Page 938 – Physics World

Home » Page 938

Flash Physics: Sun’s magnetic reach revised, committee gender quotas analysed, CERN gears up for restart

Cassini reveals new shape to Sun’s magnetic influence

As NASA’s Cassini spacecraft begins its final series of orbits around Saturn, scientists report that it has helped identify an alternate view of the Sun’s magnetic fields. To date, it was thought that the Sun’s heliosphere – the bubble of the Sun’s magnetic influence – had a comet-like shape because of the solar system’s movement through interstellar space. Now, however, Kostas Dialynas of the Academy of Athens in Greece and team suggest a different picture based on data from Cassini, Voyager and the Interstellar Boundary Explorer – the heliosphere may have rounded ends, making it almost spherical. Although Cassini’s main role over the last decade has been to explore Saturn’s system, it has measured fast-moving neutral atoms related to the heliosphere. As charged particles from the inner solar system travel through the heliosphere boundary, some exchange electrons with neutral gas atoms from the interstellar medium. Some of these are then bounced back into the inner solar system as fast-moving neutral atoms. Cassini’s measurements have revealed that particles coming from the heliosphere’s supposed comet-like tail behave almost exactly as those coming from the nose, suggesting it is much more rounded and symmetrical than a comet’s shape. The researchers hope the data, presented in Nature Astronomy, will provide an insight into the interstellar boundary that helps shield Earth from cosmic rays. Meanwhile, after over a decade of investigating Saturn and its moons, Cassini has completed its final close approach of Titan. On 26 April the spacecraft will begin a series of 22 dives between Saturn’s rings before its “Grand Finale”, where it will plunge into the planet’s atmosphere.

Committee gender quotas under the spotlight in new study

Photograph of people evaluating CVs — Evaluating evaluators: male evaluators are less favourable to female candidates when women are on the evaluation committee. (Courtesy: Aalto University)

Introducing gender quotas to scientific search committees could have a detrimental effect for female candidates, according to a new study by economists at Aalto University in Finland. By looking at 100,000 applications to associate and full professorship positions in 16 academic fields in Italy and Spain, the researchers found that a woman’s chances of being hired decreased when a female researcher sat on the scientific hiring committee. Led by Manuel Bagues at Aalto University, the study discovered that male evaluators become less favourable towards female candidates as soon as a female evaluator joins the committee. They also found that female evaluators are also not significantly more favourable towards female candidates. According to Bagues, one explanation for this effect could be that in all-male committees evaluators may feel that they have a “moral obligation to worry about sexism and therefore seek to overcome it by expressing more positive – and perhaps less discriminatory – views about female candidates”. “When there are women on a committee, men may feel licensed to express more honest opinions about female candidate,” he adds. The study is presented in American Economic Review.

CERN gears up for LHC restart

Photograph of the Super Proton Synchrotron (SPS) — Out of hibernation: LHC begins reboot after winter shut down. (Courtesy: Piotr Traczyk/CERN)

CERN’s Super Proton Synchrotron (SPS) has begun circulating proton beams for the first time this year as the lab gears up to restart the Large Hadron Collider (LHC) following the winter shutdown. The start-up of the 7 km-circumference SPS, which feeds the LHC with high-energy protons, means that all four parts of CERN’s accelerator chain – Linear Accelerator 2, the Proton Synchrotron Booster, the Proton Synchrotron and the SPS – are now in operation. The SPS was also upgraded during the shutdown, which involved the installation of a new beam dump. The LHC is now expecting to begin proton–proton collisions within the next few weeks.

You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics.

Seeing through fog using noisy light

A simple, optical technique for tracking obscured or hidden objects has been developed by physicists in the US. The method uses randomized light signals to detect moving objects obscured by fog, cloud or other scattering media. The researchers say the technique could not only be useful for military and civilian surveillance, overcoming the limitations of radar and lidar, but also have biomedical applications.

Remote tracking of moving objects has many applications, including in military and civilian surveillance. Radar and lidar, for example, involve transmitting electromagnetic waves – radio or microwaves in the case of radar and ultraviolet, visible or near-infrared light for lidar – and then analysing the waves that bounce back from objects.

