Page 700 – Physics World

Home » Page 700

The physics of baking, the controversial $3m prize and the new, new wonder material

This week’s podcast begins with something close to all our hearts, or mouths for that matter. We’re talking cakes, biscuits and pastries – that’s because Sarah Tesh is here to discuss how nuclear engineer Rahul Mandal used his knowledge of physics, chemistry and biology to win last year’s Great British Bake Off, turning the Sheffield University researcher into something of a cult hero among TV viewers and amateur bakers alike.

Next up, Michael Banks is on hand to discuss the ding-dong in the physics community this month about the award of a $3m Special Breakthrough Prize to three theoretical physicists who developed the theory of “supergravity” that’s never been experimentally verified – or at least not yet. The prize has polarized opinion and we bring your views on Twitter about so much cash being handed out for this kind of work.

Now if you’re a regular reader of Physics World you’ll know we spend a lot of time reporting about research into graphene — the wonder material made of a single layer of carbon that’s got some eye-popping physical properties. Our materials editor Anna Demming and reporter Belle Dumé is here to discuss new work by researchers in China into a new material called T-graphene that could superconduct without the need for doping at temperatures as low as 20K.

And finally, Anna’s back to talk about the physics behind Simone Biles’ incredible triple-twisting, double somersault at the 2019 US Gymnastics Championships.

Changing the ground (water) rules

In 2014 California introduced the Sustainable Groundwater Management Act (SGMA) into state law to help manage the conflict between ground and surface water. But updating legal structures to accommodate evolving scientific knowledge involves far more than simply rewriting statutes, according to researchers in the US.

“Understanding the interconnections between groundwater and surface water doesn’t make those conflicts go away,” says Dave Owen of University of California, Hastings. “But at least acknowledging those interconnections in law puts legal decision-makers in a position to start managing conflicts, rather than just letting them play out without any legal oversight.”

The Sustainable Groundwater Management Act governs the extraction of groundwater in order to protect beneficial uses of surface water. Before that, an artificial distinction between surface and groundwater meant that, while the use and quality of surface water was monitored by local, state and federal agencies, groundwater was subject only to patchy and inconsistent local oversight.

Extending the law to recognise the connection between ground and surface water should help prevent the effects of excessive groundwater use, including the depletion of lakes and streams, damage to ecosystems, and shortages of irrigation water for farmers. That, at least, is the theory; achieving the aim is more complicated.

Owen and colleagues investigated the challenge of correcting a legal framework that had grown organically from disparate policies and practices.

The researchers talked to experts from state government, academia and non-governmental organizations, to analyse the complex interaction of science and policy. Their analysis should serve as a roadmap for future legislation in California.

To map out the legal landscape that scientists and policymakers must negotiate when considering new legislation, Owen and colleagues created two categories: policy interfaces with written law, and interfaces with institutions and practices.

Difficulties with written law arise because any given piece of legislation has limits to its scope, so its edges cannot help but rub up against existing laws. When current policies conflict with one another, the introduction of additional laws does not always make things more manageable.

In California, for example, water usage rights have traditionally been granted according to both land ownership and historical precedent. The Sustainable Groundwater Management Act does not resolve this discrepancy, so potential for tension and uncertainty still exists, with the added possibility of conflict relating to matters that fall under the new act. What’s more, many parties have considerable interests in sticking with the old ways of doing things.

“Groundwater users generally would prefer to keep pumping without a new source of legal restraint,” says Owen. “After all, they wouldn’t be pumping groundwater if they weren’t making money from doing so. Often their interest is backed by years of investment in farming operations, including, increasingly, growth of perennial crops that can’t just be watered in the wet years.”

Institutional interfaces

The law consists of more than the text that appears in statute books; legal reality is also embodied in the institutions that interpret the law and the agencies that monitor and enforce its application. The success of these bodies often relies on expertise and extensive networks that have developed over time, so they cannot be replaced or repurposed overnight.

Updating a legal system composed of many interdependent parts will always be a lengthy and complex process, and the involvement of parties with mutually exclusive interests means that it will also be fraught with conflict.

Owen and colleagues reported their findings in Environmental Research Letters (ERL).

Square Kilometre Array hit with further cost hike and delay

Plans to build the world’s largest radio telescope, known as the Square Kilometre Array (SKA), have suffered another setback after it emerged that the estimated cost of the observatory has risen by €100m over the past year. Project organizers are confident that the price hike can be met by contributions from new member states, but it is also possible that an already slimmed-down design will be shrunk further.

Once complete, the SKA is expected to consist of thousands of mid-frequency radio dishes spread out across southern Africa and a million low-frequency dipole antennas located in Australia. Given the project’s expected multi-billion Euro price tag, however, its 10 current member states have concentrated on designing a smaller version of the telescope known as SKA 1.

