Antheil also tend towards quite comparable tone clusters. With Edgar Varèse and Charles Ives, two composers should be mentioned whose works, which are exceptional in every respect, cannot be attributed to any larger movement and whose significance was only fully recognised in the second half of the century. The increasing industrialisation, which slowly began to take hold of all areas of life, is reflected in an enthusiasm for technology and (compositional) machine aesthetics, which was initially carried by the Futurist movement. Thus, the various technical innovations, such as the invention of the vacuum tube, the development of radio technology, the sound film and tape technology, moved into the musical field of vision. These innovations also favoured the development of new electric playing instruments, which is also significant with regard to the original compositions created for them. Lew Termen's Theremin, Friedrich Trautwein's trautonium and the Ondes Martenot of the Frenchman Maurice Martenot should be highlighted here. The partly enthusiastic hope for progress that was attached to the musically useful application of these early experiments was, however, only partially fulfilled. Nevertheless, the new instruments and technical developments possessed a musically inspiring potential that, in the case of some composers, was reflected in extraordinarily visionary conceptions that could only actually be technically realised decades later. The first compositional explorations of the musical possibilities of pianola also belong in this context. The medial dissemination of music by means of records and radio also made possible the enormously accelerated exchange or reception of musical developments that had been almost unknown until then, as can be seen from the rapid popularisation and reception of jazz. In general, it can be said that the period from around 1920 onwards was one of general "departure for new shores" – with many very different approaches. Essentially, this pluralism of styles has been preserved until today or, after a short period of mutual polemics between Serialism and adherents of traditional compositional styles (from about the mid-1950s onwards), has ceased again. Historical preconditions In the 20th century, a line of development of musical progress continued; every composer still known today has contributed something to it. This old longing for progress and modernity – through conscious separation from tradition and convention – can, however, take on a fetish-like character in Western society, which is shaped by science and technology. The appearance of the "new" is always accompanied by a feeling of uncertainty