This, however, was only one of the results derived from the application of the thermionic valve. The idea of harnessing the flow of electrons was applied in the electron microscope, radar (a detection device depending on the capacity of some radio waves to be reflected by solid objects), the electronic computer, and in the cathode-ray tube of the television set. The first experiments in the transmission of pictures had been greeted with ridicule. Working on his own in Britain, John Logie Baird in the 1920s demonstrated a mechanical scanner able to convert an image into a series of electronic impulses that could then be reassembled on a viewing screen as a pattern of light and shade. Baird’s system, however, was rejected in favour of electronic scanning, developed in the United States by Philo Farnsworth and Vladimir Zworykin with the powerful backing of the Radio Corporation of America. Their equipment operated much more rapidly and gave a more satisfactory image. By the outbreak of World War II, television services were being introduced in several countries, although the war suspended their extension for a decade. The emergence of television as a universal medium of mass communication is therefore a phenomenon of the postwar years. But already by 1945 the cinema and the radio had demonstrated their power in communicating news, propaganda, commercial advertisements, and entertainment. Military technology
It has been necessary to refer repeatedly to the effects of the two World Wars in promoting all kinds of innovation. It should be observed also that technological innovations transformed the character of war itself. One weapon developed during World War II deserves a special mention. The principle of rocket propulsion was well known earlier, and its possibilities as a means of achieving speeds sufficient to escape from Earth’s gravitational pull had been pointed out by such pioneers as the Russian Konstantin Tsiolkovsky and the American Robert H. Goddard. The latter built experimental liquid-fueled rockets in 1926. Simultaneously, a group of German and Romanian pioneers was working along the same lines, and it was this team that was taken over by the German war effort in the 1930s and given the resources to develop a rocket capable of delivering a warhead hundreds of miles away. At the Peenemünde base on the island of Usedom in the Baltic, Wernher von Braun and his team created the V-2. Fully fueled, it weighed 14 tons; it was 40 feet (12 metres) long and was propelled by burning a mixture of alcohol and liquid oxygen. Reaching a height of more than 100 miles (160 km), the V-2 marked the beginning of the space age, and members of its design team were instrumental in both the Soviet and U.S. space programs after the war.
Test launch of a V-2 rocket.Camera Press/Globe Photos
Technology had a tremendous social impact in the period 1900–45. The automobile and electric power, for instance, radically changed both the scale and the quality of 20th-century life, promoting a process of rapid urbanization and a virtual revolution in living through mass production of household goods and appliances. The rapid development of the airplane, the cinema, and radio made the world seem suddenly smaller and more accessible. In the years following 1945 the constructive and creative opportunities of modern technology could be exploited, although the process has not been without its problems. Space-age technology
The years since World War II ended have been spent in the shadow of nuclear weapons, even though they have not been used in war since that time. These weapons underwent momentous development: the fission bombs of 1945 were superseded by the more powerful fusion bombs in 1950, and before 1960 rockets were shown capable of delivering these weapons at ranges of thousands of miles. This new military technology had an incalculable effect on international relations, for it contributed to the polarization of world power blocs while enforcing a caution, if not discipline, in the conduct of international affairs that was absent earlier in the 20th century.
The fact of nuclear power was by no means the only technological novelty of the post-1945 years. So striking indeed were the advances in engineering, chemical and medical technology, transport, and communications that some commentators wrote, somewhat misleadingly, of the “second Industrial Revolution” in describing the changes in these years. The rapid development of electronic engineering created a new world of computer technology, remote control, miniaturization, and instant communication. Even more expressive of the character of the period was the leap over the threshold of extraterrestrial exploration. The techniques of rocketry, first applied in weapons, were developed to provide launch vehicles for satellites and lunar and planetary probes and eventually, in 1969, to set the first men on the Moon and bring them home safely again. This astonishing achievement was stimulated in part by the international ideological rivalry already mentioned, as only the Soviet Union and the United States had both the resources and the will to support the huge expenditures required. It justifies the description of this period, however, as that of “space-age technology.” Power
The great power innovation of this period was the harnessing of nuclear energy. The first atomic bombs represented only a comparatively crude form of nuclear fission, releasing the energy of the radioactive material immediately and explosively. But it was quickly appreciated that the energy released within a critical atomic pile, a mass of graphite absorbing the neutrons emitted by radioactive material inserted into it, could generate heat, which in turn could create steam to drive turbines and thus convert the nuclear energy into usable electricity. Atomic power stations were built on this principle in the advanced industrial world, and the system is still undergoing refinement, although so far atomic energy has not vindicated the high hopes placed in it as an economic source of electricity and presents formidable problems of waste disposal and maintenance. Nevertheless, it seems probable that the effort devoted to experiments on more direct ways of controlling nuclear fission will eventually produce results in power engineering.
Meanwhile, nuclear physics was probing the even more promising possibilities of harnessing the power of nuclear fusion, of creating the conditions in which simple atoms of hydrogen combine, with a vast release of energy, to form heavier atoms. This is the process that occurs in the stars, but so far it has only been created artificially by triggering off a fusion reaction with the intense heat generated momentarily by an atomic fission explosion. This is the mechanism of the hydrogen bomb. So far scientists have devised no way of harnessing this process so that continuous controlled energy can be obtained from it, although researches into plasma physics, generating a point of intense heat within a stream of electrons imprisoned in a strong magnetic field, hold out some hopes that such means will be discovered in the not-too-distant future. Alternatives to fossil fuels
It may well become a matter of urgency that some means of extracting usable power from nuclear fusion be acquired. At the present rate of consumption, the world’s resources of mineral fuels, and of the available radioactive materials used in the present nuclear power stations, will be exhausted within a period of perhaps a few decades. The most attractive alternative is thus a form of energy derived from a controlled fusion reaction that would use hydrogen from seawater, a virtually limitless source, and that would not create a significant problem of waste disposal. Other sources of energy that may provide alternatives to mineral fuels include various forms of solar cell, deriving power from the Sun by a chemical or physical reaction such as that of photosynthesis. Solar cells of this kind are already in regular use on satellites and space probes, where the flow of energy out from the Sun (the solar wind) can be harnessed without interference from the atmosphere or the rotation of the Earth. Gas turbine