Climate change has increased the severity of flooding across north-west Europe over the last five decades, a continental-scale study by researchers in 24 European countries has found. The largest increases in flooding were seen northern parts of the UK.
Led by scientists at the Vienna University of Technology in Austria, the multinational team looked at river flow data from almost 4000 monitoring stations across Europe between 1960 and 2010. They identified clear regional patterns of both increases and decreases in floods across Europe over the 50 year period. These ranged from increases in flood levels of 11% per decade in northern England and southern Scotland to decadal decreases of 23% in parts of Russia.
According to the researchers, the changes are broadly consistent with climate model predictions for the next century and provide evidence that climate driven changes in flooding are already occurring. They add that their results support the idea that climate impacts now need to be considered when designing flood management strategies.
This is the first time we actually see climate impact on flood observations at the continental scale
Günter Blöschl
“This [study] is the first time that we see evidence of climate change in flood observations,” Günter Blöschl, a hydrologist at the Vienna University of Technology, told Physics World. “People have done simulations in the past of climate impact on floods and people have looked at individual catchments and looked at trends in flood observations, but this is the first time we actually see climate impact on flood observations at the continental scale.”
Key drivers are changing
As well as flow data, the scientists assessed changes in key drivers of flooding, including precipitation, soil moisture and air temperature. This enabled them to identify three regional trends. Increases in autumn and winter precipitation and wetter soils are increasing floods in north-west Europe, while in southern Europe floods are decreasing due to a reduction in precipitation and increased evaporation of soil moisture. Floods are also decreasing in eastern Europe, but this is driven by reduced snow cover and snowmelt due to warmer spring temperatures – the team found that in some areas spring air temperature has increased by as much as 1 °C per decade.
In north-west Europe around 69% of flow-gauging stations showed an increasing flood trend, with an average increase of 2.3% per decade. In southern Europe three quarters of stations showed a decrease in floods, with an average drop of 5% per decade. In eastern Europe about 78% of stations show a decreasing flood trend, with an average decrease of 6% per decade.
According to the researchers these changes are linked to changes in atmospheric circulation patterns, such as storm tracks and jet streams. The poleward shift of the subpolar jet stream – which sits between the cooler mid-latitude air and the warmer equatorial air – and changes in its associated storm tracks, and the slowing of the northern jet stream, have led to increases in precipitation in north-east Europe and increased the chances of stalled weather patterns.
Pressure difference
Blöschl says that we now understand why flooding has increased in north-west Europe. “The pole is warming more strongly than the equator, so the pressure difference between the pole and the equator is changing, which shifts [weather systems] further to the north,” he explains. Also, the speed at which these systems move across Europe is a little slower than in the past, so the duration of extreme rainfall events is longer than before.
The northward shift of the subpolar jet has also allowed the expansion of the Hadley cell, a tropical atmospheric circulation. This, according to the researchers, has led to a decrease in precipitation and an increase in the evaporation of soil moisture in southern Europe. Over the period studied, they found that soil moisture reduced by around 5% per decade in this region.
Jamie Hannaford, a hydrologist at the UK‘s Centre for Ecology & Hydrology, who was involved in the research, says that the study “adds to a growing body of evidence that shows that flood magnitude has increased in the UK over the last five decades, particularly in parts of northern and western Britain”.
“We show this is part of a continent-wide pattern of changes in flooding which is in line with what we may expect in a warming world,” Hannaford adds. “This highlights the importance of long-term hydrological monitoring and the benefits of data sharing and collaboration at a European scale in order to better understand the mechanisms behind observed changes in flooding.”
A Croatian theoretical physicist has been released from prison after he was jailed last month following a two-month sit-in at the science ministry in Zagreb. Boris Ivetić, 36, was arrested when protesting to end alleged corruption at the University of Zagreb’s natural sciences faculty, where he is a PhD student. After serving five days in the notorious Remetinac jail near Zagreb, Ivetić was later released with all charges dropped. Ivetić says he is unsure whether he will continue to protest over conditions at the university.
According to the political party Free Croatia, Ivetić was arrested on 23 August following an altercation with the science minister Blaženka Divjak at the entrance of the ministry in Zagreb during the sit-in. Divjak allegedly tried to take away a banner held by Ivetić, which accused Divjak of hiding corruption at the University of Zagreb’s natural sciences faculty. Ivetić resisted the attempt and the ministry alleges that the physicist then verbally attacked Divjak and started walking in an intimidating way towards her. The ministry then called the police, who arrested him.
During the entire two months of demonstration, employees of the ministry have ensured Mr Ivetić’s right to demonstrate with dignity
Croatian science ministry
Ivetić told Physics World that he was not aggressive towards Divjak but that his purpose was to demonstrate against “a series of irregularities” in the faculty’s work, which he claims to be able to back up with evidence. Ivetić alleges that the faculty accessed people’s e-mail accounts and hacked computers as well as sold off faculty property at below-market prices. He also claims that he has worked at the faculty for four and half years without receiving a salary. According to ministry, Ivetić demanded to be back-paid 5 million Croatian kunas (£610,000) for this work but he has denied any interest in money.
