A A A

Archive for the 'Mathematical & Physical Sciences' Category

Representing resource use at UCL… using chemistry glassware and electronics

By Kat F Austen, on 20 October 2014

Elements

Elements

How do you represent the complexities of the resource use of a university using just what you can find in a chemistry lab – and some collective ingenuity?

That’s what Andrea Sella, Joanna Marshall-Cook and I set out to do over the course of last week with the help of Rae Harbird and Stephen Hailes.

The result, Elements, is on show in UCL’s North Cloisters for Degrees of Change, a week long endeavour by UCL’s Sustainability team to explore the environmental consequences of all the world-class teaching, research, collecting, exhibiting, making, inventing and outreach that goes on at the university.

During the research for the installation I learned some interesting statistics. For instance, a typical chemistry fume cupboard uses 10,000kWh of electricity per year (£1,000), and our heating comes from a series of underground pipes.

The installation is a visual metaphor for how the university’s heating and water systems work. We often don’t think about the consequences of running a tap, or pouring a bucket down a drain, flushing a toilet, taking a shower. Chemical glassware in all its varied and complex forms provides a perfect toolbox to explore the convoluted system of flows in resource infrastructure. Elements incorporates soxhlets - a type of chemical glassware normally used for extracting liquid from a solid, such as producing essential oils – which act as reservoirs within the system as a whole, just as we act as reservoirs for water either within ourselves or by our actions.

Lots of crazy glassware and - lit up in green and looking suspiciously like UCL Engineering's logo, an EngDuino computer, monitoring the water level in the system

Lots of crazy glassware and – lit up in green and looking suspiciously like UCL Engineering’s logo – an EngDuino computer, monitoring the water level in the system

The crazy glassware installation also has a 5L round bottomed flask and an electric pump – after all, it takes power to heat and move all the university’s water. The flask is like the water infrastructure external to UCL – and is monitored by an EngDuino and sensor, programmed by Rae and Stephen, that alerts us when the water levels are low.

A sensor detects the water level and reports back to the Engduino if the level is too low

A sensor detects the water level and reports back to the Engduino if the level is too low

At a time of increasing water scarcity and climate change due to our energy use, it’s important to realise that our actions on a personal scale have a real affect that ripples through the infrastructure that helps us live as well as we do.

Mapping the light of the cosmos

By Oli Usher, on 1 September 2014

This image shows one possible scenario for the distribution of light in the cosmos. Photo credit: Andrew Pontzen/Fabio Governato

This image shows one possible scenario for the distribution of light in the cosmos. Photo credit: Andrew Pontzen/Fabio Governato

Figuring out what the structure of the universe is surprisingly hard. Most of the matter that makes up the cosmos is totally dark, and much of what is left is in tiny, dim galaxies that are virtually impossible to detect.

This image shows a computer simulation of one possible scenario for the large-scale distribution of light sources in the universe. The details of how light (and hence galaxies and quasars) is distributed through the cosmos is still not a settled question – in particular, the relative contributions of (faint but numerous) galaxies and (bright but rare) quasars is unknown.

A faint dwarf galaxy

(New research from UCL cosmologists published last week shows how we should be able to find out soon.)

However, astronomers know that on the largest scales, the universe is structured as a vast web made up of filaments and clusters of galaxies, gas and dark matter separated by huge, dark voids. Observational astronomy is making strides forward in mapping out these structures in gas and light, but the smallest galaxies – less than a pixel across in the image above – might never be seen directly because they are simply too faint.

A Hubble image of a nearby faint dwarf galaxy (right) shows the challenge involved in observing these objects even when they are in our galaxy’s vicinity.

These computer models are one way of trying to extrapolate from what we know to what is really there. New research from UCL now shows how we can also use future observations of gas to find out more about this elusive population of tiny galaxies.

This simulated image shows the distribution of light in an area of space over 50 million light-years across. The simulation was created by Andrew Pontzen of UCL and Fabio Governato of the University of Washington.