Despite being powerful tools, they require a direct line of sight between the object and the antenna, becoming much less effective when an object is obscured by conditions that scatter the waves, such as clouds, rain and fog. Although it is possible to track obscured objects by repeatedly imaging them, this requires complex equipment and data processing. As the scattering effect of any disturbances increases, the techniques can become so ineffective that they can even fail.

Part of the problem is that conventional methods for tracking hidden objects rely on regular wave pulses at a certain frequency, or combination of frequencies – deterministic signals. “If you have a signal that is regular, something that is deterministic, and you pass it through some disturbance it becomes corrupted – more or less depending on the strength of that disturbance,” explains team member Aristide Dogariu from the University of Central Florida.

Can’t break what’s broken

To tackle this difficulty, Dogariu and Milad Akhlaghi, also at the University of Central Florida, tried a different approach. In their latest research, published in Optica, they describe a technique that uses a random, or “noisy”, light signal to track a moving object surrounded by concealing scattering media. This works because although the noisy signal is corrupted when it is sent through the disturbance, its average properties are much more robust than those of a regular signal. “What is already destroyed cannot be destroyed further easily,” says Dogariu.

Dogariu and Akhlaghi developed statistical methods that allowed them to separate fluctuations in the frequency of the light emitted by the obscuring medium from those that are returned by the moving object. This only works, however, if the object and the obscuring medium are moving at different speeds, which means they each return a different spectral composition.

“You take the intensity variations of the light that comes out and then you construct a power spectrum of those fluctuations and you look in different frequency bands in that spectrum,” Dogariu explains. “This is done in real time as it does not require sophisticated calculations – it is just a power spectrum analysis.”

The researchers tested this idea by placing a small object in a plexiglass box covered with scattering layers of synthetic acrylics. They then shone a primary source of coherent light onto one of the scattering walls, creating a secondary light source inside the box. This light scattered off the target and was further randomized when it passed back through the acrylic walls, before being detected by a light detector in the form of a photomultiplier tube. By statistically analysing this signal, the researchers could track the full 3D trajectory of the object. This was effective for measurements of the signal taken from any location outside of the scattering box.

Hidden details

This technique cannot provide detailed information on the object being tracked, just its direction and speed of movement, as well as its rough size – based on the size of the signal it returns. As Dogariu explains, to know more about the object requires more expensive, sophisticated tests. “This is just a simple way of telling if [the target] starts moving and where it is going,” he adds.

The researchers now plan to test the technique in real-world, outdoor environments, adding that although they demonstrated a technique at optical frequencies, the method should work for other acoustic and microwave signals. They are also exploring possible biomedical applications.

Eye-catching signs from March for Science Bristol

By James Dacey

On Saturday, there were almost 600 sister events across the globe in support of the March for Science gathering in Washington, DC. One such event occurred in Bristol, UK, where Physics World magazine is produced, which featured a march and speeches from science communicators. I popped along to the event with my camera and here are some of the most eye-catching signs from the day.

(more…)

Thousands march for science in Washington

Thousands of people took to the streets of Washington, DC on Saturday 22 April to voice their support for science. Endorsed by more than 200 scientific organizations including the American Physical Society, the March for Science sought to promote the value of science – and scientists – to society. It was part of a co-ordinated series of similar protests at almost 600 other venues around the world.

The Washington march had been organized to coincide with Earth Day and many protestors held placards with environmentally-themed messages such as “We want solar! With science”, “There is no planet B” and “The tides are rising – and so are we”. Others, meanwhile, were concerned about science budgets. “We need to make a statement that basic research funding is important for this country,” said Shawn Westerdale, an experimental physicist.

“Science is truth”

Although the organizers intended the event in Washington not to be political, some protestors had a clear message for politicians in the Trump administration. “It’s an abomination what’s going on,” said Bob Bruninga, an engineer. “Science is not political, but if there are some people who don’t want to understand science and they want to make it a political game, then they can. Science is truth.”

Those views were echoed by theoretical biophysicist Lauren McGough – another protestor who joined those marching from the Washington Monument to Capitol Hill. “Science research funding and general truth are under threat in the current administration and I am really concerned about what that’s going to mean for basically the whole American public and, in the end, the Earth,” she told Physics World.

Kenan Diab – a physicist holding an umbrella and a placard stating “Theoretical physics uncovers beautiful new possibilities” – felt the march could have long-term benefits. “One should take a stand on the correct side, which is to believe in the existence of an objective reality,” he said. “If that’s a partisan issue that’s sad, but hopefully our actions will make it non-partisan again.”

