By Michael Banks
Avid readers of this blog may remember the 560-piece LEGO model of CERN’s ATLAS detector at the Large Hadron Collider (LHC), which was built by particle physicist Sascha Mehlhase of the Niels Bohr Institute in Copenhagen.
Not to be outdone, LEGO fan Jason Allemann then created a LEGO-inspired particle accelerator – dubbed the LEGO Brick Collider – that was submitted to the LEGO Ideas site, which lets fans share blueprints of their own models.
Those of us who have lived through the past two or three decades cannot help but be amazed by the revolutionary transformation of communications, both in scientific research and in everyday life. But how does one convey this defining phenomenon of our time in a museum exhibition? After all, the fascination of computers and mobile phones lies mostly in what their software can do, rather than in the external appearance of the hardware – despite the endless efforts of designers and advertisers to persuade us otherwise.
This was the problem the Science Museum in London faced when planning its permanent new gallery on “The Information Age” and in compiling the general-interest book (published under the same title) that acts as a companion to the exhibition. As Tilly Blyth, the museum’s keeper of technologies and engineering, confesses in the book’s introduction, “There is something fundamentally contradictory and incongruous about ‘capturing’ or ‘displaying’ the information age in a museum. What is the meaning of displaying an information machine, if the information it carried or processed cannot be seen?” By way of analogy, observing the players in an orchestra is a lot less satisfying for an audience than hearing them play music.
Both the exhibition and the book solve the problem brilliantly, though, each in a way that suits its medium. The exhibition displays 19th-century, 20th-century and near-contemporaneous objects (including a model of an Apple computer I discarded only in 2010!), mixed with information that moves, speaks and sometimes interacts with the viewer via screens, soundtracks and computer keyboards. The book, for its part, offers easily readable and authoritative text written by Blyth, her fellow curators and several outside contributors, including the journalist Tom Standage writing on telegraphy (a technology he dubbed “The Victorian Internet” in his 1998 book on the subject); David Attenborough on the introduction of colour television; and entrepreneur Mo Ibrahim on the spread of mobile-phone networks in Africa. Their words are illustrated throughout with numerous, well-chosen colour photographs of such ravishing three-dimensionality that some readers will feel like running their fingers over the wires of the first transistor (admittedly a replica) or warming their hands with the heat of thermionic valves. (But let’s not become sentimental and nostalgic about childhood electronics…)
Both the exhibition and the book cover the last two centuries of information technology by dividing the period into six thematic sections (hence the reference to “six networks” in the book’s subtitle). The first section, “The Cable”, covers electric telegraphy, invented in the 1830s; the second, “The Broadcast”, is about radio and television; the third, “The Exchange”, concerns telephony; the fourth, “The Constellation”, deals with satellite communications; the fifth, “The Web”, investigates computer networks; and the sixth, “The Cell”, is devoted to mobile and cellular networks. In each instance, the science behind the technology is explained (albeit more fully in the exhibition than in the book) along with its impact on society.
One persistent theme that emerges is that new technologies can require a long time to find their way in the world. For example, the tele-phone took until the 1970s – some 80 years after its commercial introduction into Britain – to realize its potential “to ease domestic isolation and sustain British women’s relationships with family and friends”, as historian Lucy Delap observes in her essay “Women and the ‘tele-phone habit’?”. Indeed, when the tele-phone was invented in the 1870s, it was initially regarded not as an altogether new technology but rather as an improvement of the electric tele-graph; Alexander Graham Bell’s 1876 patent on the telephone was entitled “Improvements in Telegraphy”. In a letter to potential British investors, Bell argued that “All other telegraphic machines produce signals which require to be translated by experts, and such instruments are therefore extremely limited in their application. But the telephone actually speaks.”
Almost as surprising is that the scientists and engineers who founded the computing industry between the 1940s and 1960s did not foresee that personal computers would be useful to white-collar workers in offices; that vision arrived only in the mid-1970s with the founding of Apple and Microsoft. Lasers are not part of the book, but I was nevertheless reminded of how they were regarded as potentially useless for several years after their invention in the 1960s. Colleagues famously used to tease Charles Townes, one of the inventors, by calling the laser “a solution looking for a problem”. As Townes admitted some four decades later, “The truth is, none of us who worked on the first lasers imagined how many uses there might eventually be.”
