Andrew Jaffe: Leaves on the Line

Although the big satellites get most of the press, a lot of astronomy is done from balloons, huge mylar bubbles that can carry a gondola up to about 120,000 feet over the earth — more than 22 miles or 32 km. That’s high enough that much of the atmospheric contamination is gone, but a lot cheaper and easier to reach than orbit. I’ve been involved in the BOOMERaNG and MAXIMA balloon experiments, to measure the Cosmic Microwave Background, and currently with EBEX. Some experiments, BOOMERaNG among them, take advantage of the conditions at the South Pole and launches from Antarctica, using the “polar vortex” in the atmosphere to keep the balloon aloft for as much as a couple of weeks. (I should point out that for me, “involved with” means that I stay home where it’s warm and comfortable, but get to play with the data once my hardier colleagues return from the field.)

If you want to get a feel for ballooning, check out BLAST!, a film made of the campaign to fly the eponymous experiment (the acronym stands for Balloon-borne Large-Aperture Sub-millimeter Telescope), made by Paul Devlin, the film-maker brother of one the experiment’s Principal Investigator. It follows the team from their university labs to the Northern launch site in Scandanavia, and finally to Antarctica. I haven’t seen the whole thing yet, but I’m told it does a good job of giving the impression of the alternating excitement and boredom — and lofty goals — of these experiments.

If you’re in the UK, you can see it this week on BBC 4’s Storyville, this Wednesday, 7 January 2009, at 10:00pm; other screenings are listed here.

Out of the blue last weekend, I was invited to participate in a review of the year’s science stories on PressTV, which I subsequently learned was an Iranian-oriented news channel; according to my Teheran-raised grad student, “the Iranian government doesn’t have much control over them, so they are sort of free of sides”. Media whore that I am, I didn’t hesitate too long before accepting, and started to mull over the biggest science stories of the past year.

After a few moments reflection, I couldn’t come up with a very exciting list. The biggest pure-science story was the start of the Large Hadron Collider, but (even if it hadn’t broken!) we wouldn’t expect to see any results until next year or later. There was the launch of the Fermi Space telescope (née GLAST), giving the first map of the whole sky in gamma rays. There were the tantalizing hints from PAMELA of an excess in the cosmic-ray spectrum, potentially the signal of decaying Dark Matter, and certainly the prompt for some interesting intra-science controversies. There was the Nobel Prize for the uncovering of fundamental symmetries (and its own controversies), and the Gruber Prize in cosmology. There were new PhDs for three outstanding scientists, and another one that was a bit more newsworthy. Here in the UK, perhaps the biggest science story, still not completely played out, was the £80 million shortfall in the Science and Technology Facilities Council’s physics budget: results from the last few weeks seem like grants around the country have been cut severely.

Of all of these, only the LHC made the list from PressTV. Instead, we were presented with a list including using mobile phones for medical consultations and data-taking; Iran’s first rocket launch (which was inevitably tied to the country’s putative nuclear ambitions, but was more interesting in the context of scientific launches by China and India this year); and a throwaway article on homeopathy that the editors (frighteningly) didn’t originally realize was a spoof (but at least eventually discarded). Update: The show was shown on Christmas Day and is available now for streaming or downloading. Painful…

But really the biggest science story of the year was the biggest story of the year, period (full stop): the election of Barack Obama. He’s got Steve Chu, a Nobel-prize-winning physicist in the Cabinet as Energy Secretary and John Holdren, a PhD physicist and environmental expert from Harvard directing the White House Office of Science and Technology: with these appointments, along with biologists Jane Lubchenko heading NOAA, and Harold Varmus and Eric Lander co-chairing with Holdren the Council of Advisers on Science and Technology, it looks like science in general, and climate change in particular, will be taken seriously and taking center stage in the new administration. Of course there are still some details, such as the fate of NASA’s post-shuttle launch capabilities and in particular its scientifically-derided Mars program, which aren’t clear; you can weigh in via the NY Times here. Let’s hope it’s coupled to and not separated from (or, worse, at odds with) the economic policies needed to get the US — and the world — out of the credit crunch/recession/depression.

I’ve been asked by Katherine Blundell, a colleague in the Oxford Astronomy department, to spread this information about a chance to get a piece of astronomical history, and help a child in need. Please be generous!

