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    Edinburgh scientists have taken part in the first detection and analysis of a powerful astronomical event – the merger of two very dense neutron stars.

    The results give unprecedented insight into the processes involved when neutron stars collide in deep space.  The event, some 130 million light years away, is the latest discovery made using sophisticated gravitational wave detectors.

    It is the first binary neutron star collision to be observed by the international Laser Interferometer Gravitational Wave Observatory (LIGO) collaboration, and the first gravitational wave event to be observed by conventional telescopes.

    Multiple sources

    Observing the same event in different ways provides much more information about the processes involved when neutron stars collide in deep space.  It has also allowed a measurement of the rate at which the universe is expanding – known to scientists as Hubble’s constant. 

    David Homan, a PhD student from the School of Physics and Astronomy was working at the NTT telescope in Chile when the team there was alerted to the event.  Jonathan Gair, a researcher from the School of Mathematics also took part in the gravitational wave data analysis and scientific interpretation of the event.  They were able to capture some of the first visible evidence of it, and to track its development over several days.  Energy in the form of gravitational waves, gamma rays, X-rays, light and radio waves was detected in the aftermath of the collision, helping astronomers around the world confirm and characterise the event.

    Scientific insights

    The collision offers valuable insight into elusive explosions known as gamma ray bursts.  A type of gamma ray burst can occur in the aftermath of a binary neutron star collision.  These emit energy equivalent to that produced by an entire galaxy in a year, in a matter of seconds.

    Scientists also found evidence of a kilonova event – an outburst of visible light that astronomers had predicted may occur following a neutron star merger, as a by-product of the production of heavy chemical elements.

    The international LIGO team gathers and analyses data from a pair of highly sensitive detectors in the US.  Measurements from an additional gravitational wave detector in Italy, named Virgo, helped scientists pinpoint the location of recorded events.  The detectors were conceived to demonstrate the existence of gravitational waves, which are ripples in spacetime created by extreme astronomical events, and for use as a revolutionary new kind of telescope.

    Nobel-winning research

    Gravitational waves were detected for the first time in 2015, a discovery that led to the award of the 2017 Nobel Prize for Physics.  Latest findings from the international collaboration have been published in a series of scientific papers including Physical Review Letters and Nature.

    David Homan reported:  “This is truly an exceptional discovery: a never before seen event with the potential for many new insights and discoveries. Given the size of the collaborative effort involved, from LIGO and Virgo to different observatories around the world, I am just excited to have played a small part.”

    A consortium of European astronomers are involved in a project aimed at catching the spectra of transient events.  Included in this is Professor Andy Lawrence from the School of Physics and Astronomy.   

    Professor Andy Lawrence announced:  "This is the culmination of the hard work of hundreds of people over decades.  But it is also the start of something new - multi-messenger astrophysics!  We can learn about the Universe from light, gravitational waves and particles all at the same time.”

    The UK contribution to LIGO is supported by the Science and Technology Facilities Council.

    On Saturday 7th October, Edinburgh staff and students can be seen on-screen at the Edinburgh Filmhouse, in a film which recounts the life of the famous astronomer Charles Piazzi Smyth, and re-creates his famous experiments of 1856.

    In the mid-nineteenth century Charles Piazzi Smyth felt sure that the right way to do astronomy was from the top of mountains, not from smoky cities like Edinburgh. With his geologist wife Jessie, he organised an expedition to Tenerife to prove he was right, living and working on top of Teide for several weeks. He made classic experiments on the sharpness of seeing, the solar spectrum, the zodiacal light, and was the first person to detect infra-red radiation from the Moon. On his return he wrote a popular best seller as well as technical reports, and Astronomy has never looked back since.

    In 2016, several Edinburgh students travelled to Tenerife, met up with Spanish students, and lived on the mountain, re-creating Piazzi Smyth's experiments (with some much better equipment!). This experience was filmed as part of "A Residence Above the Clouds", a film about Piazzi Smyth by Spanish film-maker Guillermo Carnero-Rosell. The film is partly a record of our 2016 trip, partly an account of Piazzi Smyth himself, but also a blend of science, art, and music. For part of this experience we were joined by the Queen guitarist Brian May, who relived his experiences as an Astronomy student in the 1970s, measuring the zodiacal light in Tenerife.

    The film is having its UK premiere at the Edinburgh Spanish Film Festival, on Saturday 7th October in the Edinburgh Filmhouse.

    The School of Physics and Astronomy opened its doors to visitors and showcased the research undertaken at the Institute for Condensed Matter and Complex Systems.

    The School of Physics and Astronomy was delighted to open its doors to visitors on Saturday 23rd September. As part of the Edinburgh-wide Doors Open Days event ran annually by the Cockburn association, over 500 visitors were greeted in the foyer of the James Clerk Maxwell Building by a team of thirteen PhD students and Postdoctoral staff from the Institute for Condensed Matter and Complex Systems (ICMCS).