Often, of course, the barrier to a technology’s establishment is an economic one. In “Connecting Africa”, Ibrahim – who was born in Sudan, but trained as an engineer in Britain with what was then British Telecom – writes of the impossibility of raising international finance for telephony in Africa in the 1990s, because of the continent’s reputation for genocide, dictators and famine. But in the end, he notes, this failure had an upside: “The failure to build robust fixed-line networks enabled African countries to leapfrog that technology and land firmly in the mobile age.”
The book’s only serious weakness might be said to be terminological, rather than technological. Exactly what do we mean by “information”? James Gleick, author of The Information, takes up the challenge of defining this slippery concept in his introductory essay “Information: the blood and the fuel, the vital principle”. He deals well with how Claude Shannon mathematized the hitherto vague concept of information in the late 1940s, but then takes refuge in a hyperbolic comment by quantum theorist John Wheeler (of “It from Bit” fame): “What we call reality arises in the last analysis from the posing of yes/no questions.” He also aptly informs the reader that “hardly any information technology becomes obsolete”, citing the earliest information technology of all, written language, which remains crucial to communication. But then he seriously misleads by claiming that “The first code of all – the one that gave birth to all the rest – is the one we take for granted: the alphabet.” Not only were the most ancient writing systems – the decidedly non-alphabetic Mesopotamian cuneiform and Egyptian hieroglyphs – invented a millennium and a half before the first appearance of the alphabet in Palestine, some current writing systems, such as those of China and Japan, did not originate from the alphabet.
That said, it is heartening to find the Science Museum and its publisher Scala still investing substantial money, time and expertise in an information technology that is so many centuries old. The Information Age is a book that will undoubtedly “inform, educate and entertain” – in the famous phrase of the first director-general of the BBC, John Reith – for many years to come.
Has anyone ever asked you to explain physics “in terms your grandmother would understand”? If so, did you ever stop to think that this might be just a tad unfair on those grandmothers who have, say, several scientific diplomas squirrelled away in their attics, or who started programming computers back when it involved vacuum tubes and punch cards and actual bugs crawling in and shorting out connections, so don’t you come to me complaining about the battery in your smartphone, young lady, I mean, honestly, kids these days, tcha! Grandma Got STEM is a blog that collects and disseminates the stories of women like this, with the goal of inspiring the next generation and countering assumptions about the kinds of people who “get” science and technology.
The blog’s founder and editor is Rachel Levy, a mathematician at Harvey Mudd College in California, US. She started Grandma Got STEM after becoming frustrated at the casual (but usually not malicious) ways that older people, especially women, are stereotyped as being unable to understand complex concepts in science, technology, engineering or mathematics (STEM). Most of the blog’s entries are written by other contributors, who are often children, grandchildren or colleagues of scientifically minded women. Occasionally, the “grandmas” themselves contribute first-person accounts of their careers and experiences in science.
There are a few well-known names in the mix, including the physicists Lise Meitner and Maria Goeppert-Mayer and the crystallographers Dorothy Hodgkin and Rosalind Franklin. However, the real strength of Grandma Got STEM is the way it brings recognition to dozens of women who had perfectly ordinary scientific careers – ordinary, that is, except for the fact that they worked in fields that were (and in some cases still are) heavily dominated by men. A good example is an entry written by Gizem Karaali, a mathematician at Pomona College in the US who counts two STEM-savvy women among her forebears. One of them is her mother, Artemis Karaali, a chemical engineer and food scientist who recently retired from Istanbul Technical University. The other is her paternal grandmother, Selma Karaali, who earned a PhD in optics and spent most of her career as a physicist at Ege University in Izmir, Turkey. Karaali describes her grandmother as “the smartest woman I ever met” and recalls spending afternoons working with her on geometry proofs as a schoolgirl. When she took the proofs to class the next day, Karaali recalls, “if there were no volunteers to put the solution on the board for the problem, my teacher would ask: ‘So Gizem, what has your grandmother to contribute to this discussion?'”
