IELTS Academic Reading Practice Test 85

Fire has threatened cities since the earliest times, but the idea of a permanent body of people whose only duty was to fight fires developed slowly. In most early settlements, every household was expected to keep a bucket close at hand. When flames were seen, neighbours would hurry outside and form a human chain from a well, river or pond to the burning building, passing water from hand to hand. This system could be painfully slow, and in the crowded wooden quarters of large towns a neglected hearth or a spark from a workshop might destroy an entire district before enough water could be delivered.

The first organised fire service for which there is clear evidence was created in ancient Rome by the emperor Augustus in AD 6. The corps, known as the Vigiles, originally consisted of freedmen organised into cohorts and stationed in barracks around the city. They patrolled the streets at night, acting both as watchmen and as firefighters, and they would break down burning buildings to create gaps that slowed the spread of flames. They were equipped with buckets, hooks and axes, and Roman writers also describe simple pumps that could force a jet of water onto a fire.

After the collapse of Rome, urban firefighting in Europe declined sharply. In most medieval towns there was no standing brigade, and when a fire broke out the church bells were rung to call inhabitants into the street. People arrived with whatever buckets and hooked poles they owned, but the usual strategy was not to extinguish the fire so much as to pull down neighbouring buildings before the flames reached them. Towns stored a few ladders and fire hooks in a central building, and officials issued regulations about hearths and thatched roofs, yet there was little formal training or equipment.

The Great Fire of London in 1666 destroyed more than 13,000 houses and left tens of thousands of people without shelter. In its aftermath, private fire brigades were created by the insurance companies that sold fire policies to property owners. Houses covered by a particular company were identified by a metal plate, known as a fire mark, fixed to the outside wall. When a fire was reported, a company's brigade would attend only to buildings displaying its own mark. In London the result was a strange patchwork of private brigades, but it also meant that for the first time substantial numbers of trained men and purpose-built engines were available in one city.

A decisive step toward a public service was taken in Edinburgh in 1824, with the appointment of James Braidwood to lead the town's fire establishment. This body is widely regarded as the first municipal fire brigade in the world. Braidwood believed that training, discipline and careful organisation mattered more than brute strength, and he insisted on regular drills.

He selected able men, gave them uniforms and a clear chain of command, and taught them how to search burning buildings for occupants and how to judge when a structure was too unsafe to enter. His ideas were so successful that in 1833 he moved to London as superintendent of the London Fire Engine Establishment.

The nineteenth century transformed firefighting technology. Steam-powered fire engines, which began to replace manual machines from the 1850s onward, removed the need for manual pumping and allowed water to be thrown in a continuous stream for long periods. The new engines were still pulled to fires by horses, but they offered far greater power and reliability than the hand-operated pumps they superseded. Municipal brigades became increasingly common in Britain and continental Europe during the same decades, as local governments took over duties that had previously belonged to insurance crews, parishes or volunteer companies.

The early twentieth century brought the motorised fire engine. Motor engines could travel further and faster than horse-drawn vehicles, and they carried longer ladders, more hose and heavier pumps. Communications improved as well: fire alarm telegraph boxes placed on street corners allowed the public to summon help quickly, and the spread of the telephone enabled brigades to receive and pass on calls with far less delay. In many places the fire service also began to employ full-time officers responsible for inspecting buildings and advising on fire prevention.

As buildings grew taller and industry used more dangerous materials, firefighting became more specialised and technical. The development of breathing apparatus permitted crews to enter smoke-filled rooms in relative safety, and hydraulic platforms and aerial ladders allowed them to reach upper floors. Brigades also devoted increasing energy to preventing fires rather than merely extinguishing them. Public campaigns encouraged the use of smoke alarms, the safe storage of flammable liquids and regular inspection of electrical wiring, and building regulations were tightened in order to reduce the likelihood that a fire would break out and spread.