    Visitors engaged in a number of highly interactive activities, such as making slime, lava lamps, playing with a non-Newtonian fluid made of corn-starch and water, and investigating the possibility of life on Mars. In addition, research lab tours ran all day and academic staff demonstrated and explained the cutting-edge research work they undertake.

    A fantastic insight into science.

    The activities were amazing and the staff was very enthusiastic.

    The event was organised by the Edinburgh Complex Fluid Partnership, the Ogden Trust, the UK Centre for Astrobiology and the Condensed Matter CDT, with the generous support from numerous volunteers across ICMCS.  School colleagues based in the Institute for Astronomy also took part in the Royal Observatory, Edinburgh Doors Open Day event.

    Researchers from Edinburgh are taking part in a flagship international experiment to study the properties of fundamental sub-atomic particles, called neutrinos, which could help explain more about how the universe works and why matter exists at all.

    The UK Government is investing £65million in the partnership project, based in the United States.  It will create the Long-Baseline Neutrino Facility (LBNF) and the Deep Underground Neutrino Experiment (DUNE) in the US.  The LBNF will fire neutrinos a distance of 1300 km from the Fermilab facility in Illinois towards the DUNE detector at the Sanford Underground Research Facility (SURF) in South Dakota.

    Scientists will detect neutrino behaviour to study differences in behaviour between neutrino particles and their antimatter counterparts, antineutrinos.  If this effect, known as CP violation, were observed in neutrino oscillations, this could explain why we live in a universe dominated by physical matter.

    Once constructed, the LBNF and DUNE facility will operate for at least 15 years, undertaking a broad programme of scientific research.

    Scientists will also use DUNE to study the neutrinos produced when a star explodes, which could give insights into the formation of neutron stars and black holes.

    Researchers will investigate whether protons - positively charged subatomic particles - exist forever or eventually decay. This result would bring scientists a step closer to fulfilling Albert Einstein’s dream of a grand unified theory.

    Physicists from the School of Physics and Astronomy at Edinburgh will take part in the collaboration alongside the Universities of Birmingham, Bristol, Cambridge, Durham, Imperial, Lancaster, Liverpool, Manchester, Oxford, Sheffield, Sussex, Warwick and UCL.

    Edinburgh’s scientists will contribute to creating electronic read out systems for the detector and will participate in creating computer networks to process the vast amounts of data from the experiment.

    Professor Franz Muheim reported: “This is fantastic news. We are very excited to be part of the UK consortium on this flagship experiment. This brings together expertise and cutting edge technology to address one of the most fundamental problems in science.”

    UK Universities and Science Minister Jo Johnson signed the agreement with the US Energy Department in Washington, DC.

    UK Science Minister, Jo Johnson said: “Our continued collaboration with the US on science and innovation is beneficial to both of our nations and through this agreement we are sharing expertise to enhance our understanding of many important topics that have the potential to be world changing.”

    The UK’s Science and Technology Facilities Council (STFC) will manage the UK’s investment in the international facility.

    HI-SEAS

    University of Edinburgh and UK Centre for Astrobiology PhD student Samuel Payler completes NASA’s 8-month long HI-SEAS Mars isolation mission.

    HI-SEAS (Hawai’i Space Exploration Analog and Simulation) is a habitat on an isolated Mars-like site on the Mauna Loa side of the saddle area on the Big Island of Hawai'i.  HI-SEAS studies the impacts of long term isolation on crew performance and cohesion in preparation for future missions to the red planet.  Samuel was serving as the Science Officer on the mission.

    Prior to this project, Samuel worked on the UK Centre for Astrobiology’s MINAR program, and NASA’s BASALT project, both of which gave him the opportunity to learn about and contribute to aspects of technology development and mission support architectures for future Mars exploration.  HI-SEAS has now provided him with the astronaut’s side of space exploration. 

    Samuel commented:  “Knowing that information acquired from our mission will contribute to overcoming the problems caused by isolation, is well worth all the personal challenges imposed by living in a dome on the side of an active volcano with only shelf stable foods and five other people to talk to.  Luckily participation was made much easier by having an excellent crew.  Everyone worked extremely hard on everything from task work to personal relationships. We started the mission as strangers and are leaving as close friends."

    Snapshots of typical DNA configurations

    Topology plays a key role in biophysics, from genome organisation to cellular motion. Our work suggests a new role in DNA melting.

    When a double-stranded DNA helix is heated up, the H-bonds keeping the double helix together break, and DNA melts into two single strands.  Long ago, experiments revealed that DNA melting in circular DNA is much smoother than in linear DNA.  Why is this the case?  Most theories attempted to identify a mechanism turning the abrupt, first-order transition of linear molecules into a smooth, second-order one.  Our simulations led us to an alternative explanation, based on the fact that circular DNA needs to conserve the linking number between its two strands.  