“I’m demonstrating against the ‘black market’ of teaching assistants, who work without any contract and without the approval of the faculty’s teaching committee,” says Ivetić. “Some of those assistants have been receiving their salary without any confirmation or receipts.” He also alleges that some individuals at the faculty “have been siphoning off money through bonuses for special achievements or for taking on more work, through fictitious contracts and expenses”.
‘A respectable public institution’
The faculty’s dean, Aleksandra Čižmešija, has denied all allegations about “criminality” at the faculty. “The [faculty] is a respectable public institution and it works transparently and in accordance with the law,” she told Physics World. Čižmešija adds that Ivetić’s documentation has been examined by the state labour inspectorate which found no irregularities. She refrained from further comment to not prejudice ongoing proceedings involving Ivetić at the municipal labour court in Zagreb.
The Croatian science ministry, meanwhile, says that it has held several meetings with Ivetić regarding the allegations. “During the entire two months of demonstration, employees of the ministry have ensured Mr Ivetić’s right to demonstrate with dignity,” the ministry notes.
Warm reception: Einstein was greeted with enthusiasm on his first visit to the US in 1921, but his first visit to the UK later that year was more muted, at least initially. (Courtesy: Everett/Shutterstock)
It is difficult to imagine the modern world without the life and work of Albert Einstein. Not only is he one of the most quoted figures of the 20th century, he is also one of the most quoted people who ever lived – on subjects ranging from physics and mathematics to genius, marriage, income tax and peace. “To punish me for my contempt of authority,” he joked in 1930, “fate has made me an authority myself.” By 2015 – the centenary of the publication of Einstein’s general theory of relativity – there existed some 1700 individual books about him, in many different languages, according to a careful count made by Diana Kormos Buchwald, the director of the Einstein Papers Project at the California Institute of Technology.
His fame began in November 1919, after a historic meeting of the Royal Society and the Royal Astronomical Society in London. Arthur Eddington, the Plumian Professor of Astronomy at the University of Cambridge, and Frank Dyson, the Astronomer Royal, announced that their observations of a solar eclipse on 29 May from west Africa (Príncipe) and north-eastern Brazil (Sobral) had confirmed – almost for sure, but still with a margin of uncertainty – a key prediction of Einstein’s controversial theory of 1915. Light from distant stars passing the Sun, on its way to the Earth, is deflected by solar gravity through a particular angle, 1.75 arcseconds – twice the angle predicted by Isaac Newton’s theory of gravity.
Warring views
Almost immediately, Einstein was celebrated on both sides of the Atlantic. When he first visited the US in 1921, New Yorkers lined the streets to cheer his appearance in a motorcade. When he travelled to Britain for the first time, just after his US visit, and gave a lecture in German on relativity at King’s College in London, there was also an overflowing audience. In London, however, they kept silent when Einstein mounted the platform, and refused to applaud him. Only later, after Einstein’s lecture had won them over with tact and charm, came a storm of encouraging applause. Why such an astonishing disparity in Einstein’s British and American receptions? The reason was the First World War. Well after the end of this terrible struggle in 1918, anti-German feeling still ran high in Britain, unlike in the US.
Einstein had published his general theory of relativity in wartime Germany in 1915–1916. As a Swiss citizen, and a self-proclaimed pacifist, he had managed to avoid any work for the military, unlike his German scientific colleagues, such as Fritz Haber. Eddington, almost alone in Britain, embraced Einstein’s theory and published a version of it in English in 1918. Eddington too was a pacifist; a Quaker conscientious objector who nearly went to jail. He remained free only with the support of Dyson, who was determined that Eddington should lead the 1919 eclipse observations. Eddington argued with fellow British scientists, and was against demonizing German scientific colleagues both during and after the war. Post-war Britain still formally excluded German scientists from conferences. In early 1920 the Royal Astronomical Society even withdrew its recommendation of a Gold Medal for Einstein – to the embarrassment of Eddington – because of nationalist feeling among the society’s fellows, who viewed Einstein as German, not as Swiss.
Relativity’s complex relationship with the world war is the subject of three significant new books
Relativity’s complex relationship with the First World War, plus the story of solar eclipse expeditions – before, during and after the war – are the subject of three significant books published during the centenary of the 1919 observations. No Shadow of a Doubt, by physicist and Einstein scholar Kennefick, is a thorough study intended more for academics than general readers, with far more technical detail on the eclipse observations than Einstein’s War by historian of science and Eddington scholar Stanley. His book is aimed more at a general readership than Kennefick’s, thanks to his skilful interweaving of the lives of Einstein and Eddington into a readable narrative.
Getting personal
By contrast, Proving Einstein Right, by physicist Gates and novelist Pelletier, is deliberately light on physics but vivid on human drama, including Einstein’s painful divorce of 1919 and Eddington’s challenging working conditions in Africa. Using both familiar and newly researched material, Gates and Pelletier tell the personal stories of not only Einstein and Eddington, but also a wide variety of less-familiar scientists, such as the German astronomer Erwin Finlay-Freundlich and the American astronomer William Wallace Campbell. They were involved with solar-eclipse expeditions in the decade between 1911, when Einstein first proposed the deflection of light by gravity (but agreed with Newton’s value), and 1922, when Campbell’s eclipse observations in Australia finally settled beyond any doubt that the deflection conformed with Einstein’s prediction of 1915–1916 (twice that of Newton).
