I recently attended a two-day event at the Royal Society in London on using tokamaks as a fusion-energy source. People have, of course, been working on fusion for years – even TV pioneer Philo Farnsworth, whom I mentioned in last month’s column, developed a prototype reactor, called the “fusor”, back in the 1960s. But why has fusion proved so hard to harness here on Earth? As people often like to ask, why is fusion always 30 years away?
Why has fusion proved so hard to harness here on Earth? As people often like to ask, why is fusion always 30 years away?
You only need to look up to the Sun for proof that fusion works. Achieving it here on Earth is just an engineering problem, right? Simply fuse two nuclei together to make a bigger atom, which releases four times as much energy as fission. A lot of smart people are working on fusion and a lot of money has been spent. So why don’t we have clean, cheap fusion power right now?
The problem, as I quickly realized from the Royal Society meeting, is getting the nuclei close enough for long enough for fusion to occur. That will happen only if you can exceed a figure of merit known as the “triple product” of heat, confinement density and time. Some amazing approaches have been adopted to solve this problem including huge superconducting magnets, massive pulsed lasers, fused ion beams and mechanical rams.
Many have achieved fusion, but that’s not enough. What you want is to generate more energy than is used to start the reaction. No-one has yet reached “breakeven”, but when we do, we’re on the road to generating power. Most of the world’s effort is on doughnut-shaped reactors called tokamaks, which usually employ the tritium reaction – heavy hydrogen – to produce helium, energy and fast-moving neutrons.
The Royal Society event showcased a bewildering list of engineering and physics challenges, including achieving temperatures of way above 5×107 K in a low-vacuum plasma and confining it using high-performance superconductors to generate a fusion reaction. This, in turn, involves cooling superconducting magnets to below 30 K even though they’re barely 300 mm from the hot plasma.
What you build is important because materials hit by high-energy neutrons released by the fusion reaction change over time. Nickel in stainless steel, for example, transforms into cobalt-60. So how should you shield the reactor walls from these neutrons? And how do you perform maintenance on the reactor, given that it has now become highly radioactive? The challenges are immense. But so are the rewards.
Smaller is better
The quest for fusion reminded me of the time I worked for an optical company in the 1990s when the race was on to deliver lower-cost integrated optics components. I was involved in other products but also sat in on engineering meetings attended by a much bigger group of colleagues, who had to fulfil a huge, multi-million dollar order for lots of telecoms components.
The customer had been given a spec sheet and some PowerPoint roadmap slides, but after many iterations, which involved working on several tricky problems in parallel over the course of a year or so, little progress had been made. Improving the design in one area simply made things worse in another and they still didn’t have a prototype that was up to spec – let alone a manufacturable product.
I envisaged a different approach. No-one in the team wanted to hear it but – undeterred – I spoke to the company’s chief executive, who asked me how long my idea would take. When I replied “six weeks or so”, the next thing I knew, I was running a team to put my idea into practice. My tactic was to focus on the specification and the application, not the utopian PowerPoint picture. So I hopped on a plane and presented a mock-up of the new product to the customer, who said it was exactly what they wanted. The team delivered a prototype just three weeks after that – and the customer liked it too.
Our company’s philosophy thereafter was to develop the “minimal viable product” and do so faster. It proved successful for the firm. All I did was change the number of problems we tackled at once. What we built wasn’t perhaps as small or as cool as the original PowerPoint vision, but it worked.
Business brains
So what has this got to do with fusion? Well, the current global fusion effort is the $18bn ITER experimental reactor being built in France. It’s a multinational, “big-science” affair, involving China, the EU, India, Japan, Russian, South Korea and the US. The latest plan is for ITER to come on line in 2025 and that, by 2035, it should point the way to a commercial fusion reactor (DEMO), which would then be built and connected to the electricity grid by 2060.
But to build enough of these reactors to get past 10% of global demand could take until the end of the century. This strikes me as a little too late. I see more hope from the business sector. Firms such as Tokamak Energy, TAE Technologies, General Fusion, Lockheed Martin and Commonwealth Fusion Systems seem to be iterating on shorter timescales to home in on economically viable, smaller reactors. Tokamak Energy, for example, believes it will have production reactors by 2030 by iterating designs on timescales of a few years.
So who will get there first: the commercial hares or the big-science tortoises? I know which my money is on.
The headline figure in REN21’s 2018 review of the global status of renewable energy is that, in 2017, renewables supplied 26.5% of global electricity, which coincidentally was about the same as for the UK. The UK has now moved up to around 30% and that may well be true globally too. Certainly, REN 21 says that renewables’ share of final energy consumption has continued to grow globally, at around 5.4% averaged over the last 10 years for modern renewables, more for some technologies. By contrast, over that period, fossil and nuclear only grew by 1.6% and energy demand by 1.7%.
REN 21 reports that 178 GW of renewable power generation capacity was added in 2017. That was 70% of net additions to global power generating capacity in 2017, the largest percentage so far, bringing the global total to 2195 GW, with non-hydro renewable capacity (in all 1081 GW) likely to overtake hydro capacity (1114 GW) in 2018. Of the new capacity added in 2017, 159 GW was non-hydro renewables and 19 GW hydro. Overall, with hydro included, renewables accounted for 26.5% of total global electricity generation in 2017, up from 24.5% a year earlier, with hydro at 16.4%, wind 5.6%, bio-power 2.2%, solar PV 1.9%, and 0.4% for ocean power, concentrated solar, and geothermal combined.
