physicsworld--2020-11-06--Controversy erupts among astronomers over whether phosphine really was discovered on Venus - Physics

Controversy erupts among astronomers over whether phosphine really was discovered on Venus - Physics World

Doubt has been cast on the supposed discovery of phosphine in the atmosphere of Venus after several papers were published on the arXiv preprint server , challenging the result .
The discovery had been announced in September when a team of researchers led by Jane Greaves of the University of Cardiff claimed it had observed the spectral fingerprint of phosphine ( PH ) in the clouds of Venus .
If true , the paper would have been our strongest evidence yet of life beyond Earth , but the tone of some of the resulting criticism – as well as a @ @ @ @ @ @ @ the press coverage of the work – has outraged astronomers .
Phosphine – a potential biosignature – is created in the high temperatures and pressures within the interiors of Jupiter and Saturn , but on Earth it is only produced by anaerobic microbial life .
To detect phosphine on Venus , the researchers used the James Clerk Maxwell Telescope ( JCMT ) in Hawaii and the Atacama Large Millimeter/submillimeter Array ( ALMA ) in Chile .
Shortly after the announcement , however , the organising committee of the International Astronomical Union ( IAU @ @ @ @ @ @ @ statement lambasting Greaves ’ team for the resulting press coverage of the claimed discovery .
“ It is an ethical duty for any scientist to communicate with the media and the public with great scientific rigour and to be careful not to overstate any interpretation which will be irretrievably picked up by the press , ” they wrote , adding that the commission “ would like to remind the relevant researchers that we need to understand how the press and the media behave before communicating with them ” .
The IAU statement was @ @ @ @ @ @ @ including the commission ’ s own members , many of whom said the organising committee did not speak for them .
The statement was then swiftly retracted by the IAU Executive , who insisted that it did not reflect the view of the organisation .
In its own statement , the executive added that the organising committee of Commission F3 had “ been contacted to retract their statement and to contact the scientific team with an apology.
” The IAU said it will now produce a procedure for future public communication that all @ @ @ @ @ @ @ The dust had barely settled from that brouhaha when a paper entitled “ No phosphine in the atmosphere of Venus ” was submitted to Nature Astronomy ’ s “ Matters Arising ” section .
It argued that Greaves ’ team had misidentified the absorption line of sulphur dioxide in Venus ’ atmosphere as that of phosphine .
Written by a group led by Geronimo Villanueva of NASA ’ s Goddard Space Flight Center , the team ended its abstract with the “ suggestion ” that Greaves ’ team retract their original paper – @ @ @ @ @ @ @ The furore around this paper led to an apology by Villanueva ’ s team .
“ We agree that the sentence calling for retraction was inappropriate and we apologise for harm caused to the Greaves et al team , ” the team notes in a statement .
They add that the specific language had been used because of a misinterpretation of the guidelines issued by Nature Astronomy , who had encouraged Villanueva ’ s team to post the preprint for public discussion .
Mark Thompson , an astrophysicist from the University of Hertfordshire @ @ @ @ @ @ @ the phosphine discovery , agrees that the statement from the organising committee of Commission F3 and the abstract to Villanueva team ’ s paper overstepped the mark .
However , he thinks that the IAU statement has a point , agreeing that the fallout “ comes in large part from the over-hyping of the result by some parts of the press.
” The key argument of Thompson ’ s paper is how Greaves and colleagues calibrated their data .
The absorption line of phosphine appears against a bright continuum of thermal emission from @ @ @ @ @ @ @ the spectrum .
This baseline has to be removed , which is normally a simple process of subtraction , but when the baseline emission is complex , as is the case with Venus , the baseline needs to be fitted as a higher-order polynomial before being subtracted .
However , the higher the polynomial , the more parameters and assumptions there are .
Greaves ’ team used a twelfth-order polynomial , which is considered exceptionally high and often comes with unintended consequences , potentially including the creation of false positives .
“ As @ @ @ @ @ @ @ with four parameters I can fit an elephant and with five I can make him wiggle his trunk ’ , ” says Thompson .
Has evidence of life been found in the clouds of Venus ?
Although Greaves ’ team justified its choice of using a high-order polynomial in order to address “ ripples ” – instrumental artefacts in the data that become apparent when observing an object as bright as Venus – Thompson says that he does “ worry that the resulting absorption feature may be the elephant wiggling its trunk instead @ @ @ @ @ @ @ Similarly , a team led by Ignas Snellen of Leiden Observatory has also come to the same conclusion about the baseline calibration .
Whereas Greaves ’ team report the phosphine absorption line as being 15 times stronger than the surrounding noise , “ What we see is that the strength of the feature is about a factor of 2 higher than the noise , which is below statistical significance , ” Snellen told Physics World .
For now , the phosphine paper is the only set of results that has undergone peer review @ @ @ @ @ @ @ until the arXiv papers have been similarly vetted and Greaves ’ team have conducted their own re-analysis .
If , after all that , the results are still in dispute , then it may be that new observations at different frequencies are required .
Phosphine is difficult to detect from the ground but NASA ’ s airborne Stratospheric Observatory For Infrared Astronomy telescope , which flies at an altitude of over 13.7 km on board a modified Boeing 747SP , could confirm or deny the finding .

Concerns have been raised over the analysis that pointed to phosphine in the atmosphere of Venus. (Courtesy: NASA/JPL)
Doubt has been cast on the supposed discovery of phosphine in the atmosphere of Venus after several papers were published on the arXiv preprint server challenging the result. The discovery had been announced in September when a team of researchers led by Jane Greaves of Cardiff University, UK, claimed it had observed the spectral fingerprint of phosphine (PH 3 ) in the clouds of Venus. If true, the paper would have been our strongest evidence yet of life beyond Earth, but the tone of some of the resulting criticism – as well as a surprising statement from an international body over the press coverage of the work – has outraged astronomers.
Phosphine – a potential biosignature – is created in the high temperatures and pressures within the interiors of Jupiter and Saturn, but on Earth it is only produced by anaerobic microbial life. To detect phosphine on Venus, the researchers used the James Clerk Maxwell Telescope (JCMT) in Hawaii and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.
As John von Neumann once said: with four parameters I can fit an elephant and with five I can make him wiggle his trunk Mark Thompson
Shortly after the announcement, however, the organizing committee of the International Astronomical Union (IAU) Commission F3 on Astrobiology released a statement lambasting Greaves’ team for the resulting press coverage of the claimed discovery. “It is an ethical duty for any scientist to communicate with the media and the public with great scientific rigour and to be careful not to overstate any interpretation which will be irretrievably picked up by the press,” they wrote, adding that the commission “would like to remind the relevant researchers that we need to understand how the press and the media behave before communicating with them”.
The IAU statement was met with scorn from many quarters, including the commission’s own members, many of whom said the organizing committee did not speak for them. The statement was then swiftly retracted by the IAU executive, who insisted that it did not reflect the view of the organization. In its own statement, the executive added that the organizing committee of Commission F3 had “been contacted to retract their statement and to contact the scientific team with an apology”. The IAU said it will now produce a procedure for future public communication that all members will be advised to follow.
Wait and see
The dust had barely settled from that brouhaha when a paper entitled “No phosphine in the atmosphere of Venus” was submitted to Nature Astronomy’s “Matters Arising” section. It argued that Greaves’ team had misidentified the absorption line of sulphur dioxide in Venus’ atmosphere as that of phosphine. Written by a group led by Geronimo Villanueva of NASA’s Goddard Space Flight Center, the team ended its abstract with the “suggestion” that Greaves’ team retract its original paper – seen by some as unduly aggressive.
The furore around this paper led to an apology by Villanueva’s team. “We agree that the sentence calling for retraction was inappropriate and we apologise for harm caused to the Greaves et al. team,” the team notes in a statement. It adds that the specific language had been used because of a misinterpretation of the guidelines issued by Nature Astronomy, which had encouraged Villanueva’s team to post the preprint for public discussion.
Mark Thompson, an astrophysicist from the University of Hertfordshire who has written his own critique of the phosphine discovery, agrees that the statement from the organizing committee of Commission F3 and the abstract to Villanueva team’s paper overstepped the mark. However, he thinks that the IAU statement has a point, agreeing that the fallout “comes in large part from the over-hyping of the result by some parts of the press”.
The key argument of Thompson’s paper is how Greaves and colleagues calibrated their data. The absorption line of phosphine appears against a bright continuum of thermal emission from Venus, which forms a baseline in the spectrum. This baseline has to be removed, which is normally a simple process of subtraction, but when the baseline emission is complex, as is the case with Venus, the baseline needs to be fitted as a higher-order polynomial before being subtracted.
However, the higher the polynomial, the more parameters and assumptions there are. Greaves’ team used a 12th-order polynomial, which is considered exceptionally high and often comes with unintended consequences, potentially including the creation of false positives. “As John von Neumann once said, ‘with four parameters I can fit an elephant and with five I can make him wiggle his trunk’,” says Thompson. Read more Has evidence of life been found in the clouds of Venus?
Although Greaves’ team justified its choice of using a high-order polynomial in order to address “ripples” – instrumental artefacts in the data that become apparent when observing an object as bright as Venus – Thompson says that he does “worry that the resulting absorption feature may be the elephant wiggling its trunk instead of being a true detection”.
Similarly, a team led by Ignas Snellen of Leiden Observatory has also come to the same conclusion about the baseline calibration. Whereas Greaves’ team reports the phosphine absorption line as being 15 times stronger than the surrounding noise, “What we see is that the strength of the feature is about a factor of 2 higher than the noise, which is below statistical significance,” Snellen told Physics World.
For now, the phosphine paper is the only set of results that has undergone peer review. Thompson encourages discussion to now wait until the arXiv papers have been similarly vetted and Greaves’ team have conducted their own re-analysis. If, after all that, the results are still in dispute, then it may be that new observations at different frequencies are required. Phosphine is difficult to detect from the ground but NASA’s airborne Stratospheric Observatory For Infrared Astronomy telescope, which flies at an altitude of over 13.7 km on board a modified Boeing 747SP, could confirm or deny the finding.