Flash Physics: Supernova appears in four places, spins galore in germanium, Chinese rocket docks with space lab

Supernova appears in four places at once

Astronomers have observed a single supernova appearing at four different locations in the sky. The multiple images are caused by gravitational lensing – a phenomenon first predicted by Albert Einstein as part of his general theory of relativity. It occurs when the gravity of a huge cosmic object bends and magnifies the light of a more distant object. In this case, a galaxy in between the type Ia supernova (called iPTF16geu) and Earth is magnifying the star’s light more than 50 times over and splitting it to create the four separate images. As type Ia supernovae have a well-known intrinsic brightness, the increased signal drew the attention of astronomers when it was seen by the intermediate Palomar Transient Factory (iPTF) – a wide-field sky survey based at Palomar Observatory in the US. Ariel Goobar from Stockholm University in Sweden and colleagues were able to resolve iPTF16geu’s separated images using the Hubble Space Telescope, the W.M. Keck Observatory in Hawaii and the Very Large Telescope in Chile. “Normally, when we view a lensed object we don’t know the intrinsic brightness of that object, but with type Ia supernovae, we do,” says Goobar, “This will allow us to better quantify and understand the phenomenon of gravitational lensing.” Type Ia supernovae, often referred to as “standard candles”, are used to study the expansion rate of the universe. The astronomers hope that iPTF and the network of scientists and telescopes called the Global Relay of Observatories Watching Transients Happen (GROWTH), will help discover similarly lensed type Ia supernovae. The work is presented in Science.

Germanium is a surprisingly good source of spins

Germanium is much better at producing electron spins than had been previously thought – according to Federico Bottegoni and colleagues at the Polytechnic University of Milan in Italy and the University of Grenoble-Alps in France. The discovery could be a boost to researchers trying to develop spintronic devices, which use the spin of the electron to store and process information in much more efficient ways than possible with conventional electronics. The spins are generated by the spin Hall effect (SHE), which involves an electrical current flowing through a material in which the electrons experience an interaction between their spin and orbital angular momentum. Under certain conditions, spin-up electrons will veer off in one direction and spin-down electrons in the opposite direction. The overall effect is a spin current that flows in a direction perpendicular to the electrical current. This leads to an accumulation of spin-up and spin-down electrons at opposite edges of the material. Previous studies of the SHE in germanium revealed very small spin currents, which is why the material had been overlooked for spintronics. Once a spin current is created in germanium, however, it is longer-lived than spin currents in other materials. Bottegoni and colleagues realized that large amounts of spins could accumulate in germanium, despite the relatively weak spin current. When they tested this in the lab, they found that the accumulated spin density in germanium is about 100 times greater than that seen in indium gallium arsenide and on a par with gallium arsenide. Unlike these two compound semiconductors, germanium is compatible with silicon – which makes it more attractive for practical spintronic applications. The research is described in Physical Review Letters.

China takes key step towards permanent space station

China has successfully docked a cargo craft with its Tiangong-2 space lab, taking a major step towards establishing a permanent space station by 2022. On Thursday China launched the Tianzhou-1 cargo resupply spacecraft and two days later it successfully docked with Tiangong-2 in an automated manoeuvre. Tianzhou-1 can carry six tonnes of goods and two tonnes of fuel, although it did not have any actual supplies as there are no astronauts aboard Tiangong-2. The cargo vessel and Tiangong-2 will now have two further docks, including one that will be accelerated to take six hours rather than the usual two days. Tiangong-2 was launched in September 2016 and a month later two Chinese astronauts spent a month aboard the lab in what was the country’s longest-ever manned space mission. It is unlikely that Tiangong-2 will be occupied again and instead China will begin launching the Tiangong-3 station from 2018.

You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on the March for Science in Washington, DC.

Snooker cues, negative mass, apps for waiting and CERN croissants

By Sarah Tesh

With the World Snooker Championship taking place at the moment, it’s that time of year when those of us who are usually snookered by the game are suddenly in its pockets. Right on cue, Phil Sutton from Loughborough University in the UK helps bridge the gap between science and snooker. In his video big break, he looks at why players use chalk on their cue tips. Interestingly, there is a right way to help you spin out a 147 and a wrong way that could leave you pocketing the white.

