Science of the Cosmic Spectrum (2019)

By Ivan Baldry

The Cosmic Spectrum (2019) was an art and science collaboration exhibit by the Katie Paterson Studio. The idea was to take the colour of the universe concept and turn it into a colour wheel, with the colour of the universe through time shown around the wheel. For the art exhibit, the wheel was spun creating a visual merging of the colours. Follow this link for the video.

A picture of the colour wheel (with numbered annotations added) and the explanation that went with the exhibit are shown below. The orientations are not quite the same: the zero on the left picture is the time zero point.

To estimate the colour as perceived by the human eye, we take a model or observed spectrum (intensity versus wavelength) for each epoch in the universe, and calculate the CIE xyz coordinates or its chromaticity. I was involved in this collaboration by calculating these coordinates and giving feedback on the explanations. Then it is an artistic choice to either to display the colour at its maximum brightness or darken it.

0 to 1. From time zero to 380,000 years after the big bang, the universe expands and cools from millions of degrees to 3000 degrees (Kelvin). From 300 seconds on, light photons are bouncing around between electrons, protons and Helium nuclei. The colour is perfectly defined by its colour temperature.
1 to 2. From 380,000 years to 200 million years. Atoms form (Hydrogen and Helium) and the universe becomes transparent. This is called the 'dark ages' because no light is produced but the glow of the big bang still pervades the universe becoming cooler and cooler till about 50 degrees Kelvin (-220 Centigrade). This is illustrated by the darkening red.

2 to 3. The first stars form in their nascent galaxies at around 200 million years after the big bang. The universe is no longer defined by a single temperature with hot stars, cool stars and active galactic nuclei producing light at different wavelengths. The early galaxies would be blue with the light dominated by hot young stars. Over time cooler, redder, giant stars have an increasing contribution to the mix.
3 to 4. The present-day universe is about 14 billion years old. The light from a large sample of galaxies can be measured to determine a cosmic spectrum. This gives a pale yellow, beige or cosmic latte colour. From now on, over billions of years, the fuel for new stars is running out so galaxies will become redder as more long-lived stars dominate the light.

4 to 5. Because of the expected universe's continued expansion, it will become darker and darker. Some have speculated that a new big bang could emerge, and thus one ends up at the beginning of the colour wheel.

Links: - See more details at Cosmic Spectrum original page, return to my home page.

0 to 1. From time zero to 380,000 years after the big bang, the universe expands and cools from millions of degrees to 3000 degrees (Kelvin). From 300 seconds on, light photons are bouncing around between electrons, protons and Helium nuclei. The colour is perfectly defined by its colour temperature.	1 to 2. From 380,000 years to 200 million years. Atoms form (Hydrogen and Helium) and the universe becomes transparent. This is called the 'dark ages' because no light is produced but the glow of the big bang still pervades the universe becoming cooler and cooler till about 50 degrees Kelvin (-220 Centigrade). This is illustrated by the darkening red.
2 to 3. The first stars form in their nascent galaxies at around 200 million years after the big bang. The universe is no longer defined by a single temperature with hot stars, cool stars and active galactic nuclei producing light at different wavelengths. The early galaxies would be blue with the light dominated by hot young stars. Over time cooler, redder, giant stars have an increasing contribution to the mix.	3 to 4. The present-day universe is about 14 billion years old. The light from a large sample of galaxies can be measured to determine a cosmic spectrum. This gives a pale yellow, beige or cosmic latte colour. From now on, over billions of years, the fuel for new stars is running out so galaxies will become redder as more long-lived stars dominate the light.
4 to 5. Because of the expected universe's continued expansion, it will become darker and darker. Some have speculated that a new big bang could emerge, and thus one ends up at the beginning of the colour wheel.