Results matching “Planck”

Me, the MP, Planck and Paris

If I’ve got any longtime readers, they may recall that I spent a week paired with Anne Snelgrove MP in the UK Parliament a couple of years ago, as part of a program connecting scienctists with Members of Parliament (described here and here). This week, Anne kept up her side of the bargain and visited us here at Imperial; our press office has done a better job describing it than I could do.

Right now, I am in Paris, attending a meeting of the Planck Surveyor Satellite High Frequency Instrument Core Team, doing my meager bit planning for what we’ll actually do once the data starts flowing in a year or so. Also, enjoying as much French wine and food as I can manage in about 48 hours.

Mapping the Galaxy from Portugal

I spent the week before last in Portugal working with the team designing and building the GEM telescope: The Polarized Galactic Emission Mapping Project in Portugal. GEM (aka GEM-P or even P-GEM-P) aims to measure the emission of our Milky Way galaxy using light at a wavelength of 6 cm. Those frequencies are dominated by synchrotron emission, generated by electrons deflected by the magnetic field of the galaxy. These measurements will give us invaluable information about the structure of the galaxy. Moreover, this emission is an important contaminant for the cosmological maps that experiments like the Planck Surveyor and its successors like the BPol project that many of us have just proposed to the European Space Agency.

GEM-P is being built mostly by a small group at the Instituto de Telecomunicações and the Universidade de Aveiro. Here’s me with a large part of the Aveiro team:
GEM-P team small
That’s Rui Fonseca, Domingos Barbosa, me, Dinis Magalhães and Luis Cupido. This wasn’t taken at the GEM-P lab, by the way, but in Luis’s backyard, and that’s the 5.5 meter dish he keeps there to play with and do things like track NASA spacecraft in the outer reaches of the solar system!

Aveiro is a lovely town (even The New York Times agrees) experiencing a pretty remarkable building boom that manages to combine a high-tech University with an old-fashioned fishing village. For me, that meant the useful combination of pretty ubiquitous wifi and great seafood. (More pictures of Aveiro here).

(I also got to spend some time wandering around Porto, where I stayed right down the road from Rem Koolhaas’s new Casa de Musica, just shortlisted for the RIBA Stirling Prize. Photos of the older bits of Porto here.)
Casa da Musica


Congratulations to Professor Michael Rowan-Robinson, former head of our Astrophysics Group at Imperial and president of the Royal Astronomical Society. This week, Imperial hosted a meeting in Michael’s honor on the occasion of his 65th birthday, From IRAS to Herschel/Planck: Cosmology with infrared and submillimetre surveys. Astrophysicists came from all over the UK, Europe and even the US and Asia to discuss the cosmology and long-wavelength astronomy that Michael has been studying since the late 1960s. (The talks, on galaxy evolution, cosmology, and the brightest galaxies in the Universe, will eventually be posted for download.) A particular highlight was a presentation from Richard Ellis on his team’s possible observation of the most distant galaxies ever seen.

At the conference dinner, Michael was roasted by Lord Martin Rees, president of the Royal Society, a classmate at Cambridge in the 60s, and by George Efstathiou, head of the Institute of Astronomy at Cambridge today. We heard about the books Michael has written over the last few decades, what it’s like working at a telescope with him late at night — and some of the poetry he wrote in his youth.

Finally, all of my new readers who have found this blog searching for information about a certain rock star astronomer will be happy to know that Brian May successfully reprised his talk on the Zodiacal Light for the even more demanding international crowd.

Hard Rock in the Solar System

The Zodiacal Light is a fuzzy glow visible in the morning and evening sky, stretching along the line along which the constellations of the zodiac appear — the ecliptic that we now know to be the plane made up of the sun and the orbits of the planets. Observations of the zodiacal light show it to be due to reflections from dust in the plane, dust thought to be mostly the detritus of collisions between and among asteroids, comets, and more distance objects from the Kuiper Belt.