Links

High resolution image

Why art, not science, deserves credit for these pioneering dinosaur reconstructions

By Oli Usher, on 26 August 2014

A century and a half ago, Britain was swept by dino-mania. The discoveries of ancient fossils and the first characterisations of dinosaur species, combined with new scientific theories that posited that the Earth was far older than previously thought, fuelled a fascination with all things ancient.

A concrete example of this period is still visible today, in the form of the dinosaur statues in Crystal Palace Park. These date to 1854 and were built for the reopening of the Crystal Palace in Sydenham, when it was rebuilt there following the 1851 Great Exhibition in Hyde Park

The Crystal Palace Dinosaurs in 1854, by John Haygarth. Picture credit: Wellcome Trust (CC-BY)

The Crystal Palace Dinosaurs circa 1854, by George Baxter. Picture credit: Wellcome Library (CC-BY)

A naïve view of these is that they are a quaint, even amusing, example of how ignorant the Victorian scientists were – the statues predate Darwin’s theory of evolution by five years, and in some cases they bear little resemblance to the animals they claim to represent.

Joe Cain (professor of history and philosophy of biology in UCL Science and Technology Studies) has studied the statues’ history and says that naïve view is nonsense. The scientific origins of these statues is far more nuanced and interesting – and in any case, the credit for them lies with the sculptor, Benjamin Waterhouse Hawkins, far more than it does with the zoologist Richard Owen, who supposedly directed their design.

Megalosaurus at Crystal Palace Park. Photo credit: O. Usher (UCL MAPS) (CC-BY)

Megalosaurus, one of the statues at Crystal Palace Park. Photo credit: O. Usher (UCL MAPS) (CC-BY)

***

Hawkins was a scientific illustrator, an experienced translator of scientific ideas. Owen was just one of several sources he consulted, and Hawkins kept up with the rapidly expanding literature of the animals he was working to model for his displays. Hawkins even represented competing theories of reconstruction in his statues. There are two Iguanodon statues, for instance. One is long, low and lizard-like; the other is stocky and raised on its four legs, more like a hippopotamus or rhinoceros.

There is plenty to show that the artist wasn’t merely doing what he was told, but was actively interpreting the scientific evidence.

There also is plenty that science didn’t (or, couldn’t) tell him. Even more than today, the Victorians had only partial specimens, made of various bones of various origins and in various conditions, leaving Hawkins to fill very large gaps. On top of this, Hawkins had to invent elements such as pose, movement, and facial expressions. None of these could be gleaned even from perfectly preserved and well-understood fossils.

Given the uncertain (and disputed) scientific theories, the limited selection of fossils to work from, and the inevitable necessity of artistic licence, Cain thinks the dinosaur statues are something to admire rather than ridicule.

In any case, while some of his statues, are quite different from today’s reconstructions…

Hawkins' megalosaurus (left) doesn't look much like modern reconstructions. Photo credit: CGP Grey (CC-BY) and Mariana Ruiz (public domain)

Hawkins’ Megalosaurus (left) doesn’t look much like modern reconstructions. Photo credit: CGP Grey (CC-BY) and Mariana Ruiz (public domain)

…others, such as his plesiosaur, are remarkably similar to what we have now.

Hawkins' plesiosaur (left) and a modern artist's impression (right). Photo credit: Berlt Watkin (CC-BY) and Dmitry Bogdanov (CC-BY)

Hawkins’ plesiosaur (left) and a modern artist’s impression (right). Photo credit: Berlt Watkin (CC-BY) and Dmitry Bogdanov (CC-BY)

***

Cain’s interpretation of how the Crystal Palace Dinosaurs came about rings very true to me. In a previous life I worked with some of the people who prepare scientific visualisations, animations and artists’ impressions for the Hubble Space Telescope. The case of HD 189733b – a planet that was observed being scorched by a stellar flare (among other research) – is remarkably similar to the dinosaurs of Crystal Palace.

Much like Benjamin Waterhouse Hawkins, those animators had a great deal of scientific information they could draw on – on the size and brightness of the flare, on the optical properties of the atmosphere, on the colour of the star and its appearance. But as with the Crystal Palace Dinosaurs, these were just pieces of a puzzle, with plenty missing and some educated guesswork involved in putting them together.

The resulting animations are rather beautiful, and like with the dinosaurs, the artist deserves at least as much credit as the scientist does.

