Viewing a single comment thread. View all comments

Magnergy t1_j2krhfu wrote

Reply to comment by Aseyhe in Is any "movement" visible in the fluctuations of the CMB over time, or does it appear static? by JarasM

Tens of years... Wow, so short. Really puts the temperature uniformity in a new perspective for me.

Are this and this still about right for how we think it would have looked?

37

Aseyhe t1_j2kswjm wrote

Sorry, I typed "reionization" but meant "recombination"... I've fixed that.

To clear things up:

  • Recombination is a process that occurred at a time of around 370000 years. At this time, the universe cooled enough that all of the free protons and electrons condensed into neutral hydrogen. Without all of the free electric charges, the universe became transparent. (The "re" in "recombination" is a complete misnomer.)

  • Reionization is a process that occurred at a time of around 200 million to 1 billion years. This is what those videos are showing. When the first galaxies formed, the light emitted by their stars and black hole accretion disks ionized essentially all of the neutral hydrogen in the universe. (The universe didn't become opaque again, though, just because the hydrogen was far too sparse by this time.)

44

mpinnegar t1_j2lhckc wrote

One of the reasons we know the universe had to have been much smaller and closer together in the past is that to have that uniform temperature over such a large scale (the entire cmb) those parts needed to be close together at some point to "coordinate" on what temperature they should all be.

8

mfb- t1_j2mffhy wrote

Tens of years shift in a process that took tens of thousands of years.

3