This week we in the Imperial astrophysics group were treated to a talk on the zodiacal light by Brian May, the group’s newest postgraduate student (and one of the eldest). Brian started his Imperial PhD in the early 1970s, but decided to leave to play guitar, eventually, on the roof of Buckingham Palace. Last year, he decided to return to astrophysics and, perhaps amazingly, has finished his PhD thesis under the supervision of Michael Rowan-Robinson, the former head of our group and current President of the Royal Astronomical Society. He was actually lucky in his choice of topics: it hasn’t been a major research area since his last astronomical work three and a half decades ago but is coming to the fore again as we start seeing similar dust clouds orbiting distant stars, and as we worry about the obscuring properties of the local dust as we peer through it with ever-more-sensitive instruments, such as the Planck Surveyor.

For someone so, um, inexperienced in public speaking (or at least in giving scientific presentations), Brian gave a very good distillation of the history of the field (including the missing 35 years while he was indisposed) including his own work, and his own interpretations speculating that some of the light may be due to our movement through an even larger cloud of interstellar dust.

As is customary, we took Brian May (still “Mr. May” until he gets his PhD later in the Summer) out to dinner with members of the group, and he even joined us afterward for a pint at one of our locals. He paid for a round, and he was extremely gracious to the crowds who stared, pointed, and came up to chat. He was also accompanied by his chauffeur, a very nice guy who was also one of the… widest… men I’ve ever seen (and who seemed happy to sit in the very nice Lexus while Brian ate and drank with us).

Who would have through astrophysics would give me a taste of the rock’n’roll lifestyle?

I was travelling through Schiphol airport in Amsterdam today (more later on the various reasons why) when I was delighted to see the Sunday New York Times on sale at the airport news-stand… until they tried to charge me €14.50 (about $20 or £10). It’s still the best paper in the world (especially on Sunday), but the 400% markup seems a bit steep (not to mention encouraging the waste of transporting these newspapers thousands of miles across the world).

April First (and Second)

We take so much of the web for granted today, we often forget how very contingent it all is. Without the very specific work by Tim Berners-Lee inventing the http protocol, perhaps some sort of hypertext communication standard would have come along, but it’s hard to believe that it would be quite the same. Berners-Lee has always advocated a still more open “read/write” web, and about the closest we come to that is, of course, the weblog. Well, blogs were arguably launched ten years ago, on April 1, 1997, by Dave Winer. Scripting News was an outgrowth of his DaveNet emails, but had all the usual hallmarks of a blog: short items, lots of links, and, crucially, reverse chronological order. Dave has gone onto a career as a general computer pundit and curmudgeon — and also invented RSS (that orange “XML Feed” icon over at the side).

Of course, the first of April has another name. If you read this blog regularly, you know that we physicists have a fantastic collective sense of humor, as evidenced here, here and here. Funny, huh?

My own April Fool’s incident came a bit early, last Thursday night, unable to make my way from the arrival hall of Rome’s Fiumicino airport to the airport Hilton. I arrived around midnight, after the trains stop running into town. What they don’t tell you is that all the passageways between the airport buildings are also shut — without signs to tell you where to go. After conflicting information from three different sets of people, I found myself staggering around the deserted parking lots searching for the warm bed I had booked (I did eventually find it, and the front desk took pity on me in the form of an upgrade to the “executive suite” floor). The next day, although a bit sleepy, was at least a productive discussion of the next step in our proposal for a new mission to measure the polarization of the microwave background — in about 2015 or 2020.

But since today is really April 2, you can also read a real blog post by Amedeo Balbi, my cosmology colleague (on MAXIMA and Planck and probably more in the future) over in Tommaso Dorigo’s blog; he’s got one of his own, but it will only make sense if you read Italian.

Big Smoke Science

In his comment on last week’s post, fellow physicist blogger Tommaso lets me know that he’ll be attending a meeting that we’re hosting here at Imperial College next week, Outstanding questions for the standard cosmological model. We’ll be casting a critical eye over current cosmological models and data, but I expect most of us will come to the conclusion that the whole structure is surprisingly weather-sturdy.