physicsworld--2020-11-06--Discrete time crystals could boost quantum simulations - Physics World

Researchers in Japan have developed a new mathematical technique to explore the characteristics of time crystals .
The team , led by Kae Nemoto at the National Institute of Informatics in Tokyo , used a combination of graph theory and statistical mechanics to show how the exotic quantum materials evolve over time .
Their work opens new routes to practical applications for time crystals , including simulations of complex quantum networks .
Time crystals are an exotic newcomer to physics , and researchers have much to learn about their unusual properties .
First proposed in 2012 , and finally observed @ @ @ @ @ @ @ continually as structures that repeat regularly in time .
This is analogous to normal crystals , which have structures that repeat regularly in space .
A normal crystal breaks translational symmetry in space because it is not the same everywhere in the crystal ( some locations have atoms , while locations are empty space ) .
Similarly , time crystals break translational symmetry in time , with the structure changing as a function of time .
When time crystals were first proposed there was a fair amount of debate about whether they could @ @ @ @ @ @ @ theory and experiment have shown that some non-equilibrium quantum systems driven by a periodic external force can become “ discrete time crystals ” ( DTCs ) .
Nemoto ’ s team further explored DTCs using graph theory – which can model a wide variety of complex discrete systems as mathematical structures containing interconnected groups of nodes .
In this case , the nodes represented the different states of a DTC .
By mapping out asymmetrical links between states , the researchers could reliably predict how the system evolves over time in various situations @ @ @ @ @ @ @ hard , the system can “ melt ” – causing it to stop oscillating and lose its time crystal order .
To explore this process further , Nemoto and colleagues combined graph theory with statistical mechanics to model how a DTC ’ s graph structure evolved over time , until melting completely .
This gave the team a far more complete insight into the nature of the crystals than ever achieved previously .
Where useful applications of the materials have remained speculative until now , the results revealed how a DTC ’ s @ @ @ @ @ @ @ connected systems .
Using their newly developed toolset to translate DTCs into the language of graph theory , Nemoto ’ s team showed how the materials can be used to simulate networks the size of the global Internet , using just several quantum bits .
They also showed that DTCs could be exploited to achieve quantum simulations of quantum many-body systems , whose dynamics are notoriously difficult to model .
Through further improvements , the researchers ’ techniques could become suitable for applications including advanced machine learning algorithms , the analysis of natural @ @ @ @ @ @ @ the brain .
The study is described in Science Advances .

Melting time: Kae Nemoto looked at the melting of discrete time crystals. (Courtesy: iStock/William Potter)
Researchers in Japan have developed a new mathematical technique to explore the characteristics of time crystals. The team, led by Kae Nemoto at the National Institute of Informatics in Tokyo, used a combination of graph theory and statistical mechanics to show how the exotic quantum materials evolve over time. Their work opens new routes to practical applications for time crystals, including simulations of complex quantum networks.
Time crystals are an exotic newcomer to physics, and researchers have much to learn about their unusual properties. First proposed in 2012, and finally observed experimentally in 2017, time crystals evolve continually as structures that repeat regularly in time. This is analogous to normal crystals, which have structures that repeat regularly in space. A normal crystal breaks translational symmetry in space because it is not the same everywhere in the crystal (some locations have atoms, while locations are empty space). Similarly, time crystals break translational symmetry in time, with the structure changing as a function of time.
When time crystals were first proposed there was a fair amount of debate about whether they could exist in nature. More recently, theory and experiment have shown that some non-equilibrium quantum systems driven by a periodic external force can become “discrete time crystals” (DTCs).
Interconnected groups of nodes
Nemoto’s team further explored DTCs using graph theory – which can model a wide variety of complex discrete systems as mathematical structures containing interconnected groups of nodes. In this case, the nodes represented the different states of a DTC. By mapping out asymmetrical links between states, the researchers could reliably predict how the system evolves over time in various situations.
When a DTC is driven too hard, the system can “melt” – causing it to stop oscillating and lose its time crystal order. To explore this process further, Nemoto and colleagues combined graph theory with statistical mechanics to model how a DTC’s graph structure evolved over time, until melting completely. This gave the team a far more complete insight into the nature of the crystals than ever achieved previously. Where useful applications of the materials have remained speculative until now, the results revealed how a DTC’s characteristics can be exploited to simulate intricately connected systems.
Using their newly developed toolset to translate DTCs into the language of graph theory, Nemoto’s team showed how the materials can be used to simulate networks the size of the global Internet, using just several quantum bits. They also showed that DTCs could be exploited to achieve quantum simulations of quantum many-body systems, whose dynamics are notoriously difficult to model. Through further improvements, the researchers’ techniques could become suitable for applications including advanced machine learning algorithms, the analysis of natural ecosystems and simulations of neural structures in the brain.
The study is described in Science Advances.


physicsworld--2020-11-06--Snake vision inspires pyroelectric material design - Physics World

Vipers , pythons and boa constrictors all use infrared vision to locate their prey , but the exact source of this slithery sixth sense is unknown .
A team of researchers at the University of Houston in the US has now developed a mathematical model for how cells in a specialized snake organ convert infrared radiation into electrical signals .
As well as potentially solving a longstanding puzzle in snake biology , the work could also aid the development of thermoelectric transducers based on soft , flexible structures rather than stiff crystals .
Certain species of snake can generate unsettlingly @ @ @ @ @ @ @ warmer than their surroundings .
Venomous pit vipers , for example , can detect infrared ( IR ) light at wavelengths between 50 nm and 1 mm , which translates into a frequency range of between 1.8 THz to 2.5 PHz .
This heat-sensing ability enables them to hunt warm-blooded prey such as birds and rodents even in total darkness , and scientists believe that it derives from a structure in their heads that acts as an “ antenna ” for IR radiation .
The structure , known as a pit organ , @ @ @ @ @ @ @ 15 mm thick , encased in a thin membrane with a surface area of around 30 mm2 .
Despite extensive studies , the precise mechanism by which the pit organ converts infrared radiation into processable electrical signals remains controversial , notes team leader Pradeep Sharma .
He and his colleagues have now constructed a mathematical model to test the theory that cells within the pit organ membrane are pyroelectric – that is , able to generate a temporary voltage when heated or cooled .
This idea is itself somewhat controversial , since pyroelectricity @ @ @ @ @ @ @ stiff materials such as crystals .
These materials are naturally electrically polarized and so contain large electric fields .
When they change temperature , the position of their atoms also changes slightly .
This shift in position alters their polarization , which in turn produces a temporary voltage across the material .
If the temperature then remains constant at its new value , the pyroelectric voltage slowly dissipates due to leakage current .
To show that snake cells could also act as pyroelectric materials , the researchers used methods from the continuum mechanics @ @ @ @ @ @ @ and thermal expansion strain .
They also factored in material properties such as the elastic modulus and thermal expansion coefficients of the cells .
Using these inputs , the researchers calculated that , based on the pyroelectric responses of their pit organ cells , boa constrictors and vipers ought to be able to detect temperature differences at the millikelvin level .
This is better than any human-made heat sensor , and according to Sharma , it implies that the snakes can sense the presence of an animal that is a mere 10 degrees @ @ @ @ @ @ @ it appears for only half a second at a distance 40 centimetres away .
Similar calculations for rattlesnakes and pythons indicate that they can perform the same feat at 100 cm and 30 cm , respectively .
All three results agree qualitatively with physiological measurements , Sharma says .
The new work shows that soft and flexible structures can indeed display pyroelectricity .
Such structures , Sharma explains , contain embedded static , stable electrical charges that don ’ t leak out .
They can also deform in shape and size and are @ @ @ @ @ @ @ now undertaking preliminary experiments on synthetic soft materials that resemble a snake ’ s pit organ .
The results of these experiments might confirm the new model , they say , although further research would still be needed to prove that the proposed mechanism is indeed occurring in the snakes ’ cells .
Previous biological studies suggested that protein channels known as TRPA1 were involved , but it remains unclear how these channels might relate to the new model .
“ Using this model , I can confidently create an artificial soft material @ @ @ @ @ @ @ is no doubt , ” Sharma says .
“ And we are fairly confident that we have uncovered at least part of the solution of how these snakes are able to see in the dark.
” Now that they ’ ve developed the model , he adds , other scientists can do experiments to confirm or disprove their theory about snakes ’ IR-sensing abilities .
The researchers , who report their work in Matter , say they now plan to fabricate bespoke soft materials that are highly pyroelectric while also demonstrating the ( @ @ @ @ @ @ @ , applying an electric field can reduce the temperature and thus provide a sort of cooling , ” Sharma tells Physics World .
“ Such an effect has only been appreciably demonstrated in hard materials so far .
”

