School of Physics and Astronomy

Scientists have discovered fresh insights into the metallic core at the centre of our planet.

An international team of researchers carried out sophisticated experiments to replicate conditions at the Earth’s core. Using high energy laser beams and optical sensors, they were able to observe how samples of nitrogen behaved at more than 1 million times normal atmospheric pressure and temperatures above 3,000C. Their observations confirmed that, under such conditions, nitrogen exists as a liquid metal.

The findings give scientists valuable insight into how nitrogen behaves at extreme conditions, which could aid understanding of how the planets were formed. It may help to explain why Earth is the only planet known to have an abundance of nitrogen in its atmosphere – where it exists as a gas. Nitrogen in the air could emerge from deeper within the planet, where, for example, it could mix with other liquid metal. In addition, the findings could also shed light on how the planet’s atmosphere evolved and how it may develop in future.

The study, carried out by the University of Edinburgh with researchers in China and the US, was published in Nature Communications. It was supported by the Engineering and Physical Science Research Council and the British Council.

Dr Stewart McWilliams of the School of Physics and Astronomy said: “Earth’s atmosphere is the only one of all the planets where nitrogen is the main ingredient – greater even than oxygen. Our study shows this nitrogen could have emerged from deep inside the planet.”

Local secondary school pupils receive award and gain an insight into studying physics

The School of Physics and Astronomy and the Ogden Trust hosted an awards ceremony for the ‘School Physicist of the Year’.  The ceremony rewarded the most deserving high school students who are currently in year 3, based on their progress in Physics.  18 pupils based in schools in Edinburgh were selected by their Physics teachers and 15 were able to attend the evening, along with around 35 parents and teachers. The students were rewarded with a £25 National Book Token and a certificate enabling them to apply to events and programs organised by the Ogden Trust.

The event also enabled school pupils to gain a flavour of studying physics at University level. Academic staff, research colleagues and physics undergraduates students from the School of Physics and Astronomy shared information on their work and experience here, guests got the chance to take part in demonstrations and experiments, and an inspirational talk on ‘Squidgy Business’ was given by Prof. Wilson Poon as he shared information on how businesses use his expertise in soft matter.

Thank you for a lovely evening last night, the award ceremony was most enjoyable and very inspiring not only for our young people  but I'm  sure for all who attended

A new stochastic equation for active, growing interfaces predicts the evolving shape of a cellular membrane.

From a physicist's point of view, perhaps the most intriguing feature of biological systems is that they are constantly held away from thermodynamic equilibrium by active processes: the inert atoms and molecules of classical statistical mechanics are replaced by active entities which consume energy and may move of their own volition. Likewise active matter - which is composed of many such active entities - can itself grow and change shape.

The range of lengthscales spanned by theories of active matter is stunningly large. Consider a cell: on the one hand it is the active component of bigger systems such as tissues, on the other hand it is itself an active system, whose constituents are those proteins regulating the whole cellular machinery.

Francesco Cagnetta (Higgs STFC PhD student), Martin Evans (Professor of Statistical Physics) and Davide Marenduzzo (Professor of Computational Biophysics) analyse the effects of activity on growing interfaces and how this produces the striking patterns that have been puzzling experimentalists studying red blood cell membranes.  Specifically, the authors extend the celebrated Kardar-Parisi-Zhang (KPZ) equation, known to predict the universal features of many out-of-equilibrium systems, to deal with the local source of growth provided by membrane proteins.  Their theory proposes an explanation for the self-organisation of proteins: dynamic nanoclusters of proteins are formed which induce travelling waves of growth in the membrane. Intriguingly, these travelling undulations of the membrane are in turn surfed by the protein nanoclusters that produced them!

The work was made an Editors' Selection in Physical Review Letters and has been highlighted by a Viewpoint in APS Physics.

Edinburgh researchers will help further the understanding of the physical universe following a major upgrade to create the High-Luminosity Large Hadron Collider (HL-LHC).