The fourth book, Einstein’s Wife – by Cassidy, a historian of science, and mathematician Esterson, with a brief essay on “Women in science” by Sime, biographer of Lise Meitner – contains little physics and nothing about the eclipse of 1919. It focuses, instead, on the personalities of Einstein and his first wife. Its purpose is to establish, as far as possible from the limited documentary evidence available, whether Mileva Marić contributed substantially to Einstein’s physics. This is something that has been controversially claimed by certain writers since the first sensational publication, in the 1980s, of Einstein’s correspondence with his wife. After a well-argued, exhaustive (and frankly exhausting) dissection of the claims, the book’s answer is that she did not. It is hard to disagree, especially given the unquestioned facts that Marić herself never made this claim and her letters to Einstein do not discuss physics – not to mention that Einstein’s creation of general relativity in 1915–1916 (after his separation from Marić in 1914) was a famously solitary achievement.
Proof positive: A photographic plate of the solar eclipse from the 1919 expedition to Sobral. (Courtesy: F W Dyson, A S Eddington and C Davidson)
Inevitably, both Kennefick and Stanley cover similar scientific material. Their interpretations of the eclipse observations are broadly comparable. However, they differ significantly about the influence of the First World War on the reception of the observations. In Stanley’s view, during the world war Einstein had to fight a private “war” on behalf of his theory – with sceptics who believed in Newton’s absolute space and time, and the long-established concept of the ether, in which light could not be deflected by gravity. “Einstein’s personal war was not unlike the Western front. It had been in a stalemate for some time,” observes Stanley. “Relativity’s sudden explosion, and Eddington’s zealous evangelism for it, would never have happened in quieter times,” he argues. “The theory had few applications for decades and, even if it had been confirmed, would likely have languished in dusty journals until cosmologists or GPS engineers realized they needed its delicate adjustments. Without the war, relativity would have been just one more theory, true but obscure; without the war, Einstein just one more name for bored schoolchildren to memorize.” He concludes: “If Eddington had not cared about pacifism, we would not have had the relativity revolution in 1919.”
Kennefick, by contrast, writes that: “I find it difficult to believe that Eddington’s experience of being a pacifist during the war led him to expect public approbation for his efforts.” The vital ingredient in Eddington’s success was instead his scientific background: both theoretical and practical. “He was a theorist with the right mathematical training who worked on the topic of celestial mechanics, which was suffering from the incompatibility of gravitational law with relativity theory. In addition, he had done extensive work in astrometry, the skill required for actually carrying out the observational test. It is true that Eddington and Einstein shared pacifist ideals and internationalist sentiment, but their common scientific interests are what brought them together.”
Both books deal with the long-running allegations by contemporary and later scientists against the expedition astronomers (Eddington in particular) that their results were not as conclusive evidence for general relativity as they claimed. It is alleged that, essentially, Eddington claimed more precision for the observations than was technically possible with the telescopes available in 1919, fudging the data because he was theoretically biased in favour of Einstein’s relativity. For example, Stephen Hawking comments in A Brief History of Time: “This proof of a German theory by British scientists was hailed as a great act of reconciliation between the two countries after the war. It is ironic, therefore, that later examination of the photographs taken on that expedition showed the errors were as great as the effect they were trying to measure. Their measurement had been sheer luck, or a case of knowing the result they wanted to get, not an uncommon occurrence in science.”
Sceptical convert
While the evidence of the photographic plates is complicated, it seems to acquit Eddington of fudging, if not of bias. In addition, a relevant aspect of the expeditions has been underestimated, even though it is beyond dispute, as explained by Kennefick. In a nutshell, Dyson’s role was as important as Eddington’s. First, Dyson – who launched the expedition project in 1917 with money from the British government – was a long-time sceptic about relativity.
In December 1919, soon after the great announcement in London, he wrote to another astronomer, George Ellery Hale of the Mount Wilson Observatory in California: “I was myself a sceptic, and expected a different result. Now I am trying to understand the principle of relativity and am gradually getting to think I do.” Only in 1922, following the American eclipse observations in Australia, did Dyson declare: “I don’t think there is ‘any possible shadow of doubt’ about the correctness of Einstein’s prediction of the deflection of light, whatever difficulties may be found with the rest of his theory.”
Second, and even more important, Dyson, not Eddington, carried out the analysis of the data from Sobral, which actually confirmed Einstein’s prediction – the data from Príncipe, obtained by Eddington, were too meagre for definite conclusions as a result of cloudy weather obscuring the Sun. According to Kennefick, “We can conclude the Sobral data reduction was conducted independently of Eddington. The initials on the data sheets; the fact that the reduction was undoubtedly performed at Greenwich and not at Cambridge, where Eddington was; and the fact that Dyson was solely responsible for discussing the Sobral data in his written report all reinforce this impression.”
