Dark matter remains dark - for now

CDMS detector. Courtesy of Fermilab.

For the past month and a bit, the biggest story in physics has undoubtedly been dark matter.

When Sam Ting, the charismatic Nobel Prize winning director of the AMS project, announced in February that the team who monitor his orbiting Alpha Magnetic Spectrometer, latched to the ISS, would be announcing 'significant results' in the search for dark matter, the whole physics community held its breath.  Somewhat skeptically.

The results, when they were announced on 30 March at CERN, seemed to add weight to the measurements made by PAMELA, in 2008, and were certainly of significant interest.

AMS-02 on ISS. Courtesy of CERN

But they perhaps fell short of what many were hoping for. As theoretical physicist, Katie Mack put it on 5 April in Physics Focus - somewhat bluntly, it should be said, "the AMS-02 detector on the International Space Station has not detected dark matter. It hasn't found 'indications' of dark matter, or even 'hints'. It certainly is not providing the 'best evidence yet' of dark matter's existence."

She did, however, acknowledge the important measurements the AMS-02 detector has made:

"What AMS has done is measure, to very high accuracy, the amount of antimatter the galaxy is bombarding us with. [....]. The AMS experiment detects cosmic rays - protons, electrons, and the antimatter counterparts of each, antiprotons and positrons. Before the experiment ran, we had predictions of how the matter/antimatter fraction should vary with the energy of the particles. AMS tells us our predictions were wrong. The antiprotons look about right, but there's a huge excess of high-energy positrons over what astrophysical models predict, and a bump in the electron flux at high energies. All of these results were actually seen by earlier experiments PAMELA and Fermi, but AMS confirms them to higher precision and higher energies. There's more antimatter than we thought; now we have to figure out why."

This is a concise explanation of the so-called 'positron-excess', which is one of the key indicators that dark matter - whatever it is - exists.  Mack goes on to explain, that the radio astronomers' favourite phenomenon, pulsars, are thought by many astrophysicists to be the cause of the positron excess.

"Pulsars [...] can use their extreme magnetic fields to accelerate particles and create electron-positron pairs. The fact that pulsars do this is solidly in the realm of known physics, and theoretical models can easily fit the signals seen in the cosmic ray experiments."

This is far from an accepted theory of the origin of dark matter, but it is a fascinating one nonetheless.  But where else might we look to find out about the origins of dark matter? The answer is: the mines.

Far beneath the surface of the earth, some of the most significant searches for dark matter have been underway for years. This week, one of the most notable of these, the CDMS experiment (the Cryogenic Dark Matter Search) in the Soudan mine in Minnesota, posted some extremely interesting results. Graduate student, Kevin McCarthy, reported at the American Physical Society meeting in Denver on 13 April that CDMS has found "three promising clues" of dark matter. The their silicon detectors had picked up possible signs of three weakly interacting massive particles (or 'WIMPs', as physicists call them).  Their evidence is verifiable to a level of three-sigma.

As Jason Palmer explains, particle physics has an accepted definition for a "discovery": a five-sigma level of certainty. "The number of standard deviations, or sigmas, is a measure of how unlikely it is that an experimental result is simply down to chance, in the absence of a real effect Similarly, tossing a coin and getting a number of heads in a row may just be chance, rather than a sign of a "loaded" coin The "three sigma" level represents about the same likelihood of tossing nine heads in a row. Five sigma, on the other hand, would correspond to tossing more than 21 in a row. With independent confirmation by other experiments, five-sigma findings become accepted discoveries."

So CDMS' three-sigma result falls short of this, but it most certainly counts as a 'tantalising hint'.

As science writer Valerie Jamieson notes, the CDMS dark matter signal fits with recent theories that suggest dark matter is, "not a single entity, but a 'dark sector of particles' that could include dark antimatter".

"This may be the start of a very big deal" observes dark matter theorist Dan Hooper, of Fermilab, who manage CDMS.

So whilst dark matter remains enigmatic, and most certainly dark, for now, there's some hope we may be closing in on its secrets.

Sources:

http://www.aps.org/meetings/april/

http://is.gd/coldwater

http://cdms.berkeley.edu/

Storifying Critical Citizen Science

MadLab Scientists investigating food products. Image (cc) MadLabUK, 2013.