In 2017, 52 GW of wind capacity was added, bringing the global total to 539 GW. But that was lower growth than in the previous year, due mainly to a slowdown in China, in part a result of problems with curtailment – about 42 TWh of wind energy was curtailed in China last year. Even so, at 19.7 GW, China was still the leader in new installations. Of the total global installed wind power, 18.8 GW was offshore, with nine countries adding 4.3 GW in 2017, led by the UK (1.7 GW), Germany (1.2 GW) and China (1.2 GW).
Solar photovoltaics (PV) have continued to expand rapidly, installing more capacity than any other power generating technology, and rising by 98 GW, about 33%, in 2017. That has increased the global total to about 402 MW. China led, with PV installations growing more than 50%.
However, while progress was good for electricity, REN 21 says “the power sector on its own will not deliver the emissions reductions demanded by the Paris climate agreement…to ensure access to affordable, reliable, sustainable and modern energy for all. The heating and cooling and transport sectors, which together account for about 80% of global total final energy demand, are lagging behind”.
That point is reinforced by REN21’s new adjusted figures for the total global renewable energy contribution, including biomass, which has only grown by 2.3% over the last decade, mainly since the use of traditional biomass, e.g. in China, has fallen, cutting global biomass’ growth rate to 0.2%. The result of that, and other changes, is that the estimated total global renewables share of final energy consumption was only around 18.2% in 2016, down from the 19.3% estimate in the 2017 REN21 review, with modern renewables now at 10.4%.
Seeking to improve that, REN21 looks at system integration, and better end-use efficiency, e.g. in heating and transport. Rana Adib, executive secretary of REN21 said: “We may be racing down the pathway towards a 100% renewable electricity future, but when it comes to heating, cooling and transport, we are coasting along as if we had all the time in the world. Sadly, we don’t.” REN21 said of particular concern was that global energy demand and energy-related carbon dioxide emissions rose for the first time in four years in 2017, by 2.1% and 1.4% respectively.
The International Energy Association’s Tracking Clean Energy Progress review came up with a similar message, but reflecting the IEA’s wider set of technology commitments, including nuclear and fossil carbon capture and storage (CCS). While there was some good progress, energy efficiency improvements had slowed and progress on CCS had stalled. Progress in deploying onshore wind and energy storage had also slowed. Nuclear was also unlikely to meet the level envisaged in the IEA’s 2025 Sustainable Development Scenario. Overall, Fatih Birol, IEA head, said: “there is a critical need for more vigorous action by governments, industry, and other stakeholders to drive advances in energy technologies that reduce greenhouse gas emissions. The world doesn’t have an energy problem but an emissions problem, and this is where we should focus our efforts”.
However, there have also been some more positive reports, mapping out a different, more optimistic view, with energy efficiency seen as key. Indeed, in its Energy Transition Outlook, the DNV-GL global consultancy company claims that efficiency will dominate so demand will fall. It says the energy intensity of the global economy, i.e. the energy used per unit of economic output, will improve more quickly than the rate of global economic growth in the next three decades. As a result, global energy demand will flatten for the first time in our post-industrial history.
This view is also central to a new academic study. Published in Nature Energy, the study claims that it is possible to reduce global energy demand so that by 2050 it falls to 245 EJ, around 40% lower than today, despite rises in population, income and economic activity. Using an “integrated assessment modelling” framework, it shows how changes in the quantity and type of energy services, affecting demand patterns, drive structural change in intermediate and upstream supply sectors. Overall it says that “down-sizing the global energy system dramatically improves the feasibility of a low-carbon supply-side transformation”. Its Low Energy Demand (LED) scenario meets the Paris 1.5 °C climate target as well as many sustainable development goals, without relying on negative emission techs.
One of the keys is seen to be smart digital IT-based energy systems. “The integration of multiple service functions in single devices (particularly smartphones) yields up to a 100-fold potential power saving while in use. Devices increasingly become ‘smart’ & interconnected, which opens up potential for controllability, system integration (including load management) and demand response.” That also helps with mobility services and transport while, overall, “energy intensity improves drastically due to the combined effects of electric vehicles and new organizational models of service provision, which include shared mobility”.
Energy and resource-use efficiency is upgraded in all sectors, cutting demand: “Industrial-process energy efficiency improves by one-fifth. The aggregate total material output decreases by close to 20% from today, one-third due to dematerialization, and two-thirds due to improvements in material efficiency. ‘Dematerialization’ describes a lower absolute material use due to increases in asset utilization, for example, shared-car fleets that require fewer cars. ‘Material efficiency’ includes light-weighting, for example, less material input per car”.
Changes in energy end-use drive a supply-side transformation, with “strong electrification of energy end-use, consistent with the narrative of pervasive digitalization and more versatile end-use technologies that are also non-polluting at the point of use. Over the longer term, hydrogen also increases its share of the final energy demand (in addition to its role for energy storage)”. Consistent with the LED scenario narrative, “granular energy-supply technologies, such as heat pumps, fuel cells and solar photovoltaics proliferate. Granularity, decentralization and variable renewables pose significant challenges for system management and balancing, addressed via ‘smart’ transformation of physical networks and control systems and scaled-up storage and load-management options”.
The study team admits that a massive effort would have to be made to bring all this to reality: there would have to be “rapid innovation, cost reductions and performance improvements from the widespread diffusion of granular end-use and low-carbon supply technologies”, that would require “sustained innovation policies aligned to credible efforts to stimulate market demand”, while regulators “need to ensure that space is opened up for new business models, digital integration and distributed service provision to overcome incumbents’ vested interests to slow structural change”. But it claims it is technically viable. If so, that’s a huge game changer, allowing renewables to deliver all that’s needed, and cutting emissions fast. Too good to be true? It certainly looks impressive, if a little fantastic. A vast series of technical fixes. See Carbon Brief’s review of the paper.
But for very different views, see some of the oil company scenarios in my next post.