In fact if you’re any sort of astrophysicist, particle physicist or cosmologist, Imperial Physics is likely to have a meeting for you in London over the next few months. In addition to “Outstanding Questions”, we’ll have

  • A meeting making plans for XEUS, April 2-4. XEUS is the X-Ray Evolving Universe Spectroscopy mission, an X-Ray telescope satellite under consideration by the European Space Agency;
  • PASCOS (Particles, Strings and Cosmology) 07, July 2-7, the latest in a series of meetings examining the interface between theoretical particle physics and cosmology; and
  • From IRAS to Herschel-Planck, July 9-7. This is a special meeting, in honor of Professor Michael Rowan-Robinson on his 65th Birthday. Michael is currently the head of our Astrophysics group, and is one of the founders of the field of sub-millimeter and infrared astronomy, using long-wavelength photons to observe those parts of the Universe often hidden behind clouds of dust — veiled stellar nurseries where indeed a significant fraction of the stars were formed in the universe’s first few billions of years. IRAS was the first large-scale infrared satellite, and Herschel (along with its sister spacecraft, Planck, about which you’ve heard plenty here) will be the next ambitious project to observe the whole sub-millimeter sky.
Hope to see you in London…

Planck scanning strategy

OK, this is going to be very technical. In his comment to my last post, my colleague Ned Wright asks a couple of important questions about the way that the Planck Surveyor satellite is going to observe the sky. In the spirit of Mark Trodden’s question about the use of blogs in the research process, let’s see if we can answer these questions in a way that will satisfy Ned (who knows more about observing the CMB than most people on the planet) and not be completely opaque to the rest of my readers. Ned asks:

What is the current plan for the Planck scan pattern? I see this quote from the 2005 Blue Book:

The spacecraft will spin at 1 rpm around an axis offset by 85 degrees from the telescope boresight, so that the observed sky patch will trace a large circle on the sky (Dupac and Tauber, Astronomy & Astrophysics 430, 363, 2005)….

As the spin axis follows the Sun, the circle observed by the instruments sweeps through the sky at a rate of 1 degree/day. The whole sky will be covered (by all feeds) in a little more than 6 months; this operation will be repeated twice, resulting in a mission lifetime of around 15 months.

This describes a terrible scan pattern that may ruin Planck’s ability to measure the low-ell polarization signal that is essential for deterimining tau.

And the claim of covering the whole sky is wrong since as described, a 5 degree radius about each ecliptic pole is left out. That’s most of the sky, but not all.

The inner quote describes the way Planck will scan the sky — every minute, the satellite will observe a circle with an opening of twice the 85 degree angle described in the quote (a great circle that goes through the poles would have twice 90 degrees). Here’s a picture (from Dupac and Tauber 2005) of Planck’s location and the way it will scan the sky:


Ned is worried about two things, but I’ll discuss them in the opposite order.

He points out that the scan strategy leaves “holes” about five degrees across in the North and South poles. Indeed, the so-called “nominal” scan strategy above does suffer from this (although this is somewhat ameliorated by the fact that Planck has many detectors all looking at spots up to eight degrees from one another on the sky, so in fact those holes are largely filled). A more realistic scan strategy, as described in the paper by Dupac and Tauber mentioned above, will dip up and down out of the plane defined by pointing away from the sun, earth and moon. The exact way we perform these dips (how quickly and with what pattern) remains to be decided, but in any event will fill in those holes. For one possible strategy, the coverage looks like the following, from the same paper (yellow and red areas are observed more than blue and green):


Second, and most important, are the effects of long-term drifts in our detectors. An instrument like Planck can’t just look at a point in the sky and measure the temperature directly. Instead, the background level coming out of our detector is drifting over time, and these drifts can actually be large compared to the tiny CMB signal we’re trying to measure (for aficionados, this is often known as 1/f noise, after the power spectrum of the noise often observed in cases like this). This means that it’s relatively easy to measure the relative temperature of points that are observed nearby in time — since the background hasn’t drifted by much. But it’s much more difficult to measure relative temperatures over long periods of time. Therefore (as Ned points out), it might be difficult to observe patterns on large angular scales, across many individual rings. This is “the low-ell polarization signal that is essential for deterimining tau”: only on these scales can we observe the effects on the CMB of the very first objects to “light up”, more than twelve billion years ago.