Alice Bell recently drew my attention to a fascinating piece of writing by the Goldsmiths academic, Dan McQuillan. The piece entitled, What is Critical Citizen Science? (A Dialogue), is a meditation on the emerging field of citizen science. It takes the form of a fictional dialogue between 'nomad', the apotheosis of a free-thinking scientist-cum-hacker, and 'royalist', a caricature of an antediluvian traditionalist academic. Through the voices of these archetypes, McQuillan sets out what he refers to as 'critical citizen science', a bottom-up, participative scientific movement.

The piece is published on Storify, the social media service that lets users create stories using elements from other platforms such as Twitter, YouTube or Instagram.  Users build a story from video, images, and quotations from various places, using their own words to formulate a narrative.

Through a combination of well-chosen references, polemics and poetry, a sense of what 'critical citizen science' might be, gradually emerges from McQuillan's text. The dialogic format inevitably calls to mind the conversations between Achilles and the tortoise in Zeno, Carroll, and perhaps most fittingly, Hofstadter's Gödel, Escher, Bach. In McQuillan's work too, the medium of dialogue lends itself well to an inquiry into the complex ethics, aesthetics and politics that 'critical citizen science' might be engaged with.

Intriguingly, over the course of the dialogue, McQuillan correlates emerging community science and technology practices, exemplified by crowdmapping initiatives like Harassmap, hackerspaces such as MadLab, and open hardware projects such as Safecast and Water Hack, with an analysis of radical media art practice of the late 20th century, particularly the Electronic Disturbance Theater.

Ricardo Dominguez, Electronic Disturbance Theater

As someone very much engaged with the wider context of tactical media as a cultural strategy in the 1990s, and now equally fascinated by emerging forms of participatory science, I found McQuillan's juxtaposition of these two discrete areas, deeply compelling.

Here's a short extract, where we listen in on nomad and royalist, discussing new sites of scientific learning:

nomad: there is already an emerging set of learning spaces for critical citizen science; hackerspaces, makerspaces and fablabs...

royalist: what nonsense. these aren't labs, they're garages; and it's not science, merely an obsessive meddling with hardware.

nomad: popularly known as hacking. i refer you to early hacktivists the Electronic Disturbance Theater and their 'science of the oppressed" - "...alternative social forms of life and art that fall between the known and unknown, between fiction and the real, between clean science and dirty science - each a part of a long history of an epistemology of social production which privileges the standpoint of the proletariat, the multitude, the open hacks of the DIY moments, and of autonomous investigators who stage test zones of cognitive styles... concrete practices as speculation and speculation as concrete practices - at the speed of dreams."

This is not a manifesto for 'critical citizen science' (or perhaps just as accurately, 'tactical citizen science'?). It's more of a persuasive suggestion.  But one can't help but recall another grass-roots movement which argues for a similarly critically engaged approach to science and technology. In October 2011, Julian Oliver, Gordan Savicic and Danja Vasiliev published the Critical Engineering Manifesto.  It begins by stating:

"The Critical Engineer considers Engineering to be the most transformative language of our time, shaping the way we move, communicate and think. It is the work of the Critical Engineer to study and exploit this language, exposing its influence."

As co-author, Oliver noted in an interview in 2012, "as thinkers with technical abilities in several areas, we want to take on our built and increasingly automated environment by the terms in which it's given, opening it up for post-utilitarian conversation, for play and interrogation. If there's ever a time to be doing that, it's now, especially with opaque and hidden infrastructure in the telecommunications space deeply impacting diplomatic relations and civil liberties world wide."

The manifesto provides an analytical framework for artistic practice which exposes the technological and scientific systems which unpin much of society. By making these infrastructures and systems visible, the 'critical engineer' reveals the political and power structures at play, instigates critical discussion, and questions who has agency within these systems.

Transparency Grenade (2011) by Julian Oliver

Projects such as Oliver's Transparency Grenade (2011) and Oliver and Vasiliev's Newstweek (2011) are designed as both functional tools, which both reveal and disrupt the invisible information and communication networks that surround us, and conversation-starters about our unquestioning reliance on technological systems we often don't understand.  Their intention is to expose the deep reach that science and technology have in our lives, and to try and encourage more active forms of intervention and agency.  As Oliver (2012) has noted, we all "think through tools both before and while we use them and the more we depend upon a tool the more we are changed by it."

