Observing, days 1-2

I am sitting in the control room of the James Clerk Maxwell Telescope (JCMT), 14,000 feet up Mauna Kea, on Hawaii’s Big Island. I’m here to do observations for the SCUBA-2 Cosmology Legacy Survey (CLS).

I’m not really an observer — this is really my first time at a full-sized, modern telescope. But much of JCMT’s observing time is taken up with a series of so-called Legacy Surveys (JLS) — large projects, observing large amounts of sky or large numbers of stars or galaxies.

JCMT is a submillimeter telescope: it detects light with wavelength at or just below one millimeter. This is a difficult regime for astronomy: the atmosphere itself glows very strongly in the infrared, mostly because of water vapour. That’s why I’m sitting at the cold and dry top of an active volcano (albeit one that hasn’t erupted in thousands of years).

Unfortunately, “cold and dry” doesn’t mean there is no precipitation. Here is yesterday’s view, from JCMT over to the CSO telescope:

Snowy view of the CSO from JCMT

This is Hawaii, not Hoth, or even Antarctica.

Tonight seems more promising: we measure the overall quality as an optical depth, denoted by the symbol τ, essentially the probability that a photon you care out will get scattered by the atmosphere before it reaches your telescope. The JLS survey overall requires τ<0.2, and the CLS that I’m actually here for needs even better conditions, τ<0.10. So far we’re just above 0.20 — good enough for some projects, but not the JLS. I’m up here with a JCMT Telescope System Specialist — who actually knows how to run the telescope — and he’s been calibrating the instrument, observing a few sources, and we’re waiting for the optical depth to dip into the JLS band. If that happens, we can fire up SCUBA-2, the instrument (camera) that records the light from the sky. SCUBA-2 uses bolometers (like HFI on Planck), very sensitive thermometers cooled down to superconducting temperatures.

(You can keep track of the conditions here, and specifically monitor the optical depth here. News flash: as I type this, τ=0.199, less than 0.2!)

Later this week, I’ll try to talk about why these are called “Legacy” surveys — and why that’s bad news.

 

meTube

Some time last year, Physics World magazine asked some of us to record videos discussing scientific topics in 100 seconds. Among others, I made one on cosmic inflation and another on what scientists can gain from blogging, which for some reason has just been posted to YouTube, and then tweeted about by FQXi (without which I would have forgotten the whole thing). There are a few other videos of me, although it turns out that there are lots of people called “Andrew Jaffe” on YouTube.

I’m posting this not (only) for the usual purposes of self-aggrandizement, but to force — or at least encourage — myself to actually do some more of that blogging which I claim is a good thing for us scientists. With any luck, you’ll be able to read about my experiences teaching last term, and the trip I’m about to take to observe at a telescope (a proper one, at the top of a high mountain, with a really big mirror).

[On a much more entertaining note, here’s a song from a former Imperial undergraduate recounting “A Brief History of the Universe”. Give it a listen!]

Academic Blogging Still Dangerous?

Nearly a decade ago, blogging was young, and its place in the academic world wasn’t clear. Back in 2005, I wrote about an anonymous article in the Chronicle of Higher Education, a so-called “advice” column admonishing academic job seekers to avoid blogging, mostly because it let the hiring committee find out things that had nothing whatever to do with their academic job, and reject them on those (inappropriate) grounds.

I thought things had changed. Many academics have blogs, and indeed many institutions encourage it (here at Imperial, there’s a College-wide list of blogs written by people at all levels, and I’ve helped teach a course on blogging for young academics). More generally, outreach has become an important component of academic life (that is, it’s at least necessary to pay it lip service when applying for funding or promotions) and blogging is usually seen as a useful way to reach a wide audience outside of one’s field.

So I was distressed to see the lament — from an academic blogger — “Want an academic job? Hold your tongue”. Things haven’t changed as much as I thought:

… [A senior academic said that] the blog, while it was to be commended for its forthright tone, was so informal and laced with profanity that the professor could not help but hold the blog against the potential faculty member…. It was the consensus that aspiring young scientists should steer clear of such activities.

