“Dance of the Black Holes” is an original composition by CIERA Post-Baccalaureate Research Fellow Darsan Swaroop Bellie (on drums) and the debut performance of the Star Eyes Initiative. The performance took place during the CIERA-hosted LIGO-Virgo-KAGRA collaboration meeting networking event on March 15, 2023.
Composer’s Notes below:
Focusing on a binary black hole system, the piece journeys through its formation channel and subsequently its inspiral, merger, and ringdown phases.
We begin by establishing our setting, a star cluster in the cosmos, through some extended techniques on the drums and cymbals. The piano then enters in a classical style, depicting a possible formation channel where the two black holes are not yet gravitationally bound and are floating through space looking for a partner, like lost souls. Once they find each other, we reach a brief moment of musical resolution before the black holes start interacting with each other. The saxophone and trumpet, representing the primary and secondary mass respectively, play out this initial interaction––a cosmic first date. They inquisitively communicate back and forth to learn more about one another, all in the backdrop of a steady bowed bass line that represents their weak but ever-present gravitational wave emissions.
The horns and bass then transition in a more unified manner into the piece’s main melody, signifying that the black holes are now comfortable enough with each other to become gravitationally bound: they are now a cosmic couple (“a match made in heaven”) and have entered their inspiral phase. Halfway through the melody, the piano and drums enter with a Latin tinge, setting the two-body orbit into motion. After the melody, the rhythm section settles into a piano solo in the style of a slow but groovy cha- cha-cha, thereby commencing the dance of the black holes in their stellar ballroom. Careful, you might find yourself dancing too!
The inspiral is the longest of the three phases, with its early stages experiencing the largest orbits, lowest orbital frequencies, and fewest gravitational wave emissions. As a binary system approaches the merger phase, the orbit shrinks more and more rapidly with time, while the frequencies and amount of gravitational wave emission increases. My main goal during the piece’s inspiral section was to depict this key concept, and I have used improvisational solos as an effective tool to accomplish this. First, during the piano solo, the rhythm section increases tempo considerably. Once we settle into a certain faster tempo, we segue into a propelling new groove and musical theme. The inspiral is now well underway and the black holes are interacting often, producing more and more gravitational wave emission. The horns trade solos with each other, again representing the binary’s interactions. As their trading continues, they become more aggressive and eventually start playing over each other.
Suddenly, we move to a new musical theme in a different time signature and key signature, and everything breaks down to a drum solo. This drastic change represents gaps in our understanding of the dynamics that occur in the late inspiral and merger phase, including the start of the ringdown phase when the black holes interact with each other inside the photon sphere. The drum solo acts as both an exploration of these dynamics and a representation of the complex general relativistic formalisms describing this stage. It is a brief departure from the overall narrative of the piece, and instead conveys the formidable gravitational wave research explorations that are being, and must continue to be, pursued.
The drum solo provides a transition back to the theme that led into it, but at a much faster tempo. We have passed the innermost stable circular orbit, and have entered the short merger phase. The ensemble joins back in, collectively and aggressively improvising until the music disintegrates into chaos. The band then abruptly stops, indicating the occurrence of the merger itself: our cosmic couple’s passionate dance ends by them merging into a single black hole. A cymbal bell ding immediately follows, representing a formal marker for the ringdown phase. We conclude the piece by restating the main melody from the early inspiral, starting only with the bowed bass line to emphasize the overtones produced and as an extension the importance of studying overtones when improving ringdown models. This iteration of the melody is supported by the suggestion of a bossa nova groove, creating a more tranquil vibe and releasing most of the rhythmic tension built up during the inspiral and merger phases.