This difficulty can only be ameliorated by “cross-linking” — making sure that you observe the same point at many different times. This lets us recalibrate the baseline of the detector every time we revisit that point or, better, set of points. The experiments that Ned Wright himself has worked on, COBE/DMR and WMAP, cleverly achieve this by the very complicated way they observe the sky.

Planck will definitely have a harder time, since its cross-linking only occurs at those points near the poles with many repeated observations. This puts a strong constraint on our detectors: they can’t drift very much over the one minute it takes to make a single circular scan. In this article, my Planck colleagues Christopher Cantalupo, Julian Borrill & Radek Stompor show that we can indeed handle these problems for more-or-less realistic kinds of noise.

To be sure, the real world is always more complicated than our simulations. The hard part will be dealing with what we euphemistically call “systematic effects” — roughly speaking, those errors that we don’t know how to describe very well, or that we don’t know about when we first fly the satellite. The ability to find these systematic effects is another reason why we want both very small known sources of error and the greater redundancy afforded by cross-linking, by comparing the same signal seen under very different conditions at different times during the mission.

Undoubtedly, we will encounter such unexpected sources of noise when we confront real data from Planck late next year, but we hope that the quality of our detectors, combined with the design of our scan strategy, will give us enough extra information to account for these inevitable problems. (But I probably won’t be able to tell you for sure until about 2011 when we’re due to make our first release of Planck results!)

Update: Further comments from Ned below. Discretion being the better part of valor, I shan’t comment on why these decisions have been left until now (although it is certainly arguable that flexibility is a good thing), and why Ned himself wasn’t consulted (suffice to say I wasn’t a member of the team that far back). However I must certainly agree that Planck’s ability to measure the polarization of the CMB would certainly be better if, as he suggests, the scan strategy visited pixels from many different directions, rather than approximately along lines of “longitude”; the measurement of polarization depends on just those directions, and having many different such measurements at the same location would make it easier to account for the aforementioned 1/f noise and possible systematic effects. Indeed, the experience of the WMAP team teaches us the difficulties of the measurement of large-scale polarization. We do believe that our raw sensitivity will be such that we can recover this polarization sufficiently accurately, but the proof will be in our results, and not in any simulations we do beforehand.

Planck Press

With only [sic] about a year and a half to go before launch, The Observer has a story on the ESA Planck Surveyor mission that I’ve spending much of my time working on over the last several years. (In fact, I have to spend the day writing a program that will play a very small part in working out exactly where the satellite’s detectors are pointing while it’s spinning around in space.)

Update: The BBC has got an article that goes more in-depth (and with more Nobel prize-winners, but less of me…).

The New York Times opines on the physics Nobel:

…The award is richly deserved, and the agency deserves great credit for making the work possible. Too bad the program that yielded these pioneering discoveries was reined in not long ago so that NASA could pour billions of dollars into resuming shuttle flights, finishing the international space station, and developing spacecraft to pursue the Bush administration’s ambitious space exploration program.

…Huge teams of government and academic researchers measured and analyzed the cosmic microwave background radiation that permeates the universe. Their findings provided strong support for the Big Bang theory of the origins of the universe, and turned cosmology, previously rather speculative, into a precise science. The discoveries have been hailed as one of the greatest scientific advances of the past century.

The COBE satellite was part of NASA’s Explorers Program, which uses small satellites to conduct important studies that don’t need gigantic, costly space platforms. Yet these and similar small-scale missions were disproportionately cut to free up money for more grandiose programs. The Nobel award suggests that NASA needs to rebalance its portfolio, a task the agency says is in progress.