“The equation we derived lets us predict how much sea level will rise based on river flow, and then compare that prediction to actual measurements and observations,” says Chris Piecuch of Woods Hole Oceanographic Institution (WHOI). “Based on our model and the observations, we’re finding that variations in the amount of water that comes out of a river annually can raise or lower coastal mean sea level by several centimetres.”
Piecuch and colleagues combined decades’ worth of river level and tidal data from gauges throughout the eastern US with information on water density, salinity and the Earth’s rotation. The result was a model describing the link between river discharge and sea level on an annual basis.
The team found that most of the sea-level change caused by a river occurs on one side of its mouth. Freshwater is less dense than saltwater so river outflow floats on the ocean’s surface; the Earth’s rotation forces it to turn sharply along the coast. In the northern hemisphere the water follows the right-hand side of the river, pushing water up against the shoreline and raising local sea levels. In the southern hemisphere the water follows the left-hand side of the river.
Satellite measurements don’t have enough resolution to provide accurate readings of ocean height within a few miles of the coast so the model, currently a proof-of-concept, could ultimately help calculate the effects of sea-level rise on certain coastlines.
“When you think of societal impact, you want to know what’s happening at the coast,” says Piecuch. “In low-lying areas like Bangladesh, we don’t yet know how sea level and river outflow combine. But if a major storm comes through, even a small rise in the background mean sea level could have a huge impact on flooding.”
Piecuch and colleagues, who reported their results in PNAS, aim to extend the work to understand how individual events like a hurricane or massive rainfall affect ocean levels.
“Many processes can affect sea level, making predictions of regional sea level change a challenging endeavour,” says Larry Peterson of the US National Science Foundation. “These scientists show that discharge from rivers can play a significant but overlooked role in the interpretation of sea level from downstream tide gauges. The work has important implications for climate models, remote sensing, and the projection of coastal flood risks.”
Researchers at the University of Nottingham have demonstrated an optimized method to analyse magnetoencephalography (MEG) data that can improve spatial resolution to the order of 3-5 mm. They achieved this with the aid of an optimized algorithm and custom 3D-printed foam headcasts that restricted participant head movement to about 1 mm. First shown in simulation, then validated in participants who performed a finger movement task, this improved accuracy enabled better measurement of spatial organization of human brain electrophysiology, non-invasively (NeuroImage 10.1016/j.neuroimage.2018.06.041).
What is MEG?
MEG measures the magnetic fields generated by neural current flow in the brain with high (millisecond) temporal resolution, allowing measurement of very fast time-frequency dynamics of brain networks. This is unlike brain imaging techniques such as functional MRI (fMRI), which rely on a lagged, indirect blood oxygenation measure of neural activity, making it difficult to capture fast events.
Spatial mapping of electrical sources using MEG is, however, complicated since there are many more voxels in the brain than there are magnetic field sensors in the scanner. This makes the inverse problem (inferring source distributions based on extracranial fields) non-unique, and hence requires the use of complicated localization algorithms, such as beamforming. Blurring of the measured fields due to having fewer sensors than current sources is exacerbated by participant movement. In this work, the researchers minimized blurring due to the inverse problem by optimization of the beamforming algorithm, while head movement was mitigated using the foam headcasts.
In the healthy brain, movement (of a finger, for example) causes measurable changes in brain waves, with a decrease of beta waves (13-30 Hz) during movement, followed by an increase above baseline after movement cessation. The latter effect, the so-called rebound, is thought to be a marker of neural inhibition and is spatially specific.
Simulation studies
In simulations, the researchers modelled two point sources with time courses that were alternately on and off in response to theoretical stimulation. By segmenting the MEG data into two datasets and calculating separate beamformer weights (for spatial localization), rather than beamforming the whole dataset, the spatial separation of the sources was improved significantly.
In other words, removing sources of no interest left fewer sources to be minimized by the beamformer equation, leading to a sharper localized peak. However, the team suggest that there should be sufficient data to allow this segmentation; for a detectable signal, many MEG trials must be acquired.
For the experiments, participants performed multiple runs in the MEG scanner while tapping either their index (D2) or little (D5) finger, with rests in between each tap. A similar task was performed using fMRI, for comparison.
Since the same participants underwent fMRI and MEG, the maps of digit representations in the brain from the two neuroimaging modalities could be overlaid on the same anatomical image. The researchers could then calculate distances between MEG D2 or D5 and fMRI D2 or D5 in the same space.
Digit distances
The researchers found that the representations of the index (D2) and little (D5) finger in the cortex of individual subjects could be separated spatially using MEG, even when separation distances were only about 3-5mm. The beta rebound was shown to be mapped topographically in accordance with well characterized topography of the sensorimotor cortex. Furthermore, they showed significant overlap between MEG and fMRI.
However, the overlap between blood oxygenation level dependent (BOLD) fMRI and MEG responses were not perfect – the distances between D2 and D5 in each modality were different, with fMRI giving larger distances. This may be due to assumptions in the MEG models used to derive sources. Alternatively, the differences may be neurophysiological in origin: the BOLD activity may be more spread out, encompassing somatosensory (touch) and motor regions, whereas the beta rebound may be more specific.
Corresponding author Matthew Brookes (left) and lead author Eleanor Barratt.
The authors note that the construction of custom headcasts is expensive, and that this should be taken into account for large cohort studies – although the benefits to data quality may outweigh the costs.
This research showed that MEG has the required spatial resolution to delineate separate digit responses in the same hand, using the beta rebound; first in simulation and then validated experimentally. MEG therefore has an untapped potential in spatial resolution, which could be exploited in patient cohorts with possible sensorimotor alterations, for example focal hand dystonia (writer’s cramp).