That said, the severely limited data raise a fascinating question. How did Einstein come up with his theory in 1915? He developed it from a very narrow empirical base, relying primarily on his scientific imagination, notes Kennefick. But it has passed every subsequent test for more than a century, most recently its prediction of gravitational waves and black holes.
When Einstein himself lectured on “The origin of the general theory of relativity” at the University of Glasgow in 1933, he disarmingly confessed: “In the light of the knowledge attained, the happy achievement seems almost a matter of course, and any intelligent student can grasp it without too much trouble. But the years of anxious searching in the dark, with their intense longing, their alternations of confidence and exhaustion and the final emergence into the light – only those who have experienced it can understand that.”
A material that remains a superconductor when heated well beyond the boiling point of water has been predicted by physicists in China. Hanyu Liu, Yanming Ma and colleagues at Jilin University have calculated that lithium magnesium hydride will superconduct at temperatures as high as 473 K (200 °C).
The catch is that the hydrogen-rich material must be crushed at 250 GPa, which is on par with pressures at the centre of the Earth. While such a pressure could be achieved in the lab, it would be very difficult to perform an experiment to verify the prediction. The team’s research could, however, lead to the discovery of more practical high-temperature superconductors.
Superconductors are materials that, when cooled below a critical temperature, will conduct electricity with zero resistance. Most superconductors need to be chilled to very low temperatures, so the holy grail of superconductivity research is to find a substance that will superconduct at room temperature. This would result in lossless electricity transmission and boost technologies that rely on the generation or detection of magnetic fields.
Atomic arrangements
Hydrogen-rich materials could provide a route to room-temperature superconductivity because they resemble metallic hydrogen – which is expected to exist at pressures greater than about 400 GPa. While metallic hydrogen has yet to be reliably made in the lab, it is predicted to be a superconductor at room temperature. The idea behind using hydrides instead of pure hydrogen is that the hydrogen atoms in some hydrides are arranged such that high-temperature superconductivity can occur at significantly lower pressures.
A key challenge facing physicists looking for suitable hydrides is predicting which materials have the desired crystal structures to support high-temperature superconductivity. In 2014, Liu, Ma and colleagues came up with a computer simulation that can predict the structures of hydrides at high pressures. This led to the experimental measurement of superconductivity in hydrogen sulphide at 203 K and 150 GPa in 2015. Then the simulation identified the current record holder lanthanum hydride, which has been measured as a superconductor up to about 250 K (-23 °C) when subjected to 170 GPa.
Now the team has extended its search to include ternary hydrides — substances such as lithium magnesium hydride that comprise three different atomic species. While the high-pressure structures of these materials can be harder to predict than binary compounds, the presence of a third atom increases greatly the number of materials that can be investigated.
In the case of lithium magnesium hydride, the team calculates that donor electrons from the lithium atoms prevent the material from breaking-down at high pressures. Describing their work in Physical Review Letters, they say that using donor electrons to stabilize structure at high pressures could pave the way for exploring the properties of more complicated ternary and quaternary hydrides that are high-temperature superconductors.
One-atom thick materials like graphene (a 2D sheet of carbon) conduct protons extremely well but they become impermeable to protons the thicker they get. Indeed, 2D molybdenum sulphide (MoS2) becomes completely impermeable to protons at just three atoms thick. A team of researchers from the UK, China and Belgium has now found that materials known as ion-exchanged micas are highly efficient proton conductors even when they are ten atoms thick. This surprising new result could prove to be important for applications such as fuel cells and other hydrogen-related technologies.
Micas (a type of mineral commonly found in soil) are made up of aluminosilicate layers that are normally covered with cations, such as potassium ions (K+). These native ions can readily be exchanged for other ions, like protons (H+), lithium (Li+) or caesium (Cs+). It is particularly easy to substitute H+ for the native ions.
Aluminosilicate slabs pierced by tubular channels
As well as being efficient proton exchangers, micas also have a relatively sparse crystal structure that contains hexagonal rings roughly 5.2 angstroms in size in the basal plane. These rings are much bigger than those that make up graphene or MoS2, for example, which are around 2.5 and 3.2 angstroms respectively. “We can thus think of micas as aluminosilicate slabs pierced by tubular channels,” says Marcelo Lozada-Hidalgo of the University of Manchester, who co-led this research effort together with Nobel laureate Andre Geim. “These channels aren’t empty but filled with hydroxyl (OH–) groups that resemble the proton-conducting 1D chains in water, so they are thus permeable to protons.”
The researchers studied two types of micas (known as muscovite and vermiculite), which are made up of silicon-oxygen (Si-O) and aluminium-oxygen (Al-O) octahedra that form a 2D sheet. They were able to prepare atomically thin samples of these materials by shaving off single layers using the now-famous mechanical exfoliation technique – the same that was used to first prepare graphene back in 2004. They then immersed these sheets in 0.1 M caesium nitrate solution at 80°C for a week so that Cs+ ions could exchange for the native ions through the entire volume of the material.
