I just finished watching the first season of the 2005 remake of Battlestar Galactica. Generally the music stays out of the way, especially compared with the 1978 original. However, there is one interesting feature in Bear McCreary's music for the remake that has stood out to me. Whenever the Cylon "Number Six" appears, a musical motive also appears. This motive alternates the tonic major triad (the main, stable, "home" chord for a musical key) with a major flat-VI chord (a major chord built on the sixth note of the minor scale). This is both really interesting imagery, and a substantial missed opportunity. Here's what I mean...
First the imagery. The alternation of "home" (the tonic chord) with a VI chord is a fairly obvious reference to Number Six as she interacts with a human. There is also an interesting sense of mixture here. By using major flat-VI instead of the minor vi chord that normally comes in a major key, McCreary is mixing major and minor ― what music theorists call modal mixture. The mixture of major and minor is a great accompaniment to this new breed of Cylon ― a machine at its core, but fully human in appearance. In other words, uncanny.
The uncanny has a long tradition in musical drama. In particular, theorist Richard Cohn has pointed to one very prominent musical motive that repeatedly appears in support of the uncanny in the music of Richard Wagner: the alternation of major tonic with minor flat-VI ― just one note different from McCreary's Number Six motive. There are a number of reasons why I – ♭vi represents the uncanny well. Like I – ♭VI, it mixes major and minor. Also, as Cohn points out, both chords contain the other's leading tone ― the note that more than any other in a musical key says "please resolve me!" ― making it difficult to discern which chord is the "real" tonic chord, the stable chord that resolves all harmonic tension. (This leading tone is the one note missing from McCreary's Number Six motive, which uses major flat-VI.)
Cohn also points out that this uncanny motive, while mixing aspects of major and minor, belongs to a scale that is neither major nor minor. The six notes of the tonic and minor-flat-VI chords make up what is known as the hexatonic scale. In addition to mixing aspects of major and minor, the hexatonic scale is perfectly symmetrical. And symmetrical scales are often used in music with ambiguity or uncertainty, as their symmetry makes multiple tonics (multiple stable points of arrival) equally likely. Perfect for the uncanny. Since these chords form compliments in the hexatonic scale and each contain the other's leading tones, Cohn calls this chord pairing hexatonic poles.
Of course, McCreary can compose whatever he likes. And by using modal mixture, an unstable "asymmetrical" meter, and prominent VI chords, he can effectively portray the uncanny while making a clear "Number Six" reference to those who know basic music theory. However, if he had changed just one note, he could have amplified the uncanny effect and connected to a larger musical tradition. Even more, McCreary could have added to the six-ness and Cylon-ness of his Number Six motive by using hexatonic poles ― an unstable, artificial, six-note collection.
The Number Six motive works. But with one small change, McCreary could have given Battlestar Galactica nerds so much more fodder for their nerdiness. Oh well. This blog post will have to do. :p