McQuillan's speculations on critical citizen science seem to originate from a similar desire to question the power structures and politics of scientific practice. He insinuates an anxiety about popular citizen-science efforts such as Galaxy Zoo and LHC@Home, which harness the labour of users, without deeply engaging them in the scientific process.  To frame that concern, he cites Tiziana Terranova's critique of user-generated content outlined in her text, Free Labor: Producing Culture for the Digital Economy (2000).

His text also conveys an unease with the exponential hype surrounding 'big data' and 'open data':

royalist: [...]  The networks you rely on for your delocalised tinkering have already given birth to a new science; and it's name is Data Science; and its Data shall be Big.

nomad: [...] As our data is always ambiguous, we shall Glitch; becoming the discontinuities and unexpected artefacts in the big data you crave.

Later, McQuillan points to the value of critical citizen scientists in bearing witness to events which governments and bureaucracies would prefer citizens not to see, let alone intervene into:

nomad: [....] Why not look to the example of white coated citizens weapons inspectors for responsible empiricism. In a horsemeat crisis, the critical citizen scientist packs their DIY bio and flashmobs the nearest Lidl. This isn't an idle fantasy; only recently, Madlab testers set up shop as the Deptford Market DNA FoodLab.

Elsewhere the piece, McQuillan muses whether 'critical citizen science' could be the site at which the Internet of Things becomes the "Parliament of Things" as described by Bruno Latour in his 1991 book, We Have Never Been Modern. By this, Latour was referring to a kind of symmetry between people and what he calls "non-human entities" (or "things"). He argues that our society is comprised of people assembled around "things". Latour dismantles the barrier between culture and nature, between subject and object, proposing more subtle relations between humans and "things", in which the latter are granted the same amount of agency as we are. McQuillan spiritedly picks this up, in the voice of nomad, contending:

"Through citizen science, the Parliament of Things will become the Occupy of Objects."

Whilst I was originally drawn to the subject of the piece - its evocation of radical tactical art media practices, entwined with new community science efforts, and echoing (perhaps inadvertently) the philosophy of the critical engineering movement - the methodology of the story construction is also worthy of note.  When I first read the piece and started thinking about it, I opined to the science policy researcher, Justin Pickard, that such evocative material deserved to be written up in a more formal manner.  He responded by saying:

"This *is* it written up properly. Storify-native STS. Look how reliant it is on the video clips, images, and hyperlinks."

So, tools like Storify enable writers and makers to build layered, interwoven narratives around science and technology research and ideas. These tools provide us with a different vector to be able to express heterogeneous, emerging and often conflicting ideas.  As such, they have the potential to develop into an intriguing and valuable alternative platforms for science communication, and the analysis of scientific research.

Source:

http://storify.com/danmcquillan/what-is-critical-citizen-science-a-dialogue/

Neutrinos back in the spotlight

It's been a big couple of weeks for neutrinos. First, the OPERA experiment in Italy revealed that they had detected the transformation of a muon neutrino to a tau neutrino for only the third time in their history. Soon after, Fermilab's NOvA neutrino detector in the States published their first three-dimensional images of the elusive particles (pictured above).  All this followed hard on the heels of one of the most discussed and celebrated science results of the year so far - the new Planck measurement of the cosmic microwave background - which has interesting implications for neutrino physics.

Neutrinos are among the more mysterious and slippery inhabitants of the fundamental particle zoo. They can be created by certain types of radioactive decay, or nuclear reactions like those that take place in stars, or when cosmic rays hit atoms. They have barely any mass and therefore rarely interact with other types of matter.  This makes them fiendishly difficult to observe.  But they are a fascinating area of study for physicists.  Many of the neutrinos around today are thought to have originated in the Big Bang, so understanding their properties will give us important new insights into what the universe was like 13.7 billion years ago, and how it operates on a fundamental level now.