A few of them aren’t – at least, not in the strict biological sense. One of the other physicists featured in the blog is Elizabeth Rona, a Hungarian-born nuclear scientist who worked with Frédéric and Irène Joliot-Curie in Paris in the 1920s and later on the Manhattan Project in the US. Rona never married and had no children, but the author of her entry on Grandma Got STEM, retired physicist Carl Helrich, remembers her as “a grand old lady of nuclear physics” and an inspiration to him and many other scientists at Oak Ridge National Laboratory, where she spent her later career.
Of course! Grandma Got STEM is a collaborative project and Levy welcomes contributions from anyone with a story to tell about inspiring older women who work, or used to work, in a STEM field. If you like the idea, but can’t think of anyone to interview, check out Levy’s post from December 2014, which includes some tips about selecting interviewees and deciding what questions to ask them. She is particularly keen to get students to become “junior reporters” for the site by interviewing women in their own families or communities (it would make a great class project for almost any age group), and she is also trying to make the blog more geographically diverse, as the “grandmas” featured in it currently hail from only a handful of countries. Finally, it must be noted that there aren’t many physicists yet in Levy’s list of STEM-friendly grandmas. Surely this is a problem that Physics World readers can help solve?
Scientists in the US have made the first direct measurement of the increase in the greenhouse effect caused by rising carbon-dioxide levels in the atmosphere. Their ground-based observations were carried out over a period of 11 years at two different locations – Oklahoma and Alaska – and show that infrared emissions from carbon dioxide have increased during that time in agreement with theoretical predictions for man-made climate change. Their study also includes the first direct observation of the large annual dip in greenhouse heating that occurs in spring, when there is a sharp increase in the uptake of carbon dioxide by plants.
Much of the near-infrared, visible and ultraviolet light from the Sun passes straight through the atmosphere and warms the surface of the Earth. The warm surface emits infrared light that gets absorbed by carbon dioxide and other atmospheric gases, before being re-emitted in all directions. Much of this emission is downwards, making the surface of the Earth warmer than if it had no atmosphere. The strength of this greenhouse effect is quantified in terms of “radiative forcing” – the difference between the rate at which solar energy is absorbed by the Earth and the rate at which it is radiated back into space.
Although the role of carbon dioxide as a greenhouse gas has been well established by lab experiments, scientists have struggled to measure its effect in the real atmosphere, which contains a mixture of different greenhouse gases, as well as clouds and other weather-related phenomena. Now, however, Daniel Feldman and colleagues at the Lawrence Berkeley National Laboratory and other institutes in the US have used two ground-based Atmospheric Emitted Radiance Interferometer (AERI) facilities to measure how much infrared light is returned to the surface of the Earth from carbon dioxide alone. According to Feldman, the team has also “controlled for other factors that would impact our measurements, such as a weather system moving through the area”.
Feldman and colleagues examined a total of 8300 measurements made in Oklahoma and 3300 made in northern Alaska between 2000 and 2010. They found that radiative forcing by carbon dioxide has increased in both locations at a rate of about 0.2 W m–2 per decade. To put that into perspective, scientists have calculated that the total forcing today caused by human-related carbon-dioxide emissions since the start of the Industrial Revolution is about 1.82 W m–2.
The results agree with radiative-forcing values calculated using CarbonTracker 2011, which is a measurement and modelling system that provides carbon-dioxide concentrations at a regional level. This means the measurements back up predictions that the greenhouse effect is becoming more significant as a result of increased carbon-dioxide emissions from human activities such as the burning of fossil fuels. The results also suggest that current climate models are doing a good job of describing the impact of carbon dioxide on the Earth’s climate.
“Numerous studies show rising atmospheric carbon-dioxide concentrations, but our study provides that critical link between those concentrations and the addition of energy to the [Earth] system, or the greenhouse effect,” Feldman says. His team’s measurements also show the sharp annual drop in radiative forcing that occurs in the spring when plants absorb large amounts of carbon dioxide from the atmosphere. While this effect is predicted by theory, this is the first time the effect of plants has been measured directly.
The research is described in Nature.