We have 18 months before we plan to start construction activities, and even then we don’t have to have all the funding committed on day one
Philip Diamond

Proposed in 2013, SKA 1 initially envisaged 250 dishes and 250,000 antennas being built so that costs are kept below a cap of €674m. But that design has since had to be cut back twice following price rises, and there could now be additional trimming in the wake of reviews by consortia set up to work on different aspects of the design. In a meeting of member states held at the SKA Organisation’s headquarters at Jodrell Bank in the UK in July, the organisation’s deputy director general Joe McMullin revealed that construction costs for the “design baseline” now stand at €914m (in 2017 prices). A year ago that figure was €814m.

Cost caps

McMullin’s boss, director general Philip Diamond, says he hopes that the capped funding, currently set at €691m, will be provided by the countries who signed a treaty in March to set up an intergovernmental body for the observatory’s construction — Australia, China, Italy, the Netherlands, Portugal, South Africa and the UK – as well as perhaps Canada, India and Sweden. New Zealand announced last month that it was pulling out of the project, and Diamond will not say which of the other members has promised funding. But he points out that the Netherlands recently became the first country to ratify the treaty, describing the mood among members and potential members as “very positive”.

New Zealand pulls out of the Square Kilometre Array after benefits questioned

Diamond says that the single biggest contributor to the latest price hike has been a rise in contingency costs. This is to cover unexpected increases in the cost of steel, fibre and electronic components, for example, which he says had been underestimated by the design consortia. He hopes that the arrival of new member countries, such as Spain or France, will cover the difference between the cost cap and the price of the design baseline, maintaining that there is plenty of time to negotiate terms with new members. “We have 18 months before we plan to start construction activities, and even then we don’t have to have all the funding committed on day one,” he says, adding that construction should be complete by 2028.

Diamond says the project could still go ahead even if all of the funding is not forthcoming, given that the SKA, as he puts it, “is inherently scalable”. Heino Falcke, a radio astronomer at Radboud University in the Netherlands, agrees. He points out that costs can be saved by building fewer antennas or reducing computing power, for example. “Not all of those will kill science cases, but rather may delay them,” he says. “It depends on the magnitude. It is not like you have a fixed launch date, where everything has to be ready and functional – you can and you will expand as you go.” But, he adds: “It still can hurt”.

Timeline: The Square Kilometre Array

2006

Southern Africa and Australia are shortlisted to host the Square Kilometre Array (SKA) beating off competition from Brazil and China. Due to be completed in 2020 and cost €1.5bn, the facility would comprise about 4000 dishes, each 10 m wide, spread over an area 3000 km across

2012

The SKA Organisation fails to pick a single site for the telescope and decides to split the project between Southern Africa and Australia

Philip Diamond is appointed SKA’s first permanent director-general replacing the Dutch astronomer Michiel van Haarlem, who had been interim SKA boss

2013

Germany becomes the 10th member of SKA, joining Australia, Canada, China, Italy, the Netherlands, New Zealand, South Africa, Sweden, the UK

SKA’s temporary headquarters at Jodrell Bank in the UK opens

SKA members propose a slimmed-down version of SKA known as SKA1. With a cost cap of €674m, it would consist of 250 dishes in Africa and about 250 000 antennas in Australia

2014

Germany announces it will pull out of SKA the following year

2015

Jodrell Bank beats off a bid by Padua in Italy to host SKA’s headquarters

India joins SKA

2017

Members scale back SKA again following a price hike of €150m, which involves reducing the number of African dishes to 130 and spreading them out over 120 km

2018

The first prototype dish for SKA is unveiled in China

Spain joins SKA

2019

Convention signed in Rome to create an intergovernmental body known as the SKA Observatory

The Max Planck Society in Germany joins SKA

New Zealand announce it will pull out of SKA in 2020

Simulations guide targeted ablation of atrial fibrillation

Atrial fibrillation – irregular heartbeats caused by abnormal electrical signals from the heart’s upper chambers – is the most common cardiac rhythm disorder. If left untreated, atrial fibrillation significantly increases the risk of stroke and heart failure. The disorder is typically treated using radiofrequency (RF) ablation, in which a catheter inserted into the heart delivers RF energy to destroy the cardiac tissue creating the erratic electrical signals.

To guide this ablation and increase treatment precision, scientists at Johns Hopkins University have created personalized digital replicas of the upper chambers of the heart. These simulations can accurately identify where clinicians need to destroy tissue to restore the heart’s normal rhythm (Nature Biomed. Eng. 10.1038/s41551-019-0437-9).