Neutrinos come in three different types, called "flavours": electron, muon and tau.  Forty years ago physicists posited that these particles may occasionally be able to change from flavour to flavour - for instance starting out as a muon neutrino and ending up as a tau neutrino. This transformation could explain one of the great puzzles of neutrino physics.  Theoretical models imply there should be far more neutrinos raining down on the Earth from nuclear reactions in the Sun, than there actually are.  So the mystery of the 'missing neutrinos' has been bothering physicists for over a generation. If it could be proven that the missing particles are actually neutrinos which have changed flavour as they move through space, then this mystery could be solved.

The OPERA experiment in Gran Sasso, Italy was set up specifically for this purpose. It is designed to detect and analyse exactly these kinds of transformations.  But spotting them is no easy matter. On 26 March 2013, OPERA announced that it had observed this exceptionally rare act of 'shape-shifting' for just the third time.  A muon-type neutrino produced at CERN in Geneva arrived at the Gran Sasso laboratory as a tau neutrino. This has only been observed only twice before, once in 2010 and again last year.

OPERA works by studying beams of neutrinos produced at CERN in Switzerland, which travel 732km to the underground laboratory at the Gran Sasso facility, where they can be studied by physicists working on the OPERA detector.   As Kathryn Jepsen, writing in Symmetry, puts it, "the OPERA experiment is a fast-moving, long-distance game of catch, with CERN laboratory at the border of France and Switzerland pitching a concentrated beam of neutrinos toward the 1250-ton OPERA detector. The neutrino is a difficult ball to snag; it interacts so rarely with matter that it can zip unflinchingly through an entire planet."

The neutrinos which leave CERN are muon neutrinos. OPERA is configured to detect tau neutrinos. If it spots one, it can deduce that a 'change of flavour' has occurred en-route.  Detecting such a flavour oscillation, as the team did this March, is significant.  Not only is it, "an important confirmation of the two previous observations", as the the head of OPERA's international research team, Giovanni De Lellis, has said; it also provides more evidence that flavour oscillation may indeed be the reason why the flux of neutrinos from the Sun and Earth's atmosphere is so much smaller than what theorists predict it should be.

Over on the other side of the Atlantic, Fermilab are in the process of establishing the NOvA experiment as the most powerful neutrino detector in the States. They recently took a significant step towards this goal, by releasing their first three-dimensional images of particles analysed in the under-construction detector.

NOvA detector in construction - near Ash River, USA, photographed in 2012. Image courtesy NOvA collaboration.

NOvA is a collaboration of 180 scientists, technicians and students from 20 universities and laboratories in the U.S and another 14 institutions around the world.  Later this year, the NOvA detector at Ash River, near the Canadian border will start receiving beams of neutrinos sent from Fermilab, the US equivalent of CERN, which is based near Chicago. The beams of neutrinos will travel 500km from Fermilab to NOvA.  As they say, "when a neutrino interacts with the detector, the particles it produces leave trails of light in their wake. The detector records these streams of light, enabling physicists to identify the original neutrino and measure the amount of energy it had."

Using the first completed section of the NOvA detector, physicists have begun collecting data from cosmic rays - the particles produced by a constant stream of atomic nuclei falling on the Earth's atmosphere from space. The 3D particle images they have produced as a result of this work are helping the physicists fine-tune the instrument. When cosmic rays pass through the NOvA detector, they leave straight tracks and well-understood energy signatures. As Mat Muether, a Fermilab researcher, notes, "they are great for calibration. Everybody loves cosmic rays for this reason. They are simple and abundant and a perfect tool for tuning up a new detector."

Fermilab state, "the detector at its current size catches more than 1000 cosmic rays per second. Naturally occurring neutrinos from cosmic rays, supernovae and the sun stream through the detector at the same time. But the flood of more visible cosmic-ray data makes it difficult to pick them out. Once the upgraded Fermilab neutrino beam starts, the NOvA detector will take data every 1.3 seconds to synchronize with the Fermilab accelerator. Inside this short time window, the burst of neutrinos from Fermilab will be much easier to spot."

And this is important. As Gary Feldman of Harvard University says, "the more we know about neutrinos, the more we know about the early universe and about how our world works at its most basic level".