    Instead of a traditional transition between zipped and melted state, increasing the temperature takes the system into a coexistence region between a denaturation bubble of unlinked single-stranded DNA, and a double-stranded phase where the DNA linking lost in the bubble is stored as writhe (so the double-stranded section looks like a coiled up phone cord).  This coexistence region can extend over a wide temperature range, with the DNA fraction in the bubble and double-stranded phases varying gradually with temperature, which may account for the experimental results.  Our results suggest new single molecule experiments to be performed on topologically-constrained DNA melting.

    Dr Davide Michieletto reported "Topology plays a key role in biophysics but its understanding is often limited by the lack of a suitable theoretical framework.  In this work we have managed to put together theory and simulations to give a qualitative description of how topology affects DNA melting that explains existing experimental observations."

    Students Enrique Cervero and Hamish Geddes who form part of the University of Edinburgh Hyperloop Team, known as HypED, worked for over ten months to design and build a Hyperloop prototype, a method of levitating transportation propelled along a vacuum tube.

    Much of their summer was spent at the mechanical lab in King’s Building drawing sketches, tightening bolts and drilling holes with the ultimate purpose of bringing their Hyperloop Pod, Poddy McPodface, to life.

    All this work culminated at the end of August in Los Angeles, where HypED was invited by SpaceX to participate in the finals of one of the most prestigious engineering competitions in the world: The Hyperloop Pod Competition II. A total of 25 teams from all over the world were invited to unveil and race their prototypes at the space company’s headquarters, HypED being the only British team and one of four European teams.

    The team arrived in LA about a week before the competition where they brought their prototype to a local workshop in Los Angeles, Urban Workshop, where they spent most of the pre-competition days giving the final touches to the design.

    Enrique Cervero: "Our main worry before the competition was that we would not finish our pod in time, that there would be some flaw or eventuality that we had not planned for and that would ultimately prevent us from competing at SpaceX.   We therefore worked hard trying to get everything done perfectly to meet SpaceX’s requirements."

    When the pod was complete, they drove it to SpaceX in Hawthorne, LA, where it was tested for safety, systems and functionality before the competition. Out of the 25 teams who got invited to the competition, only 3 would be allowed to test their pod and race it in the vacuum tube.

    HypED’s prototype was unfortunately not one of the 3 chosen by SpaceX. However, the team was given clearance to test their pod at a speed of 40m/s (144km/h) in the vacuum track, which would have made it one of the fastest Hyperloop Pods ever tested.

    Enrique Cervero commented: "Over the entire year and competition, I have learned that real world applications of engineering are never simple and require a level head and persistence to complete: there must be a lot of thought put into a design, many drafts, scraps and failures need to be done before arriving at the finalised product.   I have also acquired a lot of technical experience, how to use industrial machinery, solve real world mechanical problems and work as a team to bring our ideas to life."

    The outcome of the competition was also an imperative learning experience for the team which they will use to their advantage in next year’s competition. They will learn from their design flaws and mistakes and remove them in their next design, use the advice and knowledge given to them by Tesla and SpaceX engineers, and improve on the design’s advantages.

    Oil and water don’t mix. This is why a bottle of French dressing has to be shaken before use and why, when an oil tanker sinks, the oil that is spilled can be scooped off the surface of the sea.

    The tendency of oil molecules to avoid mixing with water (called hydrophobicity) is very common and has many effects and applications. Soap and detergent contain molecules that have an oily (hydrophobic) 'tail' and a water-loving  (hydrophilic) 'head' so that when a greasy plate is washed the oily tails bind to the grease and the heads bind to the water, forming microscopic blobs of grease that are happy to disperse in the water. The membrane enclosing cells in all living things are formed from similar molecules, which organise themselves to form sheets so that they can bury their water-hating tails inside the membrane, exposing their water-loving heads to water on the outside.

    Now a group of physicists in the Centre for Science at Extreme Conditions at the University of Edinburgh have shown in a paper to be published in Science Advances that there are circumstances where a water-hating molecule can be made to mix with water.  They studied water and methane (the simplest possible oil and the major component of natural gas) at pressures up to and beyond 20,000 times atmospheric pressure (20 times higher than the pressure at the bottom of the ocean: Marianas Trench).  A mixture of methane and water 0.1mm in diameter and 0.05mm thick was squeezed between two diamonds and the behaviour was observed under a microscope.  At low pressures methane and water don’t mix and, as the left hand picture shows, droplets of methane become surrounded by water.  As the pressure is increased above 13,000 atmospheres, the methane droplets start to shrink and eventually disappear, so that the sample becomes a uniform liquid mixture of methane and water as shown in the right hand picture. The Edinburgh team were able to estimate the amount of mixing from the relative areas of the droplets in pictures like the one on the left.  They found that the amount of mixing increased from less than 1% at 13,000 atmospheres to almost 50% at 20,000 atmospheres, so that 4 of every 10 molecules in the mixture is a methane molecule.