New research lends further support to the idea that a detection of surprisingly strong absorption by primordial hydrogen gas, reported earlier this year, could be evidence of dark matter. The new results, described in three papers in Physical Review Letters, are theoretical and do not settle the issue. Indeed, one group is sceptical of the dark-matter interpretation. But the work heightens interest in ongoing observations of the “cosmic dawn”, with new results from radio telescopes expected within the next year.
According to cosmologists, the hydrogen gas that existed in the very early universe was in thermal equilibrium with the cosmic microwave background (CMB), which meant that the gas would not have been visible either through absorption of the microwave photons or through emission. But at the start of the cosmic dawn about 100 million years after the Big Bang, ultraviolet light from the first stars would have excited the hydrogen atoms and shifted the distribution of electrons within the lower and upper levels of the hyperfine transition. As such, the hydrogen would have started to absorb much more radiation at the transition wavelength (21 cm), which would be seen today as a dip at longer, re-shifted wavelengths in the CMB spectrum.
The stakes are high because if the signal is real, this experiment is worth two Nobel prizes
Abraham Loeb
In February, researchers working on the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) telescope reported in Nature that they had seen just such a dip at a wavelength of 380 cm in data from their small ground-based antenna system in Western Australia. The observation was exciting news, but nevertheless in line with standard cosmological theory. However, the dip was actually twice as deep as expected – immediately leading theorists to speculate that the hydrogen was in fact interacting with particles of dark matter.
“The stakes are high because if the signal is real, this experiment is worth two Nobel prizes,” says Abraham Loeb of Harvard University. “One for being first to detect the 21 cm signal from the cosmic dawn and the second for finding an unexpected level of hydrogen absorption that may be indicative of new physics.”
New or old force?
The idea is that the dark matter would have been colder than the hydrogen atoms and so interactions between the two would have transferred energy from the gas to the dark matter – so cooling the gas and boosting absorption. The possibility of this mechanism being tied to the switching on of the first stars was proposed by Rennan Barkana of Tel Aviv University in Israel, but Barkana suggested that the interaction could involve a new fundamental force between dark and ordinary matter.
However, Loeb and Harvard colleague Julián Muñoz argued that there could be no such force as it would have led to stars cooling more quickly than is observed. Instead, they reckon that the interaction could be that of familiar electromagnetism – requiring that a small fraction of dark matter particles have little mass and carry about a millionth of the charge of the electron.
That view has now won cautious backing from other researchers in the US. By imposing constraints from a wider range of cosmological and astrophysical observations, Asher Berlin of the SLAC National Accelerator Laboratory in California and colleagues have shown in a new paper that dark matter interactions could indeed explain the EDGES results if up to 2% of dark matter weighs in at less than a tenth the mass of the proton and has a charge less than 0.01% of the electron’s. Berlin and colleagues do, however, add that this scenario would require “additional forces” to subsequently deplete the dark matter so its abundance is in line with observations of the present universe. “Although it’s possible that dark matter could produce the EDGES result, it is not easy or simple to do so,” says Berlin’s colleague Dan Hooper of Fermilab near Chicago.
Extraordinary claims
Loeb acknowledges that “extraordinary claims require extraordinary evidence,” adding that the apparent 21 cm signal from EDGES could be nothing more than instrumental noise or absorption by dust grains in our galaxy. He looks forward to new results from other experiments operating at different sites – including SARAS-2, LEDA, and PRIzM – and expects new data to be available within the next year.
Even if the signal is confirmed, however, dark matter is not necessarily the culprit. Guido D’Amico and colleagues at CERN in Geneva argue in the second new paper that proponents of the dark-matter interpretation have carried out an “incomplete analysis” by neglecting the heating effect of dark-matter annihilation. In particular, they say that annihilations could inject electrons and low-energy photons into the hydrogen gas, thereby potentially heating the gas more than it is cooled. As such, they conclude, dark-matter annihilations are “strongly constrained” by a 21 cm signal.
In a third new paper, on the other hand, Anastasia Fialkov of the Harvard-Smithsonian Center for Astrophysics in the US and colleagues (including Barkana) show that the dark-matter hypothesis yields an additional prediction that can be tested using different kinds of radio telescope. They have found that the 21 cm signal should vary across the sky by up to 30 times as much as it would do if there were no charged interactions between ordinary and dark matter – and pointing out that this prediction can be tested using low-frequency interferometers.
Muñoz is enthusiastic about these spatial measurements, explaining that they are far more immune to foreground noise and other potential systematic errors than the data collected by EDGES, and are therefore, he says, “more reliable”. He reckons that a couple of interferometers – LOFAR in the Netherlands and HERA in South Africa – might have gathered sufficient data within the next five to ten years to establish definitively whether or not the dip at 21 cm really is due to charged dark matter.
Stepping down: Scott Pruitt has resigned as head of the Environment Protection Agency. (Courtesy: EPA)
Scott Pruitt has resigned as head of the US Environmental Protection Agency (EPA), just 17 months after taking up the position. US president Donald Trump has announced that Andrew Wheeler – a former lobbyist for the coal industry – will become acting administrator until a new EPA administrator is found. “I have no doubt that [Wheeler] will continue with our great and lasting EPA agenda,” Trump said announcing Wheeler’s promotion.
Pruitt’s time at the EPA has been controversial (see box). When Pruitt was attorney general of Oklahoma from 2011 to 2017 he sued the EPA 14 times. His nomination to lead the EPA in late 2016 even led to the US Environmental Defense Fund to announce its opposition – the first such action in the fund’s 50-year history. Those concerns did not recede during his time in office. Some his decisions, wrote Christine Todd Whitman, EPA administrator under President George W. Bush, presented “real and lasting threats to the nation’s land, air, water, and public health”.