The most headline-stealing physics result of the year so far has given us breathtaking new insights into the early universe and our world at it's most basic level. On the 21 March 2013, scientists working with the Planck Space Telescope unveiled the most detailed map ever created of the cosmic microwave background (CMB) - the leftover radiation from the Big Bang.  Whilst the Planck measurement of the CMB hasn't given us that many clues as to what the fundamental properties of neutrinos are, it may have helped us learn what they are not. In recent times, physicists have begun to speculate that there may be a fourth type of neutrino flavour - the sterile neutrino, so called because it is not effected by the weak nuclear force, and therefore interacts even less with other particles than it's shy and retiring, tau, muon and electron neutrino cousins.  But as John Matson writing in Scientific American has noted, Planck's findings suggest that physicists hoping for experimental proof of the sterile neutrino are going to have to look harder or rethink altogether.

All and all, these are fascinating times for neutrino physics, and we shouldn't be surprised if these ghostly little particles take their share of the limelight in the coming year.

Sources:

http://www.fnal.gov/

http://www.infn.it/news/newsen.php?id=663

http://www.symmetrymagazine.org/

D mesons flipping

The magnet at the LHCb detector

A result today from the LHCb had me humming:
"On the 18th day of shut-down, my true love sent to me: D mesons flipping".

To put this in English, the Large Hadron Collider's LHCb detector has published highly significant results indicating that they have detected particles called D mesons, oscillating from matter into antimatter. The results come 18 days after the LHC shut down for maintenance.

Their paper, pre-published on arXiv, outlines how the D mesons, the last of the four types of mesons to be 'observed' undergoing this oscillation, were detected to a five-sigma level of certainty.

As science writer Jason Palmer puts it:
"In the complicated zoo of subatomic physics, particles routinely decay into other particles, or spontaneously change from a matter type to their antimatter counterparts. This "oscillation" forms an important part of the theory that attempts to tame the zoo - the Standard Model. Mesons are part of a large family of particles made up of the fundamental particles known as quarks. The protons and neutrons at the centres of the atoms of matter we know well are each made up of three such quarks.
Mesons, on the other hand, are made of just two - specifically one quark and one antimatter quark. Theory holds that four members of the meson family can undergo the matter-antimatter oscillation - the matter and antimatter quarks both flip to their opposites."

The LHCb, which has had a series of stunning results with B mesons, had observed two types of B mesons and a K meson oscillating between matter and antimatter before.  But with this new paper, the team provide evidence that the last of the four types of particles, D mesons, has now been detected undertaking the same type of oscillation.

As Chris Parkes, LHC researcher from University of Manchester said:
"This is a nice moment, it's a sort of completeness.”

It is striking to note that the abstract on arXiv lists 60 authors, with another 550 not cited, due to lack of space. This really underscores the collaborative nature of physics at the Large Hadron Collider.

The results are significant because the LHCb is investigating the unsolved question of why there is more matter than antimatter in the Universe. According to the Standard Model, particles of matter and antimatter come in pairs, and matter and antimatter should obey the same laws.  Therefore, we ought to expect an equal amount of both.  So the question, "where's all the antimatter?" has had physicists scratching their heads for some time. The team at the LHCb, are undertaking some of the most significant and fundamental work to try and answer this question.

LHCb's result comes through two and half weeks after the LHC was shut-down for a lengthy period of maintenance.  But it emphasises just how much science will be carrying on whilst the main detectors are serviced and upgraded. The data collected by researchers during the first phase of collisions will be pored over for years to come, and we should expect more fascinating results like these, in the coming months.

Source: http://arxiv.org/abs/1211.1230
http://www.bbc.co.uk/news/science-environment-21594357

Ensonifying space

It is very heartening and interesting to read so many fascinating articles, emerging from my Tuning into the Universe piece for Huffington Post this weekend.

Scientists and journalists from Huffington Post community have published a range of pieces on everything from data sonification, to astereoseismology, to the reminiscences of a former astronaut. Together these articles greatly expand the field of general knowledge around the physics of radio astronomy, and our capacity to sensorially experience it.

One of the pieces draws on an interview with radio astronomer, and the co-founder of the SETI Institute, Jill Tarter. Amplifying the central message of  Tuning into the Universe, Tarter notes that:

"when SETI listens to the cosmos, the institute is actually receiving electromagnetic radiation. And then, just the way your radio does, that energy can be used to make audible sound."