The standard approach in the developed world is for people with a vision impairment to visit an optician for an eye test. They are given a prescription, the lenses are produced and they can choose the frames they would like from a shop. In this scenario one relies on the presence of trained opticians and the infrastructure to produce and distribute the required materials. But these are not present in many parts of the world. “Roughly speaking, in parts of sub-Saharan Africa there’s going to be about one optician per million of the people,” says Silver.
To get round this limitation, Silver – who is an atomic physicist at Oxford University – developed a concept in the 1980s for glasses that can be self-tuned to meet an individual’s prescription. The basic idea is that each lens consists of two flexible membranes filled with a liquid. So, by adding or removing fluid, the shape and thus the power of the lens can be adjusted by the individual wearer.
In this podcast, Silver talks about how the first incarnations of his so-called Adspecs have already made a huge difference to individual lives in some parts of the world. But he has also been busy developing the technology to improve the quality and make it more accessible. Silver’s team at the Centre for Vision in the Developing World is now producing an updated version of the glasses called “New Adspecs”, which make it easier for individuals to set their own prescriptions. Some 500 pairs of these were distributed to Syrian refugees in Jordon in 2014. He is also looking to develop new styles of glasses, which could also help to improve the uptake of the technology.
Silver was interviewed by Physics World reporter James Dacey at the UNESCO headquarters in Paris during the opening ceremony of the International Year of Light (IYL 2015). Find out more about that event and some of the other light-based technologies in the spotlight this year in this short film.
Also, don’t forget to check out our free-to-read digital collection of 10 of the best Physics World features related to the science and technology of light, including an in depth article about Silver’s Adspecs initiative.
Astronomers studying the spectrum of a distant quasar have found that the ratio between the mass of the proton and that of the electron is constant – its value 12.4 billion years ago was identical to its value today – with a precision of 10–6. The study is crucial if physicists are to test theories that go beyond the Standard Model, as well as the nature of the mysterious dark energy that is accelerating the expansion of the universe. The results allude to the fact that dark energy – if it exists – has remained unchanged since the universe’s early days.
Using data gathered by the European Southern Observatory’s Very Large Telescope (VLT) in Chile, the team of astronomers, led by Julija Bagdonaite of VU University of Amsterdam, made use of light from a quasar – a distant galaxy powered by a hugely energetic and luminous supermassive black hole – shining through a “foreground” galaxy. In this case, the foreground galaxy itself existed 12.4 billion years ago, at a redshift of 4.22, when the universe was barely a 10th of its current age, while the quasar, at a redshift of 4.42, is even more distant. Molecular hydrogen in the foreground galaxy absorbs the quasar’s light, so that it is possible to detect specific energy transitions thanks to their recognizable spectral features. Should the value of the mass ratio “μ” be different, it would shift the levels of the energy transitions in the hydrogen.
The mass of the proton – 1.67 × 10–27 kg – and the mass of the electron – 9.11 × 10–31 kg – are fundamental constants, along with other supposedly invariable properties such as Planck’s constant, the speed of light and the gravitational constant. The values of these constants cannot be derived from theory; as far as we can tell, they just are. However, some speculative theories that attempt to take physics beyond the Standard Model predict that these constants can change. The presence of scalar fields in the universe – fields with a single mathematical quantity that inhabit every point in space, such as dark energy’s quintessence or the Higgs field – may provide a means for this variance.
“Such scalar fields are likely to interact with fundamental particles such as electrons and quarks, and possibly affect how massive they appear,” says team member Michael Murphy of the Swinburne University of Technology in Melbourne, Australia. “It is possible that scalar fields, including a quintessence field, may cause variations in the fundamental constants, including μ.” The universe spent the first half of its life gradually transitioning from a matter (gravity)-dominated cosmos to a universe dominated by dark energy. Should μ be found to be different on either side of this transition, it would hint at the nature of dark energy. As well as measuring the proton–electron mass ratio, last year Murphy was also part of a team using this method and data from the VLT, Keck and Subaru observatories to search for variations in the fine-structure constant.
In 2013 Bagdonaite and co-author Wim Ubachs, also from VU Amsterdam, were part of a team that constrained any variation in μ to less than 10–7 in a galaxy that existed seven billion years ago, based on energy transitions in the spectra of methanol in interstellar clouds. This is an order of magnitude more precise than the new measurement, but it is much more difficult to make these measurements at higher redshifts. Rodger Thompson of the University of Arizona, who has made previous measurements of μ but who was not involved in the current research, says that the team’s result is very important as “it is the highest redshift limit on the variance of μ that exists”.