Heat sssssensorsss A large-eyed green pit viper. The pit organs are small depressions between the snake's nostrils and eyes. (Courtesy: iStock_TommyIX)
Vipers, pythons and boa constrictors all use infrared vision to locate their prey, but the exact source of this slithery sixth sense is unknown. A team of researchers at the University of Houston in the US has now developed a mathematical model for how cells in a specialized snake organ convert infrared radiation into electrical signals. As well as potentially solving a longstanding puzzle in snake biology, the work could also aid the development of thermoelectric transducers based on soft, flexible structures rather than stiff crystals.
Certain species of snake can generate unsettlingly accurate thermal images of objects that are warmer than their surroundings. Venomous pit vipers, for example, can detect infrared (IR) light at wavelengths between 50 nm and 1 mm, which translates into a frequency range of between 1.8 THz to 2.5 PHz. This heat-sensing ability enables them to hunt warm-blooded prey such as birds and rodents even in total darkness, and scientists believe that it derives from a structure in their heads that acts as an “antenna” for IR radiation. The structure, known as a pit organ, is a hollow chamber about 10 to 15 mm thick, encased in a thin membrane with a surface area of around 30 mm2.
A pyroelectric possibility
Despite extensive studies, the precise mechanism by which the pit organ converts infrared radiation into processable electrical signals remains controversial, notes team leader Pradeep Sharma. He and his colleagues have now constructed a mathematical model to test the theory that cells within the pit organ membrane are pyroelectric – that is, able to generate a temporary voltage when heated or cooled.
This idea is itself somewhat controversial, since pyroelectricity was previously thought to be limited to stiff materials such as crystals. These materials are naturally electrically polarized and so contain large electric fields. When they change temperature, the position of their atoms also changes slightly. This shift in position alters their polarization, which in turn produces a temporary voltage across the material. If the temperature then remains constant at its new value, the pyroelectric voltage slowly dissipates due to leakage current.
To show that snake cells could also act as pyroelectric materials, the researchers used methods from the continuum mechanics of soft matter to couple electric fields and thermal expansion strain. They also factored in material properties such as the elastic modulus and thermal expansion coefficients of the cells. Using these inputs, the researchers calculated that, based on the pyroelectric responses of their pit organ cells, boa constrictors and vipers ought to be able to detect temperature differences at the millikelvin level. This is better than any human-made heat sensor, and according to Sharma, it implies that the snakes can sense the presence of an animal that is a mere 10 degrees warmer than its surroundings, even if it appears for only half a second at a distance 40 centimetres away.
A rattlesnake’s pit organ. Credit:
Darbaniyan et al. /Matter
Similar calculations for rattlesnakes and pythons indicate that they can perform the same feat at 100 cm and 30 cm, respectively. All three results agree qualitatively with physiological measurements, Sharma says.
Applications to synthetic materials
The new work shows that soft and flexible structures can indeed display pyroelectricity. Such structures, Sharma explains, contain embedded static, stable electrical charges that don’t leak out. They can also deform in shape and size and are sensitive to temperature.
The researchers are now undertaking preliminary experiments on synthetic soft materials that resemble a snake’s pit organ. The results of these experiments might confirm the new model, they say, although further research would still be needed to prove that the proposed mechanism is indeed occurring in the snakes’ cells. Previous biological studies suggested that protein channels known as TRPA1 were involved, but it remains unclear how these channels might relate to the new model.
“Using this model, I can confidently create an artificial soft material with pyroelectric properties – of that there is no doubt,” Sharma says. “And we are fairly confident that we have uncovered at least part of the solution of how these snakes are able to see in the dark.” Now that they’ve developed the model, he adds, other scientists can do experiments to confirm or disprove their theory about snakes’ IR-sensing abilities.
The researchers, who report their work in Matter, say they now plan to fabricate bespoke soft materials that are highly pyroelectric while also demonstrating the (converse) electrocaloric effect. “Here, applying an electric field can reduce the temperature and thus provide a sort of cooling,” Sharma tells Physics World. “Such an effect has only been appreciably demonstrated in hard materials so far.”


physicsworld--2020-11-06--A century of change: the Institute of Physics turns 100 - Physics World