The standard ablation procedure used to treat atrial fibrillation involves destroying tissue around the atria’s four pulmonary veins, which is where researchers believe the misfiring signals usually begin. However, patients with a persistent form of atrial fibrillation and atrial scarring don’t benefit from this approach. They often have to undergo multiple procedures because abnormal signals keep emerging from new areas of their atria. With each procedure, new scar tissue forms, which changes the atria’s electrical activity and makes targeting of the misfiring areas much harder.

“The personalized digital replicas allowed us to accurately simulate and analyse heart electrical activity and determine where tissue needs to be destroyed,” says Natalia Trayanova from Johns Hopkins University Schools of Engineering and Medicine. “The beauty of working with such replicas is that we could test for and predict where irregular heartbeats persist in ways we never could in the clinic. We ran a mock of the clinical procedure over and over again, until we were sure irregular beats will not re-emerge.”

The new approach – called optimal target identification via modelling of arrhythmogenesis (OPTIMA) – reconstructs computational models of the atria from a patient’s contrast-enhanced MRI scans, thereby personalizing the ablation procedure for each patient. As the targets are calculated offline before the clinical procedure, the approach avoids lengthy invasive mapping of the patient’s atrial electrical activity. The technique has the potential to eliminate the process of trial-and-error in treating persistent heart rhythm disorders and to prevent repeat procedures.

Clinical feasibility study

To demonstrate the feasibility of OPTIMA in patient treatments, the team used it to guide ablation in 10 patients with a persistent form of atrial fibrillation and atrial fibrotic remodelling. The researchers used the patients’ late gadolinium enhancement MRI scans to create personalized digital replicas of the diseased atria. For each model, they ran initial simulations to predict erratic electrical signals and where tissue should be destroyed. Because each ablation reconfigures the atrial electrical activity and can create new arrhythmias, they performed virtual ablations until no new arrhythmias emerged.

The researchers then took the final map of tissue target areas and imported it into the clinical system for catheter navigation. Physicians then steered the catheter towards not only the tissue that currently causes errant electrical firing, but also towards tissue that will cause misfiring in the future, as predicted by the simulations. The entire process, from obtaining an MRI to displaying the final map in the operating room took less than a week. In the future, the team hopes to shorten the entire process to a day.

The researchers note that atrial fibrillation did not recur in any of the patients after more than 300 days of observation. Out of the 10 patients, only one returned for another ablation, for a simpler atrial arrhythmia.

“I’m very optimistic that this personalized simulation-driven approach will prove to be the missing link needed to markedly improve catheter ablation outcomes in patients with more advanced forms of atrial fibrillation,” says Hugh Calkins from Johns Hopkins Medicine. “This new approach may transform the current approach to catheter ablation of atrial fibrillation.”

The proof-of-concept study provides a promising step towards simulation-driven treatments and sets the stage for the team’s FDA-approved clinical trial, which is slated to begin later this year.

Flawed narratives

Remarkable mind: Hypatia is one of the few female scientists covered in *The History of Science in Bite-sized Chunks*. (Courtesy: Jules Maurice Gaspard)

“Different branches of science explore literally everything in the universe, from its origins to its tiny particles, from the human body to rocks and minerals, and from the power of lightning to invisible forces such as X-rays, radioactivity and gravity.” Reading this excerpt from the introduction to Nicola Chalton and Meredith MacArdle’s recently republished book, The History of Science in Bite-sized Chunks, I find myself almost wishing I were able to juxtapose my thoughts on this work with a similar review by my younger self. As a pale, bespectacled, bookworm of a child, I had a voracious appetite for broadly pitched popular-science books. Back then I would have enjoyed poring uncritically through this dense yet accessible volume of facts – yet I am now left wondering whether this is a book I am able to unreservedly recommend.

The volume must first be credited with the easy manner in which it synthesizes past and present snippets from across the diverse breadth of sciences. Although the back cover’s claim that the book touches upon “all the key discoveries and remarkable minds in each scientific field” may be inherently unrealistic, Chalton and MacArdle maintain a good flow throughout, with each covering a broad scientific area, from physics and chemistry to geology and metrology. I particularly enjoyed the section on third-century Egyptian scholar Hypatia, and that on Ahmed Zewail, inventor of the field of femtochemistry, both of whose work I was (one is ashamed to admit) previously unfamiliar with. There are also many enchanting anecdotes sprinkled throughout the pages – my favourite being René Descartes’ quip that Blaise Pascal, who had recently proved the existence of vacuums, “has too much vacuum in his head”.