The results do not signal the end for unchanging constants. Indeed, Bagdonaite told physicsworld.com that “finding a variation at, say, the 10–9 level would be just as exciting and revealing, and I think that efforts to improve on the current limits will continue”.
The research is published in Physical Review Letters.
By Tushna Commissariat
In a sweeping win for science-themed films at this year’s Oscars, British actor Eddie Redmayne has won the best actor award for his portrayal of the theoretical physicist Stephen Hawking in the film The Theory of Everything. Redmayne, 33, plays Hawking in the biographical film that was inspired by the memoir Travelling to Infinity: My Life with Stephen written by Hawking’s former wife Jane, who is portrayed in the film by the British actress Felicity Jones. The Theory of Everything was also nominated for best picture, original score and adapted screenplay, while Jones was nominated in the best actress category. Redmayne’s success at the Oscars comes after his win in the best actor category at this year’s Bafta awards, which also saw The Theory of Everything pick up best film. The movie chronicles Jane’s relationship with Hawking – from the early days of their courtship to Hawking’s diagnosis of amyotrophic lateral sclerosis at the age of 21 and his success in physics until the two divorced in 1995. I was lucky enough to attend an early screening of the film, and I thought it was a very worthy candidate for the awards season. You can read my review of the film here.
Unexplained discrepancies between mathematical models of the Sun and astronomical observations could be resolved by the presence of dark matter in the Sun, according to the latest work from an international team of researchers. The team’s model – which looks at dark matter that has a particular, momentum-dependent interaction with normal matter – explains the observed data much better than more conventional dark-matter models. The researchers believe that the particles they postulate could potentially be seen either by direct detectors or in particle accelerators.
In recent years, scientists have reduced their estimates of the proportion of elements heavier than hydrogen and helium in the Sun. These new estimates, based on reinterpretations of spectroscopic data, create a problem. When applied to conventional mathematical models of the solar structure, they create multiple conflicts with the values of various quantities that are measured by looking at periodic changes in size of the Sun caused by acoustic pressure waves. This study of the internal structure of the Sun via acoustic waves is known as helioseismology. To resolve these inconsistencies, researchers are seeking new ways that heat can reach the surface of the Sun from its core. One possibility is that the Sun might contain dark matter that it captures as it passes through the galactic halo. Such matter could carry heat from the core to the cooler outer layers of the Sun.
Particle physicists have postulated numerous candidates for dark matter, ranging from weakly interacting massive particles (WIMPs) and axions to supersymmetric particles such as neutralinos. In most of these, the probability of two particles interacting (an interaction cross-section) is independent of the momentum exchanged in such a collision. However, more recently, newer theories have been constructed containing asymmetric dark matter – where dark matter could have its own antimatter counterpart. Some of these models permit an interaction cross-section that depends on the square of the exchanged momentum. Astroparticle physicist Aaron Vincent of Durham University in the UK, together with colleagues at Imperial College London and the Institut de Ciències de l’Espai in Spain, looked at how models of asymmetric dark matter that interacted in various ways with normal matter would affect the relationship between theoretical solar models and observations.
The researchers looked at multiple properties of the Sun measured from various sources, using accepted mathematical models to infer the speed of the acoustic waves throughout the Sun, the depth of the convective envelope and the intensity of neutrinos given off. They compared these values with those predicted first by the standard solar model and then by models that incorporated dark matter interacting with the baryonic (regular) matter in three possible ways. In two of the three ways, the interaction cross-section was independent of momentum, while the third considered a cross-section that was proportional to the square of the momentum exchanged. In each case, they chose parameters, such as the mass of the dark-matter particle, to provide the best possible fit to the observational data.
They found that the model with the momentum-dependent interaction cross-section gave an excellent fit if the dark-matter particle had a mass of about 3 GeV, whereas neither the solar standard model nor the other two dark-matter models could produce anything even remotely consistent with the observed values. Particles where the interaction cross-section shows this type of momentum dependence have a larger mean free path inside the Sun and can therefore transport heat more effectively to its outer layers. Vincent explains that such an interaction would probably not involve one of the four known fundamental forces, saying “this would be some new interaction between dark matter and the standard model”.