In his resignation letter to Trump, Pruitt cited “unrelenting attacks on me personally, my family” as his reason for stepping down. Yet Pruitt has come under increasing pressure for a number of months following questions about his spending and housing arrangements. In accepting his resignation, Trump noted that Pruitt had done an “outstanding job”.
Trump then quickly announced that Wheeler would become acting administrator. In April, Wheeler was confirmed by the US Senate as Pruitt’s assistant administrator and he has previously served in the EPA’s Office of Pollution Prevention and in the office of Oklahoma Senator James Inhofe. Yet while Wheeler brings more Washington experience than Pruitt, he is also a strong denier of anthropogenic climate change. “We are definitely concerned that he will continue Scott Pruitt’s record of hostility to environmental protections,” says Benjamin Longstreth, a lawyer at the Natural Resources Defense Council.
Analysis: Scott Pruitt leaves a cloudy legacy
When he resigned from his position as administrator of the Environmental Protection Agency (EPA) last week, Scott Pruitt left a cloudy political legacy. Despite the scandals that led to his departure, he had worked hard to fulfill the Trump administration’s platform of reducing environmental regulations to encourage industrial growth. But many of his efforts have had little permanency, making them vulnerable to reversal by any succeeding administration. And others were drafted so poorly that they were almost immediately tied up in legal challenges.
Pruitt had some successes in achieving the Republican party’s environmental policy goals. He played a key role in persuading US president Donald Trump to pull out of the Paris agreement on climate change. He sidelined government scientists inside the EPA and outside academic advisers from policy-making meetings in favour of industry representatives.
Changing government regulations is a complex and time-consuming process that can face frequent legal roadblocks. In several cases, such as the proposal to relieve car companies of the need to improve their fleets’ fuel efficiency, Pruitt issued only initial proposals, without the legal details. Indeed, courts have already overturned at least half a dozen efforts to pull back regulations produced by President Barack Obama’s EPA, on such issues as controlling lead paint and pesticides.
While environmentalists have expressed joy at Pruitt’s departure, such celebrations may be short-lived depending on who succeeds him.
Just after 2.30 p.m. local time on 6 May 2010, Wall Street experienced one of the biggest, and briefest, crashes in its history. Within minutes, the Dow, one of the three most-followed US market indices, plunged 9%, while prices of individual shares became intensely volatile, in some cases fluctuating between tens of dollars and cents in the same second. More than $850bn was wiped off stock values – although by the end of the trading day they had mostly recovered.
What caused the Flash Crash, as it came to be known? Early theories blamed either an error in trading software, or a human at a computer inadvertently selling a large number of shares – the so-called fat-finger hypothesis. Some analysts even claimed the Flash Crash was merely part of the more exaggerated ups and downs we should expect as financial trading becomes more decentralized and complex. But many suspected foul play.
In April 2015, at the request of US prosecutors, Navinder Singh Sarao was arrested at his parents’ semi-detached home in Hounslow, west London, UK. A lone trader, Sarao, then 36, was accused of crafting “spoofing” algorithms that could order thousands of future contracts, only to cancel them at the last minute before the actual purchases went through. By exploiting the resultant dips in markets, he allegedly earned some $40m (£27m) over five years.
High speed; high stakes
Sarao was found guilty of spoofing and wire fraud by a US court earlier this year, but it is still not known whether his actions actually caused the Flash Crash. In fact, based on current financial infrastructure, performing an accurate postmortem on an extreme market event can be nigh-on impossible, because it involves knowing when – precisely when – all the trades took place.
Back in the days when traders called out buys and sells on the bustling floors of stock exchanges, keeping official time records of transactions was hardly a problem. But we now live in an era of automated, high-frequency trading, in which orders are executed in microseconds, if not faster (see “The art of the algorithm”, below). Observers have struggled to keep up. In response to a report by US regulators five months after the Flash Crash, David Leinweber, the director of the Center for Innovative Financial Technology at Lawrence Berkeley National Laboratory in the US, wrote that those same regulators were “running an IT museum”, with totally inadequate resources to forensically analyse modern transactions.
One of the main problems is that of synchronization, and the proof of it. In a financial organization, a trade may be timestamped as having occurred in a certain microsecond; but how does that organization, or indeed a regulator, know that that microsecond is the same as everyone else’s? With the increasing prevalence of atomic clocks, which can keep monthly time to within a fraction of a nanosecond, you might assume microsecond accuracy is child’s play. But even the most precise clock needs to be initially informed of the correct time, and it then needs to transmit that time to anyone who relies on it. Such signalling itself takes time, of course – the question is how much.
Leon Lobo is well equipped to answer this. Since 2011 he has been working at the UK’s National Physical Laboratory (NPL), which in 1955 developed the caesium atomic clock, the first clock proven to be more reliable for timekeeping than the duration of the Earth’s motion around the Sun. The “ticks” of an atomic clock are the oscillations between two specific energy states in an atom; a feedback loop locks the frequency of a light source to that of these electronic oscillations, thereby creating a stable frequency standard.
The art of the algorithm
(Courtesy: iStock/gorodenkoff)
These days, even the most insightful human trader comes with a big flaw: sluggishness. In the amount of time it takes a human to observe a change in the market, decide on the best response and execute an order, a computer can have processed millions of financial transactions. It is no wonder that modern finance has replaced many human operators with algorithmic, high-frequency traders.
For obvious reasons, precisely how various proprietary trading algorithms work is kept secret, but they share similar goals. One is to exploit slightly different prices of commodities in different markets, buying in the cheaper market and then immediately selling in the more expensive market. Such arbitrage is as old as market trading itself, except in this case the price differences are small, while the volumes of transactions are huge. A difference of $0.0001 might not seem like much, but if it can be repeated a million times a second, that equates to $6000 a minute.