Today the fire service in most wealthy countries is a professional, publicly funded body, although volunteer departments remain essential in many rural and small-town areas. Firefighters still respond to fires, but they also deal with road accidents, chemical spills, floods and other emergencies. The idea that a specially trained, permanently available group of people should stand ready to protect a community from fire now seems self-evident, yet it is comparatively recent. It required not only new engines and pumps but also changes in law, in public attitudes and in the willingness of communities to pay for protection before a fire begins.

Gravitational waves are ripples in the fabric of space and time, produced when very massive objects accelerate violently. According to Albert Einstein's general theory of relativity, published in 1916, a moving mass should disturb the geometry of the universe around it, sending out disturbances that travel at the speed of light. These waves squeeze and stretch space itself, but only by an extraordinarily small amount. The most powerful events in the cosmos, such as the collision of black holes or the collapse of a star's core, should generate waves strong enough, in principle, to be measured by instruments on Earth.

Einstein himself was inconsistent about the reality of the waves, at times arguing that they were mathematical artefacts rather than physical phenomena, and he never expected them to be detected. Early direct searches began in the 1960s, when the American physicist Joseph Weber built large aluminium cylinders designed to vibrate when a gravitational wave passed through them. Weber announced signals in 1969, but other laboratories could not reproduce them, and his claims were eventually rejected. By the 1970s researchers were therefore looking for a more indirect but reliable route.

That route was found through a pulsar, a rapidly rotating neutron star that emits regular pulses of radio waves. In 1974 Russell Hulse and Joseph Taylor discovered a pulsar in orbit around another compact star. They noticed that the two stars were gradually spiralling together, and the rate at which their orbit was shrinking matched the energy loss that general relativity predicts would be carried away by gravitational waves. This was not a direct detection, but it provided strong evidence that the waves were real, and it earned Hulse and Taylor the Nobel Prize in Physics in 1993.

The design of modern detectors grew out of a simple device known as a laser interferometer. A laser beam is split into two beams that travel at right angles along long arms, reflect between mirrors, and are then recombined. If a gravitational wave passes, one arm becomes slightly shorter while the other grows slightly longer, so the recombined light forms a different interference pattern. The change is tiny: in an arm four kilometres long, the expected movement is thousands of times smaller than the width of an atomic nucleus. Nevertheless, the method allows many repeated measurements and can be made extraordinarily sensitive.

Building a working interferometer proved formidably difficult. The mirrors must be shielded from seismic noise, passing traffic, wind and even the thermal vibrations of the mirrors themselves. They are suspended on elaborate systems of pendulums and springs, and the entire light path is enclosed in a near-vacuum to prevent air currents from disturbing the beam. The first large projects, including the Laser Interferometer Gravitational-Wave Observatory in the United States, completed initial observing runs without detecting any signals. Advanced LIGO, with upgraded lasers, mirrors and isolation, began taking data in 2015.

On 14 September 2015 the upgraded detectors in Louisiana and Washington recorded a signal lasting about one fifth of a second. Named GW150914, it came from the merger of two black holes roughly 1.3 billion light-years away. One black hole had a mass about 36 times that of the Sun and the other about 29 times, and they combined to form a single black hole of about 62 solar masses. The remaining three solar masses had been converted, in an instant, into the energy of gravitational waves. The discovery was announced in February 2016 and confirmed a major prediction of general relativity.

A second landmark came in August 2017, when LIGO and the European Virgo detector observed waves from a pair of neutron stars merging. Unlike black holes, neutron star collisions were expected to produce light as well as gravitational radiation. Within seconds of the detection, telescopes around the world and in space were pointed at the source. Astronomers found a gamma-ray burst and a glowing cloud of heavy elements known as a kilonova, confirming that such mergers are an important site where gold and platinum are formed. The event marked the beginning of multi-messenger astronomy, in which information from gravitational waves and electromagnetic radiation, including light, is combined.

The field is now expanding rapidly. Additional detectors in Japan and elsewhere have joined the network, and planned instruments will be sensitive to more distant or less violent events. Scientists are also developing a space-based observatory known as LISA, which would use arms millions of kilometres long to detect lower-frequency waves that cannot be seen from the ground. Pulsar timing arrays, which monitor the pulses of many neutron stars, are being used to search for very slow gravitational waves with periods of years. Each new instrument opens a different frequency window, and astronomers expect that gravitational-wave observations will become as routine as those made with ordinary telescopes.

