IELTS Academic Reading Practice Test 126

For much of the twentieth century the telephone was fixed to a wall or a desk. The idea of dividing a city into small geographical areas, each served by its own low-powered radio transmitter, was set out by engineers at Bell Telephone Laboratories in the United States in 1947. Because each area, or cell, could use the same radio frequencies as a cell far enough away, the scheme promised far more capacity than a single powerful transmitter covering a whole city. The engineers could see how such a network would operate, but the transistor had only just been invented, and the electronics required to build it did not yet exist.

Progress was slow. The radio telephones of the 1950s and 1960s were bulky equipment fitted in cars, and each call needed a free channel and an operator to connect it. In April 1973 an engineer at Motorola named Martin Cooper made a call in a street in New York using a hand-built portable telephone. He deliberately rang a rival at Bell Laboratories to show that a handheld device was feasible. The prototype weighed about a kilogram.

Commercial cellular services began in 1979, when NTT, Japan's national telephone company, opened a network in the Tokyo area. Two years later Denmark, Finland, Norway and Sweden launched the Nordic Mobile Telephone system, which allowed subscribers to use their phones in any of the four countries. Coverage expanded slowly, and in most countries a handset remained a luxury. These first-generation networks carried speech as an analogue radio signal, so anyone with a suitable receiver could listen to a conversation, and the handsets themselves were extremely expensive.

The decisive change was the move to digital. In 1982 a group of European postal and telecommunications administrations began work on a common standard that would allow a phone to work anywhere in Europe. The result, the Global System for Mobile Communications, or GSM, was first launched commercially in Finland in 1991. Turning speech into digital data allowed many more calls to share the same frequencies and made it possible to scramble them, so that casual eavesdropping became far harder.

GSM also contained a facility that nobody had planned as a commercial product. The standard set aside a channel for short written messages between handsets, intended chiefly for engineers testing the network. The first such message was sent in December 1992, and texting was expected to remain a minor feature. Instead it became, for a time, the most profitable data service the industry had, and an entire compressed vocabulary grew up around the 160-character limit. A generation of users learned to type with their thumbs.

Third-generation networks, which began in Japan in 2001, raised data speeds enough to make it practical to send photographs and browse the web from a handset. The more consequential change, however, was in the design of the devices themselves. The first phones to be marketed as smartphones combined a telephone with the functions of a pocket computer and were operated with a stylus; from 2007 a new generation replaced the stylus with the fingertips. Once a handset could run software written by anyone, its functions were no longer fixed at the factory.

Batteries shaped the industry as much as radio did. Early handsets used nickel-cadmium cells, which were heavy and could lose capacity if repeatedly part-charged, a problem known as the memory effect. The commercial arrival of lithium-ion batteries in the early 1990s allowed lighter phones with more energy per kilogram, and the same chemistry, steadily refined, still powers most portable electronics. Removable batteries also allowed owners to carry a spare, a practice that has since disappeared from most designs.

Underlying all of this was the shrinking of electronics. A handset of the 1980s contained hundreds of separate components; the integrated circuits that replaced them became cheaper and more capable year after year. The first handheld cellular phone sold in the United States, in 1983, cost several thousand dollars, yet by the early 2000s mobile subscriptions worldwide outnumbered fixed telephone lines.

The consequences were not evenly spread. Mobile networks allowed countries with almost no fixed-line infrastructure to skip an expensive stage of development. In parts of Africa and South Asia the phone became a means of transferring money, a source of market prices for farmers and a way of keeping in touch. It was used for these purposes long before it became a general-purpose computer. The technology did not simply arrive in existing societies; it altered what was possible within them.

Governments discovered that the right to use radio frequencies could be sold. Auctions of third-generation licences in the early 2000s raised tens of billions of dollars for European treasuries, and the sums operators paid were reflected in the prices their customers were charged. Spectrum is a public resource, and the auctions turned a licence to transmit into a tradable asset.

None of this was inevitable. Each stage rested on decisions about technical standards, about who would be allowed to use which frequencies, and about whether networks would interconnect. Those decisions were taken by committees, regulators and companies, and their choices are now invisible in the device in a pocket.