(more…)

Science not a priority in Trump White House, says physicist John Holdren

The influence of science and scientists on US government policy is being downgraded by the administration of US president Donald Trump – according to the physicist and former science adviser John Holdren. However, Holdren is hopeful that both the US Congress and private industry will reject some of Trump’s planned cuts to science funding.

Holdren served as presidential science adviser and head of the Office of Science and Technology Policy (OSTP) during Barack Obama’s presidency. He told Physics World that it was still unclear whether Trump will appoint a science adviser and senior OSTP staff, who must be approved by the Senate. “I think it would be a serious error if the president does not create a very serious science and technology capability in the White House.”

He believes that the Silicon Valley entrepreneur Peter Thiel is currently advising Trump on science and technology. “It’s pretty clear he knows a lot more about technology than about science. There’s a rumour that the OSTP may be more technology-heavy than science-heavy.”

Pretty lonely

While OSTP leadership appointments are on hold, Holdren says that “one member of the Trump ‘landing team’, Michael Kratsios, has been working very hard to understand the role of science adviser”. “I’m told that he has a good idea of the role. But will he have the ear of the Trump administration? He may be pretty lonely.”

Holdren says that one week before the presidential inauguration in January a member of Trump’s campaign team visited the OSTP. “We spent an hour talking about the functions of the OSTP and the science adviser. We had prepared a very detailed transition book with documentation of all the OSTP’s responsibilities, which we handed over. That was the last we heard.”

Major setback

Holdren fears that the influence of scientists at the White House is waning. He says that Trump’s proposed budget in March “shows no sign of any significant input from anyone who understands science’s role in making recommendations on government policy for government agencies’ science and technology budgets”. Holdren hopes that the budget will be rejected by the US Congress, and calls the plan “a major setback for research, climate science, energy research – just devastating cuts for government support in domains where companies aren’t involved”.

Holdren points out that the proposed cuts will affect programmes that have direct benefits to American society – citing the $6bn drop in the budget of the National Institutes of Health and proposed cuts to NASA’s Earth-observation programmes.

However, Holdren believes that initiatives in science education and the Obama climate action plan both have strong industry support. Although under threat, he says these programmes are likely to survive. “The majority of technology companies accept that climate change is real and we need to do something about it,” he says, adding that the US must ensure that it remains competitive in the development of climate-friendly technologies.

An interview with Holdren will appear in the May issue of Physics World.

Flash Physics: Exoplanet seekers are influential, how to see black-hole hair, alien life search comes up cold

Exoplanet searchers named among 100 Most Influential

Photograph of Natalie Batalha — Far-reaching: Natalie Batalha is not just influencing space exploration. (Courtesy: NASA)

Three physicists have made TIME magazine’s 100 Most Influential People for 2017. In its 14th year, the list highlights those individuals that make the most impact worldwide rather than the most popular or famous. Listed together within the pioneers category (rather than individually like most others), the three physicists honoured by TIME are astronomers searching for exoplanets. Natalie Batalha is the lead scientist for NASA’s Kepler space telescope and is the first woman at NASA to make the list. Her work includes the mission’s first confirmation of a rocky planet outside the solar system and she has identified more than 5100 possible exoplanets over her career. Also honoured is Guillem Anglada-Escudé of the Queen Mary University of London in the UK who discovered the exoplanet orbiting our closest neighbouring star, Proxima Centauri, and Michaël Gillon of the University of Liège in Belgium who announced in February the discovery of Trappist-1. Other scientists on this year’s list include artificial intelligence researcher Demis Hassabis and Guus Velders, an atmospheric chemist.

Ringdown could reveal black-hole hair

Data from the two LIGO detectors showing ringdown — Hair-raising: ringdown could reveal black-hole baldness. Data from the two LIGO detectors showing gravitational waves from the first-ever detection of a binary black hole merger. The lower-amplitude signals on the right correspond to ringdown. (Courtesy: LIGO)