Algorithms get predictive, too – they can be designed to expect a commodity to ultimately revert to a mean price, or to a long-term up/down trend, or to some more complex pattern of activity based on an analysis of historical data. Algorithms can even delve deep into company performance figures and assets in an attempt to determine a company’s real value, and therefore whether the market valuation is over- or under-priced.
In general, algorithms are not designed to make rash decisions – moderate gains made often is the name of the game. But they have come in for a lot of criticism. One is that the necessary computing infrastructure can be very expensive, meaning that the rewards go to the big investment companies that can afford it, rather than to smaller companies and lone traders – even if the latter are shrewder. But perhaps more worrying is that when transactions are processed so quickly, it is impossible for humans to oversee they are all being made prudently. When failures occur, they can escalate at lightning speed.
Keepers of time
Time sync: Leon Lobo wants to provide financial institutions with time-synchronization hardware accurate to the microsecond. (Courtesy: NPL Management Ltd)
Based in the Teddington suburb of London, NPL is responsible for disseminating time to the rest of the UK via fibre-optic, Internet, radio and satellite links. Now, with Lobo as the strategic business development manager for time, it is applying the fine craft of synchronization to financial trading. “You can have your own atomic clock, but a clock in itself is just a stable oscillator – a regular tick,” he says. “It doesn’t necessarily give you the correct time. That’s where our expertise comes in.”
Synchronization involves offsetting for time delays, but it is not so simple as dividing the length of the communication route by the speed of the communication. For starters, the communication route may be unreliable. Many of the big financial institutions rely on satellite navigation systems, such as the US’s GPS or Russia’s GLONASS, to synchronize their internal systems with Coordinated Universal Time (UTC), the global time standard. But these are weak signals that are vulnerable to failure, either by solar activity or deliberate jamming. In January 2016 the GPS signals themselves strayed by 13 microseconds for 12 hours, according to the UK time-distribution company Chronos, apparently because they were erroneously fed the wrong time from the ground. The failure triggered system errors in companies and organizations the world over.
The Internet is another option for timing information, but here the length of the communication route is not always the same. For example, a signal could travel more or less directly from the source to the receiver one day; another day, it could be redirected via servers on the other side of the world. Even once it reaches a financial organization, the signal has to find its way to individual computers, which are often spread all over a building. Remember, this is a world in which – rumour has it – traders compete to be closer to their building’s mainframe, to be sure that their decision-making is at no infinitesimal disadvantage.
What happens inside computers is no more reliable. Every time a signal is processed, it is subject to some delay, which may or may not be consistent. Most computers keep time according to their clock rate – a two gigahertz processor, for example, usually executes two billion instructions per second. But modern software has vagaries. Programs written in the Java programming language have “garbage collection” routines, which periodically reclaim memory but can interrupt timestamping in the process. Meanwhile, according to Lobo, anyone whose computer is running older versions of Microsoft Windows could be whole seconds fast or slow relative to UTC.
At the microsecond level, I would say no-one in the City of London has the same time
“You occasionally have incidents called negative deltas, where if I timestamp some data as it leaves and you timestamp it as it arrives, owing to poor synchronization, the arrival time can actually appear to be before the leaving time,” he says. “At the microsecond level, I would say no-one in the City of London has the same time.”
All of which makes the forensics of past market shocks rather tricky. Neil Horlock, a technical architect at the multinational investment bank Credit Suisse, believes ambiguity is the issue. He gives the example of a big investor instructing a broker to offload shares in oil, for no other reason than a new-found concern for the environment. Momentarily before the broker executes this order, another broker also sells his shares in the same oil company. Both sales drive down the market value of the oil company, but the second broker, being ahead of the curve, subsequently re-buys his shares and makes a profit. His timing may have been lucky coincidence. On the other hand, he may have had insider knowledge of the big investor’s forthcoming sale – an illegal practice known as “front running”.
Dirty tricks
This is a simple example: dirty tricks in modern finance can be much more sophisticated. In any case, as Horlock explains, distinguishing guilt from innocence involves reconstructing a precise chronology of events, which can be microseconds apart. “Having better clock synchronization means that, if there is an investigation, [the investigators] can ask for all the logs, to demand proof that that the trading was completely above board,” he says. “If the trades are uncorrelated, they can see that quite often by the timestamps.”
This year, in order to bring more protection to markets, the European Union introduced the second version of its Markets in Financial Instruments Directive (MiFID II), which imposes strict requirements on the accuracy of clock synchronization, in some cases down to 100 microseconds. At NPL, Lobo has developed a solution to help big financial organizations achieve that level of accuracy – and more.
NPL’s Krzysztof Szymaniec (right) works on the caesium-fountain frequency standard, which realizes the SI definition of the second. (Courtesy: NPL Management Ltd)
Rigour is key. Delivered with various industry partners, NPL’s solution involves sending timing information through dedicated fibre optics – as well as channels shared with select other service providers – of known length and proven resiliency. Every piece of hardware along the way is chosen for its deterministic behaviour, so that NPL engineers can calculate with great precision how much delay will be incurred. At the client side, timing software is eschewed in favour of hardware-based, NPL-certified time-protocol units. “We manage the time end to end,” says Lobo.
Every minute, these timing units are “pinged” by NPL to ensure that their time is in sync with its record of UTC. The timing protocol accounts for the basic travel time of the pings, but to account for any unknown latencies, one of NPL’s live caesium atomic clocks is transported to the far end of the fibre, where the actual received signal can be calibrated against UTC. At all times, NPL keeps an atomic clock at a hub away from Teddington, to make sure that the timing of the units is correct in case of a fibre breakage.