The LHC, the largest science experiment on Earth, produces high-energy collisions between fundamental physical particles at close to the speed of light inside a 27km ring. Its upgrade, scheduled to be completed by 2026, aims to increase by more than five times the number of particle collisions that take place during large experiments. This increase will enable scientists to gather about 10 times more data, compared with previous experiments, in the decade following the HL-LHC start-up. Discoveries in particle physics are based on collecting large amounts of data, so a greater number of collisions increases the chance of discovering a new particle.

The upgrade will also allow further research into the Higgs boson particle, which was predicted by Professor Peter Higgs when he was a researcher at the University in the 1960s, and discovered by the CERN team in 2012. Experiments at the new LHC will enable the Higgs’ properties to be defined more accurately, and to measure with increased precision how it is produced, how it decays and how it interacts with other particles.

Professor Victoria Martin, School of Physics and Astronomy reported:

The very intense collisions between protons at the High-Luminosity LHC will allow scientists, including our team from the University of Edinburgh, to look at physics at the smallest accessible distances. This will provide a deeper understanding of what the fundamental constituents of the Universe are, how they behave, and how they build the structure of the Universe around us.

Professor Phillip Clarke, School of Physics and Astronomy commented:

The HL-LHC will allow us to use the Higgs boson as a probe for new physics. This is a new type of particle, being a spin-less boson, and it is very interesting to explore all its interactions with nature - it even self-interacts. As a researcher who specialises in the simulation of particles produced within the ATLAS detector at the LHC, I look forward to this next phase and the discoveries ahead.

Barkla family members, City of Edinburgh Council representatives, Hermitage of Braid friends and University colleagues attended an unveiling of a plaque located at Hermitage House to commemorate Noble Laureate Charles Glover Barkla.

Charles Barkla lived in Hermitage House, which is set within the Hermitage of Braid and Blackford Hill Local Nature Reserve, from 1922 to 1938.  The house was built in 1785 and the style reflects the old Braid Castle thought to have been in what is now known as Midmar Paddock at the end of Hermitage Drive.

Charles Barkla took up the Chair in Natural Philosophy at the University of Edinburgh in 1913.  Barkla's most significant research centred around the physics of X-rays. Along with C. A. Sadler, he was the first to demonstrate that X-rays consist of waves oscillating in different planes that can be separated. This discovery transformed our understanding of X-rays, showing that they have similar properties to light and hence aided the development of the theory of Quantum Mechanics – one of the key planks of modern physics.

His most significant work was on the characteristic X-ray emitting properties of the chemical elements, which won him a Nobel Prize in 1917.

Fresh insight into how stars are formed is challenging scientists’ understanding of the Universe. A study of intense starbursts – events in distant galaxies in which stars are generated hundreds or thousands of times faster than in our Milky Way – is changing researchers’ ideas about cosmic history.

The findings will help scientists understand how galaxies in the early Universe evolve into those we see today. Instead of observing the optical light from starbursts, which is obscured by enormous quantities of dust, scientists instead observed radio waves, measuring the relative abundances of different types of carbon monoxide gas. They were able to differentiate between the gas expelled from massive stars, which shine very brilliantly for a short time, and that expelled from less massive stars, like our own Sun, which can shine steadily for billions of years. Applying this novel technique for the first time, astronomers found that stars born inside galaxies undergoing a powerful starburst tend to be massive. In this regard, these are very different from those born inside galaxies that build up their stars over billions of years.

Scientists verified their findings using powerful computer models based on the evolution of our Milky Way galaxy and by observing starburst galaxies in the early Universe, which formed within a few billion years of the Big Bang. Such young galaxies are unlikely to have undergone previous episodes of star formation, which might otherwise have confused the results.

Researchers collected their data using the powerful ALMA telescope in the high Atacama Desert in Chile.

The five-year study, published in Nature, was carried out by astronomers at the University of Edinburgh and the European Southern Observatory (ESO), working alongside experts in Italy and Greece. It was supported by the European Research Council. The ALMA telescope is operated by a partnership of the ESO, the US National Science Foundation and the National Institutes of Natural Sciences of Japan, in cooperation with the Republic of Chile. 