There is a one-off opportunity to buy vintage prints of the original photographic plates of the Palomar All-Sky Survey. Although no longer useful for science (they fell into disuse two decades ago because of modern data digitization) they make rather handsome objets d’art when suitably mounted and framed.

These prints are for sale to raise money for Alexander Thatte’s treatment for leukemia - Alexander is the 5-year old son of two of our colleagues.

The mounted/framed photographs could make very nice Christmas presents and we will deliver them to your department/college office at a mutually convenient time. For a small additional payment we can deliver them to you already tastefully gift-wrapped.

A very limited number of photographs have kindly been signed by Jocelyn Bell Burnell - please email us if you wish to request one of these.

Please see www.physics.ox.ac.uk/skyphoto for an order form and further details. Please feel free to forward this email to anyone whom you think might be interested in purchasing a piece of astronomical history, and helping a child in need.

Best wishes,

Katherine & the Astro Grads

Professor Katherine Blundell
Oxford University Astrophysics
Keble Road, Oxford, OX1 3RH, UK

I'll be introducing this event tomorrow. Come on over for an evening of scientific poetry...

 

	Inua Ellams is one of the UK's most talented performance poets. He is establishing a great reputation for the power and quality of his work. His live appearances have included the BBC Politics show (TV), The Royal Festival Hall, the Glastonbury Rock Festival and Latitude. As part of Generation Txt, an anthology of new talent in UK poetry, he has toured nationwide. His work is influenced by both Classic Literature & by Hip Hop.   Isobel Dixon - Born in South Africa, this wonderful poet is the daughter of a keen amateur astronomer. Her debut Weather Eye won the Olive Schreiner Prize and her latest collection A Fold in the Map was published by Salt in 2007. She will also bereading poems by Rebecca Elson, the distinguished astronomer and poet whose work focused on nebular clusters, and who died in 1999, aged only 39.   Diana Syder one of Britain's leading poets of science, is a writer who can cross the boundaries between disciplines, using ideas and vocabulary from cosmology and physics to inspire her work. Her poetry collections include Hubble, Maxwell's Rainbow and String, all published by Smith/Doorstop Books. In 2002 she received a Public Awareness of Science Award from the Institute of Physics.   Mario Petrucci is a well-known poet and educator. He is also a former research scientist, who has written widely about scientific issues. His recent poetry collections include Heavy Water: a poem for Chernobyl (2004), Flowers of Sulphur (2007). His new collection, Monte Cassino, will be published shortly.
	Escaping the Matrix is a series of poetry events featuring contemporary poets and guest speakers, and forms part of Poet in the City's successful and innovative New Audiences initiative. The three events in the Imperial series have been programmed and managed by Daniel Macadam, Josephine Ivie and Lucy Clouting respectively. Thanks should also go to Ben Gwalchmai, the chair of New Audiences. Poet in the City is a registered charity committed to attracting new audiences to poetry, making new connections for poetry, and raising money to support poetry education, in particular the placing of poets in schools. Charity Commission number 1117354, Company limited by guarantee registered number 05819413. The series is being hosted by Imperial College London, South Kensington Campus, London SW7 2AZ.
	The Escaping the Matrix events will be held at Imperial College London, South Kensington Campus, London SW7 2AZ. Nearest tube stations are Gloucester Road or South Kensington (on the District and Circle line) or Knightsbridge (on the Piccadilly line) Poetry and Work 9th October Clore Lecture Theatre, Huxley Building Poetry and Space 13th November G16, Sir Alexander Fleming Building Poetry and Maths 4th December Lecture Theatre 220, Mechanical Engineering If you would like to see one or more of the events in the Escaping the Matrix series please RSVP as soon as possible to Poet in the City. Call Daniel Macadam on 07754 252212 Email dfamacadam@gmail.com or Write to Poet in the City, c/o Dechert LLP, 160 Queen Victoria Street, London EC4V 4QQ. Booking is essential!