Imagine being a physicist in 1920 , the year the Institute of Physics was formed .
The ordered world of classical physics was being turned upside down by a rapid succession of startling discoveries and radical ideas .
Quantum theory was emerging as the most perplexing and yet most promising way of understanding the secrets of the atomic world , while Albert Einstein had stunned the scientific community with his general theory of relativity .
It challenged Newton ’ s laws of gravity with mind-expanding concepts such as curved space–time and predicted gravitational effects such as the bending of light @ @ @ @ @ @ @ just been obtained by Arthur Eddington on his eclipse expedition of 1919 .
Life for physicists had been very different just 30 years earlier , when it had seemed that all the major problems in physics had been solved .
Classical mechanics could reliably predict the movement of objects on Earth as well as the planets and stars ; the laws of thermodynamics had been put to work in the development of steam engines ; and James Clerk Maxwell ’ s seminal equations had unified the theories of electricity and magnetism .
Such @ @ @ @ @ @ @ the observable world , and most physicists thought that their only remaining tasks would be to finesse existing models and improve the accuracy of their measurement techniques .
That view was first challenged in 1895 , when German physicist Wilhelm Röntgen discovered X-rays , which could pass through solid objects and the human body – beautifully demonstrating his finding with an image showing the skeletal structure of his wife ’ s hand .
Just a year later , while working at the National Museum of Natural History in Paris , Henri Becquerel was @ @ @ @ @ @ @ he had locked away in a drawer emitted radiation of their own accord .
The discovery inspired Marie Curie , also based in Paris at the time , to perform pioneering experiments that led her to conclude that the radiation was emitted by the uranium atom itself – in conflict with the prevailing notion that atoms were indivisible .
Physicists then had to come to terms with the discovery of the electron , made by British physicist J J Thomson in 1897 .
Five years later the New Zealander Ernest Rutherford and others @ @ @ @ @ @ @ radiation were emitted by the spontaneous breakdown of heavy atoms into lighter ones .
Meanwhile , theorists were developing new models to explain puzzling electromagnetic phenomena that could not be reconciled with classical theory .
In 1900 German physicist Max Planck had introduced the revolutionary idea that atoms could only absorb or emit energy in discrete “ quanta ” to resolve the energy distribution of blackbody radiation , a concept that Einstein exploited in 1905 to show that the photoelectric effect could be explained by treating light as quantized particles .
That year @ @ @ @ @ @ @ s “ annus mirabilis ” , during which he also published papers on Brownian motion , special relativity and the equivalence between energy and mass .
“ No physicist who has reached middle age can forget the romantic interest of the 10 years following 1895 , ” remarked American physicist Henry Bumstead during a lecture at Yale University in 1920 .
Summing up the mood of the time , he recalled how “ startling discoveries followed each other in rapid succession and the physical journals were awaited with an impatience not unlike the @ @ @ @ @ @ @ the news was all good news , and recorded an almost unbroken series of victories ” .
Those 10 remarkable years at the turn of the century were followed by further breakthroughs that underlined the need for a new approach to physics , including Rutherford ’ s work on defining and splitting the atomic nucleus , American Robert Millikan ’ s confirmation of Einstein ’ s photon theory of light , and British physicist William Henry Bragg ’ s conclusion that X-rays must also be “ corpuscular ” in nature .
By 1920 @ @ @ @ @ @ @ World War began to abate , it had become clear that physicists would need to revise some of their most fundamental ideas .
In his lecture that year at Yale , Bumstead noted that the laws that govern atoms may be quite different from the laws of mechanics and electrodynamics that were so familiar to physicists of the time , remarking that this would be “ rather a wrench for those of us who have been nursed and reared in the old regime ” .
But this discomfort , he felt , was @ @ @ @ @ @ @ the fascinating and apparently inexhaustible field for research and speculation which is now being opened up for our use and pleasure ” .
That sense of wonder and excitement heralded a new era of modern physics .
The discoveries of the past quarter century had been reported widely in the mainstream press , attracting a new generation of scientists who were keen to solve the riddles posed by atomic and quantum physics .
The First World War had shown that physics could have practical benefits too .
Bragg and Rutherford , for example @ @ @ @ @ @ @ submarines , and their research on underwater sound paved the way for Canadian physicist Robert Boyle and Paul Langevin , in France , to produce the first practical pulse-echo system based on piezoelectric transducers in 1918 .
No credit where credit was due While many of the early pioneers had enough time and money to pursue their own scientific interests , the university laboratories of the time were small and poorly equipped , at least in the UK .
“ 50 years ago physical labs were very few , and very very sparsely @ @ @ @ @ @ @ speech in 1921 .
“ There were few advanced students , and fewer still who intended to make physics the business of their life ; and indeed that was a very reckless and dangerous thing because the only positions open to physicists in those days were a few – very few – badly paid professorships.
” By the start of the 1920s , Thomson estimated that between 800 and 1000 scientists were engaged in some sort of physics research in the UK .
New laboratories had sprung up across the country for training @ @ @ @ @ @ @ , while the Cavendish Laboratory at the University of Cambridge had become a world-renowned research centre with more than 40 graduate students working alongside senior academics .
Physicists were also employed in government laboratories , as well as in a growing number of industries that were making use of advances in electronics , optics and communications .
But there was still very little recognition for physics as a distinct profession .
Indeed , there was real concern among physicists about the attitudes towards their occupation , and younger scientists in particular were seeking @ @ @ @ @ @ @ There was little or no recognized position for physicists , ” said Richard Glazebrook in a speech to fellow physicists , shortly after retiring as the first director of the UK ’ s National Physical Laboratory in 1919 .
“ Men [ sic ] who have done important work in physics have , in some cases , only been given an official status by being termed research chemists.
” This lack of recognition led to low wages , insecure employment prospects and scant money for experimental apparatus .
Newer universities struggled to attract @ @ @ @ @ @ @ the most established research centres had to cope on meagre finances .
George Paget Thomson – the son of J J Thomson – later recalled how , in his early days at the Cavendish Laboratory , senior academics had to rely on college fellowships worth about £250 ( roughly £11,000 in today ’ s money ) to top up their salaries .
Demand also frequently outstripped supply for standard equipment such as galvanometers , pumps and even resistors .
Timeline of the Institute of Physics The Institute of Physics headquarters moved to King @ @ @ @ @ @ @ Courtesy : Institute of Physics ) 1874 The Physical Society of London meets for the first time to enable scientific discussion and the demonstration of new results and techniques , followed by the first publication of the Proceedings of the Physical Society of London 1914 The first Guthrie Lecture – established to honour the founder of the Physical Society of London , Frederick Guthrie – is given by Robert Wood on “ Radiation of gas molecules excited by light ” 1920 The Institute of Physics ( IOP ) is formally incorporated as a @ @ @ @ @ @ @ Memorandum and Articles of Association are approved 1923 The Journal of Scientific Instruments is published by the IOP for the first time 1932 The Optical Society and Physical Society of London merge to form the Physical Society 1934 The first international physics conference takes place in the UK , organized jointly by the Physical Society and the Royal Society ( the UK ’ s national academy of sciences ) in conjunction with a meeting of the Union of Pure and Applied Physics 1956 The 1000th fellow of the IOP is admitted to membership @ @ @ @ @ @ @ 1000th graduate members 1960 The Physical Society and IOP merge to create a single learned and professional society 1966 The IOP journal Physics Education is launched to enable professional development among physics teachers 1986 IOP Publishing is created as a separate business unit to manage all publishing activities 1996 The IOP moves its headquarters to 76 Portland Place , London 2001 The Chartered Physicist programme is introduced to strengthen the professional recognition of qualified physicists 2018 The IOP opens new headquarters at 37 Caledonian Road , London 2020 The membership of the IOP @ @ @ @ @ @ @ the First World War the need for a professional association for physics in the UK was becoming clear .
While the Physical Society of London had been founded in 1874 , its focus was to provide a forum for discussing and demonstrating new scientific results .
Back then , scientists such as Maxwell and Rayleigh would not have imagined that anyone would be able to earn a living through physics , let alone that scientific research would be put to practical use by industry or the government .
Now what was needed was @ @ @ @ @ @ @ of professional physicists , while also co-ordinating the activities of the Physical Society of London and smaller but related learned bodies based in the UK – notably the Optical Society and the Faraday and Röntgen societies .
At a meeting in 1918 , representatives from all interested parties discussed the possible activities of a proposed “ Institute of Physics ” , which included awarding diplomas to physicists with adequate training , registering the qualifications of members , creating a shared headquarters and library , and establishing new exhibitions and publications .
A board @ @ @ @ @ @ @ Glazebrook would be the first president , and the Institute of Physics ( IOP ) was formally incorporated in November 1920 .
By then 300 physicists had joined the new organization as fellows or members .
“ It is a tribute to the status already acquired by the newly formed Institute that its diploma is now being required from applicants for government and other important positions requiring a knowledge of physics , ” the UK newspaper The Times noted , “ and the physicist is now being recognized as a member of a @ @ @ @ @ @ @ years the IOP ran in parallel with the now simply named Physical Society , the former looking after professional matters with the latter continuing to focus on scientific results and discussion .
Speaking at the IOP ’ s inaugural meeting in 1921 , J J Thomson – who later that year was to become the IOP ’ s second president – clearly defined the scope of the new body .
“ This Institute is one which , like similar organizations of doctors , lawyers , engineers and chemists , has been founded to @ @ @ @ @ @ @ ” he said , “ to act as a bond of union , to ensure that the highest standard of efficiency is reached by those interested in it , and also to ensure a high standard of professional conduct.
” To underline its role for representing physicists in government and industry , one of the IOP ’ s first major initiatives was to launch the Journal of Scientific Instruments in 1923 , which is still published today as Measurement Science and Technology .
Proposed by Glazebrook , the new journal aimed to deal @ @ @ @ @ @ @ the theory , construction and use of instruments as an aid to research in all branches of sciences and engineering ” .
There was a clear desire even then to make the journal interdisciplinary in nature , with biologists , engineers , chemists and instrument makers invited to join physicists on the scientific advisory committee .
As the IOP expanded , it created subject groups that catered for growing specialization within the field , as well as overseas and regional branches .
It also issued certificates to members who were proficient in specific @ @ @ @ @ @ @ as glass blowing , that young researchers were still routinely required to learn .
By the end of the Second World War the IOP was increasingly working with government to help shape science policy and physics education , particularly as it was becoming clear in the post-war years that there were too few physicists to fill the growing number of vacancies in industry , academia and science teaching .
Salary surveys offered guidance on the wages that new and experienced physicists could expect to earn , with the 1948 edition suggesting that graduates @ @ @ @ @ @ @ roughly £22,000 in 2020 ) by age 30 , with an upper limit of around £1250 ( about £46,000 now ) for the most experienced and able IOP fellows .
The IOP had also assumed much of the administrative work of the Physical Society , and by 1944 the two organizations agreed to co-operate on many of their core activities , including conferences and publications .
After a prolonged period of will-they-won ’ t-they , the two bodies merged in 1960 to create “ The Institute of Physics and The Physical Society ” @ @ @ @ @ @ @ shortened to “ The Institute of Physics ” when the IOP was awarded its Royal Charter in 1970 .
Since then the combined professional body and learned society has continued to champion physics and professional physicists .
The IOP has developed and supported physics education , provided advice and expertise to policymakers , encouraged innovation and growth in industry , worked internationally with other physical societies across the world , and inspired people from different backgrounds to explore the wonders of physics .
Meanwhile , its commitment to disseminate scientific research has enabled @ @ @ @ @ @ @ to become a leading international publisher of research journals , ebooks and , of course , Physics World .
Among the IOP ’ s lesser-known achievements was the creation of a benevolent fund in 1924 , seeded by a donation of £100 from Major Charles Phillips – a British physicist and a founder of the IOP – and topped up by regular contributions from members .
The value of the fund had risen to more than £1m by the start of the 21st century , allowing the IOP to provide direct financial support @ @ @ @ @ @ @ in need .
More recently , astrophysicist Jocelyn Bell Burnell – who served as the IOP ’ s first woman president – donated her £2.3m winnings from the Breakthrough Prize for her work on discovering pulsars , allowing the IOP to launch last year a fund to support PhD students from under-represented groups at universities in the UK and Ireland .
Looking to the future , meanwhile , the IOP has just launched a major new campaign to widen participation in physics ( see box above ) .
The physics community of 2020 @ @ @ @ @ @ @ existed in 1920 when the IOP was founded .
It is far bigger now , of course , but thankfully also much more diverse , and the myriad of careers that physicists today pursue – from IT and engineering to finance and education – would surely have been enthusiastically welcomed by J J Thomson .
“ I should like , on behalf of those interested in physics , ” he said , while addressing the first meeting of the IOP , “ to express our obligation to those who have conceived the idea @ @ @ @ @ @ @ borne the labours in connection with its initiation.
” One wonders what Thomson would say were he to address the IOP ’ s membership today .

