Explore a musical Solar System where gravity changes the speed of time.
Hear Time is an interactive audio-visual simulation that helps you understand gravitational time dilation by turning it into music.
Each planet has its own melody. As you move through space and enter deeper gravity wells, those melodies speed up or slow down around you.
Instead of reading about time dilation, you can hear it.
What is Hear Time?
Hear Time is a browser-based simulation of a stylised Solar System.
You can fly between the Sun and planets in first-person view while listening to the music they generate.
Every celestial body has its own repeating sequence of notes. The notes remain the same, but their duration changes depending on your position in space.
When you are in a shallow gravity well, objects in deeper gravity wells sound slower.
When you are in a deeper gravity well, objects in shallower gravity wells sound faster.
That changing rhythm is the sound of relative time dilation.
Why use sound?
Time dilation is real, but it is difficult to imagine.
In ordinary life, time seems to pass at the same rate everywhere. But according to Einstein’s theory of relativity, gravity affects the passage of time.
Stronger gravity makes time pass more slowly compared with weaker gravity.
That effect is usually far too small to notice in the real Solar System. Hear Time exaggerates it so the idea becomes easier to experience.
By converting time dilation into rhythm, the simulation makes an invisible idea perceptible.
You do not need to know the maths. You can simply move, listen and notice what changes.
How the simulation works
Hear Time uses a simplified model of the Solar System.
The Sun and planets are assigned exaggerated time-dilation states. These states are not physically accurate. They are deliberately amplified to make the effect audible.
The Sun has the deepest gravity well. Jupiter, Saturn and Neptune have strong gravity wells. Earth, Venus and Uranus have moderate gravity wells. Mercury, Mars and open space are treated as undilated.
As you move through the simulation, your own observer state changes depending on which gravity well you enter.
The app then compares your observer state with the time-dilation state of each celestial body.
That comparison controls the length of the notes you hear.
Short notes represent faster observed time.
Long notes represent slower observed time.
The music system
Each celestial body has a unique sixteen-note musical sequence.
All notes are drawn from the C major seventh chord: C, E, G and B. This keeps the sound harmonious even when many bodies are playing at once.
The size of each body is represented by octave.
The Sun plays in the lowest octave. The largest planets play higher than the Sun, and the smallest planets play in the highest octave.
The tempo remains constant at 140 beats per minute.
The note sequences stay synchronised, but their note lengths change as your position changes.
This means the simulation remains musical while still communicating different rates of time.
Spatial audio
Hear Time also uses stereo positioning and volume to help you locate objects.
A planet to your left sounds to your left.
A planet to your right sounds to your right.
Nearby objects sound louder.
Distant objects sound quieter.
What to listen for
Try flying from open space toward Jupiter or the Sun.
As your observer state changes, the music around you changes too.
Some melodies stretch into long, slow tones.
Others begin to move more quickly.
The notes are the same, but time is being heard from a different point of view.
That is the core idea of Hear Time: gravity changes time, and music makes the change noticeable.
Is Hear Time scientifically accurate?
Hear Time is accurate in its core idea, but not in its scale.
Real gravitational time dilation exists, but the effect within our Solar System is extremely small.
This simulation deliberately exaggerates the strength of gravity wells so users can hear the difference.
It should be understood as an educational and artistic model, not a precise scientific calculation.
Its purpose is to make a difficult idea intuitive.
A project by Martin Dillon
Hear Time is part of a broader exploration of how sound can communicate spatial and abstract information.
Some things are easier to understand when you can hear them.