The 2008 Nobel Prize in Physics has been awarded to Nambu, Kobayashi and Maskawa. Nambu, although not exactly famous outside of physics circles, is one of the most influential theoretical particle physicists of the last half-century. He proposed the basis of quantum chromodynamics, which is the theory of how quarks interact to form subatomic particles like protons, neutrons and pions, helped found string theory, and discovered spontaneous symmetry breaking in field theory. Spontaneous Symmetry Breaking is the idea that a theory can have fundamental interactions which are much simpler than those that appear to actually be manifested in the particles which we actually observe. Indeed, this is the idea behind the Higgs Mechanism which gives mass to all of the particles that we see in the world, and whose eponymous particles is one of the main treasures being searched for by the Large Hadron Collider at CERN.

Kobayashi and Maskawa brought together several strands of field theory and helped lead to the standard model of particle physics. The first piece was the fact that particles seem to violated what is known as CP symmetry — some aspects of the Universe would behave differently if you switched particles with antiparticles and simultaneously exchanged left and right. The second was the idea that different sorts of particles — in this case quarks, could actually mix with one another depending on the circumstance. If you measure the mass of the particle, you have a different object than if you concentrate on the strength of its interactions. But the details of that mixing is limited by the constraints of quantum field theory. Kobayashi and Maskawa realized that the theory made a lot more sense if their were six quarks — only three were known when they write their paper in 1972, but all six have since been observed.

And because this is a blog, and therefore really about me, I’ll point out that my first paper on cosmology was called Cosmological constraints on pseudo Nambu-Goldstone bosons which examined some of the repercussions of a variant of Nambu’s theory on the evolution of the Universe and the objects within it.

Update: There’s been a bit of controversy over why Kobayashi and Maskawa didn’t share the prize with Nicola Cabibbo, the Italian physicist who first wrote down the expression for mixing between two quarks, and whose name is always associated with the other two in the full CKM quark mixing matrix. Similarly, there’s an argument for Nambu sharing the prize with Jeffery Goldstone; the two share recognition for one important repercussion of broken symmetry: the Nambu-Goldstone boson (as per my paper above, of course). Indeed, outside of Japan and the University of Chicago, it’s often just the Goldstone Boson. The prize can only to go to three winners at a time, so the committee must have decided this was an adequate compromise (less so if you’re Goldstone or Cabibbo, of course).

A quick pointer to Initiative for Cosmology (iCosmo). The website brings together a bunch of useful calculations for physical cosmology — relatively simple quantities like the relationship between redshift and distance, and also more complicated ones like the power spectrum of density perturbations (which tells us the distribution of galaxies on the largest scales in the Universe) and quantities derived from that like the distortions in the shapes of galaxies due to gravitational lensing, when the path of light from galaxies is perturbed by intervening mass in the Universe. Combined with good documentation and tutorials (and downloadable source), it makes a good companion to sites such as LAMBDA’s CMB toolbox, which provides similar services targeted specifically at Cosmic Microwave Background science. iCosmo looks like it will be useful for researchers in the field as well as students, so thanks and congratulations to its creators (I’d like to point directly at the page listing them, but that doesn’t seem to be possible… instead, there’s a discussion forum at CosmoCoffee.).

The Wakeham Review on the state of UK Physics has been released. Andy Lawrence has a good executive summary and The Guardian an overview. It seems to be positive about the state of physics overall, but perhaps lacks the rage and invective the community was hoping for. I am travelling but will try to digest it; let this serve as a placeholder until then.

So, apologies for taking so long between posts. For now, I’ll blame twitter and its ADD version of blogging, because that at least lets me point to an interesting meeting that went on last week: the .Astronomy Conference on Networked Astronomy and the New Media. the conference brought together several related strands of astronomical computing, from the grid (the Virtual Observatory), to “citizen astronomy” (Galaxy Zoo, which is apparently being upgraded to “Universe Zoo”, Google Sky, and blogs and podcasts), to hacks and mashups built on top of current bits of distributed infrastructure, not to mention twitter itself. (Connectivity is terrible here, but much of the material from the conference is available from the conference site.)

Unfortunately, I spent that time in a meeting room doing my part on STFC committees to keep the UK physics funding process moving along as well as possible during these still-troubled times.

Now, I’m in the Macedonian Greek city of Thessalonika, lucky enough to have been invited to give a talk at From the Antikythera Mechanism to Herschel and Planck: 2500 Years of Observational Astronomy, organized by one of Imperial’s postdocs. I won’t let it go to my head, but it’s nice being treated as someone vaguely important: lunch with the vice-mayor, nice hotel, and amusing Thessaloniki swag to cart home (although when Ute Lemper came to sing she had lunch with the Mayor himself…). My talk is this evening, but the rain outside is precluding much local exploration, but at least I have some time to finish my talk (and write this).