  • The Friends of Crystal Palace Dinosaurs website has extensive information on the dinosaurs, where to visit them and the campaign to conserve them. Joe Cain is one of the leading members of the Friends, and sits on the group’s management board.

Kathleen Lonsdale interview

By Oli Usher, on 19 August 2014

If you don’t know who Kathleen Lonsdale was, you should.

Lonsdale was a hugely important chemist (in the field of crystallography), an outspoken political activist and president of what is now the British Science Association. She was also, from 1949, the first woman to become a professor at UCL.

BBC Woman’s Hour interviewed her in 1967, shortly before she retired from UCL. The programme, available on iPlayer, is well worth a listen.



Lonsdale retired from UCL in 1968, and died in 1971, but she is commemorated in the name of the Kathleen Lonsdale Building on Gower Place. This building houses many of UCL’s science labs.

Lonsdale is remembered in the name of the Kathleen Lonsdale Building, which houses many of UCL's science labs. Photo: Gnesener1900 (CC-BY-SA)

Lonsdale is remembered in the name of the Kathleen Lonsdale Building, which houses many of UCL’s science labs. Photo: Gnesener1900CC-BY-SA

Thanks to Joe Cain for bringing this to our attention.

Photo album from the Dark Energy Survey

By Oli Usher, on 18 August 2014

The Dark Energy Survey, which has just begun its second year of observations, is gathering data about one of the most puzzling phenomena to be discovered in the past century: that the universe is not only expanding, but is doing so at an ever faster rate. Some as yet unknown force dubbed ‘dark energy’ is driving this acceleration.

Dark energy affects the appearance and evolution of the universe on very large scales. The Dark Energy Survey aims to find out more about this phenomenon by studying measuring four key cosmological probes:

  • The number of galaxy clusters;
  • The distances to faraway supernovae;
  • The bending of light by gravitational lensing;
  • and the pattern of the distribution of galaxy clusters across the universe.

Observing these requires sharp images that can detect very distant (and hence faint) objects, and so the the images collected by the Dark Energy Camera, the survey’s workhorse, are often quite stunning.

This image of the NGC 1398 galaxy was taken with the Dark Energy Camera. This galaxy lives in the Fornax cluster, roughly 65 million light-years from Earth. It is 135,000 light-years in diameter, just slightly larger than our own Milky Way galaxy, and contains more than a billion stars. Credit: Dark Energy Survey.

This image of the NGC 1398 galaxy was taken with the Dark Energy Camera. This galaxy lives in the Fornax cluster, roughly 65 million light-years from Earth. It is 135,000 light-years in diameter, just slightly larger than our own Milky Way galaxy, and contains more than a billion stars. Credit: Dark Energy Survey.

To mark the beginning of the second year of DES’s five-year observing run, the team have published a gallery of the most attractive images from the first year of operation, including the image of galaxy NGC 1398, pictured above. The complete the gallery is at the end of this post and in the faculty Flickr gallery.

UCL is deeply involved in DES, and Prof Ofer Lahav, Vice-Dean (Research) of Mathematical & Physical Sciences, is chair of the DES UK board and co-chair of the DES international science committee.

More information on UCL’s involvement in the DES science programme is available in an article on the UCL news pages.

Gallery

Copyright: Dark Energy Survey photos are free to use providing they are credited to the Dark Energy Survey. Any queries on reuse should be sent to Fermilab Visual Media Services at vismedsr@fnal.gov.

Links

High resolution images

The Fields Medal: a stepping stone for women in mathematics

By Helen J Wilson, on 14 August 2014

Helen Wilson

Helen Wilson

We heard yesterday that the Fields Medal, which is the closest thing to a Nobel Prize for Mathematics, has been awarded to a woman for the first time in its 78 year history.

The prize is awarded once every four years, to a small number of mathematicians (two to four each time) and is presented at the International Congress of the International Mathematical Union. This year’s winners are Artur Avila, Manjul Bhargava, Martin Hairer and Maryam Mirzakhani.

