (with Israel, Carter, and Robinson) proved this to be true. Hawking is a true expert on gravity, which seems completely appropriate for someone donning Newton’s mantle. Does Green’s appointment indicate that, at least in Cambridge’s mind, string theory is the anointed successor to general relativity?

Hawking sat in the Lucasian Chair for three decades. Green is expected to occupy it for a little less than four years, at which point he reaches Lucasian retirement age (67). Aren’t there any young whippersnappers worthy of the seat?

I am just back from Princeton where we held the annual meeting of the GRE Physics Committee of Examiners, a group of six, ahem, distinguished professors (we have grey hair) who sit around a conference table working through hundreds of potential and actual Physics GRE problem. Each year new exam forms are completed, new questions added to the pool, statistics reviewed, and a good time is generally had by all.

This was my last meeting – I have served on the committee for six years. The membership rotates roughly every two years. I had been an external reviewer and problem writer for a couple years, and was then asked to serve on the committee. I am sworn to secrecy about a lot of the details, for good reason, but let me try to tell you from my perspective as an exam writer how to study for this dreaded event in your physics education.

Firstly, there’s the format. The exam is 100 questions long, and you have 170 minutes to do it. This is, therefore, different from just about every other physics exam you have had in college, where you have, say, four to six problems in an hour-long exam. The GRE Physics problems (or “items” in assessment world jargon) are short, to-the-point questions, and just about all of them are short calculations, if any, and take little time once you see what to do. Writing such questions is a difficult thing to do, let me tell you. We are continually amazed how, after about six levels of review, we can find issues of clarity, reasoning, and even sometimes basic physics correctness in the items submitted to the pool. All the committee members spend a lot of time each year reviewing hundreds of problems, looking for flaws, but more often than you would think the face-to-face meeting in Princeton with the ETS folks reveals something previously overlooked. It’s a really interesting process.
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As Mark recently mentioned, we are deep in recommendation letter season. I’ve been in the biz long enough that I’ve probably written at least a hundred letters (estimating more than ten a year for more than a decade), and read far more than that.

After you read enough letters, they can start blend together. But, in a big stack of applications, there are usually a few letters that stand out as risible, causing a good chuckle and round of comment from the committee.

And they are almost always letters written on behalf of women.

In a standard letter of recommendation at the postdoc/faculty level, there is frequently a comparison to other successful scientists. The letter usually reads something like “reminds me of person X, Y, or Z at a similar level of their career” or “shows the same persistence and insight as person Q, and stronger big picture thinking than person P”. These comparisons are almost always favorable, saying that the applicant is in the same league as other people who are recognized as having had a significant scientific impact.

But, for some reason, some fraction of letter writers insist upon doing these comparisons only within a single gender, when the applicant is a woman. In other words, “(woman) X shows a similar level of insight as (woman) Y and (woman) Z”. I’m not saying that these comparisons are not favorable — they’re usually comparing a strong female applicant favorably with other successful female scientists. Their praise is genuine and well meant. However, one can’t but help perceive that they see women as somehow swimming in a different pool than the rest of the guys.

Now the good news is that most committees that I’ve been on have seen right through this. We note it, and have a small laugh at the letter writer’s expense. In addition, it’s not common — usually only affecting a couple of letters in an applicant pool.

So, if you’re writing a letter for someone in an underrepresented group, please save yourself from mockery by examining exactly how you perceive the applicant’s comparison sample.

As I mentioned in my last post, it has been a busy few weeks. In addition to my citizenship interview, I’ve also been traveling to deliver some talks and attend some meetings, as well as attending to all the usual requirements of my job, such as teaching.

Now that I’m basically settled at Penn, I’ve been focused primarily on working on some exciting new projects, while also trying to bring to completion a lot of different research projects that have been languishing somewhat as I got myself settled. I think most of these are back on track now (although some of my collaborators, whose Skype calls I’ve moved several times, may have a different opinion), which is a nice feeling to have after a few months of concerted effort. I even managed to get a conference proceedings finished. I’ll probably post about some of these projects when they’re done.

But over the last few weeks, I’ve also been traveling a little, starting with a colloquium at the University of Wisconsin, Milwaukee, where I talked about modifying gravity to a very knowledgeable audience, and where I was treated to a wonderful (and very late) Friday night out, courtesy of Luis Anchordoqui and Patrick Brady, to whom I owe many thanks. That trip was followed by a colloquium at NASA Goddard Space Flight Center, which seems to employ an inordinate number of people I went to graduate school with. I certainly enjoyed the talk, but particularly enjoyed the meetings they had set up for me during the day. I learned about the long-term possibility of using observations of gravitational wave sources by the LISA experiment, accompanied by optical follow-ups, as a new way to construct a Hubble diagram to trace the cosmic expansion history. While not feasible right now, I found this a fascinating possibility for the future, and I’m hoping that our resident expert may tell us more about it some time.

