IELTS Academic Reading Practice Test 112

Television did not arrive in a single moment. Its central problem — turning a scene into an electrical signal, sending it along a wire or through the air, and rebuilding it as a picture somewhere else — had been recognised long before anyone solved it. The word television was already in use in the early years of the twentieth century, and inventors in Europe and North America spent decades searching for a practical method. The first systems that worked relied on moving parts; the electronic systems that replaced them depended on a device invented for a quite different purpose.

The scanning principle behind the earliest pictures was patented in 1884 by Paul Nipkow, a German engineering student. His device was a flat metal disc pierced by a spiral of small holes. As the disc rotated, each hole swept a different part of the scene, so that a single light-sensitive cell behind it received a rapid succession of brightness values: in effect, the image was broken down into a line of points. At the receiving end, a second disc turning at the same speed reassembled them into a picture. Nipkow never built a complete television system, and several decades passed before engineering caught up with his idea.

The Scottish inventor John Logie Baird was the first to turn the idea into a working demonstration. Working in a modest laboratory in Soho, London, with equipment assembled from cheap and improvised parts, he used Nipkow discs at both the transmitting and the receiving end. On 26 January 1926 he showed moving images to members of the Royal Institution, and the faces of his subjects were just recognisable. In February 1928 his company transmitted a picture across the Atlantic to New York. Baird's images were crude, flickering and tiny, but they moved, and for a few years television meant his kind of mechanical apparatus.

In 1929 the British Broadcasting Corporation began experimental broadcasts using Baird's system, transmitted late at night after the radio programmes had finished, because sound broadcasting was considered far more important. The pictures contained only thirty lines, so faces were visible but expressions were not. Baird's company sold receivers, known as televisors, to enthusiasts, yet the audience remained small. The Corporation's own engineers were meanwhile examining a rival approach that had no moving parts at all.

The alternative was entirely electronic. In the United States, Vladimir Zworykin, a Russian-born engineer, filed a patent for a television system in 1923 and later developed a camera tube called the iconoscope at the Radio Corporation of America. In San Francisco a young inventor named Philo Farnsworth produced the first all-electronic image in September 1927: a single horizontal line. His camera tube, the image dissector, captured light on a photosensitive surface, and electrons released by that light were drawn off and scanned electrically. The two companies argued over patents for years, and RCA eventually agreed to pay Farnsworth for the use of his ideas.

Britain pressed ahead with the electronic approach. On 2 November 1936 the BBC opened the world's first regular high-definition service, broadcast from Alexandra Palace in north London. For its first months the service alternated between Baird's 240-line equipment and an electronic system of 405 lines developed by Marconi-EMI; the two broadcast on alternate weeks, and no receiver could pick up both. In February 1937 the Baird system was abandoned, and the 405-line standard, which Britain kept until 1985, took over. Germany had begun regular broadcasts in Berlin in March 1935.

Television in the 1930s was a luxury. The picture came from a cathode-ray tube, an evacuated glass cone in which an electron beam drew the image on a fluorescent screen, and receivers were bulky and expensive; a set was housed in a wooden cabinet that doubled as a piece of furniture. Programmes lasted an hour or two a day and were received only in part of London and the south-east of England. Nobody was quite sure what the new medium was for, although a short play had been televised as an experiment as early as 1930.

The service was cut off on 1 September 1939, the day Germany invaded Poland, and did not return until June 1946. The interruption had an unintended consequence. The engineers who had been developing television were dispersed to work on radar, and the techniques they acquired there, in high-frequency transmission and in reading a faint signal from a screen, came back with them when peace returned.

After 1945 television spread quickly. In the United States, commercial services had begun in 1941 and expanded rapidly once the war ended; a colour system that existing sets could still receive was adopted in 1953. In Britain the 405-line service resumed in 1946, a second channel opened in 1964, and colour arrived on BBC Two in July 1967. The remote control, which saved the viewer a walk across the room, appeared in the 1950s.

Behind these dates lies a pattern common to many technologies. The mechanical version proved that the idea could work; the electronic version made it practical; the mass market arrived only when the device became cheap enough for ordinary households. Baird, who had shown the way, spent his last years in poor health and died in 1946, at the age of 57, while the equipment he had pioneered was already being taken apart.