Amazingly, COBE’s results didn’t come from a “huge team of … researchers”, but a relatively small, focused group of a few dozen scientists. More recent results from COBE’s successor, the WMAP satellite, came from similarly-sized teams; contrast this to the 400 or so working on ESA’s Planck Surveyor Satellite. Unfortunately for the 400 of us, two important things I’ve learned in my time as a scientist is that scientists are terrible at being managed—and even worse at being managers.

Quick update

Sorry I’ve been silent… here’s a quick update:

I’m in Pasadena, California, working at JPL and Caltech on various tasks related to the Planck Surveyor Cosmic Microwave Background satellite, to be launched in a couple of years (which means “soon” in this game).

Mmmmm!I’m sure you’re waiting breathlessly to hear my commentary on such crucial subjects as Pluto’s planetary status (or lack thereof; but really, who cares?), the nature of the Dark Matter, the cosmological dark ages, and the fine cuisine of Roscoe’s House of Chicken ‘n Waffles.

But you’ll just have to wait.

Sinuous Titanium & Big Iron

Guggenheim - 10I’m recently back from my vacation in Bilbao. Aside from the usual “getting away from it all”, the first highlight was the amazing pintxos—Basque tapas like squid-and-ink croquettes and piles of jamon iberico. With a full tummy, I could handle Frank Gehry’s spectacular Guggenheim Bilbao, one of the most beautiful buildings in the world. Sheathed in somehow billowing titanium, the museum floats next to the river, but after you get used to its undoubted weirdness, you immediately see it as part of the cityscape, with people seated at the cafes that surround it, others jogging past, kids playing in the waterjets that serve as a fountain undifferentiated from the plaza around it. Inside, the glass, limestone and steel give it the beauty of a cathedral but without the hushed tones.

The Matter of TimeAlso inside, permanently installed in a football-field-sized gallery (amusingly sponsored by steelmakers Arcelor), is Richard Serra’s “The Matter of Time”, a collection of the sculptor’s Torqued Ellipses, Spirals, and Snakes. Curving sections of reddened core-ten steel, the biggest problem with the display is that you’re not allowed to touch it, when what you really want to do is rub your entire body against the plates (apologies if that’s more about me than you wanted to know).

In news about another kind of big iron, the US National Energy Research Supercomputer Center has chosen Cray to supply its next major machine. Cray, absorbed into Silicon Graphics in 1996 at the start of the last tech boom/bubble, was sold off again in 2000, making ‘supercomputers’ since the early 70s, produced the fondly-remembered T3E in the 90s, back when supercomputing was largely in support of science and engineering (as opposed to serving web pages). The new system will have almost 20,000 dual-core processors, but what matters if you’re doing science (or at least the kind that I’m most interested in), is the way that those processors are wired together: we don’t want to do 20,000 individual calculations; we need to do one calculation that’s 20,000 times too big to fit on one machine. To date, NERSC has probably supported more CMB-related supercomputing than anywhere else, and we all hope that the new machine will enable us to do even more, in particular to analyze data from coming experiments like the Planck Surveyor.

Cash for cosmology

Congratulations to my colleagues Saul Perlmutter, Adam Riess and Brian Schmidt! They are sharing the rather lucrative Shaw Prize for their leadership in the late 1990s discovery that the Universe seems to be accelerating in its expansion. In particular, through painstaking observational campaigns over many years, they observed that distant supernovae — exploding stars whose intrinsic brightness are all roughly the same — seem to be dimmer than would be expected in the simplest universe. Dimmer, hence further away than expected; further away, then, due to an accelerated expansion of the Universe as a whole.

The most obvious mechanism for this expansion is Einstein’s Cosmological Constant. The problem is that, although we don’t have any precise way to calculate its value, the best guess is either strictly zero (so no acceleration at all) or that it’s something like 122 orders of magnitude (that’s 10122) times larger than it’s observed to be (the Planck density, for aficianados). Another possibility is that the acceleration is due to something not quite as fundamental as a cosmological constant, some sort of field pervading the Universe, often called Dark Energy or Quintessence. Unfortunately, there are no particularly compelling ways to calculate its value in that case — these are more like paradigms in search of a detailed theory. A final possibility is the so-called anthropic argument: the cosmological constant has the value that it does because, if it didn’t, we wouldn’t be able to be here to observe it. Unfortunately, any version of that argument that isn’t a tautology is unpredictive, useless, or silly, at least for now.