Volunteering is often presented as a selfless act, a gift of time offered with no expectation of return. Yet a growing body of research suggests that the person who does the volunteering may gain as much as, or more than, the person being helped. Studies have linked regular volunteering with improved mental health, greater life satisfaction and even better physical health.

The idea has become popular among policy-makers, who see in volunteers a source of cheap labour for health and social services. In my view, the benefits are real but easily overstated, and the reasons for them matter more than the simple fact that giving time is good for you.

The strongest evidence comes from longitudinal studies that follow the same people over many years. Researchers distinguish between two possible explanations for why volunteers seem healthier and happier. One is selection: healthier, more sociable people may be more likely to volunteer in the first place, so volunteering does not cause their well-being. The other is causation: volunteering itself changes a person's situation in ways that improve health. Good studies try to account for selection by measuring participants' health and social connections before they began volunteering, but it is impossible to remove all such differences outside a randomised trial.

The psychological mechanisms most commonly proposed are not mysterious. Volunteering typically involves social contact, regular activity and a sense of purpose, all of which are independently associated with better mental health. It can also reduce loneliness, particularly among older people whose paid work has ended. Some researchers have called this the 'helper's high', although the phrase should not be taken too literally: the effects are modest, and they do not occur for every volunteer. A person doing monotonous tasks in an isolating setting may gain little.

Older adults are the group for whom the evidence is most consistent. A large number of studies have found that people who volunteer in later life report fewer depressive symptoms and higher life satisfaction, and some studies have even noted lower mortality over follow-up periods. However, these same studies cannot fully rule out the possibility that healthier individuals choose to volunteer. The benefit also appears to depend on the amount of time given: volunteers who give a moderate amount of time regularly tend to fare better than those who give none, but beyond a modest commitment the additional gains become small.

Young people are often encouraged to volunteer as a route to employment. There is some evidence that volunteering can help develop transferable skills and social networks, but the benefit is smaller than is often claimed. School and university programmes that require students to volunteer may produce resentment and do little for later civic engagement if the placement is chosen mainly to satisfy an application form. The quality of the experience, and the degree of genuine choice involved, seems to determine whether a young volunteer gains anything at all.

The physical health benefits have attracted particular attention. Some studies have associated volunteering with lower blood pressure and better self-rated health, but the findings are less consistent than those for mental health. It is plausible that increased physical activity and reduced stress explain part of the effect. Yet cause and effect are again hard to separate: people in good health are more able to take on volunteer tasks in the first place. Moreover, any effects may depend on the type of activity, making it difficult to isolate the contribution of volunteering itself.

There is also a less comfortable reason for caution. Governments in several countries have turned to volunteers to deliver services that were once provided by paid professionals, particularly in libraries, schools and care homes. This may save money in the short term, but it can undermine the quality and reliability of services, and it may disguise cuts. If volunteering is promoted mainly as a route to individual well-being, there is a risk that public debate will ignore these collective costs. In my view, volunteering should supplement paid public services, never replace them.

A further concern is that volunteering is not equally available to everyone. People on low incomes, those with disabilities and those caring for small children often lack the time, energy or money to give their labour free. If public services come to depend on volunteers, such groups may lose access to support while also being less able to obtain the supposed health benefits for themselves. A society that celebrates volunteering should also ask who is able to volunteer, and at what cost. This inequality is rarely discussed in campaigns that present volunteering as an individual solution to loneliness.

None of this means that volunteers themselves gain nothing. The evidence is strong enough to conclude that, for many people, particularly older adults, regular, freely chosen volunteering can protect against isolation and low mood, and may support a sense of purpose. But the gains are conditioned by the quality of the work, the degree of choice involved and the social context in which it occurs. The best volunteering is designed to be useful to the recipient and satisfying for the volunteer, and is not treated as a substitute for the obligations of the state.