Dr Zhi-Yu Zhang, of the University of Edinburgh’s School of Physics and Astronomy, who led the study, said: “Traditional telescopes are of limited use when studying dusty starburst galaxies. We reached our results using a powerful new radio telescope, hunting for traces of chemical elements from past events.  For astronomers, these are like fossils. The results challenge classical ideas about the formation of stars in galaxies across cosmic time.”

Professor Rob Ivison, of the University of Edinburgh’s School of Physics and Astronomy and ESO, said: “Our findings lead us to question our understanding of cosmic history. Astronomers building models of the Universe must now go back to the drawing board, with yet more sophistication required.”

The Higgs Centre for Innovation, which supports start-ups and SMEs working in the space and data-intensive sectors, has officially opened at the Royal Observatory Edinburgh.

Entrepreneurial boost

The centre links to industry with cutting-edge scientific and engineering expertise. It focuses on supporting business both through incubation activities and access to facilities, including laboratories and working space, for small and medium-sized enterprises (SMEs). Connecting engineers, academics and PhD students directly with small businesses will help boost their entrepreneurial experience at the start of their research careers.

The stand-alone building at the Royal Observatory Edinburgh is run by the Science and Technology Facilities Council in partnership with the University.

£11 million investment

The Centre aims to create new market opportunities, especially in big data and space technologies. It is funded through a £10.7 million investment from the UK Government. The Science and Technology Facilities Council will invest £2million over five years to operate the centre.

Prof James Dunlop, Head of the Institute for Astronomy, University of Edinburgh reported:

The construction of the Higgs Centre for Innovation is an exciting new development in the long established collaboration between STFC and the University of Edinburgh at the Royal Observatory Edinburgh. The new centre will cement Edinburgh's reputation as a world leader in the fields of astrophysics and big data, and provide new opportunities for knowledge exchange between astronomers, particle physicists, engineers and industry.

Gillian Wright, Director of the UK Astronomy Technology Centre commented:

A huge amount of work has been put in by all partners over the past few years to develop plans for the Higgs Centre for Innovation. We look forward to developing new partnerships at the centre and seeing the benefits it will bring to future generations of scientists and industry.

The Higgs Centre for Innovation is named in honour of Professor Peter Higgs of the University’s School of Physics and Astronomy. The pioneering scientist received a Nobel Prize in Physics in 2013 for his prediction of the existence of the Higgs boson particle, which enables other particles to acquire mass. This fundamental particle was discovered by scientists at the European Organization for Nuclear Research (CERN) in 2012.

Congratulations to Dr Jamie Cole and Prof Philip Clark for their success in the 2018 Teaching Awards.

Jamie won the award for Best Personal Tutor.  This is the second time Jamie has won this award, the first being in 2016. This demonstrates his continued effort in student support.

Philip achieved the runner-up award for Best Implementer of Student Feedback.

Dr Jamie Cole commented:

Personal Tutors in the School of Physics & Astronomy are dedicated to helping students realise their academic potential. The recognition I received – which belongs also to many equally deserving colleagues and to our excellent Student Support Team – will encourage the School in its desire to provide a high level of support to our students within a vibrant, challenging and hopefully rewarding learning environment.

 Prof Arthur Trew, Head of School reported:

We are incredibly pleased by this result, which demonstrates our students’ recognition of the pastoral care that we give them and our efforts in implementing course changes following feedback from students. Over the past few years we have had more than our fair share of EUSA Teaching Awards, but winning both an award and runner up place, and with a second win for Dr Cole, this is great news for us.  My congratulations to both Dr Cole and Professor Clark. 

EUSA Teaching Awards

The EUSA Teaching Awards celebrate the best contributions made to students’ learning experiences.  This year, there were over 1,600 nominations for courses, teaching staff, dissertation supervisors, professional and administrative staff.

Understanding how bacteria stick, the differences of adhesion within a population of bacteria, and its influence in biomedical applications.

Bacteria are very good at sticking to surfaces, where they can be a major source of infections. For example, they can contaminate medical devices, food packaging and drinking water systems, and there are ongoing efforts to design surfaces that prevent bacterial adhesion. A team of researchers from the School of Physics and Astronomy and School of Engineering used cutting-edge microscopy and image analysis techniques to probe the adhesion of rod-shaped Escherichia coli bacteria to glass surfaces. It appears that there are large differences between individual bacteria in how they stick to the surface that can be explained with a “patchy model”.