Depending on the content of the blog in question, this seems somewhere between a disregard for academic freedom and a judgment of the candidate on completely irrelevant grounds. Of course, it is natural to want the personalities of our colleagues to mesh well with our own, and almost impossible to completely ignore supposedly extraneous information. But we are hiring for academic jobs, and what should matter are research and teaching ability.

Of course, I’ve been lucky: I already had a permanent job when I started blogging, and I work in the UK system which doesn’t have a tenure review process. And I admit this blog has steered clear of truly controversial topics (depending on what you think of Bayesian probability, at least).

Teaching mistakes

The academic year has begun, and I’m teaching our second-year Quantum Mechanics course again. I was pretty happy with last year’s version, and the students didn’t completely disagree.

This year, there have been a few changes to the structure of the course — although not as much to the content as I might have liked (“if it ain’t broke, don’t fix it”, although I’d still love to use more of the elegant Dirac notation and perhaps discuss quantum information a bit more). We’ve moved some of the material to the first year, so the students should already come into the course with at least some exposure to the famous Schrödinger Equation which describes the evolution of the quantum wave function. But of course all lecturers treat this material slightly differently, so I’ve tried to revisit some of that material in my own language, although perhaps a bit too quickly.

Perhaps more importantly, we’ve also changed the tutorial system. We used to attempt an imperfect rendition of the Oxbridge small-group tutorial system, but we’ve moved to something with larger groups and (we hope) a more consistent presentation of the material. We’re only on the second term with this new system, so the jury is still out, both in terms of the students’ reactions, and our own. Perhaps surprisingly, they do like the fact that there is more assessed (i.e., explicitly graded, counting towards the final mark in the course) material — coming from the US system, I would like to see yet more of this, while those brought up on the UK system prefer the final exam to carry most (ideally all!) the weight.

So far I’ve given three lectures, including a last-minute swap yesterday. The first lecture — mostly content-free — went pretty well, but I’m not too happy with my performance on the last two: I’ve made a mistake in each of the last two lectures. I’ve heard people say that the students don’t mind a few (corrected) mistakes; it humanises the teachers. But I suspect that the students would, on the whole, prefer less-human, more perfect, lecturing…

Yesterday, we were talking about a particle trapped in a finite potential well — that is, a particle confined to be in a box, but (because of the weirdness of quantum mechanics) with some probability of being found outside. That probability depends upon the energy of the particle, and because of the details of the way I defined that energy (starting at a negative number, instead of the more natural value of zero), I got confused about the signs of some of the quantities I was dealing with. I explained the concepts (I think) completely correctly, but with mistakes in the math behind them, the students (and me) got confused about the details. But many, many thanks to the students who kept pressing me on the issue and helped us puzzle out the problems.

Today’s mistake was less conceptual, but no less annoying — I wrote (and said) “cotangent” when I meant “tangent” (and vice versa). In my notes, this was all completely correct, but when you’re standing up in front of 200 or so students, sometimes you miss the detail on the page in front of you. Again, this was in some sense just a mathematical detail, but (as we always stress) without the right math, you can’t really understand the concepts. So, thanks to the students who saw that I was making a mistake, and my apologies to the whole class.

Songs about f*&%ing

First, my apologies that I couldn’t resist the almost not-safe-for-work title, especially to those expecting posts about astrophysics and cosmology rather than a reference to a 1987 record by Big Black (which it’s worth pointing out can be found in its entirety on YouTube). But this is not a post about Big Black.

Rather, it’s a brief reminiscence of another album with a similar subject matter and a very different style, Liz Phair’s Exile in Guyville, which I was shocked to discover is about to have its 20th anniversary, also commemorated with an article and interview in the Chicago Tribune.