While the narrative of science forges on in reality, the book comes to an oddly abrupt end, wrapping up with a summary of the current state of climate research, with little to guide the reader forward from this point. For the physicist, also, the section describing Schrödinger’s cat seems almost to muddle the thought experiment’s intended purpose with more recent interpretations of quantum mechanics. Meanwhile, it seems disingenuous and Western-centric to refer to US geographer William Morris Davis as the originator of geomorphology, only 14 pages after describing medieval Chinese polymath Shen Kuo as the first to hypothesize how land structures formed.

The real issue with the volume, however, stems from how Chalton and MacArdle have handled that fact that the effort to relay the “big names” in science inherently draws into stark focus the regrettable and long-running gender bias in the whole enterprise. The book does not shy from noting the impact of other social factors on the history of scientific knowledge – for example, the persecution of Jewish researchers in Nazi-occupied territories. Yet it is conspicuous in its decision not to directly acknowledge the gender-bias issue or make more effort to highlight the contributions of women to science.

There are certainly prominent names absent from this volume – what of seismologist Inge Lehmann, discoverer of the Earth’s solid inner core; palaeontologist Mary Anning; primatologist and life-long conservationist Jane Goodall; or pioneering computer scientist Grace Hopper? It is especially sad to see a good proportion of the women who do appear in the book reduced to cursory mentions at the end of a section devoted to their male counterparts. Such pioneers as Ada Lovelace, Lise Meitner and Candace Pert could surely have filled a few paragraphs on their own merit. With this built-in flaw in mind, one wonders if, perhaps, it was in anticipation of such criticism that the book was rebranded from its previous and more problematic title: The Great Scientists (in Bite-sized Chunks)?

2019 Michael O’Mara Books 224pp £7.99pb

Does our energy future hold electrification, biomass and hydrogen?

In its latest “energy outlook” report, Bloomberg New Energy Finance says wind and solar photovoltaics (PV) will supply almost 50% of global electricity by 2050. Wind, it projects, will produce 26% and solar 22%, with renewables overall supplying 62% of the total. That’s despite electricity demand by 2050 increasing 62%, resulting in global generating capacity almost tripling. Nuclear will then be at 7% and fossil at 31%, according to this outlook, so renewables will clearly have won — although emissions from the fossil sector will still rise.

IRENA, the International Renewable Energy Agency, is more optimistic. In a new report it says renewables and energy efficiency, boosted by electrification, could provide 90% of the necessary reductions in energy-related carbon emissions to limit the global rise in temperature to well below 2°C by 2050. Renewables can supply 86% of global power, and with electrification, they would provide 75% of the emission reductions needed. It sees electrification as a vital part of all this, especially since it can help balance variable renewables: “Clean electricity will be the principal source of power, combined with ‘smart’ digital technologies that make it possible to take full advantage of the growing amounts of low-cost renewable power”.

Electrification ahead

“In a highly digitalized future with strong global climate policies, electrification of energy services will be pervasive,” says IRENA. “Electric or fuel cell vehicles would largely replace fossil-fuelled cars and trucks, and heat pumps and electric boilers would substitute for oil and gas furnaces in buildings and industry. Electricity from renewables could also be used to make hydrogen, synthetic gas or liquids for applications where direct electrification is difficult.”

The IRENA report looks at how this mostly variable input can be managed, with case studies from front runners China and Germany and also Italy, examining how grid balancing has been achieved. IRENA says flexibility is the key and “emerging innovations are not only further increasing flexibility on the supply side but are now also widening the availability of flexibility to all segments of the power system, including grids and the demand side”.

However, there is still a way to go. It is not just about shortfalls, for example. All too often the only option when there is too much power is curtailment — dumping it. That’s a big issue in China. But China is dealing with it, with strategies such as improved grids: curtailment levels at wind farms dropped to 7% in 2018 from 13% the year before, while at solar PV plants curtailment dropped to 3% from 5.8% over the same timescale. In terms of meeting peak loads, China has, less appealingly, retrofitted old coal plants to reduce minimum load levels. This, IRENA says, “turned out to be the most feasible approach to add flexibility in the short-term due to lower lead-times and lower costs compared to investing in open-cycle gas turbines or pumped storage”. Germany has mostly done something similar, while it waits for the (delayed) upgrade of its grid system. But what’s also needed there and elsewhere is full smart-grid demand-management and more storage, including of “Power to Gas”-derived hydrogen (P2G). IRENA looks to smart digital technologies, which it says “promise greater system flexibility, permitting maximum use of low-cost renewable power, including for transport”, along with new applications such as charging of electric vehicles and renewable-based production of hydrogen. But it also mentions frequency/voltage support systems, as provided by Italy’s synchronous condensers, used in Sardinia.

