Listening to the Sound of the Universe


Sonification: Ryan McGee , UCSB Media Arts Technology Group
Web design and graphic interface: R.J. Duran, Jr., UCSB Media Arts Technology Group
Content: Dr. Jatila van der Veen , UCSB Experimental Cosmology Group
and Education Project Manager, Planck Mission, NASA/JPL
Note: The applications are written in WebGL. Minimum system requirements:
  • Mac OSX 10.6.8 or above
  • Windows 7 or above
  • Google Chrome 29.0.1547.65
  • Safari 6.0.5 (Requires at least OSX 10.7 or 10.8)
  • We apologize, but at this time Firefox is not supported.

If you are using Google Chrome and have trouble seeing the applications, make sure WebGL is enabled in your browser settings. If you go to chrome://gpu, you should see "WebGL: Hardware accelerated" under "Graphics Feature Status", indicating WebGL is working. Verify that WebGL is enabled by going to http://get.webgl.org/. You should see a spinning cube. It is possible for the application to work on Windows XP if you have a graphics card that supports WebGL. To find out if your graphics card supports WebGL, see https://www.khronos.org/webgl/wiki/BlacklistsAndWhitelists for further support.


The Cosmic Microwave Background (CMB for short) is the oldest light we can observe, coming to us from a time when the Universe was just 380,000 years old, approximately 13.8 billion years ago. The high-precision map of the CMB that has been produced by the Planck Satellite has allowed scientists to extract the most refined values of what the universe is made of, after more that twenty years of research.

Normal matter (also called baryonic matter), that makes up stars and galaxies, planets and living things, contributes just 4.9% of the universe's total mass/energy inventory. Dark matter, which is detected indirectly by its gravitational influence on nearby matter, makes up 26.8%, while dark energy, a mysterious force thought to be responsible for accelerating the expansion of the universe, accounts for 68.3%.

Pie chart showing percentages of normal matter, dark matter, and dark energy.
Source: European Space Agency

Here is our most detailed model of the Cosmic Microwave Background, or CMB, as measured by the Planck Mission. It is a picture, in false color, of the baby universe, 13.8 billion years ago, around 380,000 years after the universe originated the Big Bang. Click and drag your mouse anywhere in the map to spin it around and see the baby picture of the universe from all sides.

The colors represent the variations in the temperature of the CMB, slightly warmer (orange) and slightly cooler (blue) than the average temperature of space, 2.726 Kelvin. The hot and cold spots indicate regions that were slightly more dense and less dense than average in the first 380,000 years of the universe, which eventually led to the formation of the structure in the universe we see today.

As the universe cooled and expanded, the dark matter began to collect into clumps, while the photons and baryons (protons, electrons, and a few helium nuclei) were tightly bound in a plasma. This action created pressure waves in the plasma of the baby universe, like rocks dropped into water set up waves. These pressure waves in the young universe were just like sound waves, except with extremely long wavelengths, on the order of 450,000 light years - approximately 50 octaves below the lowest note on the piano.

When the universe cooled down to around 3000 Kelvin, the temperature at which neutral hydrogen can form, light scattered off those primordial sound waves for the last time, and the universe became transparent. The patterns formed by the primoridal sound waves were encoded in the light we see today as the CMB.

The graph below is the Temperature Power Spectrum of the CMB. The first (largest) peak represents the fundamental, or longest sound wave (lowest note) in the primordial universe. This lowest note of the universe had a wavelength of approximately 450,000 light years. If you could hear it, it would be around 47 octaves below the lowest note on the piano!

We have translated the sounds of the primordial universe into the range of human hearing, so that you can imagine what it might have sounded like if you could have been there, immersed in the plasma of the early universe. Click on the PLAY button to hear the sound of the CMB, compressed by 50 octaves.





The CMB Temperature Power Spectrum as measured by the Planck Mission, 2013



bandwidth 
highpass   
lowpass     


You can focus in on the harmonics by sliding the bandwidth slider (top) to the left. This will produce a more bell-like tone.

The high pass and low pass sliders allow you to listen to isolated parts of the sound. Sliding the high pass filter to the right cuts out the lower tones, while sliding the low pass filter to the left cuts out the higher tones.

By using the two filters together, you can 'zoom in' on one or more harmonics, find the lowest sound you can hear, or simply create interesting sound effects.

The power spectrum of temperature variations in the CMB tells us something about the composition of the universe: how much normal matter, dark matter, and dark energy there is; how old the universe is; how fast it is expanding; and how long it took for the universe to become transparent. The rise in the power spectrum at the very low end (long wavelength) hints at possible asymmetry in the very earliest moments of the universe, and the very small fluctuations at the highest end (shortest wavelengths) tell us something about the way clumps of matter in the 'foreground' act like gravitational lenses that distort the CMB signal.

To download our Sonification of the CMB application, with which you can compare the sounds of 15 different model universes with different compositions, click HERE .