The pieces published in response to the article extend, expand and ensonify this notion.  Some of my favourites include:

The Sound of the Deep Sea of Space by radio astronomer, Dr. Tyler Nordgren equates the universe with a vast ocean, echoing Carl Sagan's famous analogy from his series, Cosmos. He poetically maps out the methods of astronomical observation available to modern astronomers, beyond the detection of visible light. He notes: "as a young radio astronomer I learned early on that every time human beings have explored the world with new senses we have discovered new and amazing phenomena".

Voices Carry by Anna Leahy and Douglas Dechow explores the sonic signature of our own planet:

"The sound of the Earth's inherent dynamics -- the movement of atmosphere and oceans -- produces a steady drone as well. Lightning produces crackling, which scientists call sferics."

Voyager Golden Record

The article includes a memorable passage about the Voyager Golden Record, which contains 'greetings in 56 languages, natural sounds like thunder and crickets chirping, and music from around the world', encoded in audio and now travelling towards the outer reaches of our solar system on board Voyager.

In An Audible Tour of the Solar System? Sign Me Up!, astronomer and planetary scientist, Jim Bell analyses our celestial neighbourhood, exploring the potential for acoustic sound on each of our nearest planets. The Perfect Quiet of Space by legendary astronaut, Jerry L. Ross, is the extraordinary account of his nine spacewalks, undertaken during his seven missions into space.

Jerry L. Ross n one of his nine spacewalks.

He writes eloquently about the silence which astronauts experience, when outside the International Space Station:

"Without the sophisticated listening devices scientists use on earth to hear the whispers of the universe, to an astronaut space is infinite quiet, a place where we bring the only sounds that break the silence."

Sound: The Music of the Universe by Mark Ballora and George Smoot III is an excellent overview of the practice of data sonification, which takes in in the brilliant work of the xSonify team, who are making sonification applications for blind scientists. The article also refers to the emerging science of astereoseismology and exoseismology, which I talked about last Friday in my Sonic Acts talk.

They clearly explain why data sonification methods can be useful:

"Symbolic renderings create other perspectives. Literal renderings are not always compatible with the capabilities of our auditory system. When data points are treated as audio samples and played back at audio rates (typically at 44100 values/second) quick changes are lost to us, as we can't hear fluctuations discretely at the millisecond level. If, instead, we treat the data points symbolically, for example as pitches, we are better able to "magnify" what we are listening to."

In Understanding the Sound of Space, Ayodele Faiyetole notes that sound is under used in science.  He draws on an interview with cosmologist, Yuko Takahashi, who believes there's a great value in presenting scientific results in a totally different dimensions, such as sound:

"Maps of CMB anisotropy can be converted to sound as a telescope sweeps across the sky to give the audience a better appreciation of the fluctuations."

As Ballora and Smoot put it, "if the universe is, at some level, music, then it seems only natural that we should study it with musical tools of thinking."

Source: http://www.huffingtonpost.com/tedweekends/

Tuning into the sound of the universe with radio

This weekend, Huffington Post have published my piece, Tuning the Universe, which contextualses my TED talk, which they are featuring as part of TED Weekends.

The piece provides some background into the audified radio waves which I played during my talk. Here's the gist of the article:

"We have been surrounded by stunning portrayals of our own solar system and beyond for generations, in books, on film and on television. But in popular culture, we have no sense of what space sounds like.  And indeed, most people associate space with silence.
There are, of course, perfectly valid scientific reasons for assuming so. Space is a vacuum. Sounds cannot propagate in a vacuum.  But through the intervention of radio, it is possible for us to listen to the Sun's fizzling solar flares, the roaring waves and spitting fire of Jupiter's stormy interactions with its moon Io, pulsars' metronomic beats, or the eerie melodic shimmer of a whistler in the magnetosphere."

My talk, and my work in this area, emerges from the science of radio astronomy.

RT16 at the Ventspils International Radio Astronomy Centre. Latvia

Whilst optical astronomers use telescopes to look at the visible light emitted by stars, radio astronomers use radio telescopes, or antennae, to detect radio waves. By combining radio astronomy with radio and sound engineering, we can hear as well as see the stars, and thus greatly expand our sensory perception of our cosmos.