Physics World. Members of the Institute of Physics can enjoy the full issue Taken from the November 2020 issue of. Members of the Institute of Physics can enjoy the full issue via the Physics World app
The Institute of Physics was created in 1920 to champion a new generation of professional physicists working in industry, academia and the government, as Susan Curtis describes
(Courtesy: IOP Publishing/Mat Ward)
Imagine being a physicist in 1920, the year the Institute of Physics was formed. The ordered world of classical physics was being turned upside down by a rapid succession of startling discoveries and radical ideas. Quantum theory was emerging as the most perplexing and yet most promising way of understanding the secrets of the atomic world, while Albert Einstein had stunned the scientific community with his general theory of relativity. It challenged Newton’s laws of gravity with mind-expanding concepts such as curved space–time and predicted gravitational effects such as the bending of light, the first evidence for which had just been obtained by Arthur Eddington on his eclipse expedition of 1919.
Life for physicists had been very different just 30 years earlier, when it had seemed that all the major problems in physics had been solved. Classical mechanics could reliably predict the movement of objects on Earth as well as the planets and stars; the laws of thermodynamics had been put to work in the development of steam engines; and James Clerk Maxwell’s seminal equations had unified the theories of electricity and magnetism. Such breakthroughs had made sense of much of the observable world, and most physicists thought that their only remaining tasks would be to finesse existing models and improve the accuracy of their measurement techniques.
That view was first challenged in 1895, when German physicist Wilhelm Röntgen discovered X-rays, which could pass through solid objects and the human body – beautifully demonstrating his finding with an image showing the skeletal structure of his wife’s hand. Just a year later, while working at the National Museum of Natural History in Paris, Henri Becquerel was surprised to find that the uranium salts he had locked away in a drawer emitted radiation of their own accord. The discovery inspired Marie Curie, also based in Paris at the time, to perform pioneering experiments that led her to conclude that the radiation was emitted by the uranium atom itself – in conflict with the prevailing notion that atoms were indivisible. Physicists then had to come to terms with the discovery of the electron, made by British physicist J J Thomson in 1897. Five years later the New Zealander Ernest Rutherford and others confirmed that alpha, beta and gamma radiation were emitted by the spontaneous breakdown of heavy atoms into lighter ones.
Keeping up to date The Cavendish Laboratory at the University of Cambridge (pictured left in 1910) was just one of a handful of UK physics labs that existed when the Institute of Physics was founded (courtesy: Cavendish Laboratory). It is currently undergoing further development to create the Ray Dolby Centre (architect’s illustration, right, courtesy: Jestico + Whiles)
Meanwhile, theorists were developing new models to explain puzzling electromagnetic phenomena that could not be reconciled with classical theory. In 1900 German physicist Max Planck had introduced the revolutionary idea that atoms could only absorb or emit energy in discrete “quanta” to resolve the energy distribution of blackbody radiation, a concept that Einstein exploited in 1905 to show that the photoelectric effect could be explained by treating light as quantized particles. That year went down in history as Einstein’s “annus mirabilis”, during which he also published papers on Brownian motion, special relativity and the equivalence between energy and mass.
“No physicist who has reached middle age can forget the romantic interest of the 10 years following 1895,” remarked American physicist Henry Bumstead during a lecture at Yale University in 1920. Summing up the mood of the time, he recalled how “startling discoveries followed each other in rapid succession and the physical journals were awaited with an impatience not unlike the desire for newspapers in wartime. But the news was all good news, and recorded an almost unbroken series of victories”.
Those 10 remarkable years at the turn of the century were followed by further breakthroughs that underlined the need for a new approach to physics, including Rutherford’s work on defining and splitting the atomic nucleus, American Robert Millikan’s confirmation of Einstein’s photon theory of light, and British physicist William Henry Bragg’s conclusion that X-rays must also be “corpuscular” in nature. By 1920, as the horrors of the First World War began to abate, it had become clear that physicists would need to revise some of their most fundamental ideas. In his lecture that year at Yale, Bumstead noted that the laws that govern atoms may be quite different from the laws of mechanics and electrodynamics that were so familiar to physicists of the time, remarking that this would be “rather a wrench for those of us who have been nursed and reared in the old regime”. But this discomfort, he felt, was “much more than compensated for by the fascinating and apparently inexhaustible field for research and speculation which is now being opened up for our use and pleasure”.
That sense of wonder and excitement heralded a new era of modern physics. The discoveries of the past quarter century had been reported widely in the mainstream press, attracting a new generation of scientists who were keen to solve the riddles posed by atomic and quantum physics. The First World War had shown that physics could have practical benefits too. Bragg and Rutherford, for example, developed better hydrophones for detecting enemy submarines, and their research on underwater sound paved the way for Canadian physicist Robert Boyle and Paul Langevin, in France, to produce the first practical pulse-echo system based on piezoelectric transducers in 1918.
There was real concern among physicists about the attitudes towards their occupation, and younger scientists in particular were seeking an improvement in their status
No credit where credit was due
While many of the early pioneers had enough time and money to pursue their own scientific interests, the university laboratories of the time were small and poorly equipped, at least in the UK. “50 years ago physical labs were very few, and very very sparsely populated,” said Thomson in a speech in 1921. “There were few advanced students, and fewer still who intended to make physics the business of their life; and indeed that was a very reckless and dangerous thing because the only positions open to physicists in those days were a few – very few – badly paid professorships.”
By the start of the 1920s, Thomson estimated that between 800 and 1000 scientists were engaged in some sort of physics research in the UK. New laboratories had sprung up across the country for training students and providing facilities for practical work, while the Cavendish Laboratory at the University of Cambridge had become a world-renowned research centre with more than 40 graduate students working alongside senior academics. Physicists were also employed in government laboratories, as well as in a growing number of industries that were making use of advances in electronics, optics and communications.
But there was still very little recognition for physics as a distinct profession. Indeed, there was real concern among physicists about the attitudes towards their occupation, and younger scientists in particular were seeking an improvement in their status. “There was little or no recognized position for physicists,” said Richard Glazebrook in a speech to fellow physicists, shortly after retiring as the first director of the UK’s National Physical Laboratory in 1919. “Men [sic] who have done important work in physics have, in some cases, only been given an official status by being termed research chemists.”
This lack of recognition led to low wages, insecure employment prospects and scant money for experimental apparatus. Newer universities struggled to attract and retain experienced physicists, while even the most established research centres had to cope on meagre finances. George Paget Thomson – the son of J J Thomson – later recalled how, in his early days at the Cavendish Laboratory, senior academics had to rely on college fellowships worth about £250 (roughly £11,000 in today’s money) to top up their salaries. Demand also frequently outstripped supply for standard equipment such as galvanometers, pumps and even resistors.
Timeline of the Institute of Physics The Institute of Physics headquarters moved to King’s Cross in 2018. (Courtesy: Institute of Physics) 1874 The Physical Society of London meets for the first time to enable scientific discussion and the demonstration of new results and techniques, followed by the first publication of the Proceedings of the Physical Society of London 1914 The first Guthrie Lecture – established to honour the founder of the Physical Society of London, Frederick Guthrie – is given by Robert Wood on “Radiation of gas molecules excited by light” 1920 The Institute of Physics (IOP) is formally incorporated as a professional society for physicists, and its Memorandum and Articles of Association are approved 1923 The Journal of Scientific Instruments is published by the IOP for the first time 1932 The Optical Society and Physical Society of London merge to form the Physical Society 1934 The first international physics conference takes place in the UK, organized jointly by the Physical Society and the Royal Society (the UK’s national academy of sciences) in conjunction with a meeting of the Union of Pure and Applied Physics 1946 The IOP establishes headquarters at 47 Belgrave Square, London 1956 The 1000th fellow of the IOP is admitted to membership, along with the 2000th associate and 1000th graduate members 1960 The Physical Society and IOP merge to create a single learned and professional society 1966 The IOP journal Physics Education is launched to enable professional development among physics teachers 1986 IOP Publishing is created as a separate business unit to manage all publishing activities 1988 Physics World is launched 1996 The IOP moves its headquarters to 76 Portland Place, London 2001 The Chartered Physicist programme is introduced to strengthen the professional recognition of qualified physicists 2018 The IOP opens new headquarters at 37 Caledonian Road, London 2020 The membership of the IOP stands at 23,000
A professional physics society
By the end of the First World War the need for a professional association for physics in the UK was becoming clear. While the Physical Society of London had been founded in 1874, its focus was to provide a forum for discussing and demonstrating new scientific results. Back then, scientists such as Maxwell and Rayleigh would not have imagined that anyone would be able to earn a living through physics, let alone that scientific research would be put to practical use by industry or the government.
Now what was needed was an organization that would boost the status of professional physicists, while also co-ordinating the activities of the Physical Society of London and smaller but related learned bodies based in the UK – notably the Optical Society and the Faraday and Röntgen societies. At a meeting in 1918, representatives from all interested parties discussed the possible activities of a proposed “Institute of Physics”, which included awarding diplomas to physicists with adequate training, registering the qualifications of members, creating a shared headquarters and library, and establishing new exhibitions and publications.
A board was formed in 1919, agreeing that Glazebrook would be the first president, and the Institute of Physics (IOP) was formally incorporated in November 1920. By then 300 physicists had joined the new organization as fellows or members. “It is a tribute to the status already acquired by the newly formed Institute that its diploma is now being required from applicants for government and other important positions requiring a knowledge of physics,” the UK newspaper The Times noted, “and the physicist is now being recognized as a member of a specific profession.”
For the next 40 years the IOP ran in parallel with the now simply named Physical Society, the former looking after professional matters with the latter continuing to focus on scientific results and discussion. Speaking at the IOP’s inaugural meeting in 1921, J J Thomson – who later that year was to become the IOP’s second president – clearly defined the scope of the new body. “This Institute is one which, like similar organizations of doctors, lawyers, engineers and chemists, has been founded to promote the interest of the profession,” he said, “to act as a bond of union, to ensure that the highest standard of efficiency is reached by those interested in it, and also to ensure a high standard of professional conduct.”
From 1920 to 2020: a century in publications Rising resources The number of papers in physics, both in interdisciplinary and core fields, has increased exponentially over the past century. Growth was disrupted during the world wars but was at its steepest between 1950 and 1970. (Adapted by permission from Springer Nature: Nature Phys. 11 791) In 1920, when the Institute of Physics (IOP) was founded, physics as a distinct scientific discipline was still in its infancy. According to a 2015 survey by the physicist Albert-László Barabási and colleagues at Northeastern University in the US, only a few hundred research papers in physics were published that year, representing just 4% of all scientific publications (Nature Physics 11 791). Since then, the research output from the physics community has grown exponentially, aside from a short pause during the Second World War. By 1950 physicists were writing around 1000 research papers every year, rising to 100,000 by 2010, and since the 1980s physics has accounted for some 22% of all scientific publications, with the IOP itself now publishing more than 85 academic journals. The scientific literature also reveals how physics has changed from an individual, single-minded pursuit to a more collaborative endeavour. A study by US science historians Donald Deb Beaver and Richard Rosen in 1978 estimated that only 20% of physics research published in 1920 involved any sort of collaboration (Scientometrics 1 65). Today, in contrast, the average number of authors on a physics paper has risen more than in any other scientific field. According to Nature Index, for papers in the 68 journals it tracks, the average number of authors in the physical sciences more than quadrupled from nine in 2012 to 39 in 2016 – driven largely by the emergence of publications with more than a thousand co-authors. Physics has also become more interdisciplinary. The analysis by Barabási and colleagues shows that before 1910 almost all research papers were published in core physics journals such as Physical Review and the Proceedings of the Physical Society. But 1920 saw a significant increase in research reports published by physicists in other fields, or in more general titles such as Nature and Science. At the same time, point out Barabási and colleagues, the myriad of different subfields of physics have developed their own lexicons, methodologies and culture, with papers published in certain domains significantly more likely to cite other publications in the same subfield and not outside it. This behaviour is particularly prevalent in nuclear and particle physics.
To underline its role for representing physicists in government and industry, one of the IOP’s first major initiatives was to launch the Journal of Scientific Instruments in 1923, which is still published today as Measurement Science and Technology. Proposed by Glazebrook, the new journal aimed to deal with “methods of measurement, and the theory, construction and use of instruments as an aid to research in all branches of sciences and engineering”. There was a clear desire even then to make the journal interdisciplinary in nature, with biologists, engineers, chemists and instrument makers invited to join physicists on the scientific advisory committee.
As the IOP expanded, it created subject groups that catered for growing specialization within the field, as well as overseas and regional branches. It also issued certificates to members who were proficient in specific experimental techniques and laboratory arts, such as glass blowing, that young researchers were still routinely required to learn.
A growing community
By the end of the Second World War the IOP was increasingly working with government to help shape science policy and physics education, particularly as it was becoming clear in the post-war years that there were too few physicists to fill the growing number of vacancies in industry, academia and science teaching. Salary surveys offered guidance on the wages that new and experienced physicists could expect to earn, with the 1948 edition suggesting that graduates should be receiving £600 per annum (roughly £22,000 in 2020) by age 30, with an upper limit of around £1250 (about £46,000 now) for the most experienced and able IOP fellows.
The IOP had also assumed much of the administrative work of the Physical Society, and by 1944 the two organizations agreed to co-operate on many of their core activities, including conferences and publications. After a prolonged period of will-they-won’t-they, the two bodies merged in 1960 to create “The Institute of Physics and The Physical Society”, a cumbersome name that was subsequently shortened to “The Institute of Physics” when the IOP was awarded its Royal Charter in 1970.
Since then the combined professional body and learned society has continued to champion physics and professional physicists. The IOP has developed and supported physics education, provided advice and expertise to policymakers, encouraged innovation and growth in industry, worked internationally with other physical societies across the world, and inspired people from different backgrounds to explore the wonders of physics. Meanwhile, its commitment to disseminate scientific research has enabled its publishing business, IOP Publishing, to become a leading international publisher of research journals, ebooks and, of course, Physics World.
Limit Less – the IOP’s new campaign The physics community has changed hugely in the 100 years since the Institute of Physics (IOP) was founded in 1920. Back then, physics was almost entirely a male preserve, limited mostly to those who had attended the few elite schools where science was properly taught. Thankfully, far more young people are exposed to physics these days, but many who might go on to enjoy a successful career in physics still choose not study the subject beyond the age of 16 – whether due to barriers of race, gender or class, or simply a lack of good careers advice. To ensure that as many young people are attracted into physics as possible, the IOP has just launched a major new campaign called “Limit Less”. Developed in partnership with the IOP’s members, the campaign aims to combat the prejudices and stereotypes that put potential physicists off the subject. By emphasizing that there are “no limits” to what can be achieved with physics, the campaign will support young people to do physics by correcting misconceptions about the subject, removing barriers to participation – especially among under-represented groups – and highlighting how physics is tackling global issues such as climate change, public health and poverty. iop.org/limitless Matin Durrani
Among the IOP’s lesser-known achievements was the creation of a benevolent fund in 1924, seeded by a donation of £100 from Major Charles Phillips – a British physicist and a founder of the IOP – and topped up by regular contributions from members. The value of the fund had risen to more than £1m by the start of the 21st century, allowing the IOP to provide direct financial support to physicists and their families who are in need. More recently, astrophysicist Jocelyn Bell Burnell – who served as the IOP’s first woman president – donated her £2.3m winnings from the Breakthrough Prize for her work on discovering pulsars, allowing the IOP to launch last year a fund to support PhD students from under-represented groups at universities in the UK and Ireland. Looking to the future, meanwhile, the IOP has just launched a major new campaign to widen participation in physics (see box above).
The physics community of 2020 is very different from the one that existed in 1920 when the IOP was founded. It is far bigger now, of course, but thankfully also much more diverse, and the myriad of careers that physicists today pursue – from IT and engineering to finance and education – would surely have been enthusiastically welcomed by J J Thomson. “I should like, on behalf of those interested in physics,” he said, while addressing the first meeting of the IOP, “to express our obligation to those who have conceived the idea of this Institute, and who have borne the labours in connection with its initiation.” One wonders what Thomson would say were he to address the IOP’s membership today.