My final two trips of the recent period were both to New York, and both to NYU. The first was to deliver a seminar at the Center for Particle Physics and Cosmology. The second was for the first of a set of one day meetings that the Center for Particle Cosmology has begun with the NYU Center. That took place a week ago, and featured talks by my colleagues Justin Khoury and Daniel Wesley, and NYU speakers Neal Weiner and Roman Scoccimarro. This was a very fun intellectual exchange, with talks on modified gravity, cyclic cosmologies, and interacting dark matter. Certainly the NYU people set the hospitality bar pretty high for us for when they visit us at Penn next semester.

However, perhaps the most time consuming activity of the last few weeks, in comparison with the rest of the year, has been writing and editing letters of recommendation. This is something I think everyone realizes professors do, but usually doesn’t realize the amount of time it takes.

I don’t know what it is like for everyone, but the first time I was asked to write a serious letter of recommendation was when I was a postdoc, and one of the graduate students I’d been working with asked me if I’d be one of his letter writers as he applied for his first postdoc. This first letter keeps you up at night. One wants to be enthusiastic about the candidate, while realizing that your letter is supposed to provide a service for your colleagues who will evaluate the application, as well as for the candidate. Thus one gets excessively stressed about painting a balanced picture of the candidate’s strengths and weaknesses, while competing with some of the glowing letters that one knows other people will write for their candidates. Nevertheless, you get over it, and you write the best letter you can and hope that it is helpful.

As a faculty member, one rather rapidly comes to realize that writing letters of recommendation is a crucial and time-consuming part of one’s job. So how does one go about it? Well, suppose that someone has asked you for a letter. They might be an undergraduate, a graduate student or a postdoc, asking for a letter for positions ranging from an REU position to a faculty job. The first thing to decide is whether you are prepared to write for them. For me, I tell a person I will write if I think my letter will leave a better impression than receiving no letter at all. If not, then I turn them down and tell them they would do better asking someone else. I also like to tell people roughly the type of letter they can expect. Obviously I don’t give details, but I don’t want there to be any confusion. They might decide they can get a better letter from someone else, or that they just don’t want me to write, and I like them to have enough information to make that decision.

But assuming you’ve made the decision to write for someone, and that they still want you to write, then you have a lot of work ahead of you. There’s some basic stuff to get out of the way up front – how long have you known the person and in what capacity? This is where you lay out why you have sufficient experience with them to be able to provide a complete and authoritative account of their skills, track record and potential. When one is rather junior and writing, this part is important to demonstrate your qualifications before you discuss the applicant’s. As a physicist becomes more senior and well-known, this part of the letter remains just as important, although now it is more because it reassures the reader that the writer actually does know this person well, as opposed to them just being another of the presumably huge number of people clamoring for letters.

Now one moves on to the meat of the matter – evaluating the technical talents of the applicant. Are they deep, broad, sophisticated, creative, and calculationally skilled? There are many nuances involved in this part. Obviously, one wants to be accurate, while highlighting the skills that have impressed you most about the person. If you have written papers with the candidate, then this is the place you’ll write about some of the details and what the candidate brought to the project. If there are relevant weaknesses, you may want to point them out; but in my case, if I’ve decided to write, then I will typically think that these are outweighed by strengths, and you want to make that clear. Perhaps the most important thing to bear in mind here is that these are just your opinions. Yes, they are informed opinions; and yes, they have been solicited by both the candidate and/or the hiring institution because they feel you are qualified to give them. Nevertheless, there is no way around the fact that there is a significant subjective component to a recommendation letter, and it is important to make sure that you recognize this and consider it carefully before making any strong statements.

This, of course, makes letter writing somewhat terrifying (naturally, having to ask for them is also scary). Of course, one doesn’t resent students, postdocs and colleagues for asking for letters (not least because we have all relied on others to do this for us many times), and you want to see your talented colleagues succeed. It’s just that because of this you owe it to everyone involved to do a good job, and this is what makes for the required time commitment. October and November are the time when most letters are requested, and so if you find yourself writing for many people (ten or more people sometimes, at various levels), then it comprises a significant portion of your work over those weeks. It’s a not-often-mentioned, but important part of an academic’s job.