It is important to remember that stars and planets are not directly audible. The recordings I played in my talk are radio waves which have been converted into sound waves using radio receives and amplifiers.  This is a process I refer to as audification. Huffington Post have also published two companion pieces which respond to the talk, the first of which emphasises this point.  Celestial Sound Effects by Seth Shostak notes correctly that, "they're electromagnetic noise, converted by electronic devices ... into signals that - when played through a loudspeaker - become the atmospheric pressure waves we call sound."

The second piece is What Is the Color of the Universe? by Mario Livio, which uses Karl Glazebrook and Ivan Baldry survey of more than 200,000 galaxies (the 2dF Galaxy Redshift Survey) as a basis for examining the colour of the universe.

Thanks to Huffington Post and Janet Lee at TED for publishing the piece.

And here's the talk in full:

Source:  http://www.huffingtonpost.com/honor-harger/tuning-into-the-universe_b_2737168.html

New Zealand recognised as major contributor to radio astronomy history

John Bolton (left) and New Zealander Gordan Stanley (centre), pictured with Jow Pawsey

New Zealand has claimed its place in radio astronomy history. As reported here a year ago, New Zealand has significant scientific heritage in the field of radio astronomy, and has begun to explore and celebrate this history.

Last week, some of the biggest names in the field gathered for an international conference which marked New Zealand's role in helping to kick-start radio astronomy research in the 1940s.  Attended by the doyenne of the field, Jocelyn Bell Burnell, and researchers and historians from New Zealand, Australia and the UK, the conference explored the work of John Bolton and New Zealander, Gordon Stanley, who detected radio waves from outside the solar system in August 1948 from sites in Pakiri and Piha in the North Island of New Zealand.

Elizabeth Alexander

The conference also commemorated the pioneering work of Elizabeth Alexander, often referred to as the first female radio astronomer, who helped helped establish some of the early foundations of solar radio astronomy in 1946. Alexander studied sources of interference effecting radar stations in New Zealand established during World War II.  During March-April 1945, solar radio emission was detected at 200 MHz by operators of a Royal New Zealand Air Force radar unit located on Norfolk Island.

The emissions became known as the "Norfolk Island effect". Alexander, then based at the Department of Scientific and Industrial Research in Wellington, heading up the Operational Research Section of the Radio Development Laboratory, carried out the most significant early work on the effect throughout 1945. In 1946. she published a paper in the journal, Radio & Electronics describing the emissions, and in doing so, furthered the fledgling field of radio astronomy.

Wayne Orchiston, writing in "The New Astronomy", has noted that Alexander's research also led to further solar radio astronomy projects in New Zealand in the immediate post-war year, and in part was responsible for the launch of the radio astronomy program at the CSIRO, in Australia."

Radar Station (Whangaroa) - one of five involved in New Zealand's investigation of solar radio emission. Image courtesy of Wayne Orchiston.

Astronomer Miller Goss, from the National Astronomy Observatory in New Mexico, puts it:

"Bolton and Stanley's discovery revolutionised twentieth century astronomy."

Following their pioneering discoveries, Bolton went on to become a major figure in Australian radio astronomy, helping found the famous Parkes radio telescope, becoming director of the Australian National Radio Astronomy Observatory and winning the the inaugural Jansky Prize in 1966 (so named after the father of radio astronomy, Karl Jansky).

Sergei Gulyaev

 The conference was organised by the extraordinary Sergei Gulyaev, who has revitalised radio astronomy in New Zealand, spearheading the nation's participation in the SKA, amongst many other efforts.

Source: http://www.stuff.co.nz/auckland/local-news/rodney-times/8250497/Stars-align-for-conference

Can particle physics transform our online experience?

One of the more intriguing papers we've happened upon early this year is some research from the University of Fribourg which suggests that particle physics can improve the technology behind recommendation systems.

Recommendation systems are software which websites such as Amazon and Facebook use to tailor information for users.  When Amazon, somewhat eerily, suggests that you check out a book by a writer you've been just been thinking about, that's a recommendation system, or "engine", in action. Recommendation engines are at the heart of online business, as the good ones are known to generate profits.  Improving them is a key goal for retailers and software companies alike.

