Ylem is a composition by Karlheinz Stockhausen for a variable ensemble of 19 or more players, and is given the work number 37 in his catalogue of compositions.
Ylem is "Ralph Alpher to refer to the essential material of the universe, in the context of the "Big Bang theory (Peters 1999, 98–99). The subject of the composition is, in short, "the 'breath' of the universe" (Lavery 1980, 21). The score is dedicated to the composer’s son Simon, who was five years old at the time of composition. It was composed in December 1972 for a tour with the London Sinfonietta, who gave the premiere on 9 March 1973 under the composer’s direction, at the Queen Elizabeth Hall, Southbank Centre, London (Stockhausen 1978, 212). The next evening, the same forces rehearsed and performed the piece on a live television broadcast from 10:50 to 11:30 pm on BBC2's Full House, hosted by John Bird, with questions from the studio audience and phoned in by viewers. Three studio recordings of this version were made on 21 March 1973 in the EMI Studios, London (Stockhausen 1992, 2 and 5).
The formal process of Ylem is notated verbally (Frisius 2008, 234). It requires a great deal of imagination from performers but is very simple in conception, consisting of the very slow attenuation and compression of a galaxy of musical points (Maconie 2005, 348). At the beginning, ten of the mobile performers stand close to the piano. After an initial explosive sound (on E♭ and A in the London version) these ten players move out into the hall, playing all the while, and take up positions around the audience, while the other players remain on the stage. This phase takes about eleven minutes, during which the players move their individual notes away from their starting pitches. At the same time, they diminish in volume and frequency of attacks, occasionally forming short melodic groups and increasingly are varied by trills and glissandos (Maconie 2005, 349; Frisius 2008, 234). Toward the end, the mobile performers return to the piano and a second explosion occurs, after which all nineteen players (the nine fixed-position players now switching to small portable instruments) disperse again through the hall and out of the building (Stockhausen 1978, 212). In the London recordings, this second explosion is a tone higher than the first (Maconie 2005, 349). The composer held that the music works best "when the players establish telepathic communication with one another (they play with closed eyes) and with a 'conductor' who listens with the utmost concentration from the middle of the hall, but does not take an active part" (Stockhausen 1978, 212).
British journalists reviewing the world premiere expressed a mixture of bewilderment and scorn. Writing in The Times, Stanley Sadie said, "Criticism is impotent on such a work as this; there is nothing to do but describe". He nevertheless concluded by comparing Ylem unfavourably to earlier works by the composer on the programme (Kreuzspiel, Zeitmaße, and Kontra-Punkte), which "made his latest piece sound, rightly or wrongly, like Nirvana-hungry doodlings" (Sadie 1973). Paul Griffiths felt that the newest work on the programme, Ylem, "provided the least newness". Although "there was occasional interest in the responding calls across the hall … the overall process is simplistic—an idea that could well have been left to Xenakis" (Griffiths 1973).
Where Sadie found contrasts to Stockhausen's earlier works, New Zealand composer and writer Robin Maconie perceives similarities: Spiel (1952), Gruppen (1955–57), Kontakte (1958–60), Momente (1962–64/69), the moment titled "Translation" in Mixtur (1964), Adieu (1966), the "Russian Bridge" in the Third Region of Hymnen with orchestra (1966–67/69), Intervall for piano four-hands (1969), and the Dr. K–Sextett (1969) all share with Ylem the technique of gradual dispersal or condensation (or both) of constellations of tones (Maconie 1976, 309; Maconie 1990, 203, 218; Maconie 2005, 320–21, 348, 350).American film and television critic David Lavery's response to what he calls "the strangest piece of program music ever composed" was more visceral:
When I first listened to Stockhausen's "Ylem", I was, at its close, nearly unable to move; the music seemed almost to have disintegrated my ordinary molecular structure, replacing it with its own aleatory form, and I waited a few moments before I attempted to move, as if I felt the need to reassemble my body. (Lavery 1980, 21)Explaining his personal reaction in the context of a recurring childhood nightmare of Rainer Maria Rilke, Herman Melville, Claude Lévi-Strauss, Paul Valéry, R. Murray Schafer, and the Śūraṅgama Sūtra. Finding that Ylem represents the Vedic "unstruck sound of the celestial realm" or anahata nad, Lavery concludes that it is representative of Stockhausen's moment form, "music made out of nothing, one of Stockhausen's most effective attempts to create a 'sequence of silences'" (Lavery 1980, 21, 23).