Fabio Iocco of the South American Institute for Fundamental Research in São Paolo, Brazil, is impressed. Iocco says that what Vincent and colleagues have accomplished is to take a certain type of dark matter “to try and see if it solves an observational problem, and apply it in a new context which is absolutely well posed – it’s been overlooked for a long time because it’s very difficult to do”.
The researchers hope to develop their model further in forthcoming work. “There’s probably a zoo of different possible particles that would give this interaction, but it’s not clear yet whether any of those would really work when you work out the details,” says Vincent. The team also hopes that forthcoming experimental work at the Large Hadron Collider at CERN and in underground dark-matter detectors such as Super Cryogenic Dark Matter Search (SuperCDMS) will either confirm the existence of such a particle or refute it. “We’re very close to finding out whether this really is an indication of dark matter or whether we have stumbled upon something that mathematically looks like dark matter but is actually something more subtle going on in the Sun,” he adds.
The research is to be published in Physical Review Letters. A preprint is available on the arXiv preprint server.
By Tushna Commissariat
There is nothing quite like a bowl of hot, buttery popcorn – and it seems as if even physicists are enthralled by it as they dig into the pops and jumps of this tasty snack. A recent article in the New York Times caught our attention this week, as it talked about how a French research duo used high-speed video cameras and a hot plate to see just why a kernel of corn not only pops, but also leaps up as it puffs. The team found that as the kernel’s hull is breached, we hear the popping sound and this is swiftly followed by the jump that happens when a puffy bit of the inside pushes out and makes the corn jump, a bit like a muscle twitch. Take a look at the lovely slow-motion video above of individual kernels leaping about like perfect puffy ballet dancers.
Dramatic reductions in the emissions of greenhouse gases are essential to help mitigate the effects of climate change, according to two reports issued last week by the National Research Council of the US National Academy of Sciences. Written by a 22-strong committee, the reports argue that removing carbon dioxide from the atmosphere is the most promising approach to tackle climate change, but conclude that the use of geoengineering to reduce the amount of solar energy that reaches the atmosphere is too risky. That type of geoengineering, the reports state, should instead be restricted to small-scale experiments rather than full deployment.
The reports identify two specific geoengineering approaches that could have a significant impact on the climate: injecting aerosols into the stratosphere – to mimic the effect of large volcanic eruptions – and brightening clouds to make them more reflective. Although these methods are cheaper than removing carbon dioxide from the air and would not require “major technological innovation”, the reports note that any future decisions on managing solar radiation – known as albedo modification – will be judged mainly on questions of risk. Indeed, many of the processes most relevant to albedo modification – such as those controlling the formation of clouds and aerosols – are among the most difficult to measure and monitor. Nor can current observational techniques monitor the environmental effects of the approach.
Marcia McNutt, a former director of the US Geological Survey who chaired the committee, says the fact that scientists are even thinking about using geoengineering to mitigate climate change should be a “wake-up call”. “The longer we wait, the more likely it will become that we will need to deploy some forms of carbon-dioxide removal to avoid the worst impacts of climate change,” she insists.
However, some climate scientists urge the need for caution. “No reputable scientist I know thinks placing tiny reflecting particles in the stratosphere is a good idea, although some support studying it,” says Philip Duffy, president and executive director of the Woods Hole Research Center, an institution that focuses on climate change. Pennsylvania State University climatologist Michael Mann takes an equally sceptical view. “I believe that we should continue to fund studies of geoengineering approaches,” he says, “if only for one purpose: to expose just how dangerous many of these schemes might be.”
Marine geochemist Scott Doney of the Woods Hole Oceanographic Institution, who helped write the reports, thinks that deploying geoengineering – or even carrying out field research into it – is not on the immediate agenda and would require further discussion. “This is not just an academic science conversation, it needs to involve society: NGOs, governments and industry,” he says. “We’re saying that we should not move forward with deployment now – and not with field research until we have more detailed conversations on governance issues.”