Proton conductivity up to 100 times higher than in graphene
Lozada-Hidalgo and colleagues chose to exchange the native ions for Cs+ in their study because Cs+ is a heavy ion that provides high contrast in subsequent scanning tunnelling microscopy imaging experiments. This means that they could more easily observe how protons exchange for the Cs+ ions when the materials are placed in a humid hydrogen atmosphere later on.
Thanks to electrical- and direct proton flux- measurements (using mass spectrometry), the researchers found that proton conductivity in atomically thin micas is 10 to 100 times higher than in graphene. “This result was surprising since even the thinnest micas are almost 10 times thicker than graphene,” explains project lead author Lucas Mogg of the University of Manchester. “This is encouraging because graphene is already being considered as a promising proton conducting material. Our results show micas could be even more promising – not least because they are abundant and inexpensive.”
Like sponges
“Micas behave essentially like sponges,” he continues. “In our experiments we made these sponges release the Cs+ ions they initially had and instead made them adsorb protons.”
The mica membranes are extremely efficient proton conductors because the big Cs+ ions initially present that “block” the pores in the sponges are replaced with protons – which are the smallest possible ions, he says. These protons take up much less space and essentially unblock the pores, allowing for proton flow.
“Our result also implies that many other 2D materials that aren’t ionic conductors could be made so by using this strategy,” adds Geim. “Many more 2D crystals with similar nanoscale channels could be explored, hopefully bringing unexpected phenomena and new applications in the field of proton and ionic conductors.”
Proton conductivity in traditionally inaccessible temperature range
And that is not all: the researchers found that the micas remain efficient conductors of protons between 100°C and 500°C – the temperature range at which fuel cells and other hydrogen-related technologies need to operate and which has been traditionally inaccessible with other such proton-conducting materials until now. “We found that the areal proton conductivity of our mica membranes can be greater than 100 S/cm2 at 500°C, which is well above the current requirements for industry,” says Lozada-Hidalgo.
“Although our devices are only at the proof-of-concept stage at the moment and significant research and development is still required before we can make industrial prototypes, micas are certainly worth investigating for such applications,” he says.
The team, which includes researchers from the Dalian University of Technology and Tianjin University, both in China, and the University of Antwerp in Belgium, is now busy working on building a mica prototype membrane that is big enough to be tested in industrial conditions.
The researchers are also looking into how the proton conductivity, and indeed other mass transport phenomena, changes when the micas are functionalized and their composition varied.
We need to stop wasting energy. So says “Shifting the focus: energy demand in a net-zero carbon UK”, the first report from CREDS, the Centre for Research into Energy Demand Solutions at the University of Oxford’s Environmental Change Institute. It claims that changes to the way that energy is used are critical to the development of a secure, affordable and sustainable energy system. “In recent decades, more than 90% of the progress in breaking the relationship between carbon emissions and economic growth globally has come from reducing the energy intensity of the economy,” it says. “By comparison, reducing the carbon emissions per unit of energy has, to date, been a relatively minor effect.”
That’s quite a bold claim and needs a bit of unpacking. There have certainly been improvements in energy efficiency in many sectors. And, as the report says, “in leading energy-importing countries, energy efficiency improvements have played a major role in reducing dependence on imported fuel”. However, some energy demand reductions have been due to structural changes in the economy, not energy efficiency initiatives as such.
Nevertheless, there has been a degree of decoupling of energy use and economic activity, which the report says “has been reflected in absolute reductions in energy demand. Primary energy demand in the UK has fallen by 20% since 2003. This has confounded official projections made at the beginning of this period, which projected slow but steady energy demand growth. This decoupling has a longer history, with an annual improvement of the GDP/energy ratio averaging 2.5% since 1970, reducing current energy demand to one third of what it would have been with no improvement”.
Decoupling dominates?
“It is difficult to exaggerate the impact of the historical decoupling of energy demand from economic activity,” the report asserts. “It has contributed more to carbon emissions reduction than the combined effects of the UK’s programmes in nuclear, renewable and gas-fired power generation. It has made energy services more affordable to households and businesses. It has improved UK energy security, both by reducing energy imports and enabling peak electricity demand to be met with less generation capacity. Much of this impact has been driven by public policy. It is recognition of this effect across the world that has led to the IEA to call for energy efficiency to be treated as ‘the first fuel’ in energy policy.”
The CREDS report admits that, in the UK case, some of the demand reduction has been linked to the movement of manufacturing activity out of the UK, in particular to Asia. “This offshoring of economic activity has reduced UK industrial energy demand; its effect has been broadly similar in scale to that of technical improvements in industrial energy efficiency,” it says. “The Clean Growth Strategy aims to halt this trend of offshoring by retaining industrial activity in the UK. This implies that further reductions in industrial energy demand would need to come from technical or process changes that reduce energy demand per unit of material produced, or wider structural changes that reduce the demand for these materials, for example, through a greater focus on resource efficiency.” That is quite an agenda. And the report makes many other recommendations, for initiatives in all sectors.