But what on earth does particle physics have to do with software like that?  Well, a group of researchers at the at the University of Fribourg in Switzerland believe that the physics which governs the behaviour of photons and electrons may also be used to optimise recommendation engines.

Stanislao Gualdi, Matus Medo, and Yi-Cheng Zhang this month published an abstract on arXiv entitled, "Crowd Avoidance and Diversity in Socio-Economic Systems and Recommendation".  The paper's key insight is that the problem with recommendation engines is that they can lead to 'overcrowding' around a specific product or service, which can be detrimental to the experience users have with it.  Surges in demand can be sometimes advantageous, but if the value of a resource diminishes as more people use it, then this creates a problem.  A good example would be a service like Netflix recommending the same movie to too many of its users, thereby creating long waiting times for everyone. Another good example, would be a travel website recommending a beach or a picnic spot because it is quiet. As Technology Review noted "this can end up destroying the peace that gives it value. Similarly, restaurant recommendations can lead to overcrowding or difficulty getting a table which again makes the dining experience unpleasant."

These examples show how over-stimulated demand can reduce the value of a resource. Gualdi, Medo and Zhang set about to tackle this issue.  They applied the logic employed in particle physics, where particles tend to occupy the most energetically favourable states. Technology Review explain:
"If the particles are bosons, such as photons, there is no limit to the number that can occupy a given state. But if they are fermions, like electrons, their physical properties dictate that no two can occupy the same state. Clearly the resulting distribution of these different types of particles is entirely different.The analogy here is with goods that any number of people can share or that only one person can have."

The latter case - products or experiences that are best experienced by small groups, or even individuals - provides a dilemma for recommendation engines. In order for these things to retain their value, they need to remain available only to limited umbers of people. Gualdi, Medo and Zhang insist that the principle of 'crowd avoidance' needs to be employed to avoid oversubscription, crowding and disappointment.

They provide evidence in their paper that building crowd avoidance into the recommendation process can increase the accuracy of the recommendation, and therefore the potential profitability of the recommendation engine. As they put it:
"We use real data to show that contrary to expectations, the introduction of these constraints enhances recommendation accuracy and diversity even in systems where overcrowding is not detrimental. The observed accuracy improvements are explained in terms of removing potential bias of the recommendation method."

It's a fascinating and quirky approach, and if they are right, and their technique is employed by the software developers who design and build our online world, it might just transform what is recommended to us, and when, and how we experience it.

Source: http://arxiv.org/abs/1301.1887

It's full of stars

This week the noted photographer and optics engineer, Stéphane Guisard posted a stunning mosaic image of the Milky Way captured at ESO's Paranal Observatory in Chile.

The mosaic is constructed from 52 fields, shot over 29 nights, and consists of 1200 separate photos and 1 billion pixels. The image transports us to the centre of the Milky Way, giving us a scalable and zoomable encounter with literally millions of stars.

As Guisard notes, "it shows the region spanning from Sagittarius (with the Milky Way center and M8/M20 area on the left) to Scorpius (with colorful Antares and Rho Ophiuchus region on the right) and Cat Paw nebula (red nebula at the bottom)."

This is the galaxy in extreme fidelity. Enjoy getting lost in the detail.

Source: http://sguisard.astrosurf.com/Pagim/GC.html

Did Einstein discover dark energy?

One of the more interesting things that popped up on arXiv this week was the quirkily titled abstract, How Einstein Discovered Dark Energy, submitted by Alex Harvey, Visiting Scholar at New York University on 22 November.

It bears repeating in its entirety:

"In 1917 Einstein published his Cosmological Considerations Concerning the General Theory of Relativity. In it was the first use of the cosmological constant. Shortly thereafter Schrodinger presented a note providing a solution to these same equations with the cosmological constant term transposed to the right hand side thus making it part of the stress-energy tensor. Einstein commented that if Schrodinger had something more than a mere mathematical convenience in mind he should describe its properties. Then Einstein detailed what some of these properties might be. In so doing, he gave the first description of Dark Energy. We present a translation of Schrodinger's paper and Einstein's response."
The full paper and references are downloadable here.


It will be interesting to hear what the responses are to this.

Source: http://arxiv.org/abs/1211.6338