Not just electricity?

The emphasis on electrification, and balancing via power grid-linked systems, is understandable. In IRENA’s vision, there will be a lot of green power available, much of it variable, and some of the balancing options are electricity based — supergrid power imports and exports, for example. But not all of them are. Apart from batteries, in which electricity creates chemical charge for short-term storage, and pumped storage, using power to create potential energy by pumping water uphill to a hydro reservoir, most longer-term storage systems rely on converting electricity to more easily stored heat or gas. It could be that heat and/or green hydrogen storage will become significant options for balancing — hydrogen via huge underground cavern stores and heat via giant hot water or hot rock stores. Some pilot projects are underway for heat storage, for example in Germany, looking ultimately to GWh-scale systems, and also for hydrogen, with a P2G-linked underground storage system in the UK.

What’s more, we are not necessarily limited to using renewable electricity for the input energy. Solar heat can have significant potential. Geothermal and biomass heat likewise. This heat can be sourced and used direct, locally. But, if need be, heat can be transmitted some distance from source to user or storage facility, without major losses. The district heating network in Prague, for example, is supplied with heat from a waste-to-energy plant 65 km away. That said, if we want to transmit energy longer distances, then gas, in pipes, makes more sense, using biogas in addition to P2G hydrogen. There can be the issue of gas leakages, as I discussed in an earlier post, and Berkeley in California recently even banned the use of gas in new buildings. But that’s all about fossil methane (and shale gas), not hydrogen or green gas. It would be unfortunate if the green gas piping/use option was blocked in the US – P2G conversion is just picking up there.

Hydrogen or biomass?

Green gas transmission might be superior to power grid transmission in some situations, and green gas can help with balancing, but will there be enough green gas — biogas and synthetic hydrogen — to transmit and then use? The World Energy Council (WEC) recently surveyed views on hydrogen, including P2G “green hydrogen” and synfuel P2X derivatives, and is quite hopeful. The Council sees hydrogen production expanding significantly and says that “hydrogen producers using electrolysis all mentioned technology maturity and falling costs as recent key developments. Combined with imports, the economic fundamentals of P2X may be about to change”. So the organization reckons hydrogen and derivatives, produced using renewable sources, may well have a bright future in some sectors. WEC sees around 47% of these sources being used for transport by 2040, 18% for balancing, about 13% each for power and heating and 9% for industry. Hydrogen is also seen as a key new option in a new IEA report, and featured heavily in the recent G20 summit in Japan, which is pushing hydrogen strongly. “The cost of producing hydrogen from renewable electricity could fall 30% by 2030 as a result of declining costs of renewables and the scaling up of hydrogen production,” says the IEA. A new report from Stanford University is also optimistic about hydrogen economics.

By contrast, although the potential biomass resource is very large, there are environmental constraints on biomass as an energy source, most obviously land-use conflicts. The use of wastes apart, biomass is a land-, and water-, hungry option. Biomass use faces impact issues in nearly all sectors, for example with the use of forestry-derived wood for power production and growing biofuels in vast palm oil plantations for vehicle fuel. What’s more, the value of biomass as an energy source is fundamentally limited by the very low efficiency of plant photosynthesis. As Stanford’s Mark Jacobson says, wind, water and (direct) solar power technologies use much less land and represent far better choices for power production, the only exception being the use of waste.

However, for heat production matters may not be so clear. Biomass, and biogas, are storable, a big advantage for the inevitably variable-demand heating sector. And the use of biomass/biogas as a storable fuel for back-up/peaking plants and for Combined Heat and Power (CHP) plants, linked to large heat stores, offers a valuable, flexible balancing option. With CHP, the ratio of heat to power output can be varied to match varying heat and power demand and varying green power supply. That may give biomass an edge.

Some optimists think that, despite the problems, biomass can also do well in many other applications — and should be pushed hard. Fatih Birol, IEA executive director, believes biomass is a vital part of the mix. “Modern bioenergy is the overlooked giant of the renewable energy field,” he says. “Its share in the world’s total renewables consumption is about 50% today, in other words as much as hydro, wind, solar and all other renewables combined.” And the IEA says that biomass will continue to lead growth in renewable energy consumption to 2023, due to its rising use in the heating and transport sectors. We shall see. But the UK’s Renewable Energy Association says that bioenergy is currently the largest UK renewable: supplying 7.4% of primary energy, 11% of electricity, 4% of heat, 2% of vehicle fuel. The association insists that expansion is vital to meet climate targets and looks to bioenergy supplying 15% of UK heat, power and transport energy by 2032. Some environmentalists won’t agree.