So let’s hope a future version of the Shaw prize goes to someone clever enough to explain the acceleration.

Thanks to Sean for pointing this out, and for noting that the ideas behind the discovery were already in the air (especially since that allows me a little self-aggrandizement). Also, in the interests of equal-time, I should point out that there are reputable astrophysicists out there who aren’t quite convinced by the Supernovae data.

Cosmology in the Mediterranean

Like fellow-blogger Mark Trodden , I’ve just spent the week at scientific meetings in Ischia, an island off the coast of Naples. The first half of the week was for the yearly consortium meeting of the Planck Surveyor satellite. Although still endangered by further delays, we expect the satellite to be launched in early or mid 2008, and by then we have to be ready to analyze the data from Planck as it gets transmitted, just a few bits at a time, from the satellite at the “L2” point, 1.5 million kilometers from the Earth, a place where the sun, earth and moon will all be in a small area of the sky — so it’s easier to shield the satellite, which is measuring temperature differences of a few parts in a hundred thousand on top of a background just three degrees above absolute zero.

Of course, at an experts-only meeting like this, we didn’t discuss the exciting scientific prospects so much as the details confronting us today: planning how the mission is going to scan the sky, how we’re going to measure the instrument’s properties in situ, and how we’re going to transform the terabytes of data it will produce into information about the universe.

After the detailed work of the consortium meeting, we turned to the scientific side of cosmology as it is today, hearing about details of early universe physics, dark matter, and, especially, Planck’s predecessor, WMAP, from Mike Nolta.

Pompeii 1I even got some time free at the end to spend a day at Pompeii, and at the National Archaeological Museum. Coming from a country only a couple of centuries old, walking through two-thousand year-old streets, it was remarkably easy to imagine the ancient Romans peddling their wares, living their lives, eating and drinking, just like us (except for the slaves, of course…). (More pictures here.)

To top it all off, I returned to find Spring finally arrived in London, my favorite plants in bloom at last. But now, no rest for the weary: after about a day and a half back home, it’s off to another meeting. But that’s an entry for later.

Management, Money, Media

Wednesday was a busy day of politicking and schmoozing (as opposed to research and teaching, which is what I actually get paid to do).

I spent the morning at a meeting reviewing the current status of developments for the Planck Surveyor satellite here in the UK (Planck will measure the temperature of the Cosmic Microwave Background, relic radiation from the Big Bang). Unfortunately, as is common in these ambitious and exciting projects, not everything is quite going according to plan. We need to cool parts of the satellite down to a mere four degrees above absolute zero. This has become relatively easy to do in a laboratory, but is still very difficult up in space, where you have stringent requirements on size, weight and power and, most importantly, where you can't fix anything once it's been launched. So this part of the project is over budget, late, and indeed faced with technological problems (like, how do you build it so it can survive shocks equivalent to 3000 times the acceleration due to gravity?!).

Part of the problem is that scientists, despite thinking that we know how to do everything, are generally bad (or at least untrained) managers, and even worse “managees” -- we don't like being told the way to do things (I can certainly speak for myself here on both counts, but at least understanding that I have these problems might be the first step towards solving them.)

The rest of the day was much more pleasant. First, I went to a short meeting debriefing those of us who participated in the Royal Society's “MP-Scientist” pairing scheme. It was great to see and talk with my cohorts from November, and then we all headed down watch the wonderful Faraday Lecture by Professor Fran Balkwill on Ovarian Cancer, which was neither dry nor depressing. The evening ended with the “Scientists Meet the Media” party hosted at the Royal Society by the Daily Telegraph and Novartis (who paid for the champagne, apparently). There were scientists from crusty old white-haired Fellows of the Royal Society on down to youngish faculty members like me and media types from TV, newspapers, magazines and science journals. Power couple Gia and Brian were there, as were Adam Hart-Davies in a frightening bright blue suit, Robert Winston in a tux, all presided over by astrophysicist Lord Martin Rees, new president of the Society. We scientists tried to keep up, but the journalists did their best to live up to their hard-drinking reputation, aided by the free-flowing wine and very scarce food. Usually the scientists are the ones with the privileged information, but on a night like this, the journalists seemed to be in control, we scientists in full media-slut mode, our not-so-secret desire for fame, or at least recognition, on show.