physicsworld--2020-11-06--Celebrating the Institute of Physics at 100: the November 2020 issue of Physics World is now out - P

Celebrating the Institute of Physics at 100: the November 2020 issue of Physics World is now out - Physics World

When the Institute of Physics ( IOP ) , which publishes Physics World , was founded in 1920 , it was to serve as a voice for the fledgling physics community in the UK .
Before then , physics had mostly been conducted by a tiny band of elite researchers at a handful of university or private labs .
But with growing demand for physicists in industry , academia and government , more and more people were realizing they could forge successful careers in physics .
The IOP was set up to represent their professional concerns , as you can @ @ @ @ @ @ @ Physics World , which is now out in print and digital formats .
You can also read the feature online here .
Elsewhere in the issue , we welcome our new pool of contributing columnists – active and thought-provoking physicists who will bring a new perspective to a range of professional matters such as education , careers , publishing , funding and diversity .
There ’ s also a great feature about the top applications of ferroelectricity and a look at attempts to make air travel greener .
If you ’ re a @ @ @ @ @ @ @ you can read the whole of Physics World magazine every month via our digital apps for iOS , Android and Web browsers .
Let us know what you think about the issue on Twitter , Facebook or by e-mailing us at pwld @ ioppublishing.org .
For the record , here ’ s a run-down of what else is in the issue .
• Superconductivity found at 1.5C – Researchers have created a material that can superconduct at room temperature under high pressures , as Hamish Johnston discovers • Cosmic pioneers bag Nobel prize @ @ @ @ @ @ @ Andrea Ghez win award for their work on black holes , as Michael Banks and Hamish Johnston report • Celebrating Black physicists – Charles Brown , Eileen Gonzales and Xandria Quichocho talk to Michael Banks about the barriers facing Black physicists and how # BlackInPhysics week aimed to boost their visibility • Reflecting the community – Matin Durrani welcomes Physics World ‘ s new pool of contributing columnists • Keeping your eyes on the prize – Chanda Prescod-Weinstein describes the social and political barriers that Black physicists face in their daily lives • @ @ @ @ @ @ @ With COVID-19 further exposing educational divides , Jess Wade says the importance of physics teachers has never been more critical • Supporting the next generation – Nicolas Labrosse says that UK research funders must recognize their responsibility to support research into university physics education • Keeping up with opportunities – Caitlin Duffy says it is more important than ever to consider your next career move despite the challenges posed by the COVID-19 pandemic • A quantum future – With a new era of quantum technology beckoning , James McKenzie reflects on recent milestones @ @ @ @ @ @ @ ” • The bank of success – After helping to set up the first major repository of protein structures 50 years ago , Helen Berman is now significantlyexpanding its scope , as Robert P Crease finds out • A century of change – The Institute of Physics was created in 1920 to champion a new generation of professional physicists working in industry , academia and the government , as Susan Curtis describes • Ferroelectricity : 100 years on – When a PhD student called Joseph Valasek discovered ferroelectricity exactly 100 years ago , @ @ @ @ @ @ @ would have on science and technology .
Amar S Bhalla and Avadh Saxena pick their favourite applications of this fundamental physics phenomenon • Physics challenges for green aviation – Commercial air travel has changed a lot since the first aeroplane took passengers around a century ago .
Brian Tillotson explores the future challenges to make aviation greener • The hunt for another Earth : a love story – Kate Gardner reviews The Smallest Lights in the Universe : a Memoir by Sara Seager • Black hole diaries – Tushna Commissariat reviews The Shadow @ @ @ @ @ @ @ Moffat • Embracing a life of variables – Steve Bullock is an engineer , physics teacher , science communicator and education consultant .
Currently the programme director of undergraduate aerospace engineering at the University of Bristol , UK , he talks to Tushna Commissariat about a career of bold choices , sideways jumps and obstacles overcome • Ask Me Anything – Michelle Simmons is director of the Centre of Excellence for Quantum Computation and Communication Technology at the University of New South Wales , Australia .
• A matter of evidence – Gary @ @ @ @ @ @ @ evidence in science