Precision and traceability
There are, in fact, two aspects to synchronization. One involves precision, which means choosing hardware that operates as quickly and deterministically as possible. The other aspect is traceability. In other words, Lobo and his colleagues can guarantee that they know the path their timing signal took, and its associated accuracy, every step along the way. “Most important is confidence in the infrastructure,” says Lobo.
Currently, the NPL solution guarantees synchronization to UTC to an accuracy of one microsecond – two orders of magnitude better than that stipulated by MiFID II. As an extra layer of confidence, NPL itself knows the accuracy to yet another order of magnitude (that is, 100 nanoseconds) – Lobo claims they could make it even more accurate, but believes there is no point if the demand is not there. The system has already been supplied to London data centres including Equinix, TeleHouse and Interxion, he says, and foreign organizations are next on the list.
Will a hi-tech solution such as NPL’s become the standard in finance in years to come? Horlock is unsure. “Here’s the thing,” he says. “While better clocks make our business less risky and better regulated, margins across the industry are smaller than they have ever been, and costs are a major factor in selecting any solution. So long as ‘free’ services such as GPS are deemed good enough – something that the European regulators are keen to assure us – then more expensive solutions will have to justify their introduction by demonstrating a return on that investment, such as enabling better analytics.”
One thing is for certain, Horlock says – big financial institutions will have to mitigate against the risks of GPS if they are going to fall in line with MiFID II standards. But there are alternatives to GPS besides NPL’s. Based on technology from the Second World War, eLORAN is a navigation system similar to GPS, using long-wave radio transmitters on the ground rather than up in space. It does not require a fixed communications channel and is cheaper than NPL timekeeping, although it is still ultimately fed by GPS and is not traceable. “Everyone will end up having an alternative to GPS,” Horlock concludes. “Leon’s is a very high-quality alternative, but it comes at a price. And it can only really be delivered to the major financial centres, whereas a lot of us are moving out.”
Lobo counters that an alternative method of timekeeping is of little benefit unless it is calibrated and continuously monitored, to know that it is accurate, stable, resilient and auditable. “The key benefits our solution offers includes end-to-end traceability, audit capability, resiliency, and effectively a trusted time for [a client’s] infrastructure, allowing them to measure internal systems against a stable, accurate reference at the ingress point.”
It is not the first time anyone has had to argue for an improved time standard. The large clock on the former corn exchange in Bristol, UK, where Physics World is published, has two minute-hands: one for “Bristol time”, and one for “London time”, which in the early 19th century was a little over 10 minutes ahead. That was before Bristol’s reluctant adoption of Greenwich Mean Time (GMT) in 1852, five years after its adoption over the rest of Great Britain as a universal time.
GMT made life a lot easier for rail operators of the day, who had until then struggled to coordinate the arrival and departure times of trains in different cities. Lobo believes the NPL system could be just as useful for modern finance. “It’s similar to that unification involving GMT,” he says, “but at the microsecond level.”
Physicists working on the ATLAS experiment at CERN have confirmed that the Higgs boson decays to two bottom quarks. The discovery was made by combining data from two runs of the Large Hadron Collider (LHC) and was announced today at the 2018 International Conference on High Energy Physics in Seoul, Korea.
Although this decay channel should account for nearly 60% of all Higgs decays at the LHC, it had proven extremely difficult to spot it amongst the vast number of particles that are produced by proton-proton collisions at the collider.
The Higgs boson and its associated field play an essential role in the Standard Model of particle physics. It arises from a symmetry-breaking event that occurred in the very early universe and created a uniform scalar field known as the Higgs field that pervades all space. Elementary particles such as leptons, quarks and the W and Z bosons “acquire” their distinctive masses by virtue of their unique and different couplings to this field.
Couple of quarks
It is this coupling to quarks that allows the Higgs to decay to two bottom quarks – or more precisely, to a bottom quark and an antibottom quark. These quarks immediately create jets of particles, which are then detected as they fly through ATLAS. The problem is that proton collisions in the LHC produce huge numbers of bottom-quark pairs in processes that have nothing to do with the Higgs boson.
In order to pick-out the much smaller Higgs signal, ATLAS physicists first made precise calculations of the expected contributions from other jet-producing processes. Then they showed that ATLAS has measured an excess number of jets at energies associated with the decay of a Higgs boson to two bottom quarks. Using data from the second run of the LHC – which involved 13 TeV collisions – the team detected the bottom quark decay channel at a statistical significance of 4.9σ.
This is just shy of the 5σ required for a discovery in particle physics, so they tried to bolster their statistics by looking at data from 7 TeV collisions that were collected in the first run of the LHC. Using this information, the ATLAS team was able to boost the significance to 5.4σ. Furthermore, the observed decay rate is in line with that predicted by the Standard Model of particle physics.
When combined with observations of the Higgs boson decaying to pairs of photons and Z bosons, physicists can make a 5.3σ observation of the co-production of a Higgs boson and a weak boson (either Z or W) at the LHC. This means that all four primary modes of Higgs production have been observed at the LHC at a statistical significance of at least 5σ.
Unwanted heat is a big problem in modern electronic systems that are based on conventional silicon circuits – and the problem is getting worse as devices become ever smaller and more sophisticated. Carrying away this heat is critical and researchers are developing efficient heat-conducting materials to meet this challenge. Three teams from around the US are now saying that crystals of the semiconductor boron arsenide (BAs) show promise in this context and they have measured a high thermal conductivity of more than 1000 W/m/K at room temperature for this material. This value is three times higher than that of copper or silicon carbide, two materials that are routinely employed for spreading heat in electronics.