Update: Here's a report from the Telegraph, focusing on the celebrities at their party...


So, why Helsinki? I was here to be the “Opponent” for a Ph.D. examination for a student at the University of Helsinki. I felt like the host of a talk show: after short presentations by the candidate and me, we sat at the front of an auditorium, and I quizzed him on topics near to our hearts (or our brains, at least): the Cosmic Microwave Background (CMB), and analyzing data from the soon-to-be-launched Planck Satellite using the specific algorithms that he had developed, implemented and tested. Some questions were hard, some were easy, and I'm sure that plenty were just asked in a confused way. But I'm happy to say that he comported himself very well, and he'll be all Doctored-up within a few weeks (in Finland, that seems to involve buying a special hat).

The whole process was very formal, very Northern European (in principle we were meant to be wearing tophat and tails, but we settled for dark suits). Most of my colleagues sniff at these things, but I'm all for a bit of ritual and symbolism -- getting your doctorate should be a big deal. That it was, indeed, a big deal was made even more plain by the next part of the ritual: the VäitösKaronkka, the party, hosted by the newly-minted Doctor in honor of the Opponent and other “respected guests”. We had several kinds of wine, foie gras, grouse (complete with buckshot; not for the squeamish) -- no reindeer, sadly. This one was held in the Hotel Kämp, a recently-restored 19th-century building where, apparently, Finnish luminaries like Sibelius had held court, drank, avoided their families, and planned Finnish independence.

Right now, I'm sitting in the Helsinki airport: right back to the UK for about 12 hours, and then off to the even more remote locale of Tokyo for a week. Next installment: General Relativity from the far East!

Science (and food) the world over

I'm in the midst of four weeks which I'll have spent mostly on the road, and as a working trip, it's a good opportunity to discuss some of the science I'm doing, for a change.

I spent last week at Lancaster University, at Origins 2005: The Origin of the Primordial Density Perturbation. Despite its location in the grey and damp North of England, the meeting was lots of fun, and sufficiently outside of my area of expertise that I actually learned quite a bit. We know that the Universe today is filled with massive galaxies, each made of billions of stars and, we think, even more dark matter. Tracing these galaxies backwards in time, we know that these huge lumps must have once been tiny fluctuations in a nearly uniform universe, and we see these tiny fluctuations reflected in the Cosmic Microwave Background (the CMB, the main subject of my research). The meeting addressed some fundamental questions about these fluctuations: Where did they come from? How did they evolve? I was happy to get to talk about some work by my smart and energetic students, looking at some of the work they've done examining the pattern of CMB fluctations on the largest scales and other topics on the generation and evolution of these perturbations and how they're reflected in the CMB.

This week I'm at Berkeley and the Computational Research Division at LBL, where I'm visiting my colleagues Julian Borrill, Radek Stompor, and Chris Cantalupo, mostly to finish a paper on a software package called Microwave Anisotropy Dataset Computational Analysis Package (MADCAP). We developed MADCAP to analyze data from experiments probing the fluctuations in the CMB. More properly, the others developed it, while I provided some background theorizing, a very early version of some of the algorithms, and moral support. MADCAP has been used to analyze data from the MAXIMA and BOOMERANG experiments -- which gave the first high precision measurements of the geometry of the Universe -- and is currently being used to analyze the successors to those experiments (MAXIPOL and B2K -- not the rappers), as well as in the planning for the upcoming Planck Surveyor mission to be launched by ESA in about 2007.