100 not out: the Institute of Physics celebrates its centenary.
When the Institute of Physics (IOP), which publishes Physics World, was founded in 1920, it was to serve as a voice for the fledgling physics community in the UK. Before then, physics had mostly been conducted by a tiny band of elite researchers at a handful of university or private labs.
But with growing demand for physicists in industry, academia and government, more and more people were realizing they could forge successful careers in physics. The IOP was set up to represent their professional concerns, as you can discover in the November 2020 issue of Physics World, which is now out in print and digital formats. You can also read the feature online here.
Elsewhere in the issue, we welcome our new pool of contributing columnists – active and thought-provoking physicists who will bring a new perspective to a range of professional matters such as education, careers, publishing, funding and diversity. There’s also a great feature about the top applications of ferroelectricity and a look at attempts to make air travel greener.
If you’re a member of the Institute of Physics, you can read the whole of Physics World magazine every month via our digital apps for iOS, Android and Web browsers. Let us know what you think about the issue on Twitter, Facebook or by e-mailing us at pwld@ioppublishing.org.
For the record, here’s a run-down of what else is in the issue.
• Superconductivity found at 1.5 °C – Researchers have created a material that can superconduct at room temperature under high pressures, as Hamish Johnston discovers
• Cosmic pioneers bag Nobel prize – Roger Penrose, Reinhard Genzel and Andrea Ghez win award for their work on black holes, as Michael Banks and Hamish Johnston report
• Celebrating Black physicists – Charles Brown, Eileen Gonzales and Xandria Quichocho talk to Michael Banks about the barriers facing Black physicists and how #BlackInPhysics week aimed to boost their visibility
• Reflecting the community – Matin Durrani welcomes Physics World‘s new pool of contributing columnists
• Keeping your eyes on the prize – Chanda Prescod-Weinstein describes the social and political barriers that Black physicists face in their daily lives
• Making a difference where it matters – With COVID-19 further exposing educational divides, Jess Wade says the importance of physics teachers has never been more critical
• Supporting the next generation – Nicolas Labrosse says that UK research funders must recognize their responsibility to support research into university physics education
• Keeping up with opportunities – Caitlin Duffy says it is more important than ever to consider your next career move despite the challenges posed by the COVID-19 pandemic
• A quantum future – With a new era of quantum technology beckoning, James McKenzie reflects on recent milestones in the quantum computing “arms race”
• The bank of success – After helping to set up the first major repository of protein structures 50 years ago, Helen Berman is now significantly expanding its scope, as Robert P Crease finds out
• A century of change – The Institute of Physics was created in 1920 to champion a new generation of professional physicists working in industry, academia and the government, as Susan Curtis describes
• Ferroelectricity: 100 years on – When a PhD student called Joseph Valasek discovered ferroelectricity exactly 100 years ago, few people realized the enormous impact it would have on science and technology. Amar S Bhalla and Avadh Saxena pick their favourite applications of this fundamental physics phenomenon
• Physics challenges for green aviation – Commercial air travel has changed a lot since the first aeroplane took passengers around a century ago. Brian Tillotson explores the future challenges to make aviation greener
• The hunt for another Earth: a love story – Kate Gardner reviews The Smallest Lights in the Universe: a Memoir by Sara Seager
• Black hole diaries – Tushna Commissariat reviews The Shadow of the Black Hole by John W Moffat
• Embracing a life of variables – Steve Bullock is an engineer, physics teacher, science communicator and education consultant. Currently the programme director of undergraduate aerospace engineering at the University of Bristol, UK, he talks to Tushna Commissariat about a career of bold choices, sideways jumps and obstacles overcome
• Ask Me Anything – Michelle Simmons is director of the Centre of Excellence for Quantum Computation and Communication Technology at the University of New South Wales, Australia.
• A matter of evidence – Gary A Atkinson looks at the importance of evidence in science


physicsworld--2020-11-06--Flat versus round earth calculator, asteroid is dead ringer for the Moon - Physics World

In case you were not convinced by our immensely popular article “ Fighting flat-Earth theory ” by Rachel Brazil , the physicist and round-Earther Steven Wooding has created an online calculator that suggests a few fun experiments that you can do to prove to yourself that the Earth is indeed a sphere .
These include how to see a second sunset , how to hide an object behind the curvature of the Earth and how to use shadows to measure the radius of the Earth .
Elsewhere in the solar system , astronomers have discovered that an asteroid called ( @ @ @ @ @ @ @ resemblance to the Moon .
The chunk of rock is smaller than a kilometre across and trails behind Mars .
A spectroscopy study done by researchers at the Armagh Observatory and Planetarium in Northern Ireland and colleagues found that the asteroid reflects light just like the Moon .
One possible explanation is that the asteroid is a chunk of the Moon that was liberated when a large asteroid crashed into the Moon .
However , the researchers believe it is more likely that the asteroid was created in a similar collision with Mars @ @ @ @ @ @ @ answered by The Guardian in “ New moon ?
Scientists claim the Earth ’ s satellite may have a ‘ dead ringer ’ ” .

Our blue sphere: a photograph of Earth, taken by the Apollo 17 mission. (Courtesy: NASA)
In case you were not convinced by our immensely popular article “Fighting flat-Earth theory” by Rachel Brazil, the physicist and round-Earther Steven Wooding has created an online calculator that suggests a few fun experiments that you can do to prove to yourself that the Earth is indeed a sphere. These include how to see a second sunset, how to hide an object behind the curvature of the Earth and how to use shadows to measure the radius of the Earth.
Elsewhere in the solar system, astronomers have discovered that an asteroid called (101429) 1998 VF31 bears a remarkable resemblance to the Moon. The chunk of rock is smaller than a kilometre across and trails behind Mars. A spectroscopy study done by researchers at the Armagh Observatory and Planetarium in Northern Ireland and colleagues found that the asteroid reflects light just like the Moon.
One possible explanation is that the asteroid is a chunk of the Moon that was liberated when a large asteroid crashed into the Moon. However, the researchers believe it is more likely that the asteroid was created in a similar collision with Mars.
Your questions about the asteroid are answered by The Guardian in “New moon? Scientists claim the Earth’s satellite may have a ‘dead ringer’”.


physicsworld--2020-11-07--Optical matter machine steps up a gear - Physics World

A new device that converts laser light into mechanical work could be used to manipulate nano-scale objects for applications in nanofluidics and particle sorting .
The device , which is based on a self-assembled hexagonal array of nanoparticles that operates like a gear , can perform work in conventional environments such as room temperature liquids , according to Norbert Scherer of the University of Chicago , who led the research effort to develop it .
The “ gear ” in this study is made up of optical matter ( OM ) – a type of material in which metal nanoparticles @ @ @ @ @ @ @ the chemical bonds that unite atoms in ordinary matter .
The radii of the nanoparticles are much smaller than the wavelength of the light , and the light-based “ bonds ” that link them stem from inter-particle interactions that cause them to self-assemble into ordered arrays ( see image above ) .
Finding a way to make these optically-powered self-assembling nanomachines perform work has been a long-standing goal in this area of photonics .
The new OM machine achieves this objective by converting spin angular momentum ( SAM ) – one of the @ @ @ @ @ @ @ of light – into the other component , orbital angular momentum ( OAM ) .
SAM is a familiar property of light that manifests itself as polarization .
It arises when the electric and magnetic field vectors of light rotate over the course of a wavelength .
OAM is less well known ( it was only discovered in 1992 ) , and its effect is to twist a beam ’ s wavefront along its propagation axis so that it takes on a spiral shape , with zero intensity at its centre .
A @ @ @ @ @ @ @ by any amount ; the greater the twist , the faster the rotation of the wavefront .
Because SAM can have only two values – right or left circular polarization – its applications are fairly limited .
In contrast , OAM , which results from the rotation of a light wave ’ s phases , can take on any value .
This variability makes it suitable for a wider range of applications , including “ optical spanners ” – devices that trap and rotate tiny particles using light .
Transferring data though optical @ @ @ @ @ @ @ another potential application .
In their previous work , Scherer and colleagues discovered that when they applied circularly-polarized light to optical matter , the nanoparticles rotated like a rigid body in a direction opposite to the rotation of the polarization .
Simply put , this means that when the incident light rotates one way , the optical matter array spins in the other .
The researchers hypothesised that they could develop a machine based on this “ negative torque ” , as it is called .
In the new experiments , which are @ @ @ @ @ @ @ out to create an OM machine that functions like a pair of interlocking gears .
When the larger gear is turned , a smaller interlocking gear spins in the opposite direction .
To fabricate a machine based on this design , the researchers used silver nanoparticles with radii of just 75 nm , suspended in water , and laser light with a wavelength of 600 nm .
The researchers explain that circularly polarized light from the laser causes the nanoparticles to form an OM array that acts like the larger gear in the @ @ @ @ @ @ @ ’ s optical field .
This OM “ gear ” converts the laser ’ s circularly polarized light into orbital or angular momentum , which in turn causes a nearby probe particle placed outside the OM gear to orbit the nanoparticle array gear in the opposite direction .
According to their experiments , a large gear containing eight nanoparticles was more efficient than one that contained seven nanoparticles .
This suggests that the efficiency of a machine could be tuned by using different numbers of particles , they say .
Making machines with @ @ @ @ @ @ @ what we demonstrated , with further refinement , will be useful in nanofluidics and particle sorting , ” says study first author John Parker .
“ Our simulations show that a much larger machine made of many more particles should be able to exert more power to the probe , so that is an aspect of refinement that we anticipate pursuing.
” The researchers are exploring the possibility of making OM machines with particles of different materials as well as larger numbers of particles .
They are also interested in making their machines @ @ @ @ @ @ @ which the nanoparticles are stationary .
This modification would allow gears to be optically addressed and combined to make more complex machines , they say .