A careful study of data from the LIGO gravitational wave detectors could reveal whether black holes have “hair” – physical properties other than mass, angular momentum and electrical charge. Einstein’s general theory of relativity says that black holes have no hair – they are “bald“– but making the observations needed to confirm this is extremely difficult. Now, physicists in the US and Canada have calculated that information about black-hole hair could be extracted from the gravitational waves that are created just after two black holes merge to form one larger black hole. The new black hole begins its life as a rotating distorted sphere that changes shape until it becomes a sphere in a process called ringdown. If black holes are bald, the gravitational waves emitted during ringdown should be as expected for a black hole with specific values of mass, angular momentum and electrical charge. Any deviation would point to the existence of hair. While a LIGO measurement of the ringdown of an individual black hole is too noisy to provide a definitive answer, Huan Yang of Princeton University and colleagues have worked out that ringdown data from a number of different black holes could be combined to reveal the presence of hair. Writing in Physical Review Letters, they say that the answer could come after one year of observation time once the LIGO detectors have been upgraded to their ultimate design sensitivities.

Extra-terrestrial life search comes up cold

A year-long search for signals from alien civilizations has yet to find any evidence for the existence of intelligent life on other planets. Funded by the physicist and billionaire investor Yuri Milner, the Breakthrough Listen initiative has acquired several petabytes of data using the Green Bank Radio Telescope in West Virginia, Lick Observatory’s Automated Planet Finder in California and the Parkes Radio Telescope in Australia. These data are being analysed by researchers at the SETI Research Center at the University of California, Berkeley, who are scanning through billions of radio channels in a search for unique signals that might indicate the presence of technology developed by extra-terrestrial civilizations. The team has now released an analysis of data from the Green Bank telescope. This identifies 11 “events” in the 1.1–1.9 GHz band that have the highest likelihood of being associated with alien technologies. These are signals with features not expected from astronomical sources such as narrow bandwidth or certain patterns of pulsing or modulation. However, further detailed analysis of the 11 events suggests that it is unlikely that any of them were created by the technology of a distant civilization. “Although the search has not yet detected a convincing signal from extra-terrestrial intelligence, these are early days,” said Berkeley’s Andrew Siemion. “The work that has been completed so far provides a launch pad for deeper and more comprehensive analysis to come.”

You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on science policy and the Trump presidency.

Nanosheet inks offer new route to flexible electronics

Printed electronics are viewed as a cost-effective and scalable route to new technologies, although the performance of these devices tends to rely less on the printer and more on the ink. Researchers at Trinity College Dublin, in collaboration with scientists at Delft University of Technology and Toyota Motor Europe, have now fabricated vertically stacked thin-film transistors (TFTs) from dispersions of two-dimensional nanosheets. Combining high performance with ease of manufacture, these nanosheet-based TFTs have the potential to compete with organic and nanotube-based electronics.

The nanosheet inks are made using a process known as liquid-phase exfoliation, where layered materials in bulk form are broken down and dispersed in liquids. Over the last 10 years this has become an established method for efficiently producing a whole library of two-dimensional materials. Due to the widely varying properties of these nanosheets, every component in the TFT can be printed: conducting graphene nanosheets are used for the electrodes, semiconducting transition-metal dichalcogenides such as molydenum disulphide or tungsten diselenide form the channel, and a boron nitride (BN) dielectric layer acts as a separator.

When printed, the inks form porous nanosheet networks (PNNs) that can be printed layer-by-layer. Their high porosity allows for the use of electrolytic gating, where liquid electrolyte contained within the network is used as a gate dielectric. During operation, ions in the liquid accumulate at the boundary between the electrolyte and the active material due to the application of a gate voltage. Charged ions at the interface then separate, forming an electrostatic double layer and inducing current to flow through the external circuit.

Nanosheet networks printed in vertical stacks function as thin-film transistors.

The research team, led by Adam Kelly and Toby Hallam, measured the electrical transport characteristics of different PNNs using a simple set up involving gold electrodes and an ionic liquid electrolyte (Science 356 6333 69). They found that the transconductance, a measure related to the gain a transistor is capable of delivering, is directly proportional to the thickness of nanosheet network. This allows the electrical characteristics of the device to be tuned by their printing conditions, with transconductance values as high as 6 mS reported by the team.

Large capacitance values were also measured for thick PNNs, due to the large amount of free volume available for ion adsorption. This gives these devices transport properties similar to those of benchmark TFTs, though such high capacitances do hinder switching times. Fortunately, the researchers believe that further experimentation with the ionic liquid electrolyte will enhance switching speeds.