Every object above absolute zero emits infrared radiation, and the warmer it is, the more it emits. A thermal camera detects that radiation and turns it into a picture, which is why the technique is sometimes called thermography. The result is a map of temperature rather than of light: a scene that looks uniformly grey to the eye resolves into a pattern of warm and cool surfaces. This is not the same as the image-intensifying night-vision equipment used by soldiers, which amplifies faint visible light; a thermal camera needs no light at all.

The existence of infrared radiation was established in 1800 by the astronomer William Herschel, who placed thermometers beyond the red end of a spectrum and found that they grew warmer. Practical imaging, however, depended on detectors able to register tiny changes of temperature. The first thermal cameras were built for military research in the 1950s and 1960s; they used cooled detectors, scanned a scene with moving mirrors and produced a picture slowly. In the 1980s engineers at the American company Honeywell developed the microbolometer, a detector that needed no cooling, and the technology became small enough, and cheap enough, to leave the laboratory.

A microbolometer pixel is a tiny plate of material, usually vanadium oxide or amorphous silicon, suspended above a silicon circuit on legs a fraction of a micrometre wide. Infrared radiation falling on the plate warms it slightly, and the change alters its electrical resistance, which the circuit beneath reads out. Because the plate is thermally isolated, a fraction of a degree produces a measurable signal. The array sits in a sealed package from which the air has been removed, because gas would carry heat away from the plates. Cooled detectors, by contrast, use semiconductors such as indium antimonide held at about 77 kelvin with liquid nitrogen or a Stirling engine. They are more sensitive, but the cooling equipment makes them heavy and expensive.

Turning resistances into a picture also requires optics. Ordinary glass absorbs long-wavelength infrared, so thermal lenses are made of germanium or zinc selenide, which transmit it; a germanium lens is opaque to the human eye and looks like polished metal. Each pixel yields an estimate of the temperature of the surface it sees, and the electronics amplify the differences and map them onto a range of grey shades. Uncooled cameras commonly offer arrays of 160 by 120 up to 640 by 512 pixels and can distinguish differences of about 0.05 kelvin, though such figures improve year by year.

Building surveyors were among the first civilian users. A camera pointed at a wall shows patches where insulation is missing, where damp has entered the structure, or where a draught leaks in around a window frame. Because each fault changes the temperature of the surface in front of it, the defect becomes visible without opening the wall.

The same principle locates overheating electrical connections and failing bearings in machinery, which glow against their surroundings long before they fail. Firefighters use thermal cameras to see through smoke, which visible light cannot penetrate, and to find people trapped in a building or the hottest part of a fire. Wildlife researchers use them to count animals at night, when many species are most active, and to pick animals out against vegetation that hides them by day. Because an animal's body is warmer than the ground, it stands out in the image. Surveys of deer, bats and birds have been carried out this way, though a warm rock or a sunlit patch of soil can produce a false reading.

In medicine the camera offers a non-contact way to measure skin temperature. It has been used to look for inflammation around wounds and joints, and to screen air passengers for fever during outbreaks of infectious disease. Screening of this kind has been criticised, because skin temperature is affected by the air, by sweat and by the time a person has spent in a cool room. A single reading is therefore a poor predictor of illness. Research on using the technique to detect breast cancer has also proved inconclusive, and thermal imaging is not a substitute for established tests.

Long-wavelength infrared does not pass through glass or water, so a camera pointed at a window records the temperature of the glass and nothing beyond it. A surface's emissivity, its efficiency at radiating heat, also matters. Polished aluminium reflects its surroundings rather than emitting, and a camera that assumes a value typical of paint or skin will report a temperature that is badly wrong. Reflections of a warm object in a cold, shiny surface can be mistaken for a hot spot. Resolution is modest by photographic standards, and although prices have fallen, a professional camera still costs far more than a visible-light one.