Microspheres create retroflective material that changes colour

Physicists in China and the US have created a retroflective material from uniform microspheres that are partially embedded in a sticky transparent film. The team, led by Limin Wu at Fudan University in Shanghai, showed that the highly tuneable film can be made to display different colours depending on the motion of an observer. The researchers believe their material could allow for road-safety improvements benefiting both drivers and pedestrians.

From butterfly wings to photonic crystals, a wide variety of both natural and artificial materials exploit nanometre or micron-sized structures to create vibrant “structural colours” when illuminated.

Recently, physicists have attempted to use such materials to create smart displays. This has been a significant challenge, however, because structural-colour materials have long-range periodic order. This means that the perceived colours change according to the angle at which a material is observed – an effect called iridescence. As a result, such displays could only be viewed within a limited range of angles.

Wider viewing range

A wider viewing range can be achieved by using structures with shorter-range order, but these tend to be darker and the colours less saturated, making them unsuitable for displays.

Wu’s team propose a solution that employs structural retroflective materials, which reflect light back towards its source regardless of the angle of incidence. In their study, the researchers created such a material by partially embedding a monolayer array of polymer microspheres in a sticky layer of transparent tape.

Within this structure, thin-film interference occurs at the sphere-film interface when the material is illuminated. Combined with the differences in total internal reflection occurring on the embedded and unembedded portions of the sphere surfaces, the effect allows the team to achieve highly-tuneable structural colouration in the retroflected light.

Moving illumination

Wu and colleagues demonstrated the capabilities of their material by using it to coat a speed limit sign, and to create roadside markers. When illuminated with a uniform white light, the material can be tuned to be reflect light of different colours in certain directions. This is done by varying the diameters of the spheres. This means that while the colour of the objects remains stable from the perspective of a driver in a fast-moving car, the combined illumination of a static white-light source and moving headlights causes them to flicker when viewed by a pedestrian.

The team believe their material could soon be used to create smart road signs that deliver colour-coded signals to night-time drivers, while alerting pedestrians to fast-moving vehicles.

“If a person is listening to loud music or isn’t paying attention while they’re walking or driving, a colour-changing sign can help to better alert them,” explains team member Qiaoqiang Gan of the University at Buffalo, New York.

By studying more sophisticated film structures, the team hopes to develop materials for applications including advertisement displays, window coatings, anti-counterfeiting technologies, and novel forms of artistic decoration.

The research is described in Science Advances.

Electricity-free cooling material system shows potential

July 2019 was the hottest month on record worldwide, according to the National Oceanic and Atmospheric Administration.

“If you put all of the Julys for the last 20 or 40 or 100 years, there’s a clear trend upward. That’s the concern — that long-term trend. Not a single day or single month in particular,” Michael Allen, a climate scientist at Old Dominion University, told TIME.

This upward trend means an increase in the demand for air conditioning worldwide. Already, the US Department of Energy estimates that air conditioning alone consumes almost 15% of electricity in buildings across the country. In warmer countries like Saudi Arabia, air conditioning consumes 70% of all electricity consumption.

To meet global demand for cooling sustainably, researchers at the University at Buffalo have developed a device that could cool buildings without electricity.

Harnessing Earth’s natural cooling power

The system combines a polymer and metal film to harness the power of radiative cooling, the process by which a body loses heat by radiation. On Earth, radiative cooling occurs via the emission of infrared light to counteract the absorption of visible energy from the Sun. However, so far technologies aiming to exploit this process have only been tested at the laboratory scale using noncommercial photonic materials.

As a commercially viable alternative, the researchers fabricated their thermal emitter from polydimethylsiloxane (PDMS) and either silver or aluminium. The PDMS film absorbs heat from the environment and then transmits the heat to cool down its surroundings. The metal reflects the solar light to prevent the transmission of sunlight to materials under the emitter, such as a roof.

While silver has shown better performance than aluminium, aluminium is far less expensive to purchase for fabrication. PDMS is also commercially available and amenable to fast, solution-based roll-to-roll processing, making the entire device much more cost-efficient than existing radiative cooling technologies.

Outdoor experiments performed in Buffalo, NY, to test the device provided cooling of up to 9 °C. Their success stems from the ability of PDMS thin films of over 100 micrometres in thickness to strongly emit in the 8 to 13 micrometre range while absorbing less than 10% of sunlight. At this thickness film roughness has little impact on the film’s performance, making the films suitable for cheaper fabrication processes.