It’s fantastic to see a female mathematician rewarded at this very highest level for the first time. I hope the news coverage around this breakthrough will encourage women in mathematics at all levels. At the moment, there are plenty of girls studying maths in the UK up to degree level, which is wonderful. We may not be quite 50:50 but the proportions are close enough that girls don’t feel as if they’re in the minority. And that’s changed since I was a student. But as you move through the academic stages – PhD, postdoc, lecturer, professor – we have a “leaky pipeline” and at the top, only 6% of UK mathematics professors are female.

Here at UCL we had one of the first female maths professors in Susan Brown (who retired a few years ago); we’re proud of our heritage but our female academic staff are still badly outnumbered and there’s still a long way to go. Maybe this Fields Medal is one more stepping stone along the way for women in mathematics.

Watch Helen Wilson discuss the Fields Medal on BBC World News

Helen Wilson is Deputy Head of UCL Department of Mathematics

Why is there no Nobel Prize in mathematics?

By Oli Usher, on 13 August 2014

Fields medalProf Mark Ronan (UCL Mathematics) asks a common question: why is there no Nobel Prize in Mathematics?

The Fields Medal, awarded today to Artur Avila, Manjul Bhargava, Martin Hairer and Maryam Mirzakhani is sometimes compared to the Nobel Prizes, but it’s restricted to under-40s and exists to encourage research among (relatively) early-career mathematicians, not to recognise a lifetime’s achievement. (UCL has done rather well out of the Fields Medal in the past, with three winners among former staff and students.)

Writing in today’s Daily Telegraph, he ponders:

One explanation is that the Swedish mathematician Mittag-Leffler had an affair with Nobel’s wife. This sounds plausible, until one discovers that Nobel was unmarried. From Sweden I now hear a fanciful story that the attractive mathematician Sofia Kovaleskaya rebuffed Nobel’s advances. Yet she died in 1891 – years before his bequest.

 

Dawn of the neutrinos

By Oli Usher, on 11 August 2014

In Fermilab, just outside of Chicago, an intense beam of neutrinos leaves a particle accelerator. Less than one hundredth of a second later, the neutrinos reach Northern Minnesota, over 700 kilometres away. Here, scientists and engineers are developing a number of large experiments to help them understand the properties of neutrinos – currently an area of considerable uncertainty in the world of physics.

One of these is a device known as CHIPS-M, pictured here at dawn on 1 August, just before it was deployed underwater in the flooded Wentworth-W mine pit in the background.

The CHIPS-M detector at dawn, on the day it was deployed in the flooded mine pit in the background. Photo courtesy Jerry Meier (University of Minnesota)

The CHIPS-M detector at dawn, on the day it was deployed in the flooded mine pit in the background. Photo courtesy Jerry Meier (University of Minnesota)

(This pit belongs to Cliffs Natural Resources who have kindly granted access and the land where the detector and control-shed are sitting has been provided by PolyMet Mining.)

This neutrino detector may look large (it is a 3.5m x3.5m cylinder), but it is in reality a small-scale prototype for a device which will be many times larger. The team developing the instrument is led by Prof Jennifer Thomas (UCL Physics & Astronomy).

Neutrinos barely interact with normal matter. Even though we know vast numbers of them pass through the Earth thanks to their production in nuclear reactions in the Sun, detecting even a single neutrino is extremely challenging, and larger detectors improve the odds of seeing one by increasing the amount of matter in their path.

Neutrino detectors can work in a number of ways. CHIPS-M works through detecting Cerenkov radiation which is produced in the water inside it. Like all methods of detecting neutrinos, it is indirect.

CHIPS-M consists of a large bag storing 50 tonnes of water, equipped with highly sensitive detectors, like the ones used in the IceCube Experiment in Antarctica,  that can pick up the tiniest flashes of Cerenkov radiation. When a muon-neutrino enters water, very occasionally, it will interact with the water and produce  a charged muon. Sometimes the muon-neutrinos oscillate into electron neutrinos and they can produce a charged electron. Both of these charged particles, if they have enough energy,  move through the water faster than light can. The electromagnetic wake these particles leave behind them is visible as a brief flash which can be picked up by the detectors.