I lived in Chicago in the early 90s when Exile In Guyville was released, although I don’t think I heard it until I left town and moved to Toronto a few months later. But she was already a presence on the scene when Chicago was taking its place in the world of post-Nirvana indie-rock (led by the Smashing Pumpkins, along with Urge Overkill, who never quite capitalised on the marquee placement of their “Girl, You’ll Be A Woman Soon” cover on the Pulp Fiction soundtrack, and my favourite, Eleventh Dream Day). It was a record full of great songs about fucking and love and being a lonely twenty-something hipster in a big city, and was a sort of homage to the Rolling Stones’ own Exile on Main Street, all of which was enough to make rock critics (and wannabes like me) wet their pants — although by now I’m sure the Stones reference is irrelevant to record’s brilliance. “Guyville” was code (surfacing first in an Urge Overkill song) for the Wicker Park neighbourhood which was the center of the Chicago rock scene, and home to my second-favourite Chicago bar, the still-going-strong Rainbo Club (alas, my favourite, Ciral’s House of Tiki, closed in 2000).

And the title of this post also covers The Book of Mormon, which I went to see in London’s West End last week, the filthy and wonderful musical comedy from the creators of South Park. Despite songs about sex with amphibians (and worse), a character named “General Butt Fucking Naked” (sort of named after a real Liberian warlord), and being self-consciously suffused with coarse stereotyping of Africans and the eponymous Mormons, manages to be old-fashioned, warm-hearted and strangely, uncynically, affirming of the ability of individuals to actually make a difference in each other’s lives.

Today was the deadline for submitting so-called “White Papers” proposing the next generation of the European Space Agency satellite missions. Because of the long lead times for these sorts of complicated technical achievements, this call is for launches in the faraway years of 2028 or 2034. (These dates would be harder to wrap my head around if I weren’t writing this on the same weekend that I’m attending the 25th reunion of my university graduation, an event about which it’s difficult to avoid the clichéd thought that May, 1988 feels like the day before yesterday.)

At least two of the ideas are particularly close to my scientific heart.

The Polarized Radiation Imaging and Spectroscopy Mission (PRISM) is a cosmic microwave background (CMB) telescope, following on from Planck and the current generation of sub-orbital telescopes like EBEX and PolarBear: whereas Planck has 72 detectors observing the sky over nine frequencies on the sky, PRISM would have more than 7000 detectors working in a similar way to Planck over 32 frequencies, along with another set observing 300 narrow frequency bands, and another instrument dedicated to measuring the spectrum of the CMB in even more detail. Combined, these instruments allow a wide variety of cosmological and astrophysical goals, concentrating on more direct observations of early Universe physics than possible with current instruments, in particular the possible background of gravitational waves from inflation, and the small correlations induced by the physics of inflation and other physical processes in the history of the Universe.

The eLISA mission is the latest attempt to build a gravitational radiation observatory in space, observing astrophysical sources rather than the primordial background affecting the CMB, using giant lasers to measure the distance between three separate free-floating satellites a million kilometres apart from one another. As a gravitational wave passes through the triangle, it bends space and effectively changes the distance between them. The trio would thereby be sensitive to the gravitational waves produced by small, dense objects orbiting one another, objects like white dwarfs, neutron stars and, most excitingly, black holes. This would give us a probe of physics in locations we can’t see with ordinary light, and in regimes that we can’t reproduce on earth or anywhere nearby.

In the selection process, ESA is supposed to take into account the interests of the community. Hence both of these missions are soliciting support, of active and interested scientists and also the more general public: check out the sites for PRISM and eLISA. It’s a tough call. Both cases would be more convincing with a detection of gravitational radiation in their respective regimes, but the process requires putting down a marker early on. In the long term, a CMB mission like PRISM seems inevitable — there are unlikely to be any technical showstoppers — it’s just a big telescope in a slightly unusual range of frequencies. eLISA is more technically challenging: the LISA Pathfinder effort has shown just how hard it is to keep and monitor a free-floating mass in space, and the lack of a detection so far from the ground-based LIGO observatory, although completely consistent with expectations, has kept the community’s enthusiasm lower. (This will likely change with Advanced LIGO, expected to see many hundreds of sources as soon as it comes online in 2015 or thereabouts.)

