Did the early universe become transparent to all wavelengths at once, or to some before others?

Question

Did the early universe become transparent to all wavelengths at once, or to some before others?

Answer 1

For "reasonable" wavelengths, say between 10,000 km and 0.01 nanometers (very long radio waves to X-rays), the universe would have become mostly transparent in just a few seconds.  You can calculate it from the expansion speed and temperature at the time of decoupling.

Answer 2

For 600000 years the cloud of matter that formed from the cooling singularity was so closely packed that light just bounced around from particle to particle, mush like it does as it tries to reach the surface of the sun, once the radiation broke through all of it spread out equally.

Answer 3

Good question, truly.

I am aware of the event to which you are referring, but this is not something that I know... yet.

Answer 4

Roughly speaking, it became transparent all at once.  Before recombination, you had free electrons and ions that coupled strongly to EM radiation.  When the electrons got captured to form neutral atoms, that pretty much decoupled matter from EM radiation.  

Of course, it didn't COMPLETELY decouple.  To this day, the universe is not completely transparent.  You can see all sorts of dark lines in the spectrum of light that passes through matter.  And sufficiently energetic radiation can still ionize matter.  But after recombination, there isn't so much of that around.