Can you hear space?
Not directly, as a human. Space is almost completely silent because sound needs something to travel through.
Sound is a vibration passed from particle to particle, like a ripple of people bumping shoulders in a crowd. On Earth those particles are air; in space there is almost nothing between the stars so there is nothing to pass the bump along. If two spaceships crashed in front of you, you would see them but hear nothing (some movies, like 2001 A Space Odyssey, do this really well; others don’t!).
Astronauts talk to each other by radio. While we associate “radio” with sound, radio is actually wavelength of light (also called electromagnetic radiation or photons), and light does not need air to travel. The radio waves that you hear from your radio set are carried by electromagnetic radio waves with the sound waves coded on top of them, and your radio turns that coded signal back into sound you can hear.
The Music of the Spheres
People have linked music and the sky for over 2,500 years.
- Pythagoras (ancient Greece) noticed that a string cut in half plays the same note one octave higher. Simple number ratios like 2:1 and 3:2 make sounds that fit together nicely. He wondered if the planets, moving in their own steady patterns, made a hidden music too.
- Johannes Kepler (1619) gave each planet its own short melody. A planet speeds up when it is close to the Sun and slows down when it is far away, so Kepler made its note rise and fall to match.
Nobody can hear this ‘music’ with their ears: it was a way of saying the universe has order and pattern, just like a good piece of music.
Turning space into sound
Scientists can’t record sound in space, but they can turn space data into sound. This is called sonification. It works like a translation: for example numbers could become pitch, loudness or rhythm or create other translations.
- Pulsars. These are collapsed stars that spin very fast and flash a beam of radio waves at us each turn, like a lighthouse. Jocelyn Bell Burnell discovered the first one in 1967 at Jodrell Bank. Turned into sound, slow pulsars tick like a clock and fast ones spin so quickly the ticks blur into a buzzing note.
- A singing black hole. A giant black hole in the Perseus galaxy cluster sends pressure waves through the hot gas around it. The note is a B-flat about 57 octaves below middle C, far too low for any human to hear. NASA has sped the waves up so we could listen to it.
- Sound from a photo of a galaxy. Our Astronomy lead, Andy Newsam, has a tool called SonifyDSS. It draws a line across a sky photo. Each point on the line gets its own pitch, low at one end and high at the other, and brighter points play louder. Moving the line around the picture creates a changing sound. Red light goes to your left ear and blue light to your right.
Sonification can also help blind and partially sighted scientists study data, and it can let anyone notice patterns the eye might miss.
Binary Dust: a universe made of sound
Some musicians go further and invent a whole universe that runs on sound instead of light. Gavin Starks, who studied both astrophysics and music and worked at the Jodrell Bank radio observatory, calls his a soniverse.
- The sonon. In our universe, light comes in tiny packets called photons. In the soniverse, the smallest piece of sound is one single wave, called a sonon.
- Sound gravity. Real gravity pulls matter into clumps that become stars and planets. In the soniverse, sounds that repeat close together pull into clumps too. Those clumps are rhythms and musical phrases.
- Bent time. A heavy star bends space around it. A big cluster of sound can bend the musical time around it in the same way.
- The listener. A sonon only becomes music when someone hears it, a bit like how some things in quantum physics are only settled when they are measured.
One of his pieces, ds² – series 1, was inspired by a real pair of pulsars orbiting each other, discovered in 2003. It was written for a 32-metre radio telescope in a Latvian forest that is used for both science and art.
To listen: search for Binary Dust on Spotify or Bandcamp, or [for example] NASA sonification for space data turned into sound.
More listening
| Piece | Composer | Year | Description |
|---|---|---|---|
| Symphonia armonie celestium revelationum | Hildegard of Bingen | c. 1150s | “Symphony of the harmony of heavenly revelations”: a medieval Music of the Spheres |
| Spem in alium | Thomas Tallis | c. 1570 | 40 voices in eight choirs placed in a ring, so the sound travels around the room |
| Brandenburg Concerto No. 2, first movement | J.S. Bach | c. 1721 | The first track on the Voyager Golden Record, now travelling beyond the solar system |
| The Creation | Joseph Haydn | 1798 | The music explodes on the words “and there was light”. Haydn visited the astronomer William Herschel, who discovered Uranus |
| The Planets | Gustav Holst | 1914–16 | One movement per planet. Based on astrology, not astronomy: a good one to discuss |
| Die Harmonie der Welt | Paul Hindemith | 1951 (symphony), 1957 (opera) | About Johannes Kepler and his planet melodies |
| Atmosphères | György Ligeti | 1961 | Clouds of sound instead of tunes, used in the film 2001: A Space Odyssey |
| Longplayer | Jem Finer | 2000 | Began on 1 January 2000 and plays for 1,000 years without repeating Listen: https://longplayer.org |
| Pluto, the Renewer | Colin Matthews | 2000 | An extra movement for Holst’s The Planets, six years before Pluto became a dwarf planet |
| Sun Rings | Terry Riley | 2002 | Written for NASA, using radio waves from space recorded by spacecraft and turned into sound |
Try it yourself
- Planet scale. Give each of the eight planets a note, lowest for Mercury and highest for Neptune. Play them in order. Does the gap between notes match the gap between planets?
- Pulsar rhythm. In pairs, one person claps a steady beat as a slow pulsar. The other speeds up until the claps sound like a buzz. At what speed do the beats stop being a rhythm?
- Sound gravity. In groups, each person picks one short sound. Repeat your sounds and drift towards whoever sounds most like you. What “clumps” form?
- Message to aliens. In 1977 the Voyager space probes carried a golden record of music and sounds from Earth. Choose three sounds you would send today, and explain why.
Keywords
| Word | Meaning |
|---|---|
| Vacuum | A space with almost no particles in it, so sound can’t travel |
| Octave | The jump between two notes where one vibrates twice as fast as the other |
| Pulsar | A spinning dead star that sends out regular flashes of radio waves |
| Sonification | Turning data into sound so we can listen to it |
| Photon | The smallest packet of light |
| Sonon | An invented word for the smallest piece of sound: one single wave |
| Soniverse | An imaginary universe built from sound instead of light |