Hi there!

[Atla]

I think there was one study that suggested that the cold spot in the CMB could actually be caused by a long tube-shaped void, and the void is positioned in such a way that we are looking right through the whole thing.

Sounds like the simplest solution, but then how reliable is the CMB in general, maybe it's basically justthe imprint of the stuff the light traveled through after it was emitted ? Although that still wouldn't explain the Hawking-points for example.

I hadn't seen this until now. One of these days I'll get around to talking about the CMB in my astro post.

We study the CMB using spherical harmonics:


When applied to the whole sky we get l's like this:


It's common to plot the multipole moments with the power spectrum because it's a powerful test of cosmological models: we can predict the shape and location of the curves on such a plot in a model-sensitive way. Since we find data points that do indeed fall along model curves, I'd say that the answer to the question "how reliable is the CMB in general" is "very reliable" since it produces testable outcomes from first principles reliably.

Ah interesting, I haven't looked into this yet. I know that first you have to compensate for the CMB dipole, but don't know what the rest of the CMB tells us.
I just thought that if it's true that a void can cause an anomaly as severe as the cold spot, then maybe it gets pretty difficult to extract data from the original Big Bang afterglow. I hope we don't just get mostly random noise by the time that light gets here, due to the regions the light traveled through since then.

[Astro Cat]

Ah interesting, I haven't looked into this yet. I know that first you have to compensate for the CMB dipole, but don't know what the rest of the CMB tells us.
I just thought that if it's true that a void can cause an anomaly as severe as the cold spot, then maybe it gets pretty difficult to extract data from the original Big Bang afterglow. I hope we don't just get mostly random noise by the time that light gets here, due to the regions the light traveled through since then.

You can't ask for a better source than Wayne Hu's page here:

[url]http://background.uchicago.edu/~whu/intermediate/intermediate.html[/url]

It has excellent animations/gifs that I've used in my own presentations.

For instance, here is a good example of how the baryon acoustic oscillations give a particularly sensitive test for different cosmological models (how the curves observed would look different under different models):

[url]http://background.uchicago.edu/~whu/intermediate/clcurvature.html[/url]

[Sy Borg]

The whole sky applications look rather like some of the orbitals of an atom :)