Graphene is a sheet of carbon atoms one atom thick, arranged in a hexagonal pattern like the wire mesh of a fence. It is not a rare substance. Graphite, the material of pencil leads, consists of countless such sheets stacked on top of one another and held together weakly. A single flake of graphene is what remains when one sheet is separated from the pile. Because carbon atoms in the sheet are bonded to three neighbours in a rigid lattice, the material combines properties that are rarely found together.

For decades physicists doubted that such a thing could exist in isolation. Theory suggested that a strictly two-dimensional crystal would be unstable: thermal vibrations would grow until the sheet tore itself apart or rolled up. The argument was widely accepted, and it was assumed that any very thin film would cling to a supporting surface. The experimental route to graphene turned out to be almost absurdly simple. In 2004 Andre Geim and Konstantin Novoselov, working at the University of Manchester, pressed adhesive tape onto a lump of graphite and peeled it away. They repeated the process until some flakes were only a few atoms thick.

The two researchers, who had been investigating the electrical behaviour of thin films, found that some of the flakes were a single layer. They were awarded the Nobel Prize in Physics in 2010. The discovery opened a field that had been thought closed, and it did so with equipment that a school laboratory could have afforded.

What made graphene remarkable was not only its thinness. It is the strongest material ever measured, with a breaking strength far above that of steel, yet it is also flexible. It conducts heat better than copper, and its electrons move through the lattice with very little resistance. Its electrons behave in an unusual way: rather than moving like particles in an ordinary metal, they travel as if they had no mass. The equations that describe them are the same ones that describe relativistic particles. These properties come from the bonding of the carbon lattice itself.

A single layer absorbs only about 2.3 per cent of the light falling on it, so a film of graphene is almost transparent while remaining electrically conductive. This combination has made it attractive as a replacement for indium tin oxide, the transparent conductor used in touchscreens and solar cells, which is brittle and depends on a metal in limited supply. Prototype touchscreens and flexible displays have been demonstrated, although at present they cost far more to make than the devices they would replace.

There is an important limitation. For a transistor to switch off cleanly, the material from which it is made needs a band gap, a range of energies in which no electron can exist. Pure graphene has none: its conduction and valence bands meet at a point, so it conducts slightly however it is switched. This does not matter for a wire or a touchscreen, but it prevents graphene from replacing silicon in digital logic. Researchers have produced band gaps by cutting the sheet into narrow ribbons, by stacking two layers at a slight angle, and by attaching other atoms to the surface. Each method, however, brings penalties in cost or quality.

Making the material is a second difficulty. Peeling with tape yields tiny flakes, perfect but useless for anything larger than a laboratory device. For bulk use, graphite is oxidised and dispersed in liquid, producing graphene oxide, which is cheap and can be coated over large areas but contains defects that must then be repaired. For electronics, the favoured method is chemical vapour deposition: a carbon-containing gas is passed over a hot metal foil, usually copper, where it breaks down and forms a film. This can cover a sheet many centimetres across, but the film is a patchwork of small crystals, and the boundaries between them scatter electrons.

Even a good film must then be moved onto the surface where it is wanted, a step known as transfer, and the process often introduces wrinkles and contamination. Commercial products that contain graphene, from tennis rackets to bicycle tyres, generally use flakes of modest quality in a composite material, where the sheets reinforce a plastic or rubber. Conductive inks, sensors and water-filter membranes are at or near the market. Applications that need large, flawless sheets remain in the laboratory.

Hype has been a problem. Graphene was announced as a wonder material that would transform electronics within a decade, and the timescale has proved optimistic. Some of the gap between promise and product is ordinary: a new material must compete with manufacturing processes that have been refined for fifty years. Some of it is the fault of researchers and journalists who overstated results.

A further uncertainty concerns safety. Graphene platelets are small enough to be inhaled, and their long-term effects on the lungs are not known. Because they are sharp and chemically stable, some scientists have urged that they be treated with the caution applied to other engineered nanomaterials. Regulators, meanwhile, have struggled to define what counts as graphene at all, since products sold under that name vary enormously in thickness and purity. These questions are simply part of what it means to introduce a new material.

