If the early universe was packed so densely that it was opaque to light, and did not become transparent until there was enough space for the smaller wavelengths of light to penetrate, then would the first visible glow of the early universe have been violet?
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$\begingroup$ The universe was opaque for roughly 380000 years. $\endgroup$– PM 2RingCommented Oct 6 at 14:58
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No. It changed for all colors all at once.
The early universe was too hot for atoms to form. This means that there were a lot of free electrons and protons. These interact strongly with light. Light could not travel very far before it hit a charged particle and scattered. It was like driving in a fog.
Once the universe cooled below a few thousand degrees, the electrons and protons could combine to form hydrogen atoms. The "fog" cleared, and the universe became transparent to all wavelengths.