The researchers recorded movies of many bacterial cells on a glass surface. Using in-house developed software, they followed the positions and orientations of the cells and studied their dynamics. Some bacteria readily adhere to the surface while others never do. Even if they adhere, there can be differences between individual cells. Some cells attach to a surface for several hours, while others bind only weakly and detach rapidly.

The results can be explained with a model in which bacteria adhere with a limited number of adhesive patches on their body. Strong adherers can stick with multiple patches, while weakly adhering cells are bound with just a single patch, and non-adhering cells have no adhesive patches at all. Interestingly, all these differences are found within populations in which all cells should have the same genes. Apparently, individual cells express these genes differently, thus making the behaviour of each cell differ.

Apart from the academic relevance, the results of the study can be used to realise novel anti-adhesion surfaces. It seems the design of such materials should take into account that not all cells stick in the same way, and that adhesion takes place on specific spots on the bacteria.

The second release of results from the European Space Agency's Gaia mission takes place to the world scientific community. Gaia Data Release 2 (GDR2) marks an enormous step forwards for astronomy, providing a map of the Milky Way galaxy in orders of magnitude larger and more precise than that available previously.

Gaia has been in routine operations for nearly four years. This ambitious space astronomy project aims to map a substantial part of our galaxy over a mission lifetime of more than 5 years, eventually scanning the entire sky around 70 times.

The spacecraft orbits the Earth at a distance of 1.5 million kilometers in the Lagrange-2 region, 4 times further away than the Moon. This is a quasi-stable point in the Sun-Earth system with an orbital period of one year, in the opposite direction to the Sun as seen from Earth.

Gaia scans continuously with a rotational period of 6 hours, building up a map of the sky with exquisite angular resolution, unhampered by the blurring effects of the Earth's atmosphere. GDR2 contains the positions, distances, optical brightness and colours of more than one billion stars. Supplementary information in the form of spectroscopic radial velocities, variability light curves and stellar astrophysical parameters are also available for subsets of the main catalogue. This release of data marks a major leap forward in our knowledge of the Galaxy with 500x more stellar distances measured than in the first data release in September 2016. That previous release was in itself a significant step forward, with 20x more stellar distances measured than by the precursor Hipparcos mission in the early 1990s.

A small team of scientists and developers based in the Wide Field Astronomy Unit of the Institute for Astronomy (IfA) in the School of Physics and Astronomy have been working on the project for more than ten years. The team currently comprises Michael Davidson, Nigel Hambly and Nick Rowell. The team is responsible for several key calibration subsystems within the on-ground data processing pipelines that have been developed for Gaia by a collaboration of hundreds of engineers and scientists spread around Europe. Further details of the IfA's involvement can be found in a previous School News item coinciding with the launch of Gaia back in December 2013.

Dr. Hambly reported  "This is a significant milestone for the Gaia project and demonstrates the superb quality of the data gathered so far. The information content of GDR2 is a huge step forward and we are continuing to work on improvements for later data releases."

Dr. Davidson said "The launch of Gaia brought many surprises and challenges as we came to know the spacecraft. Now each data release is eagerly anticipated by the astronomy community."

Dr. Rowell commented "The Gaia catalogue represents an enormous and rich dataset that will be exploited by astronomy researchers for decades to come."

GDR2 represents only an intermediate step in the science exploitation of Gaia data, being based on 22 months of observations. The European teams within the Gaia Data Processing and Analysis Consortium are already working on the next data release with improved software and calibrations. GDR3 will take place towards the end of 2020, and will contain the analysis of around 36 months of data. The calibration improvements coupled with more measurements taken over a longer time will lead to even greater precision in the 3D positions and space motions contained within the multi-billion row Gaia star catalogue.

The Wide Field Astronomy Unit's participation in the European Space Agency Gaia Data Processing and Analysis Consortium is funded by grants from the UK Space Agency and Science and Technology Facilities Council.