In order to minimise false-detections caused by cosmic rays, energetic particles that come from space, CHIPS-M is placed 60 metres deep at the bottom of a flooded mine pit: the water above it shields it from some of this interference as indeed does the orientation of the photo-detectors inside the bag.

 

The CHIPS-M detector being lowered into the mine pit and filled with water. In the boat is UCL physicist Prof Jennifer Thomas. Photo courtesy Jerry Meier (University of Minnesota)

The CHIPS-M detector being lowered into the mine pit and filled with water. In the boat is UCL physicist Prof Jennifer Thomas. Photo courtesy Jerry Meier (University of Minnesota)

And yet despite this shielding, over the year-long experiment, it is estimated that it will detect around 170,000 cosmic rays and just 20 neutrinos. Any positive identification of neutrinos in this period is in reality just icing on the cake, though – the primary objective of CHIPS-M is as a test-rig for technologies that will be used in future, for instruments far larger and more sensitive than this.

 

Links

High resolution images

 

 

Do neutrinos have mass? Anatomy of a scientific debate

By Oli Usher, on 7 August 2014

Do neutrinos have mass? And if so, how much? This apparently simple question has no simple answer and has been the subject of debate, controversy and confusion in the world of physics in recent years.

Neutrinos are subatomic particles created during certain types of nuclear reactions, including those that power the Sun. Although the Sun churns out neutrinos in unimaginably large numbers – around 80 octillion (8 followed by 28 zeroes) pass through the Earth every second – they are very hard to detect. Totally unaffected by electromagnetism, they are invisible and pass through matter unimpeded. They only interact gravitationally and, on the scale of atomic nuclei, through the weak nuclear force.

The first detection of a neutrino in a bubble chamber, in 1970. Photo credit: Argonne National Laboratory (public domain)

The first detection of a neutrino in a bubble chamber, in 1970. Photo credit: Argonne National Laboratory (public domain)

The framework of theories scientists use to explain and describe the world of subatomic particles, known as the standard model of particle physics, predicts that neutrinos, like photons, should have no mass. However experimental studies detecting solar neutrinos in recent years contradict this, suggesting that neutrinos do have mass.

So when data shows that a key element of your theoretical framework is proved wrong, what do you do? You could assume that the data are incorrect, or the theory is wrong. The consensus among physicists is that the standard model of particle physics is incomplete – but identifying what is missing from it is a complex issue.

Cosmologists are currently trying to get to the bottom of this question, with sometimes quite radical solutions. Boris Leistedt and Hiranya Peiris, two UCL researchers, have recently ruled out one of these eye-catching theories. The question won’t be settled until new data from a range of physics and cosmology experiments comes in a few years time. (Among these is the Dark Energy Survey, in which UCL is closely involved.)

The Dark Energy Camera on the Blanco telescope in Chile will give new data on the structure and distribution of galaxy clusters in the universe. Photo credit: Reidar Hahn/Fermilab (All rights reserved)

The Dark Energy Camera on the Blanco telescope in Chile will give new data on the structure and distribution of galaxy clusters in the universe. Photo credit: Reidar Hahn/Fermilab (All rights reserved)

But even before the new evidence comes in, the debate surrounding these claims and counterclaims cast light on how scientific theories develop.

***

The evidence that neutrinos have small (but non-zero) mass is now quite compelling, and scientists are in broad agreement that the standard model needs to be modified or extended to fit this new data. But how much mass they have and how much our theories needs to evolve are still open questions.

Finding the neutrino’s mass isn’t simply of academic interest. The mass of the neutrino is intimately tied up not only with the evolution of the standard model, but with our understanding of key issues in cosmology including the formation of galaxies, the way galaxies are scattered through the universe and the behaviour of the Big Bang.

Some recent studies of cosmological data have made waves this year, proposing a relatively high mass for the neutrino (of around twice the mass of previous estimates). These studies suggested that apparent discrepancies between several large datasets (including temperature fluctuations in the cosmic microwave background, the statistical distribution of galaxies through the universe, and X-ray detections of galaxy clusters) could be explained if neutrinos were heavier than previously assumed.