Full disclosure: although I’ve signed up to support both, I’m directly involved in the PRISM white paper.

Reformat

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Another technical note: I’ve just reformatted the whole blog. Let me know if there are any problems (or if you just think it’s ugly).

Infrastructure problems

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Just a quick note that the blog has been having some issues with its infrastructure: pointers to individual entries seem to be broken.

I’m on the case — apologies if you can’t get to anything you’re looking for.

Update: fixed, I think. Let me know if there are any further problems. (The blog should be a bit faster, too, as I’ve moved over to statically publishing all the pages. Don’t worry if you don’t know what that means.)

About a year ago, I wrote about TimeWave a festival of art, science and technology coming this May to London, with tendrils snaking out to New York and LA.

As part of the festival, we’re organising Quest for the Grail: An International Adventure Game, later this month: from noon to 5pm in London and right afterwards, noon to 5pm in Manhattan, New York.

The London teams will “hunt for objects in Clerkenwell hotspots…from the Order of St. John to Blackfriars Bridge to the International Magic Shop. You may be looking for a charm against the Plague, a tombstone or a silver goblet. Your team may be asked to invent something - the holiest of drinks.” The game continues with New York teams searching in “Manhattan hotspots…from Clinton Castle to the tombstones of Trinity Church to the Grand Lodge of the Masons. You may be looking for a marker of a headless ghost who haunts Wall Street, a symbol of George Washington or a troll in the East Village”, aided by London players and puppetmasters overseeing the games.

Unfortunately, I’m in sunny California recovering from my winter (and many years) of Planck work, but if you’re in either city and would like to play, you can join as an individual, a half-team of five, or a full team of ten players. There’s more information on the site, or you can contact the organisers directly at grail@timewavefestival.com.

Planck 2013: the PR

Yesterday’s release of the Planck papers and data wasn’t just aimed at the scientific community, of course. We wanted to let the rest of the world know about our results. The main press conference was at ESA HQ in Paris, and there was a smaller event here in London run by the UKSA, which I participated in as part of a panel of eight Planck scientists.

The reporters tried to keep us honest, asking us to keep simplifying our explanations so that they — and their readers — could understand them. We struggled with describing how our measurements of the typical size of spots in our map of the CMB eventually led us to a measurement of the age of the Universe (which I tried to do in my previous post). This was hard not only because the reasoning is subtle, but also because, frankly, it’s not something we care that much about: it’s a model-dependent parameter, something we don’t measure directly, and doesn’t have much of a cosmological consequence. (I ended up on the phone with the BBC’s Pallab Ghosh at about 8pm trying to work out whether the age has changed by 50 or 80 million years, a number that means more to him and his viewers than to me and my colleagues.)

There are pieces by the reporters who asked excellent questions at the press conference, at The Guardian, The Economist and The Financial Times, as well as one behind the (London) Times paywall by Hannah Devlin who was probably most rigorous in her requests for us to simplify our explanations. I’ll also point to NPR’s coverage, mostly since it is one of the few outlets to explicitly mention the topology of the Universe which was one of the areas of Planck science I worked on myself.

Aside from the press conference itself, the media were fairly clamouring for the chance to talk about Planck. Most of the major outlets in the UK and around Europe covered the Planck results. Even in the US, we made it onto the front page of the New York Times. Rather than summarise all of the results, I’ll just self-aggrandizingly point to the places where I appeared: a text-based preview from the BBC, and a short quote on video taken after the press conference, as well as one on ITV. I’m most proud of my appearance with Tom Clarke on Channel 4 News — we spent about an hour planning and discussing the results, edited down to a few minutes including my head floating in front of some green-screen astrophysics animations.

Now that the day is over, you can look at the results for yourself at the BBC’s nice interactive version, or at the lovely Planck Chromoscope created by Cardiff University’s Dr Chris North, who donated a huge amount of his time and effort to helping us make yesterday a success. I should also thank our funders over at the UK Space Agency, STFC and (indirectly) ESA — Planck is big science, and these sorts of results don’t come cheap. I hope you agree that they’ve been worth it.