For me, home for about 12 hours tomorrow night, and then off to a Planck meeting in Rome and then Palermo.

Finally let me also welcome Peter Coles to the astro blogosphere. His current prolixity is putting me to shame.

I’m at a meeting in Cambridge this week, discussing details of the way matter is arranged in the Universe, and the insight that gives us into the fundamental physics of the Universe. Many of us have got up a bit early to watch the BBC coverage of the first beams at the LHC, since CERN’s own coverage is overloaded. (It so happens that I’m at DAMTP, Stephen Hawking’s home base, but he has probably wisely decided to stay in bed.)

So far they’ve got the beam half-way around.

We cosmologists are always pleased that almost all of the PR descriptions are about the kind of work that we do: recreating the conditions of the early Universe and finding dark matter.

First mention of the Higgs Boson… but very quickly followed by more cosmology: how will the Universe end?

Pointing out that we’ll have to wait for December or so until we actually get two-beam collisions at full energy.

But now it’s time to go back to my meeting…

And now they’ve apparently had beams going both directions…

PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) is a Russian-Italian satellite measuring the composition of cosmic rays. One of the motivations for the measurements is the indirect detection of dark matter — the very-weakly-interacting particles that make up about 25% of the matter in the Universe (with, as I’m sure you all know by now) normal matter about 5% and the so-called Dark Energy the remaining 70%. By observing the decay products of the dark matter — with more decay occurring in the densest locations — we can probe the properties of the dark particles. So far, these decays haven’t yet been unequivocally observed. Recently, however, members of the PAMELA collaboration have been out giving talks, carefully labelled “preliminary”, showing the kind of excess cosmic ray flux that dark matter might be expected to produce.

But preliminary data is just that, and there’s a (usually) unwritten rule that the audience certainly shouldn’t rely on the numerical details in talks like these. Cirelli & Strumia have written a paper based on those numbers, “Minimal Dark Matter predictions and the PAMELA positron excess” (arXiv:0808.3867), arguing that the data fits their pet dark-matter model, so-called minimal dark matter (MDM). MDM adds just a single type of particle to those we know about, compared to the generally-favored supersymmetric (SUSY) dark matter model which doubles the number of particle types in the Universe (but has other motivations as well). What do the authors base their results on? As they say in a footnote, “the preliminary data points for positron and antiproton fluxes plotted in our figures have been extracted from a photo of the slides taken during the talk, and can thereby slightly differ from the data that the PAMELA collaboration will officially publish” (originally pointed out to me in the physics arXiv blog).

This makes me very uncomfortable. It would be one thing to write a paper saying that recent presentations from the PAMELA team have hinted at an excess — that’s public knowledge. But a photograph of the slides sounds more like amateur spycraft than legitimate scientific data-sharing.

Indeed, it’s to avoid such inadvertent data-sharing (which has happened in the CMB community in the past) that the Planck Satellite team has come up with its rather draconian communication policy (which is itself located in a password-protected site): essentially, the first rule of Planck is you do not talk about Planck. The second rule of Planck is you do not talk about Planck. And you don’t leave paper in the printer, or plots on your screen. Not always easy in our hot-house academic environments.

Update: Bergstrom, Bringmann, & Edsjo, “New Positron Spectral Features from Supersymmetric Dark Matter - a Way to Explain the PAMELA Data?” (arXiv: 0808.3725) also refers to the unpublished data, but presents a blue swathe in a plot rather than individual points. This seems a slightly more legitimate way to discuss unpublished data. Or am I just quibbling?

Update 2: One of the authors of the MDM paper comments below. He makes one very important point, which I didn’t know about: “Before doing anything with those points we asked the spokeperson of the collaboration at the Conference, who agreed and said that there was no problem”. Essentially, I think that absolves them of any “wrongdoing” — if the owners of the data don’t have a problem with it, then we shouldn’t, either (although absent that I think the situation would still be dicey, despite the arguments below and elsewhere). And so now we should get onto the really interesting question: is this evidence for dark matter, and, if so, for this particular model. (An opportunity for Bayesian model comparison!?)