The Cosmic Microwave Background, as observed by the WMAP spacecraft, is one of the datasets that can be reconciled with each other if the neutrino has a large mass. Photo credit: NASA (public domain)

If the neutrino has a large mass, then several major datasets, including the Cosmic Microwave Background (above) can be reconciled with each other. But just because it is mathematically plausible doesn’t necessarily mean it’s true. Photo credit: NASA (public domain)

Statistically, these studies are quite compelling as they manage to reconcile apparently incompatible data, as well as addressing the key problem of the standard model by ascribing a mass to the neutrino.

But the results, despite tidying up loose ends, have not met with everyone’s approval. In particular, the UCL team think the evidence for neutrinos having such high masses is specious. They have recently published their thoughts on the subject.

They look at this apparent evidence for high-mass neutrinos from two different angles:

  • First, if the neutrino is indeed heavy, what would that imply about the universe around us (and does it fit with what we see)?
  • Second, if it is not, what else could explain the discrepancies in the data?

On both fronts, they think the evidence points firmly at a significantly lighter neutrino, in line with previous estimates.

***

Assuming that neutrinos have a relatively large mass fits experimental datasets quite well, but, Leistedt and Peiris argue, it is disproved by looking at a broader range of evidence.

The large-scale structure of the universe is dominated by gravity, much of it caused by an exotic (and invisible) type of matter known as dark matter. This governs the distribution, size, shape and motion of galaxies on unimaginably large scales, helping galaxies form, and clustering them together.

This map shows the location of galaxies within about 250 million light years of the Milky Way. Even on this scale - a tiny proportion of the universe - they are clearly bunched together in clusters and filaments. Photo credit: Richard Powell (CC-BY-SA 2.5)

This map shows the location of galaxies within about 500 million light years of the Milky Way. Even on this scale – a tiny proportion of the universe – they are clearly bunched together in clusters and filaments. Photo credit: Richard Powell (CC-BY-SA 2.5)

A high mass for the neutrino would upset this balance, and in particular would inhibit the formation of galaxies like the one we live in, meaning there were fewer visible in the sky. It would also mean a less-structured universe on the scale of galaxy clusters and galaxy filaments. This is because very light neutrinos travel very quickly and pass through galaxies and clusters without any significant interaction, leaving them to form under the action of gravity. If neutrinos had higher mass (and hence lower velocities), they would interact far more, diffusing and scattering through galaxies and clusters, changing the way they collapse. In effect they would smear out the distribution of galaxies.

The distribution of galaxies through space seen by astronomers is extremely uneven, with filaments and sheets of galaxies surrounding huge voids, forming a vast cosmic web that fills the known universe. But the web is not consistent with what we would see if the neutrino had a high mass: structure would be washed out, voids would be larger, filaments thinner and galaxy clusters smaller.

Clustering of galaxies, as seen in this Hubble picture, would be much less pronounced if the neutrino had a large mass

Clustering of galaxies, as seen in this Hubble picture, would be much less pronounced if the neutrino had a large mass. Photo credit: NASA, ESA, HST Frontier Fields (public domain)

Moreover, the properties of the cosmic microwave background (the afterglow of the Big Bang) also undermine the idea of a high-mass neutrinos.

So, Peiris and Leistedt say, the models that propose a large mass for the neutrinos, which appear to fit the numbers quite well, turn out not to fit well at all with the individual data sets. The apparent agreement between them, they argue, is not much more than a statistical trick.

As an aside, some experiments have proposed higher-still masses for the neutrino, several times greater than even these controversial calculations. With neutrinos of that sort of mass, it is questionable whether galaxies would have been able to form at all and the universe would have been a dramatically different place.

***

Which brings us to the second question: if the discrepancies between different datasets can’t be explained by a heavier-than-expected neutrino, what does explain them?

Leistedt and Peiris think that this can be answered quite simply: actually most of the data broadly do agree with each other. It is the observations of how common galaxy clusters are in the universe which are out of line. And these are known to be the least robust of them all.

The unreliability, they argue, comes from multiple angles, including the difficulty of proving you have representative sets of galaxy data, the difficulty of knowing whether there is a selection bias in the data (e.g. large galaxy clusters being overrepresented), the difficulty of estimating cluster masses through gravitational lensing, and the extensive modelling involved which involves some degree of educated guesswork.