That said, the prognosis looks quite good. Demand for power in the UK has fallen to 1994 levels. Indeed, as CREDS says, overall UK energy use has also fallen consistently over the last 15 years, despite economic growth continuing, although it may be creeping back up in some sectors. One of the main factors has been that, with prices for energy and many other commodities and services rising, energy is now being used more efficiently, aided by the advent of new technologies and, in some cases, prosumer self-generation. And this trend may be spreading. Although energy use and electricity demand globally has still risen, power demand fell in 18 out of 30 IEA member countries over the period 2010-2017. The IEA says that over 40% of the reduction was due to energy efficiency within industry, some of the rest being due to the spread of more efficient lighting systems and domestic appliances. So there is some hope for continued progress.
Helping renewables
It certainly makes overwhelming sense to avoid energy waste, and there are also valuable synergies between renewable supply and energy saving. If demand is reduced and managed flexibly, it gets easier to meet the residual demand with renewables; flexible demand management is vital to balance variable renewables. As CRED says, “a zero carbon electricity system will only be possible if demand is more flexible. Technologies and services for demand-side flexibility will be major growth areas in electricity markets.”
In addition, if combined, renewables and efficiency can limit the rebound effect. If, instead of being spent of energy-intensive goods and services, so wiping out some of the energy and carbon savings, the money saved through energy efficiency is spent on renewable power, then the carbon savings from efficiency will be fully captured. However, in this context, there may be some conflicts. The increasingly low cost of renewables may undermine the economic attraction of energy saving. In some situations, it may be cheaper (per tonne of carbon avoided) to invest in supply than to invest in energy saving, especially once all the easy, low-cost, energy savings have been achieved. That is debated: some say there will be economies of scale as energy saving techniques develop and are widely adopted.
Otherwise, it’s a win-win package, with both the supply and demand side gaining something. It will be hard for renewables to meet demand unless that is reduced but equally, even if demand is reduced dramatically (Germany is aiming for a 50% cut by 2050), we will still need supply. What’s more, since there are some impacts from using renewables and the renewable supply technologies also have material requirements, it would in any case be foolish, in resource and impact terms, to waste the energy that they can supply and then have to generate more. Green supply has dominated policy in recent years, and it is good to see CREDS trying to rebalance that, but a balance is still needed: both are required for a sustainable energy future.
Cutting growth
That said, whatever the balance, it is also worth noting that not everyone believes that the decoupling effect is as significant as is claimed. Although energy use can be made more efficient and end-use possibly reduced, in a competitive market system based on relentless economic growth, energy demand arguably cannot continue to be constrained indefinitely.
Renewables might allow economic and energy use growth to continue, while avoiding climate impacts, if growth is what we want, but there may be other non-energy limits to economic growth. Some say we need to tame not just energy-use growth and switch to a low or zero growth “sufficiency” approach, but also to extend that to the economy as a whole, aiming for a stable state, sustainable, socio-economic system.
Plenty of big issues there, not least in terms of energy justice and social equity. For many people around the world living at or below subsistence level, growth may be their only hope, but if they do achieve some sort of affluence, then growth may undo us all. Unless it can be decoupled from energy use, and resultant climate impacts. That debate will run and run…
Images of the smallest cone photoreceptors in the retina, with colour added to represent the different wavelengths of light used to capture the images after compensating chromatic aberration. (Courtesy: Xiaoyun Jiang, Ramkumar Sabesan, University of Washington)
Wavelength-specific optical defocus can now be corrected for multiple colours simultaneously using a technique developed by researchers at the University of Washington. The team’s device, which works by varying the optical path of each wavelength by a different amount, was demonstrated in a system for testing subjects’ vision, by capturing aberration-corrected images of subjects’ retinas. As well as enabling high-resolution imaging of the retina, the approach could have applications in fluorescence imaging spectroscopy and the development of new corrective lenses (Optica 10.1364/OPTICA.6.000981).
Visual distortions introduced by irregularities in the eye act in both directions: they degrade the picture of the outside world as experienced by the subject, and they affect the clarity of retinal images captured using an ophthalmoscope. For the purposes of sight-testing or ophthalmoscopy, such higher-order aberrations (the kind not amenable to compensation by simple lenses) can be corrected using adaptive optics (AO).
But though this method is adaptable enough to handle distortions at the level of the individual eye, it does not differentiate between frequencies, applying the same correction across the full colour spectrum. As each frequency of light is refracted differently within the eye, once this correction has been applied there remains a residual wavelength-specific distortion – longitudinal chromatic aberration (LCA) – due to light of different colours being focused at different distances from the lens.
“For imaging and vision testing applications where multiple wavelengths need to be focused simultaneously on the retina, this wavelength-specific defocus needs to compensated precisely for every person,” explains Ramkumar Sabesan, who led the research group.
To achieve this in a vision-testing experiment, Sabesan and colleagues started with an AO-based system in which a subject’s contrast sensitivity is tested using patterns projected in red and green light. In this experiment, an infrared (monochromatic) reference beam is introduced into the subject’s eye, where it reflects off the retina. Distortions in the wavefront of the reflected infrared light carry information about the eye’s imperfections, and are corrected by a deformable mirror.
