In our Culture Crossover series we pick up examples of projects that delightfully bridge the worlds of technology and culture. We'll be reviewing exhibitions, giving you a heads up on cultural events or talks coming up in the UK and highlighting the best techy art.

To read more instalments of the Culture Crossover series click here.

blackhole

Those who came of age in the mid-noughties will probably remember the tortured crooning and swooping crashes of Muse's Supermassive Black Hole - the pallid luminescence of Matt Bellamy's face shining brighter than any star. But do black holes really sound like the breathy screeching of an indie rock kid circa-2006? They do not.

This month, renowned ambient musician William Basinski released a new album, On Time Out of Time, which features tracks sampling the sound of two black holes merging. The music was originally commissioned by conceptual artists Evelina Domnitch and Dmitry Gelfand, to accompany an installation piece at the 2017 Limits of Knowing exhibition at Berlin's Martin-Gropius-Bau.

Basinski is no stranger to grand, conceptual projects that play on the passage of time. One of his most famous works, The Disintegration Loops, sonically documents the disintegration of old tapes as he attempts to digitise them. The haunting result, overlaid on footage of the post 9/11 skyline captured from his Brooklyn apartment, garnered overwhelming international acclaim.

But this may be his boldest foray into the space-time continuum yet, journeying back 1.3 billion years to broadcast the sound of the cataclysmic merging of two black holes, or as he put it when presenting the work live: "When two black holes fuck".

The opening track abruptly immerses the listener into a disconcerting soundscape characterised by distant, gong-like ringing, rhythmically flecked with the patter of static and shot through with plaintive high pitched wails and eventually ominous thuds, as of an intermittent heart beat. Listen to the album here. 

The sound of the black holes merging only make up a small part of the audio, Basinski says. "I didn't use all of it because some of it was really scary, and then I extrapolated with my imagination, how these waves travelled billions of years to come to earth," he told Pitchfork.

He's not the only artist to be beguiled by the inchoate calls of outer space. Other artists to sample 'space noises' collected from NASA, among other sources, include experimental industrial musician, Lustmord, on his album Dark Matter. The resulting medley suffuses low-lying, warbling vibrations with deep, rolling shimmers and high pitched bleeps to create the foreboding sense of a vast and deserted astral plane. 

Breaking from the ambient approach but also sampling space sounds - this time the beeps heard in Apollo's space mission along with other clips from NASA's audio archives - is Quindar on their experimental electronic music album, Hip Mobility.

Isn't space silent?

'In space no one can hear you scream'. Popular culture has sunk into cultural consciousness the notion that space is silent. For 2001: A Space Odyssey, Stanley Kubrick sent crews to record silence in 12 locations across the Earth, before layering them on top of one another to create a quiet as full and impenetrable as space. But while for the most part it's true that there is no sound in space, there are occasional exceptions.

Sound requires some dense mass to travel through in order to propagate, for example air or water molecules. The 'sound' we hear is in fact a result of air molecules colliding into one another following an impact - such as a clash of cymbals - and travelling in a wave-like motion until they hit our ear drums, whereupon they're swiftly converted by our delicate inner ear apparatus and brains into 'noise'.

As sound travels through air, it causes particles to oscillate up and down. The rate of this oscillation is known as the frequency of the wave, which is measured in hertz. One hertz is equal to one oscillation per second, while the distance between the peaks or troughs of air pressure is the sound's wavelength.

The higher density an environment, the better sounds with shorter wavelengths will be able to travel through. In a more dispersed environment, only sounds with a longer wavelength will be able to propagate. The longer the wavelength, the lower the frequency and the lower the pitch we hear.

So why is there no sound in space? The problem is that in space molecules are too dispersed for sound to travel effectively, because the knock-on effect of molecules isn't possible. However, there are some very rare events in space where matter is dense enough for sound waves to travel through.

The deepest sound in the galaxy

One such event was recorded by the Chandra X-ray Observatory. A team of scientists were observing a puzzling phenomenon taking place in the Perseus Cluster group of galaxies located around 250 million light years away from Earth. They noticed that instead of cooling and creating new stars, as they'd expect, the gas in this cluster was remaining hot. It was being energised by something, but the scientists had no idea what.

In 2002, they made a discovery: it was coming from a supermassive black hole. The black hole was sucking in energy - as black holes are wont to do - but around the outer rim, energy was being pulled out too. Masses of circulating clouds of hot, magnetised gas were dragging material out of the hole at the speed of light in what are known as relativistic jets. The force of this activity was creating ripples, and, because the air was sufficiently dense, soundwaves too. 

But what does the outer edge of a supermassive black hole sound like? Although it wasn't possible for the sound to travel far beyond the outer reach of the gases, scientists were able to observe its characteristics. They managed to discover the frequency of the wave, and from this find the pitch of the siren song emanating from the bottleneck of this giant cosmic event. They claim it is a note akin to a B flat. However, at about 57 octaves below 'middle C', this would be the deepest known sound ever recorded.

It's arguably a pensive and disquieting note to thrum out into the universe. In fact, Rita Steblin in A History of Key Characteristics in the 18th and Early 19th Centuries, writes this of the characteristics of B♭ minor:

"A quaint creature, often dressed in the garment of night. It is somewhat surly and very seldom takes on a pleasant countenance. Mocking God and the world; discontented with itself and with everything; preparation for suicide sounds in this key."

So it seems the universe has spoken. Its chosen message? To mock God and the World, and prepare for imminent suicide. Charming.

Perhaps it's a good thing that humanity would remain stubbornly impervious to this note, given that it lies far outside of our hearing range. The lowest pitched noise humans can hear has an oscillation of about once every twentieth of a second; the noise emanating from the Perseus black hole has a cycle of around one oscillation every 10 million years.

This means it's lower than the lowest sound humanity can hear by about a million billion times.

Gravitational Waves

You may have heard that NASA released 'sounds of the universe' just before Halloween in 2017, compiled of recordings of events such as Jupiter's magnetosphere and Saturn's radio emissions. Did these rely on 'dense pockets of sound conducting matter' too? Actually, these were not originally soundwaves, but gravitational waves that were converted into audio.

Unlike sound waves, gravitational waves don't need to piggyback on matter to travel through the universe, and with both an amplitude and a frequency, they can be easily converted into sound waves. The largest waves captured by NASA were two black holes 'spiralling into one another' - the same cosmic love-making that Basinski chose to sample on his album.