- Karlheinz Stockhausen: Stop for Orchestra, London Version 1973; Ylem for 19 Players, First London Version 1973. London Sinfonietta; Karlheinz Stockhausen (dir.). LP recording. Deutsche Grammophon 2530 442. [Germany]: Deutsche Grammophon, 1974.
- Stockhausen: Ylem: 2 Versionen, 1973. London Sinfonietta; Karlheinz Stockhausen (dir.). Recorded 21 March 1973, second and third versions. CD recording. Stockhausen Complete Edition CD 21. Kürten: Stockhausen-Verlag, 1992
- Frisius, Rudolf. 2008. Karlheinz Stockhausen II: Die Werke 1950–1977; Gespräch mit Karlheinz Stockhausen, "Es geht aufwärts". Mainz, London, Berlin, Madrid, New York, Paris, Prague, Tokyo, Toronto: Schott Musik International. ISBN 978-3-7957-0249-6.
- Griffiths, Paul. 1973. Music in London: New Music: Stockhausen. The Musical Times 114, no. 1563 (May): 503.
- Lavery, David. 1980. "Dreaming Nothing". Parabola: Myth and the Quest for Meaning 5, no. 2 (May): 18–23.
- Maconie, Robin. 1976. The Works of Karlheinz Stockhausen. London, New York, Toronto: Oxford University Press. ISBN 0-19-315429-3.
- Maconie, Robin. 1990. The Works of Karlheinz Stockhausen, second edition. Oxford: Clarendon Press. ISBN 0-19-315477-3.
- Maconie, Robin. 2005. Other Planets: The Music of Karlheinz Stockhausen. Lanham, Maryland, Toronto, Oxford: The Scarecrow Press, Inc. ISBN 0-8108-5356-6.
- Peters, Günter. 1999. "'How Creation Is Composed': Spirituality in the Music of Karlheinz Stockhausen", translated by Mark Schreiber and the author. Perspectives of New Music 37, no. 1 (Winter): 96–131.
- Sadie, Stanley. 1973. "A Period of Cosmography: Stockhausen, Queen Elizabeth Hall". The Times (10 March): 11.
- Stockhausen, Karlheinz. 1978. "Ylem für 19 Spieler/Sänger (1972)" in his Texte zur Musik 4, edited by Christoph von Blumröder, 212–13. DuMont Dokumente. Cologne: Verlag M. DuMont Schauberg. ISBN 3-7701-0493-5.
- Stockhausen, Karlheinz. 1992. "YLEM (1972) für 19 Spieler". Booklet notes for Stockhausen: Ylem: 2 Versionen, 1973. Stockhausen Complete Edition CD 21. Kürten: Stockhausen-Verlag.
- Toop, Richard. 2000. "Von der 'Sternenmusik' zur Musik des Weltraums: Karlheinz Stockhausens musikalischer Kosmos". Neue Zeitschrift für Musik 161, no. 6 (November–December): 38–43.
- Bailey, Derek. 1992. Improvisation: Its Nature and Practice in Music, revised edition. [UK]: The British Library National Sound Archive. US edition, supplemented with photographs between pages 58 and 59, New York: Da Capo Press, 1993. ISBN 978-0-306-80528-8.
- , Ensemble Modern, Frankfurt, 1992YlemStockhausen rehearsing
- Moritz, Albrecht. 2005. " (1972)YlemStockhausen: " (Accessed 9 February 2012).
- Nordin, Ingvar Loco. Review of Stockhausen Complete Edition CD 21. Sonoloco Reviews (Accessed 9 February 2012).