Consider a small company that wants to manufacture a folding electric bicycle. It appeals for money through a website, and within a month several thousand people have each pledged a few hundred dollars. The arrangement is known as crowdfunding, and its essential feature is that a large number of people contribute a small amount, usually through a website, to finance a project. None of them would pay for the whole thing alone. In one sense there is nothing new in it. Eighteenth-century publishers raised money for books by subscription, and building societies were financed by many small deposits. What the internet changed was the cost and speed of reaching strangers.

Four main forms exist. In donation crowdfunding, contributors expect nothing back. In reward crowdfunding, they receive the product or some other token, which is not the same as a share of the profits. In lending, they receive interest, and peer-to-peer platforms match savers with borrowers. In equity crowdfunding, they buy a stake in a company. The distinctions matter because the risks, and the need for regulation, differ sharply between them.

The best-known platform, Kickstarter, was founded in 2009 to fund creative projects, and it operates an all-or-nothing rule: if the target is not reached, nobody pays and the project receives nothing. The platform keeps a percentage of the sums raised. Similar sites followed in other countries, some of which allow creators to keep whatever they raise. That design was copied widely, and the sums involved are now counted in billions of dollars a year.

Why does it work at all? The old obstacle to raising money for an unusual idea was not only the shortage of capital but the cost of finding people who might be interested. A website can put a proposal in front of millions of readers for very little, and a campaign that reaches its target in a week is public evidence that demand exists. For a manufacturer, that evidence may be worth as much as the money. A campaign also creates its own audience: backers who have paid in advance tend to want the product to succeed, and they tell others about it.

The clearest benefit is for projects that conventional finance will not touch. A bank lends against assets and a history of earnings; an investor buys a share of a business that can grow. Neither has a mechanism for funding a left-handed guitar, a documentary about a remote island, or a piece of software used by a few thousand specialists. In this narrow sense crowdfunding widens access to capital in a way that is genuinely democratic, and it has financed a long tail of work that would otherwise not exist.

The democracy, however, is imperfect. Campaigns that succeed are overwhelmingly those whose creators already know how to reach an audience: they have a following, a mailing list, or the money to hire a professional video producer. It is difficult to measure, but the pattern is familiar to anyone who has watched a well-made campaign with little substance succeed while a better idea goes unnoticed. Crowdfunding does not remove the advantage of having wealthy or well-connected backers; it merely changes the currency in which that advantage is spent.

Equity crowdfunding raises a different set of concerns. In the United States, legislation passed in 2012 made it lawful for ordinary citizens, not only the wealthy, to buy shares in private companies through such platforms, and the rules took effect in 2016. The purpose was to widen access both to capital and to investment. The risk is obvious: private companies fail often, their shares cannot easily be sold, and an amateur investor cannot easily judge whether the accounts are honest. Regulation has therefore focused on disclosure. My own view is that disclosure, though necessary, is not sufficient, and that limits on how much an individual may invest are a sensible safeguard.

The most uncomfortable use of crowdfunding is medical. On the largest donation platforms, campaigns to pay for surgery or cancer treatment are among the most numerous, and many raise only a fraction of the sum sought. The generosity of those who give is not in question. The willingness of strangers to pay for another stranger's operation is admirable. But it is also a measure of what public systems have failed to provide. A society in which medical bills are met by raffles and online appeals has not solved a problem; it has distributed the problem unevenly, in proportion to each patient's ability to tell a compelling story.

Crowdfunding, then, is a useful supplement to public provision and a poor substitute for it. For a small manufacturer, a musician or a specialist software developer, it is one of the most efficient ways ever devised to test an idea and find first customers. As a way of financing health care, housing or basic research, it is a symptom of something else. The sensible response is neither to celebrate it as a revolution nor to dismiss it as begging. It is to regulate it where money is being invested, to fund public services properly, and to remember that the medium is not neutral about who gets heard.