Building on these results, the team built a fully functional TFT using only porous nanosheet networks: graphene electrodes, a tungsten diselenide channel and a BN separator. These vertically stacked devices have on:off ratios of more than 25 and a transconductance of 22 μS. Such transfer characteristics are promising for devices that are still the early stages of development, and further improvements should be possible in the future.

Full details are reported in Science.

Computer model helps explain how LIGO’s black holes formed

In February 2016 researchers at the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) in the US announced a ground-breaking discovery – on 14 September 2015 they had made the first ever direct detection of gravitational waves. After decades of trying to observe these ripples in space–time, the scientists had at last addressed the final unverified prediction of Einstein’s general theory of relativity. Success was quickly followed by success and a few months later a second detection was reported.

In both cases (called GW150914 and GW151216 respectively), as well as a less statistically significant event (LVT151012), the gravitational waves were produced by two stellar-mass black holes in a binary orbit that merged to form one larger black hole. While the detection events are a significant breakthrough, they are still shrouded in mystery. “Previous to this, we never observed a black hole binary system, which leads to the natural question – how did these come to be?” says LIGO scientist Amber Stuver, who was not involved in this current work.

So far, several scenarios have been proposed but they struggle to explain all observed events under one framework. Now, however, scientists at the University of Birmingham in the UK and the University of Amsterdam in the Netherlands have developed a model that can describe all three events via one evolutionary path.

Close together

Before LIGO’s detections, it was thought that stellar-mass binary black-hole systems would either not form at all or, if they did, they would be too far apart to merge within the age of the universe. For two black holes to merge within the age of the universe, they have to begin very close together by astronomical standards – no more than a fifth of the distance between the Sun and Earth. But black holes are produced by massive stars that expand to be much larger than this distance during their stellar evolution.

To solve this problem Simon Stevenson from Birmingham’s Gravitational Wave Group and colleagues developed a simulation platform called Compact Object Mergers: Population Astrophysics and Statistics (COMPAS). “It is a tool for both predicting the evolution of massive stellar binaries and statistically comparing these predictions against observations,” explains team member Ilya Mandel.

Using COMPAS, the group propose an “isolated binary evolution via a common envelope phase”. This means that two massive stars begin with a quite wide separation. As these stars evolve and expand over time, they interact and undergo several episodes of mass transfer, the last of which is called a “common envelope”. This is a very rapid, unstable transfer that envelops both stellar cores in a dense cloud of hydrogen gas. The formation and subsequent ejection of this shared gas cloud is strong enough to take energy away from the orbit, bringing the stars close enough to merge. At this stage in their evolution, the stars are small enough in volume not to be in contact with each other despite their proximity, and they subsequently continue orbiting before merging as black holes billions of years later.

Wind loss

To reach this model, Stevenson, Mandel and colleagues had to make a series of assumptions about physical processes that govern stellar and binary evolution. For example, astronomers do not know the extent to which very massive stars expand and how much mass they lose through winds during evolution. With COMPAS, the researchers produced stellar binary models based on their assumptions and computed their statistical properties. They could then compare these predictions to the observational data and make adjustments accordingly.

“There are a lot of basic assumptions made to come to these results and many more to test,” comments Stuver, “but it is impressive that this one evolution scenario can explain all three of the gravitational wave events.”

As well as providing an explanation of the binary process, the simulation has also helped the team understand what type of stars can form such systems. They suggest that the massive stars have low metallicity, meaning they are almost entirely made up of hydrogen and helium. While 2% of the Sun is other elements, these massive counterparts would contain only 0.1%.

Robust framework

Writing about their proposed model, presented in Nature Communications, Mandel says that, “while [the work] doesn’t yet prove that this is indeed the dominant formation channel for forming merging binary black holes, and while this is almost certainly not the unique channel for doing so, it does allow us to build a robust framework for analysing future observations.”

The researchers hope to improve their model and figure out which assumptions are right by using data from other stellar systems, such as neutron-star binaries, supernovae and X-ray binaries. “The long-term goal is to combine all of these observations to understand how massive stars and binaries evolve,” says Mandel. “We very much look forward to further LIGO detections, and to incorporating other rich observational data sets, in order to gain a better understanding of the lives (and deaths) of massive stars.”

Browse articles by content type

Flash Physics: Sun’s magnetic reach revised, committee gender quotas analysed, CERN gears up for restart

Cassini reveals new shape to Sun’s magnetic influence