Designed to meet demand

According to the researchers, building designs have taken advantage of radiative cooling for decades. Most conventional radiative cooling techniques, however, naturally succeed at night, although cooling demand peaks during the day. The researchers therefore housed their emitter in a shelter to provide exceptional cooling despite the presence of sunlight. They coated the surface of the shelter with a spectral-selective absorber material to optimize absorption of solar illumination at its surface while efficiently reflecting all thermal radiation from the emitter. In addition they designed the shelter as a tapered wave guide that absorbs incident sunlight at a wide range of angles, as well as collimating and confining md-infrared waves to give rise to a beaming effect. So, on top of blocking daylight, the shelter also directs emissions upward rather than in all directions.

Their design lessens the surrounding environment’s ability to hinder the emitter’s cooling performance. It also allows this novel device to be implemented in urban settings where surrounding buildings would otherwise absorb the diffusely scattered heat.

“This enables the system to be more effective in urban environments, where there are tall buildings on all sides,” Qiaoqiang Gan, an associate professor of electrical and computer engineering at the University at Buffalo, said in a university press release.

The team acknowledges there are additional issues to address before commercialization is feasible. Adjusting the shelter to better protect the emitter, for example, is key to improving efficiency. While the polymer material used is durable, more studies must be done to understand its lifetime during implementation.

More details can be found in Nature Sustainability.

From humble beginnings

What do Apple, Amazon, Microsoft, Hewlett Packard and Google have in common? Answer: they’re all billion-dollar businesses that started life in someone’s garage. Indeed, three of them have gone on to become the first trillion-dollar companies. So what can we learn from them and is it a coincidence that they all have a garage in common?

Apple is the company that I’m most familiar with, not least because I’ve watched various films and documentaries about the life of its co-founder Steve Jobs. Apple started out in California in 1976 when Jobs and his friend Steve Wozniak designed the first Apple I Computer for $500. When a local retailer in Mountain View – the Byte Shop – asked for 50 computers, the two entrepreneurs got all the parts and put together the 50 machines in 30 days. Famously, they did the work from inside Jobs’ parents’ garage in Los Altos, California. (When I lived there, I confess I drove past and took pictures.)

In August 2018 Apple became the first company to have a market capitalization of $1 trillion and was joined in this elite club by Amazon shortly after. Amazon was started by Jeff Bezos in 1994 initially as an online bookstore, operating from a garage in the Bezos’ family home in Bellevue, Washington. It took almost an entire year for Amazon to sell its first book, but the firm soon started to grow exponentially. For better or worse, it has revolutionized the bricks-and-mortar high street.

The third trillion-dollar company is Microsoft, which was founded by Bill Gates and Paul Allen in 1975 – again in a small garage, where the pair had few resources to work with. What the founders did have in abundance, though, were strong programming skills and by 1980 Microsoft had entered the operating-system business with its own version of Unix. The firm’s development of MS-DOS – and a contract with IBM in the early 1980s to provide an operating system for IBM’s upcoming Personal Computer – put Microsoft on the fast track to success.

Perhaps the next trillion-dollar company is being built in a garage near you

As for Hewlett Packard, it started out as a small technology club called “Silicon Valley”, founded by Bill Hewlett and Dave Packard in a rented garage in 1938, just 10 miles from the Jobs house. Initially producing electronic test equipment, it was, for several decades, one of the world’s largest computer manufacturers. And given that Google was started by Larry Page and Sergey Brin in YouTube chief executive Susan Wojcicki’s garage in 1998, maybe the question we should ask is: who can afford *not* to set up their business in a garage?

Into the garage

The beauty of a garage is that it keeps overheads low. There’s usually no rent to pay if your family already owns the premises. A garage is the ultimate, low-risk, minimal-damage environment, where you can try things away from prying eyes without having to explain yourself. A garage gives firms time to put themselves on a sound commercial footing before moving to somewhere more permanent.

But is a garage really the right place for “deep-tech” businesses – those that have physics (rather than circuits or software) at their core? I doubt it would be the right place for, say, a nuclear company. Still, there are many success stories from such humble beginnings for physics-based companies, including from garden sheds. That’s where Martin and Audrey Wood set up Oxford Instruments while living in north Oxford in 1959. It’s now a massively successful scientific-equipment manufacturer.

These days, with so many resources available online, being in a garage or shed is even easier. There are websites like eBay to source equipment and parts. Skilled specialists can be hired from anywhere around the world as short-term freelancers through sites like Upwork, Freelancer and Fiverr. And there are countless cloud-based design tools for CAD, circuit design and mathematical modelling – all available on a pay-as-you-go basis or even free. Knowledge is so accessible and searchable too.

Of course, nothing can replace the drive, determination and ideas of the entrepreneurs who’ve had the guts to set up their own businesses.