    Discovering conditions under which oil and water do mix has far-reaching implications.  Methane and water occur widely throughout the solar system: within the Earth, in Neptune and Uranus, and in Titan and Triton.  The new finding from Edinburgh will therefore enable scientists to build more accurate models of these planets and satellites.  The finding also offers possibilities for the green agenda: it holds out the prospect of extending considerably the range of what is surely the greenest of all solvents: water.  To make this practicable however, further research is necessary to reduce the pressure at which oil-water mixing can occur.  In the meantime, the discovery has given scientists a simple system in which the love-hate relation between water and oily molecules - which is important for everything from washing up to life itself - can be 'tuned' at will and so probed and understood in new ways.

    Scientists have helped solve the mystery of what lies beneath the surface of Neptune, the most distant planet in our solar system.

    Extremely low temperatures on planets like Neptune – called ice giants – mean that chemicals on these distant worlds exist in a frozen state.  Frozen mixtures of water, ammonia and methane make up a thick layer between the planets’ atmosphere and core – known as the mantle.  However, the form in which these chemicals are stored is poorly understood.

    Using laboratory experiments to study these conditions is difficult, as it is very hard to recreate the extreme pressures and temperatures found on ice giants.  Instead, scientists at Edinburgh ran large-scale computer simulations of conditions in the mantle.  By looking at how the chemicals there react with each other at very high pressures and low temperatures, they were able to predict which compounds are formed in the mantle.

    "Computer models are a great tool to study these extreme places, and we are now building on this study to get an even more complete picture of what goes on there."  Dr Andreas Hermann, Centre for Science at Extreme Conditions

    The team found that frozen mixtures of water and ammonia inside Neptune – and other ice giants, including Uranus – likely form a little-studied compound called ammonia hemihydrate.  The findings will influence how ice giants are studied in future and could help astronomers classify newly discovered planets as they look deeper into space.

    The study, published in the journal Proceedings of the National Academy of Sciences, was supported by the Engineering and Physical Sciences Research Council.

    The work was carried out in collaboration with scientists at Jilin University, China.

    Dr Andreas Hermann also reported:  "This study helps us better predict what is inside icy planets like Neptune. Our findings suggest that ammonia hemihydrate could be an important component of the mantle in ice giants, and will help improve our understanding of these frozen worlds."

    A study of distant galaxies has enabled astronomers to make the most accurate measurement to date of the large-scale structure of the universe.

    Their findings support a theory that about 96 per cent of the Universe is made of elusive dark energy and dark matter.  In making their discovery, the international team including researchers at the University of Edinburgh, created the largest map so far of dark matter in the cosmos.  Their results draw on data collected during the first year of an international project called the Dark Energy Survey (DES).

    Scientists taking part seek to better understand dark energy, which may be responsible for the accelerating expansion of the universe.  Their latest measurements of the amount and distribution of dark matter in the present-day cosmos are as precise as information captured previously about the early universe, by the European Space Agency’s orbiting Planck observatory.  Having both sets of data enables scientists to understand more about how the structure of the universe has evolved over 14 billion years.

    For the latest study, researchers used data from a powerful dark energy camera on a telescope in Chile to create maps of galaxy positions as tracers and trace the density of dark matter.  They also precisely measured the shapes of 26 million galaxies, and used a technique called gravitational lensing – which accounts for light bending over large distances – to directly map the patterns of dark matter’s gravity over billions of light years.  To make these ultra-precise measurements, the DES team developed techniques to detect the tiny lensing distortions of galaxy images – which are invisible to the eye – enabling advances in understanding these signals.

    The DES is a collaboration of more than 400 scientists from 26 institutions in seven countries.  Scientists at the participating Universities of Edinburgh, Cambridge, Manchester, Nottingham, Sussex, Portsmouth and UCL have led work central to the team’s results.

    Their primary instrument, the 570-megapixel Dark Energy Camera, is mounted on the 4-metre Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile.

    UK researchers have led, over the years, major science analyses central to the results presented today.  DES scientists are using the camera to map one-eighth of the sky in unprecedented detail over five years.

    The study was supported by the Science and Technology Facilities Council.

    Dr Joe Zuntz of the University of Edinburgh reported: “The DES measurements, when compared with the Planck map, support the simplest version of the dark matter and dark energy theory.  This is a huge part of the puzzle of how the cosmos has evolved over the past 14 billion years.  It’s the dark Universe made visible on an unprecedented scale.