The deformable mirror configuration that restores the wavefront of the reference beam differs slightly from the configuration that would do the same for red or green light. The researchers therefore incorporated into the beam path a Badal optometer, in which a series of mirrors allow the optical distance between two lenses to be varied. The device was modified to include a long-pass filter that split the beam into two frequency bands. Green light was reflected onward to the next lens, while red light passed through to take an alternative, slightly longer path. This allowed a single deformable mirror to focus both wavelengths to the same degree.
The researchers used a similar setup for their retinal imaging experiment, with an infrared reference beam again informing the deformable mirror configuration required to correct monochromatic aberration. In this case, however, a supercontinuum laser was used to illuminate the subject’s retina in different visible frequency bands. These frequency bands entered a Badal optometer where they were separated by long-pass filters and directed along paths of different lengths.
Using this setup, the researchers were able to capture images of the retina at multiple wavelengths simultaneously, each with a resolution high enough to resolve individual cells in the fovea. The difference in focus required to achieve the best image for each frequency band varied between the four subjects in the experiment, demonstrating the benefit of being able to tailor the LCA correction to each individual. Until now, a population-average correction has been used.
“For many applications, the population-average estimate of LCA is sufficient,” says Sabesan. “However, in cases where cellular resolution across multiple wavelength bands is desired, small inter-individual variations need to be compensated.”
Next, the researchers intend to use this new ability to overcome chromatic imperfections in the eye to investigate how the retina perceives colour in the natural environment.
A funny thing happened the other day when some colleagues and I tried to come up with a name for a new venture. Although everyone was on board with the idea behind the company, its business model, and all the other important stuff, getting everyone to agree on what to call it was surprisingly challenging.
Part of the problem is that technical people tend to treat the company’s name as part of product development. The name, they argue, needs to describe the business or technology involved. My response is, okay, fine – but what if we later need to change direction?
The company now known as IBM is a case in point. Founded in 1911 through a merger of the Tabulating Machine Company, the International Time Recording Company and the Computing Scale Company, the Computing-Tabulating-Recording Company simplified its name (thank goodness) to International Business Machines in 1924. Its later abbreviation to IBM was an important step, since the firm now does much more than any of its original names imply.
For me, a business’s name doesn’t matter too much if it fulfils a few basic criteria – though marketing professionals may disagree. First, it must not be trademarked by others. It must be available both at Companies House (or the equivalent outside the UK) and as a URL for a website, ideally for a reasonable price. It’s also best to make sure that online searches don’t turn up anything undesirable, either in English or, if you’re aiming to build a global brand, in the language(s) of your target markets. This can be tricky. Even if you diligently check the translations, you can inadvertently get it wrong. Toyota didn’t sell many MR2s in France, and if you pronounce the name in French, you’ll understand why.
If you are trying to hide your company’s true intentions, you may find the story of Mitel inspiring
Sometimes, though, other factors come into play. If you are trying to hide your company’s true intentions, you may find the story of Mitel inspiring. Michael Cowpland and Terry Matthews started it in 1973 with the blessing of their employer – a Canadian telecoms firm – on the understanding that they would sell lawnmowers. The name Mitel reflects both the founders’ first names and their supposed first product: MIke and TErry Lawnmowers. Alas, their first shipment of three lawnmowers was “lost in transit”, so they pivoted to making a tone-to-pulse converter for office phones, drawing on ideas in Cowpland’s PhD thesis.
In some sectors, it is popular for the company’s name to take the underlying technology as a starting point. I have lost count of the number of quantum-tech companies with names that begin with the letter Q and derive from some aspect of quantum physics. Similarly, optics and photonics companies named opto-something or photo-something are pretty common. Adopting these conventions can make it hard for you stand out from the competition, but on the other hand, you also won’t get calls from people asking you to clean windows.
Another time-honoured naming tradition is to let your ego take over and name your company after yourself. The founders of Edison Electric, Bell Telephone, Marks and Spencer, and McDonalds all succumbed to this temptation, with great success. But again, there are pitfalls. In the town where I grew up, a man called Stuart Hall founded a travel agency. Unfortunately, the signage for Stuart Hall International Travel attracted all the wrong kind of attention, and it was changed very quickly. Presumably, the (possibly apocryphal) building firm STD Contractors met a similar fate.
Another time-honoured naming tradition is to let your ego take over and name your company after yourself
Technology business founders are usually serious people, which at some level rules out jokey names like Julius Scissor (a hairdresser’s), Lawn ‘n’ Order (a landscaping company), Codfather and For Cod’s Sake (fish and chip shops) or Luke Floor Walker (a flooring company run by a friend of mine). Then again, Elon Musk owns a tunnelling firm called The Boring Company, which is memorable, descriptive and a little tongue-in-cheek, too. The same could be said for an LED lighting firm called Big Ass Light – a spin-off from a fan manufacturer called (what else?) Big Ass Fans.