Mentors and money

Not everyone needs advice, but it can help. Surely it’s better to have a friendly mentor iron out the problems with your business plan before you seek funding – rather than having all the embarrassing flaws pointed out by an investor when the opportunity might have slipped through your grasp. But how can you afford the advice and experience in the first place? How, in other words, do you grow or fund your business so you have enough money to pay for the advice you need, mentoring from investors and board members. How do you get an experienced and well-rounded management team?

Fortunately, there is a huge range of incubator and mentoring programmes offered by universities, all following tried-and-tested approaches, to help wannabe business leaders of the future. Even our beloved Institute of Physics has launched an attractively priced incubator scheme of its own. As well as offering space to small companies at its new headquarters in King’s Cross, London, the scheme gives firms access to its business accelerator programme and an extensive network of members and fellows (beta.iop.org/iop-accelerator).

So who knows? Perhaps the next billion-dollar or trillion-dollar company is being built right now in a garage near you. And, if not a garage, maybe it’s in a hi-tech incubator somewhere.

Got a great story about how you started a business? E-mail the Physics World editorial team at pwld@ioppublishing.org

Intelligent 3D scanner helps diagnose skin cancers

3D skin mapping — Three dimensional imaging of a nevus (a) and a melanoma (b). Top: height maps and 3D views of the surface after image processing; bottom: mean profiles of each lesion. (Courtesy: *Biomed. Opt. Express* 10.1364/BOE.10.003404)

Skin cancer is the most common type of cancer in the world, requiring tens of thousands of surgical biopsies of suspicious lesions. According to the World Health Organization, two to three million non-melanoma and 132,000 melanoma skin cancers are diagnosed globally each year.

A noninvasive tool that can distinguish benign from malignant cutaneous lesions could help limit the need for biopsy to only highly suspicious lesions. This could reduce the number of biopsies performed and potentially significantly reduce the cost of skin cancer diagnosis.

Researchers from Spain have now developed a 3D scanner, based on fringe projection and machine learning, that shows potential as an in vivo skin cancer detection device. The prototype system obtains morphological parameters of skin lesions related to area, volume and perimeter with micrometric precision and can distinguish between melanomas and moles. By quantifying the volume and shape of the lesion, its capabilities extend beyond the conventional qualitative palpation used by dermatologists (Biomed. Opt. Express 10.1364/BOE.10.003404).

Fringe projection can be used to acquire quantitative information on surface heights of skin in several seconds, creating a height map that can be used to help detect non-melanoma skin cancers. High-resolution digital cameras, economically priced real-time frame grabbers and powerful image processing software have made this a viable technology to analyse skin topography.

Led by Santiago Royo and Meritxell Vilaseca Ricart, a team of researchers at the Universitat Politècnica de Catalunya designed a compact handheld prototype incorporating two monochrome CCD cameras and a Pek3 picoprojector. These create an image of a fringe pattern on the skin, which is moved horizontally during acquisition. Upon completion, the patient’s skin is illuminated with a uniform white field and a colour image is acquired. The three camera images are then calibrated, and undergo image processing to create point-wise height maps. A machine learning-based classification system then identifies the types of lesions.

Clinical testing

For the validation study, the team examined patients with a total of 654 skin lesions who had dermatology evaluations at the Hospital Clinic i Provincial de Barcelona and the Università degli Studi di Modena e Reggio Emilia. Royo told Physics World that the researchers enrolled patients who came for treatment and that they represented an overwhelmingly older Caucasian population.

While 608 lesions were in body locations that could be measured with the 3D scanner, only 194 (32%) could be analysed, due to micro-movements, inaccurate hair removal, and/or locations outside the system’s field-of-view. The authors reported that 43% of these lesions were cancerous: 31% melanomas, 9% basal cell carcinomas and 3% squamous cell carcinomas. The remainder were benign nevi and non-nevi lesions. The scanning system achieved 80.0% sensitivity and 76.7% specificity.

“In our pilot, we analysed all suspect lesions, which were subsequently confirmed by histology. It was unfortunate that there were so few squamous cell and basal cell carcinomas in this population,” says Royo. “It would be interesting to add more of these lesions to improve the specificity regarding these two cases, and to better separate them from melanoma. We are currently applying for funds to conduct this type of research.”

The team also hopes to extend the research to evaluate skin lesions on persons of colour, both African and Asian, which could be achieved by adjusting the intensity and contrast of the projected fringes.

“Our next goals are extending the study to improve the training network, and to combine the information with other sensors to get multiple inputs, which include live flow measurements using optical feedback interferometry and multispectral imaging,” says Royo. “We would also like to extend the technology to other diseases, in particular other types of cancer and illnesses related to blood flow abnormalities.”

Browse articles by content type

The physics of baking, the controversial $3m prize and the new, new wonder material