Hearing Back

NASA has a library of sound files made from Hubble images. Astronomers take the digital data — the brightness, position, and color of every object in the photograph — and assign it pitches, volumes, and timing. The resulting audio files let you hear the sky.

The Hubble Ultra Deep Field contains approximately ten thousand galaxies in a patch of sky smaller than a grain of sand held at arm's length. Each galaxy is assigned a single note. The later the note plays, the farther away the galaxy. In just under a minute, you can hear back nearly thirteen billion years.

The image already existed at the intersection of multiple time streams — each galaxy's light departed at a different point in the universe's history, some when the universe was only a few hundred million years old. But the photograph compresses all that depth into a single plane. The sonification unfolds it again: time becomes sequence, distance becomes pitch, and thirteen billion years becomes a minute you can sit with.

There is also a sonification of the Bullet Cluster — the collision of two galaxy clusters that provided the first direct proof of dark matter. In the audio file, dark matter is represented by the lowest frequencies and visible matter by the highest. You can hear the separation: the invisible mass that makes up most of the universe occupying one register, the matter we can see occupying another. The discovery that changed our understanding of what the universe is made of is now also something you can listen to.

This is the project of translation. Not replacing the thing with something else, but finding a frequency at which it can be received by a different sense, a different body, a different kind of attention. The data is the same. The form changes.

Éliane Radigue moved her music from a synthesizer into bodies for the same reason. The synthesizer could not outlive her. The frequencies it produced would go silent when the machine died. But if the music existed as knowledge in a musician's hands — as something felt and remembered and passed on — it could keep being played after the machine was gone. The form changed; the music continued.

The Yukaghir women who drew love letters on birchbark were doing the same thing. Love in the body is one frequency; love scratched into birchbark is another. The bark form has properties the body form doesn't — it can be carried, passed between hands, kept, read days later. Custom had closed the speech channel. So the love found another frequency.

The instruments I've been making are in this line. The Vanishing instrument asks you to face coordinates where a star used to be — to point toward an absence using the same technology you'd use to point toward something present. The Population III instrument tries to find a form for stars that existed 13.6 billion years ago, that no telescope has ever directly observed, that we know only through inference and the absence they left in the chemical abundances of later stars. You can't look at Population III stars. You can sit with a form that holds the shape of their absence.

None of these translations are the same as direct encounter. You are not hearing the galaxies themselves when you listen to the Ultra Deep Field sonification. You are hearing a translation of light into pitch, brightness into volume, distance into timing. Something is preserved and something is lost in every translation. The sound file cannot give you the experience of standing thirteen billion years from where you are. Nothing can.

But the translation does something the original cannot: it makes the thing receivable. It creates a form the body can enter. You can sit with a minute of music and know — in whatever partial way any of us knows anything — that you are hearing thirteen billion years. The partiality is not failure. It is what translation is.

To hear back: to receive a signal from the past. Also, as in a reply: the universe hearing you, and answering in a frequency you can use.