Still, if you don’t get the name quite right, you can always change it. In 1996 Larry Page and Serge Brin created a search engine called BackRub, then changed it to Google two years later. The newer name is a play on the word “googol”, denoting the number 1 followed by 100 zeroes, and it reflects Page and Brin’s mission to organize the staggeringly large amount of information available on the Web. Another early search engine, created by Jerry Yang and David Filo while they were PhD students at Stanford University, was initially called Jerry’s Guide. It was soon renamed Yahoo!, which apparently stands for “Yet Another Hierarchical Officious Oracle” – although no-one really needed to know this, as the name itself was memorable, unique and easy to spell.
In my view, though, no company has done a better job of renaming itself in recent years than LG.The company was called Lucky-Goldstar when it formed in 1958, and it traded under that name until it rebranded as LG in 1995. The accompanying tagline “Life’s Good” was simple, emotive and even a bit American-sounding – giving the company a wholly different feel from the South Korean firm known, in the UK at least, for selling bargain-basement TVs and radios in the 1980s.
In my view, though, no company has done a better job of renaming itself in recent years than LG
In short, company names are tough. It isn’t worth spending too much time picking one, because there are more challenging and important matters at hand (like running the actual business). Even so, you should spend enough time on it to save yourself from embarrassment – or else be prepared to spend more time later changing it and moving on.
Females can sustain their performance for longer than males during maths and science exams, which can reduce the gender gap in results if tests are long enough. That is according to researchers in Spain and the Netherlands, who have analysed the performance of four different cohorts of thousands of high-school students from around the world.
Previous research has shown that male school students tend to perform better than females on maths and science tests, while girls outperform boys on verbal and reading tests. In the latest study, Matthijs Oosterveen, from the Erasmus University Rotterdam, and Pau Balart, from the University of the Balearic Islands, went beyond just looking at overall scores and examined what happens during exams, looking at how students perform on each question.
This involved anlayzing the results from the 2006, 2009, 2012 and 2015 Program for International Student Assessment (PISA) — an international test of 15-year-old students in mathematics, reading and science that takes place every three years. In 2018 more than half a million students from 80 countries took the assessment.
We are working on a new project that aims to understand [these results] more deeply
Matthijs Oosterveen
Oosterveen and Balart found that, on average, females outperform males on reading tests, while boys do better on maths and science tests. But they also discovered that while boys scored better at the start of the maths and science tests, their performance dropped at a faster rate than that of girls. Female students were better able to sustain their performance – and this persisted across test years and the vast majority of countries. The researchers found that in more than half of the countries where female students had an initial disadvantage in maths and science, female students decreased this disadvantage by at least half during the two-hour test.
To test the idea that longer tests could reduce the gender gap, the researchers then examined a dataset of more than 400 maths tests of varying lengths. They found that males scored better than females on shorter tests, but once tests reached 125 questions the gender difference in performance disappeared.
“Unsatisfying” answers
The researchers do not fully understand why this gender difference exists. They looked at whether differences in test-taking strategies, levels of effort and non-cognitive skills played a role, but these were unable to explain the variation. “We are left with an answer that is unsatisfying, which is we don’t know yet,” Oosterveen told Physics World. “But we are working on a new project that aims to understand this more deeply”.
For now, the researchers say that their results suggest that test length may help explain some of the differences and contradictions between previous studies looking at the existence and size of the gender gap among school-aged children. Oosterveen says that the most important finding of their work is that it indicates a worldwide female difference in test taking. He adds that there are negative stereotypes around females and maths, but their results show “a female advantage in test taking”.
This year marks a major anniversary in our exploration of the Moon – it’s 50 years since the astronauts aboard Apollo 11 stepped onto the lunar surface for the fist time. While people have not returned to the Moon since the Apollo 17 mission in 1972, the exploration of our nearest neighbour is far from over.
Indeed, for the past decade, China has had a particular lunar focus, planning and launching a series of robotic missions. And earlier this year China did something that no other country had done before – put a lander on the side of the Moon that always faces away from Earth, known as the far side.
Yet China does not just have its sights set on space. As outlined in the free-to-read special report, the country is also forging ahead in synchrotron science, notably through the construction of a major fourth-generation synchrotron radiation facility in Beijing – the fourth such synchrotron in the country. And earlier this year physicists in China unveiled ambitious plans to build a massive new underground facility in the centre of the country to study gravitational waves and test Einstein’s general theory of relativity to an unprecedented precision.
• China plans gravitational-wave observatory – A new facility in central China is designed to study gravitational waves as well as test Einstein’s theory of general relativity to unprecedented precision, as Ling Xin reports
• Exploring the far side – China’s Chang’e-4 mission became the first probe to touch down on the far side of the Moon earlier this year. Ling Xin examines the consequences for lunar exploration
• China’s next big thing – Work has just begun on China’s first fourth-generation synchrotron radiation source. Robert P Crease gets a sneak preview of what’s in store
• Peering into the past – Robert P Crease talks to researchers in China who use physics-based techniques to understand the country’s history
I hope you find this special report interesting, and if you’d like to share your thoughts on it, please get in touch by e-mailing us at pwld@iop.org.