The flow of optical power in and around the seven-nanoparticle "gear" of the optical matter machine. Courtesy: N Scherer
A new device that converts laser light into mechanical work could be used to manipulate nano-scale objects for applications in nanofluidics and particle sorting. The device, which is based on a self-assembled hexagonal array of nanoparticles that operates like a gear, can perform work in conventional environments such as room temperature liquids, according to Norbert Scherer of the University of Chicago, who led the research effort to develop it.
The “gear” in this study is made up of optical matter (OM) – a type of material in which metal nanoparticles are held together by light rather than the chemical bonds that unite atoms in ordinary matter. The radii of the nanoparticles are much smaller than the wavelength of the light, and the light-based “bonds” that link them stem from inter-particle interactions that cause them to self-assemble into ordered arrays (see image above).
SAM and OAM
Finding a way to make these optically-powered self-assembling nanomachines perform work has been a long-standing goal in this area of photonics. The new OM machine achieves this objective by converting spin angular momentum (SAM) – one of the two independent components of the angular momentum of light – into the other component, orbital angular momentum (OAM).
SAM is a familiar property of light that manifests itself as polarization. It arises when the electric and magnetic field vectors of light rotate over the course of a wavelength. OAM is less well known (it was only discovered in 1992), and its effect is to twist a beam’s wavefront along its propagation axis so that it takes on a spiral shape, with zero intensity at its centre. A beam can, in principle, twist by any amount; the greater the twist, the faster the rotation of the wavefront.
OAM suitable for a wider range of applications
Because SAM can have only two values – right or left circular polarization – its applications are fairly limited. In contrast, OAM, which results from the rotation of a light wave’s phases, can take on any value. This variability makes it suitable for a wider range of applications, including “optical spanners” – devices that trap and rotate tiny particles using light. Transferring data though optical fibres without crosstalk (multiplexing) is another potential application.
In their previous work, Scherer and colleagues discovered that when they applied circularly-polarized light to optical matter, the nanoparticles rotated like a rigid body in a direction opposite to the rotation of the polarization. Simply put, this means that when the incident light rotates one way, the optical matter array spins in the other. The researchers hypothesised that they could develop a machine based on this “negative torque”, as it is called.
OM machine functions like a mechanical machine
In the new experiments, which are described in Optica, the researchers set out to create an OM machine that functions like a pair of interlocking gears. When the larger gear is turned, a smaller interlocking gear spins in the opposite direction.
To fabricate a machine based on this design, the researchers used silver nanoparticles with radii of just 75 nm, suspended in water, and laser light with a wavelength of 600 nm. The researchers explain that circularly polarized light from the laser causes the nanoparticles to form an OM array that acts like the larger gear in the machine, and spins in the laser’s optical field. This OM “gear” converts the laser’s circularly polarized light into orbital or angular momentum, which in turn causes a nearby probe particle placed outside the OM gear to orbit the nanoparticle array gear in the opposite direction.
According to their experiments, a large gear containing eight nanoparticles was more efficient than one that contained seven nanoparticles. This suggests that the efficiency of a machine could be tuned by using different numbers of particles, they say.
Making machines with many more particles
“We believe that what we demonstrated, with further refinement, will be useful in nanofluidics and particle sorting,” says study first author John Parker. “Our simulations show that a much larger machine made of many more particles should be able to exert more power to the probe, so that is an aspect of refinement that we anticipate pursuing.”
The researchers are exploring the possibility of making OM machines with particles of different materials as well as larger numbers of particles. They are also interested in making their machines more practical by creating patterned gears in which the nanoparticles are stationary. This modification would allow gears to be optically addressed and combined to make more complex machines, they say.


physicsworld--2020-11-09--Atomic clocks could detect exotic low-mass fields from merging black holes - Physics World

Global networks of quantum sensors could be used to search for hypothetical exotic low-mass field ( ELF ) signals that could be created during black-hole mergers and other violent astrophysical events .
The proposal from a team of physicists in the US , Poland and Germany involves using the existing network of atomic clocks in the global positioning system ( GPS ) or an upgrade to a global network of optical magnetometers to search for ELF signals – which if detected , could provide important insights into what lies beyond the Standard Model of particle physics .
In August 2017 @ @ @ @ @ @ @ on a small patch of sky where the LIGO–Virgo observatory had just spotted gravitational waves from the merger of two neutron stars .
Astronomers were rewarded with a vast amount of information gleaned from a broad spectrum of electromagnetic radiation given off as the merging objects exploded in a kilonova .
The success of this observation has intensified interest in multimessenger astronomy , whereby an astrophysical event is studied by detecting a range of “ messenger ” signals including gravitational waves , electromagnetic radiation , and particles such as neutrinos .
Now , @ @ @ @ @ @ @ , Reno and colleagues have set a more ambitious goal : to do multimessenger astronomy with an unknown messenger .
Black holes and neutron stars have strong gravitational fields , so it stands to reason that they could attract dark matter .
Indeed , several extensions to the Standard Model postulate that ELFs will cluster around large astrophysical objects such as black holes .
Some of these could be stripped away by the huge release of energy during a merger and blasted towards Earth .
Derevianko also points out that it could be @ @ @ @ @ @ @ black holes merge – something that we can not be sure about until we have a viable theory of quantum gravity .
As a result , trying to detect ELFs from these violent events offers a way of studying physics beyond the Standard Model .
How to detect ELFs , however , would depend on their precise nature .
Derevianko explains that using atomic clocks is one possibility : “ You could write certain interactions in such a way that , for example , the fine-structure constant changes ” .
This would affect @ @ @ @ @ @ @ level spacings within atoms , which would affect the frequency of an atomic clock .
Conveniently , a worldwide network of atomic clocks already exists in the form of the global positioning system ( GPS ) , and Derevianko and colleagues believe it could detect ELFs originating from anywhere in the observable universe .
Another possibility is that ELFs could couple to spins , making them detectable by magnetometers .
The Global Network of Optical Magnetometers for Exotic physics ( GNOME ) has 13 stations located on four continents : “ At present @ @ @ @ @ @ @ sensitive enough , but they can be in future – they are upgrading their magnetometers , ” says Derevianko .
Even without knowing the precise nature of a hypothetical ELF signal , the researchers have predicted its shape and timing .
As the particles would be highly energetic and have a very low ( but non-zero ) mass , they would be travelling at very close to the speed of light .
Moreover , because of the frequency dispersion of outer space , the high frequency components would arrive first .
The result @ @ @ @ @ @ @ “ anti-chirped ” pulse that would arrive on Earth shortly after the gravitational waves .
In principle , says Derevianko , researchers could look for ELFs from events with no detected gravitational wave signal such as supernovae .
If they were to find an ELF fingerprint of , for example , black hole mergers in GPS data , they could even trawl historical data in search of such patterns from before astronomers had the ability to detect gravitational waves .
Commenting on the work , Tien-Tien Yu of the University of Oregon says @ @ @ @ @ @ @ appealing dark matter candidate there ’ s been quite a lot of effort spent to look for these ELFs , but it ’ s hard ” .
She adds , “ Typically if you have two black holes merging with clouds of dark matter around them , you might look for an X-ray signal , for example , from the dark matter annihilating or converting into photons or something like that .
The fact that they ’ re trying to look for the dark matter itself rather than for photons is a bit @ @ @ @ @ @ @ Nature Astronomy .

ELF source an exotic low-mass field (ELF) signal could be created when two black holes merge. (Courtesy: Simulating eXtreme Spacetimes/CC-A-SA)
Global networks of quantum sensors could be used to search for hypothetical exotic low-mass field (ELF) signals that could be created during black-hole mergers and other violent astrophysical events. The proposal from a team of physicists in the US, Poland and Germany involves using the existing network of atomic clocks in the global positioning system (GPS) or an upgrade to a global network of optical magnetometers to search for ELF signals – which if detected, could provide important insights into what lies beyond the Standard Model of particle physics.
In August 2017 telescopes around the world were quickly trained on a small patch of sky where the LIGO–Virgo observatory had just spotted gravitational waves from the merger of two neutron stars. Astronomers were rewarded with a vast amount of information gleaned from a broad spectrum of electromagnetic radiation given off as the merging objects exploded in a kilonova. The success of this observation has intensified interest in multimessenger astronomy, whereby an astrophysical event is studied by detecting a range of “messenger” signals including gravitational waves, electromagnetic radiation, and particles such as neutrinos.
Now, Andrei Derevianko of the University of Nevada, Reno and colleagues have set a more ambitious goal: to do multimessenger astronomy with an unknown messenger.
Stripped away
Black holes and neutron stars have strong gravitational fields, so it stands to reason that they could attract dark matter. Indeed, several extensions to the Standard Model postulate that ELFs will cluster around large astrophysical objects such as black holes. Some of these could be stripped away by the huge release of energy during a merger and blasted towards Earth. Derevianko also points out that it could be possible that ELFs are created when two black holes merge – something that we cannot be sure about until we have a viable theory of quantum gravity.
As a result, trying to detect ELFs from these violent events offers a way of studying physics beyond the Standard Model. How to detect ELFs, however, would depend on their precise nature. Derevianko explains that using atomic clocks is one possibility: “You could write certain interactions in such a way that, for example, the fine-structure constant changes”. This would affect the Coulomb interaction, changing the energy level spacings within atoms, which would affect the frequency of an atomic clock. Conveniently, a worldwide network of atomic clocks already exists in the form of the global positioning system (GPS), and Derevianko and colleagues believe it could detect ELFs originating from anywhere in the observable universe.
Spin coupling
Another possibility is that ELFs could couple to spins, making them detectable by magnetometers. The Global Network of Optical Magnetometers for Exotic physics (GNOME) has 13 stations located on four continents: “At present levels of accuracy, magnetometers are not sensitive enough, but they can be in future – they are upgrading their magnetometers,” says Derevianko.
Even without knowing the precise nature of a hypothetical ELF signal, the researchers have predicted its shape and timing. As the particles would be highly energetic and have a very low (but non-zero) mass, they would be travelling at very close to the speed of light. Moreover, because of the frequency dispersion of outer space, the high frequency components would arrive first. The result, they say, is a tell-tale “anti-chirped” pulse that would arrive on Earth shortly after the gravitational waves.
In principle, says Derevianko, researchers could look for ELFs from events with no detected gravitational wave signal such as supernovae. If they were to find an ELF fingerprint of, for example, black hole mergers in GPS data, they could even trawl historical data in search of such patterns from before astronomers had the ability to detect gravitational waves.
Commenting on the work, Tien-Tien Yu of the University of Oregon says, “Because they’re an appealing dark matter candidate there’s been quite a lot of effort spent to look for these ELFs, but it’s hard”. She adds, “Typically if you have two black holes merging with clouds of dark matter around them, you might look for an X-ray signal, for example, from the dark matter annihilating or converting into photons or something like that. The fact that they’re trying to look for the dark matter itself rather than for photons is a bit different.”
The research is described in Nature Astronomy.