This past weekend, without much fanfare, Stephen Hawking stepped down as Lucasian Professor of Mathematik at Cambridge. This is probably the most famous “chair” in all academe, and Hawking has sat in it for the past three decades. The position is 346 years old, and has been occupied by such luminaries as Dirac, Stokes, and most impressively, Sir Isaac Newton himself.

The primary reason for Hawking’s resignation is apparently not his recent health travails. Rather, it is customary for the Lucasian Professor to retire at the age of 67. And not even Hawking messes with centuries of tradition.

The big question now: who will follow in Hawking’s footsteps?

Tomorrow, thousands of University of California faculty will walk out in protest of state budget cuts, furloughs, and increases to student fees. The action will happen across all ten UC campuses (can you name them all?) and is supported by simultaneous strikes by two unions (UTPE and CUE) representing clerical and technical employees of the university. Here at UC Davis, there is a large rally planned for the main quad in the morning to draw public attention to the issues.

Since my last post on this topic, when it appeared that there would be salary cuts announced, there indeed were. But, especially in the summer, things happen slowly at universities. The original proposal was to give everyone except graduate students a 5% pay cut. The faculty were asked for their input on whether they preferred a pay cut, a salary reduction, or a hybrid. Once it was established that the format would be furloughs, we were asked if furlough days should be on teaching days or not. Despite the overwhelming sentiment of the UC faculty that the students should feel some of the pain of the budget cuts (which they already do through increased fees this year and next) the UC Office of the President elected to mandate that furlough days not be on teaching days.

Many of us thought that it was completely crazy to make pay cuts apply to everyone. For example, on the federal grant on which I am principal investigator (meaning I manage the budget) we pay our postdocs 100% from federal funds, including their benefits and overhead, which is essentially a tax paid to the university. Cutting the salaries of our postdocs would have only a negative effect on the university budget, and would demoralize the most productive research workers at the institution. It would damage for years our ability to attract good people. These arguments won out, and so the furloughs apply only to faculty and staff. (The application to medical school personnel is even more complicated – we won’t go there.)

In the end, the faculty furloughs are on a graded scale according to pay, tooping out at 10% for those making over $240,000 per year. (You can see everyone’s salary in the whole UC system using the nice tool provided by the San Francisco Chronicle…it’s eye-opening.) But even faculty and staff earning less than $40,000 will get a 4% furlough, which, to many of us, seems cruel.

Anyway, things simmered along during the summer, with anger building steadily. The walkout was planned about a month ago, and has really caught fire now. But then, last week UC President Yudof, faced with the spectre of even deeper cuts next year (when federal stimulus money for the state of California runs out), and a continuation of the “fiscal emergency” he declared into the next academic year all but certain, he announced plans to dramatically increase student fees by 30%, to over $10,000 per year for the first time ever, in addition to the 9.3% increase pushed through in May to help close the budget gap.

Ultimately, we all realize that the budget problems we face stem from the poor economy coupled with the effects of Proposition 13, passed over 30 years ago. By requiring a 2/3 majority in the state legislature to pass budget actions, it has led to a tyranny of the minority, a minority of, yes, Republicans who simply will not accept any new tax no matter what it does to the future of the state. Prop 13 caps property taxes at 1% of assessed value of a home, and caps the rate at which that value can rise to 2% per year, unless the house is sold. Clearly in a housing market that saw huge increases past decades, with far faster increases than 2%, this has led to enormous inequities in tax rates. For example, though my neighbors across the street have a house worth about what ours is, they pay about a quarter of what we do in taxes. This has benefitted the elderly greatly, and was a strong motivation for Prop 13 originally, but it has hamstrung the ability of both the state and local governments to support education, both K-12 and higher education.

We, as a state, are eating our seed corn. The University of California and the California State University systems are a tremendous engine for both long and short term economic growth. From this great compilation of statistics about UC let me just point out a few:

• More than 220,000 students are enrolled in the University of California.
• For every dollar of state money, the university secures six dollars in federal research money.
• UC researchers patent three new inventions per day.
• UC has the highest proportion of low-income students among the country’s top research universities.

It’s just stupid to think that de-funding the university will not seriously damage the state in the long run.

When I am out on the quad tomorrow, it will be with the intention of motivating the leadership in this university to fight, fight like hell, to make the case to the public and the legislature that we MUST support a public option for higher education. So far I haven’t seen the passion. President Yudof, and the chancellors of the ten campuses should all be out there on radio talk shows, TV, and the print media making the case to the public that this situation is dire. They should join forces with other state institutions to over turn Prop 13.