Gravitational lensing - the bending of the light from distant galaxies - can be used to estimate the mass of galaxy clusters (as the extent of the bending is directly proportional to the amount of mass present). Lensed light from distant galaxies is visible in this Hubble picture as streaks and arcs of light, most obviously the large diagonal streak of blue light in the right-hand side of the image. But it is fraught with difficulties. Photo credit: NASA, ESA, HST frontier fields (public domain)

Gravitational lensing – the bending of the light from distant galaxies – can be used to estimate the mass of galaxy clusters (as the extent of the bending is directly proportional to the amount of mass present). Lensed light from distant galaxies is visible in this closeup of the Hubble picture above as streaks and arcs of light, most obviously the large diagonal streak of bluish light in the right-hand side of the image. But it is fraught with difficulties. Photo credit: NASA, ESA, HST frontier fields (public domain)

Strip this unreliable data out, and it is far from obvious that there even is an anomaly that needs to be explained – and the previous, lighter estimates of neutrino mass look far more plausible once more.

A crucial test of this assumption will come with the Dark Energy Survey, which will bring with it far more robust data on galaxy clusters, alongside measurements of the distribution and gravitational lensing of galaxies, which will cross-check this data. This should, hopefully, settle the controversy. The survey’s five year observing run began last year, with early data expected late in 2015. This early data should be enough to settle the issue, ahead of the final data release in 2017.

***

On one hand, Peiris and Leistedt’s refutation of the neutrino having a large mass seems to bring us back to square one. We still don’t have a terribly clear idea of what the neutrino’s mass is. We still have a hole in the standard model, because even if it is small, the neutrino does have mass. And we have just contradicted some research that appeared to reconcile some of the available facts.

But the practice of science is often like this, with bold predictions, competing claims and imperfect evidence.

And we’re not – quite – back where we started: a plausible theory has been ruled out, we now have a clear hypothesis about why the data had discrepancies, and there will soon be, in the form of the Dark Energy Survey, a tool to test this hypothesis.

The rival teams, at least for now, are sticking by their guns. Leistedt and Peiris think the Dark Energy Survey will prove them right.

Time will tell.

Related links

Heading to Mars… again!

By Oli Usher, on 4 August 2014

Artist's concept of Mars 2020, a proposed NASA mission to Mars. UCL is part of the consortium building the stereoscopic camera. Photo credit: NASA (public domain)

Artist’s concept of Mars 2020, a proposed NASA mission to Mars. UCL is part of the consortium building the stereoscopic camera. Photo credit: NASA (public domain)

Mars 2020 is a planned NASA Mars rover, which will be built to an almost identical design to the Curiosity rover currently exploring the Martian surface. NASA has just announced the scientific payload, and it will include Mastcam-Z – a stereoscopic zoom camera which will be built by a consortium that includes UCL.

Mastcam-Z is the pair of square ‘eyes’ on the bottom of the rover’s ‘head’ as shown on this diagram.

Labelled diagram showing the location of the instruments on Mars 2020, a proposed NASA mission to Mars. UCL is part of the consortium building the Mastcam-Z stereoscopic camera. Photo credit: NASA (public domain)

Labelled diagram showing the location of the instruments on Mars 2020, a proposed NASA mission to Mars. UCL is part of the consortium building the Mastcam-Z stereoscopic camera. Photo credit: NASA (public domain)

UCL are responsible for developing a test environment for laboratory simulations of stereo measurements, and deriving accuracy estimates for rover operations from this. Prof Andrew Coates (UCL Mullard Space Science Laboratory), who is one of the co-investigators (scientific leaders) on the project will also play a leading role in science requirements specification and exploitation, and comparison with other missions including ExoMars.  His scientific focus will be atmosphere-surface interactions.

Many congratulations to the whole team, and in particular to Prof Coates, on this success.

UCL is already leading the consortium building PanCam, the main panoramic camera on the European ExoMars probe, which will launch in 2018.

We’ll check back in on the progress of both of these projects as the design, construction and testing moves forward.

Links

High resolution images