Skip to main content Accessibility help
×
Hostname: page-component-848d4c4894-xm8r8 Total loading time: 0 Render date: 2024-06-15T23:08:30.614Z Has data issue: false hasContentIssue false

8 - What do we learn from the angular distribution of the CBR?

Published online by Cambridge University Press:  17 September 2009

R. B. Partridge
Affiliation:
Haverford College, Pennsylvania
Get access

Summary

In the standard Big Bang model (introduced in Chapter 1), the Universe is assumed to be exactly homogeneous and isotropic, and only gravitational forces between particles are considered. Under these conditions, all particles in the Universe are at rest in comoving coordinates and the CBR is completly isotropic.

The actual Universe we observe clearly differs from this idealized model in a number of obvious ways; for instance, the Universe is visibly inhomogeneous on all length scales up to many megaparsecs. Any departure from the idealized conditions assumed in the Big Bang model can introduce anisotropy into the CBR.

Sources of anisotropy in the CBR

In this section, we list briefly some cosmological processes which can introduce anisotropy into the CBR on various angular scales, starting with the largest. Suppose, for instance, that we allow large-scale magnetic fields, and not just gravity, into our cosmological model. Then the CBR will become anisotropic (Thorne, 1967). Likewise, long wavelength gravitational waves added to an otherwise homogeneous Universe will induce a quadrupole moment (Dautcourt, 1969; Burke, 1975).

A more fundamental source of anisotropy in the CBR is the anisotropic expansion of the Universe as a whole (see, e.g., Barrow et al., 1983). The cosmological equations derived from General Relativity permit a wide variety of anisotropic solutions as well as the isotropic Robertson–Walker models discussed in Chapter 1.

Type
Chapter
Information
Publisher: Cambridge University Press
Print publication year: 1995

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×