A new study looks at the average LSAT scores of students with different undergraduate majors, sometimes grouping related fields together to gather a statistically significant sample. (Via.) And the best scores were attained by students studying: (more…)

I didn’t get a chance to hear last year’s Caltech commencement speech by Robert Krulwich, and apparently I missed something good. This I gather from Chad Orzel’s Worldcon speech, which includes a great comparison due to Krulwich. I can’t really do any better than blatantly stealing three slides from Chad’s talk (although the whole thing is worth checking out).

The point of the comparison is to contrast two competing modes of scientific communication, as embodied by our two heroes. Here would be Sir Isaac:

Previously, back in Italy, Galileo had tried a different tack:

With, of course, notably different results:

Admittedly, this stretches the historical narrative a bit in the service of making a point. The divergence between Newton’s and Galileo’s career’s can’t be credited solely to their differences in publication styles. Galileo was a troublemaker by nature, while Newton was a good company man. (Although perhaps there is some correlation there with writing styles?)

But the punchline remains valid: Newtonian publication remains better for your career. And, implicitly, this hierarchy creates problems for the public understanding/acceptance of science. I would add that there’s certainly nothing wrong, all by itself, with scientific publications that are highly technical and inaccessible to a wider audience; those are always going to be a big part of the way science gets done. It’s not a moral failing to write jargon-filled manuscripts that are aimed at other scientists rather than at the general reader; in many cases, that’s simply the appropriate style for the work at hand. The failing is when that is the only kind of writing that is respected and rewarded. Encouraging a diverse portfolio of scientists and scientific publication would both increase the vibrancy of the field and lower the barriers between science and the rest of society.

Also, I would like a pony.

Another summer, another young scientist is elevated from the ranks of Humble Seeker to Wizened Oracle. Or, in more familiar terms, someone successfully gets their Ph.D. The latest elevatee is Lotty Ackerman, my first student here at Caltech. Lotty’s work is well-known to CV readers; she and I collaborated with Mark Wise on the question of a preferred direction in inflation, which was featured in the series of Anatomy of a Paper posts. She also worked with Matt Buckley, Marc Kamionkowski and me on the Dark Photon idea. And she worked with other people on other things, including cosmological density perturbations from reheating and the more experimentally-oriented question of asymmetric beams in the WMAP satellite.

Today Lotty successfully defended her thesis, and we’ll be sad to see her go. But California’s loss is Texas’s gain, as she’ll be taking up a postdoc at the new Texas Cosmology Center in Austin. Best of luck!

Gödel’s Lost Letter writes an interesting post suggesting that complexity classes — categories of computational problems related by the resources necessary to solve them — play a similar role in complexity theory as elementary particles in high-energy physics. (Via Chad.) All very fascinating stuff, no doubt. But along the way a much more important issue is raised: when there is a seminar, should we have donuts before, or after?

Back then, Yale computer science used the post-talk-food normal form. That is after the talk donuts were served to the audience and the speaker. Most places then and now use pre-talk-food normal form, but Yale was different. I always wondered why we were different, but it was Yale.

I have to say that Yale is right on this one, and yet almost everyone does it backwards. Some sort of refreshments — coffee, tea, stale cookies, donuts if you’re lucky — are generally served before a colloquium or seminar, to attract an audience and presumably put people in a good mood. The problem is: we haven’t heard the talk yet, so we can’t chat about that, and if the audience is big enough we might not even know which person is the speaker.

Whereas, if donuts or whatever are served after the talk, not only do you make it more awkward for grad students to scarf some food without sitting through the seminar, but you have offered a very natural topic of conversation — the substance of the actual talk everyone has just heard. And the resulting conversation will usually be better than the desultory Q&A that follows a typical talk. For one thing, it’s just more natural to stand around and chat while sipping coffee or munching a donut than while one person stands at the front of a room and everyone else sits in the crowd (many of whom are restless and ready to scat). For another, students who might be intimidated out of asking a question in front of the whole audience can screw up their courage in a more informal setting. And most importantly, the chances that the actual speaker will get something intellectually useful out of the whole experience are enormously larger if they get to interact with a bunch of people who have just heard their talk. (Not even to mention the abomination of the usual “lunch talk,” where the undernourished speaker seminars away in front of a collection of people happily chewing away at their meals.)

I’m sure a lot of influential people read this blog. Let’s put that power to good use. What do we have to do to change the traditions and make it standard that coffee is served after the talk instead of before?