Current research aims at several of these problems at once. Detector arrays are being made with smaller pixels and better thermal isolation, so that sensitivity improves without cooling. Engineers are also working on multispectral sensors that separate several bands of infrared, which helps distinguish a genuine hot surface from a reflection, and on software that estimates emissivity from the image itself. Cheap sensors are now built into some rugged phones or plug into a phone's charging port. At the other end of the market, industrial cameras are being combined with machine learning, so that images can increasingly be interpreted without a person.

The word influencer sounds new, but the practice is not. Manufacturers have paid well-known people to recommend their goods for as long as there has been mass advertising. What has changed is the machinery. A person with a phone and a talent for holding attention can now reach an audience of millions without a broadcaster, a publisher or an agent, and can be paid directly by the companies whose products appear in their photographs. Advertisers value this because the recommendation arrives inside the flow of ordinary life, from someone the audience feels it knows.

The economics are straightforward. Platforms sell attention to advertisers, and individuals who can deliver attention reliably take a share of that money. A single video, if it is watched by enough people, can earn more than a year of ordinary wages, which is why the occupation attracts so many young people and why the competition is so fierce. The distribution of rewards, however, is extremely uneven. A small number of accounts attract most of the audience and almost all of the income, while the great majority earn very little or nothing.

The relationship that makes this work was described long before social media existed. In 1956 the sociologists Donald Horton and R. Richard Wohl coined the term para-social interaction to describe the illusion of friendship that television presenters create when they speak straight to the camera, address viewers by name and share confidences. Social media intensifies the effect, because the audience can answer. Comments are read, occasionally liked, sometimes replied to, and the sense of a personal relationship grows. That sense is the commercial asset: it is why a recommendation from a stranger with a camera can outsell an advertisement made by a professional agency.

The style of the genre follows from this. Successful accounts present themselves as unpolished: the room is untidy, the hair is not done, the product is opened on camera and the reaction is unscripted. This performance of ordinariness is itself a technique, learned and refined, and audiences reward it because it feels more honest than a studio advertisement. The difficulty is that honesty is exactly what an advertiser wishes to borrow. A paid recommendation works only while it appears not to be one, which places the influencer in a permanent contradiction: the more commercial the content, the more it must look as though nothing is being sold.

Most countries have therefore decided that the audience must at least be told. In Britain the Advertising Standards Authority requires marketing communications to be obviously identifiable as such, and its rules apply to social media in the same way as to newspapers or billboards. In the United States the Federal Trade Commission publishes guidance requiring a clear and conspicuous disclosure, placed near the recommendation rather than buried among a list of tags. Regulators in several countries have reported that compliance is patchy: labels are omitted, abbreviated to a single character, or hidden at the end of a long caption where few readers reach them.

The sceptical response is that none of this matters much: an advertisement is an advertisement, whether it appears in a magazine or on a phone, and the audience is free to ignore it. On this view the only real question is whether particular products, such as gambling, alcohol or food high in fat and sugar, should be promoted to particular audiences at all. Several countries already restrict the advertising of unhealthy food to children on television, and there is a reasonable case for extending the same rules to personalities whose followers are mostly young.

Such restrictions seem to me sensible, but the sceptics have not identified the main problem. Individual influencers are a symptom; the cause lies in the architecture that surrounds them. A recommendation video and an unpaid video look identical, and the platform decides which of us sees which, using an algorithm whose logic is invisible to the audience and, in practice, to the person posting as well. Paid placements are fed into the same stream as news from friends. In that setting the duty to be transparent cannot sensibly rest on each individual creator's conscience.

What would help is disclosure built into the platform rather than added by the creator: a label that the account cannot remove, attached when money changes hands, visible in the feed and in every share. Enforcement should fall on the advertiser, which has the resources and the legal department, and on the platform that profits from the placement. Media education has a part to play, but it is a weak instrument against a system designed by experts to be persuasive; teaching children to spot an advertisement is no substitute for making advertisements visible.

None of this means that the influence industry is worthless or that its audience is stupid. Much of the content is entertaining, some of it is genuinely useful, and the collapse of the old gatekeepers has allowed people to be heard who would never have been published. But the question worth asking is not whether influencers are a good thing. It is who bears the cost when the line between friendship and commerce disappears, and whether that cost should be carried by the people least able to see it.