“The value we measured (on crystal sizes of about 0.5 mm) is surpassed only by diamond and the basal plane value of graphite,” says Bing Lv of the University of Texas (UT) at Dallas, who led one of the research groups together with David Cahill of the University of Illinois at Urbana-Champaign.
The other two groups, led by Zhifeng Ren of the University of Houston (UH) and Yongjie Hu of the University of California at Los Angeles (UCLA) measured local thermal conductivities of 1000 W/m/K and 1300 W/m/K respectively, with Ren’s group also measuring a value of 900W/mK on large crystals of about 4 mm x 2 mm x 1 mm.
“The UH/UT Austin paper reported transport data of about 900 W/m/K across a length of at least 2 mm using Raman spectroscopy across the same distance and TDTR, finding about 1000 W/m/K locally on a spot less than 20 microns,” explains Ren.
Predicted thermal conductivity as high as that of diamond
Researchers predicted that BAs should have a theoretical thermal conductivity as high as that of diamond (2200 W/m/K), which is the best heat conductor known, back in 2013. However, to reach this high value, high quality crystals are needed since defects and impurities dramatically degrade thermal properties.
Lv and colleagues, then at the University of Houston, made BAs crystals in 2015 but the material only had a thermal conductivity of 200 W/m/K. Since then the researchers have optimized their crystal-growing process using a modified version of a technique called chemical vapour transport. Here, they place boron and arsenic in a chamber containing hot and cold areas and the two elements are then transported (by different chemicals) from the hot end to the cooler end, where they combine to form crystals.
Heat in crystals is carried by phonons (which are vibrations of the crystal lattice). Lv explains that the large differences in the masses of boron and arsenic atoms creates a big frequency gap between acoustic and optic phonons, which allow the phonons to travel more efficiently through the crystals. The researchers measured the thermal conductivity of their BAs using a method called time-domain thermoreflectance or TDTR, which was developed in Cahill’s lab in Illinois.
Ren’s team also used chemical vapour deposition to make their large crystals (measuring 4 mm x 2 mm x 1 mm, as mentioned). These are a significant improvement on the ones they previously made, which were less than 500 microns across and were thus too small for certain measurement techniques. The researchers also measured the thermal conductivity of their BAs using TDTR as well as some other techinques.
Hu and colleagues, for their part, made BAs single crystals more than 2 mm in size with undetectable defects and measured their thermal conductivity using the TDTR technique. Their spectroscopy study combined with atomistic calculations reveal that the phonon vibration spectrum of BAs allows for “very long phonon mean free paths and strong high-order anharmonicity through a four- phonon process”.
First known semiconductor with ultrahigh thermal conductivity
The result from all three groups mean that BAs is the first known semiconductor with a bandgap comparable to silicon of around 1.5 eV to have an ultrahigh thermal conductivity and it could be a revolutionary thermal management material, according to the researchers.
And that is not all: “There is also a close match between the thermal expansion coefficients of BAs and silicon. This is a non-negligible advantage for minimizing thermal stresses and reducing the need for thermal interface materials when incorporating it into conventional semiconducting devices,” says Lv.
“Our team is now busy looking into other processes to improve the yield of this material for large-scale applications,” he tells Physics World. “We are also trying to control the types of defects that are present in these crystals and better understand how they affect its thermal conductivity.”
The research is detailed in three papers in Science.
Failure to meet the United Nations’ 2 ºC warming limits will lead to sea level rise and dire global economic consequences, new research has warned.
Published today in Environmental Research Letters, a study led by the UK National Oceanographic Centre (NOC) found flooding from rising sea levels could cost $14 trillion worldwide annually by 2100, if the target of holding global temperatures below 2 °C above pre-industrial levels is missed.
The researchers also found that upper-middle income countries such as China would see the largest increase in flood costs, whereas the highest income countries would suffer the least, thanks to existing high levels of protection infrastructure.
Svetlana Jevrejeva, from the NOC, is the study’s lead author. She said: “More than 600 million people live in low-elevation coastal areas, less than 10 metres above sea level. In a warming climate, global sea level will rise due to melting of land-based glaciers and ice sheets, and from the thermal expansion of ocean waters. So, sea level rise is one of the most damaging aspects of our warming climate.”
Sea level projections exist for emissions scenarios and socio-economic scenarios. However, there are no scenarios covering limiting warming below the 2 °C and 1.5 °C targets during the entire 21st century and beyond.
The study team explored the pace and consequences of global and regional sea level rise with restricted warming of 1.5 ºC and 2 ºC, and compared them to sea level projections with unmitigated warming following emissions scenario Representative Concentration Pathway (RCP) 8.5.
Using World Bank income groups (high, upper middle, lower middle and low income countries), they then assessed the impact of sea level rise in coastal areas from a global perspective, and for some individual countries using the Dynamic Interactive Vulnerability Assessment modelling framework.
Jevrejeva said: “We found that with a temperature rise trajectory of 1.5 °C, by 2100 the median sea level will have risen by 0.52 m. But, if the 2 °C target is missed, we will see a median sea level rise of 0.86 m, and a worst-case rise of 1.8 m.
“If warming is not mitigated and follows the RCP8.5 sea level rise projections, the global annual flood costs without adaptation will increase to $14 trillion per year for a median sea level rise of 0.86 m, and up to $27 trillion per year for 1.8 m. This would account for 2.8% of global GDP in 2100.”
The projected difference in coastal sea levels is also likely to mean tropical areas will see extreme sea levels more often.
“These extreme sea levels will have a negative effect on the economies of developing coastal nations, and the habitability of low-lying coastlines,” said Jevrejeva. “Small, low-lying island nations such as the Maldives will be very easily affected, and the pressures on their natural resources and environmental will become even greater.
“These results place further emphasis on putting even greater efforts into mitigating rising global temperatures.”