Having lived in the Bay Area for five years, I also plan on spending time with lots of old friends and eating Mexican food, dim sum, and 'dem fantastic ribs from Betelnut in San Francisco.

Finally, next week it's back to the UK for a quick stop at home before I head off to Warwick for Physics 2005: a Century After Einstein, a meeting sponsored by the Institute of Physics, where I'll be talking about the detection of Gravity Waves using the Cosmic Microwave Background radiation. These gravity waves, if they exist, are expected to be yet another relic of the early universe, one of the hallmarks of an early epoch of Inflation, a mechanism invented in the early 80s thought to be responsible for the flat geometry of the Universe, the overall uniform temperature of the CMB (about three degrees Kelvin) as well as the tiny primordial perturbations observed by the CMB experiments and discussed at the meeting in Lancaster last week. With luck, I'll also get a chance to discuss work I'm doing with yet another smart and energetic student on gravity waves generated by supermassive black holes (millions or billions times the mass of the sun!) which in the last few years we've learned live at the centers of many galaxies.

Science Publishing II: RSS & XML


For the technically-minded, here's an article (via The Role of RSS in Science Publishing: Syndication and Annotation on the Web, by Hammond, Hannay, and Lund of the Nature Publishing Group:

RSS is one of a new breed of technologies that is contributing to the ever-expanding dominance of the Web as the pre-eminent, global information medium. It is intimately connected with—though not bound to—social environments such as blogs and wikis, annotation tools such as [1], Flickr [2] and Furl [3], and more recent hybrid utilities such as JotSpot [4], which are reshaping and redefining our view of the Web that has been built up and sustained over the last 10 years and more [n1]. Indeed, Tim Berners-Lee's original conception of the Web [5] was much more of a shared collaboratory than the flat, read-only kaleidoscope"


RSS, which stands for, among other things, "Really Simple Syndication", is a file format based on XML, for quickly promulgating various sorts of summary information through the web; it's used mostly for news headlines and blogs, although it's already being used to list the latest preprints at the astrophysics archive server. Perhaps more importantly, it's also being used to foster discussion of these articles at sites like CosmoCoffee (RSS here) and Physics Comments (RSS here). You can see RSS examples for my blog from the links at the top of this page. (Due to a depressing controversy over the different RSS formats, I can't provide just a single definitive link to a "definition" of RSS, but check the appropriate footnotes in the article above, or the wikipedia.)

(To read RSS, you need a standalone program, although current versions of the Firefox browser and Thunderbird mail reader have rudimentary -- very rudimentary -- capabilities; the next generation of Apple's Safari browser is meant to be RSS-aware, too. Right now, I use the great NetNewsWire on my Mac; I haven't found a really good RSS reader for my Linux machine at work -- does anyone know of one?)

In astrophysics, we are very slowly moving toward various XML formats for data interchange, since XML can very easily be used to not only contain the so-called "raw data" (such as an astronomical image) but also the accompanying (and even more so-called) "metadata", information about the raw data (such as where in the sky the image lies, when it was taken, on what telescope, etc.). In particular, VOTable will be the underlying format for Virtual Observatories such as AstroGrid which I briefly discussed here. ESA's Planck Surveyor satellite, in which I'm also involved, will also likely use some sort of XML underneath.

The article discusses how RSS is currently being used in science publishing (although it emphasized publishing via already-extant paper journals rather than services like the archive), in particular at Nature, where the authors are employed, what sort of protocols for metadata may be needed, and other scientific uses of RSS such as data exchange and even podcasting. (I think the article gets many aspects of the RSS version history incorrect; I also feel it's worth explicitly mentioning the name of alpha-blogger Dave Winer, who more or less invented RSS and much of the blogging infrastructure we know of today.)

On its own, all this is just boring techie jargon. However, when combined with the Science Commons ideas from the last post, we begin to get a full model for disseminating scientific information: data and publications freely exchanged on the web, with open standards so authors and publishers don't have to continually re-invent the appropriate wheels, with appropriate metadata so other scientists know what they're getting, and know how to properly reference it.