The Observable Universe and Beyond

The Observable Universe
Big Bang Theory
CMBR (Cosmic Microwave Background Radiation) Spectrum
CMBR Fluctuations
CMBR Polarization
CMBR Power Spectrum
Wilkinson Microwave Anisotropy Probe (WMAP) and ESA/Planck
Dark Matter (2018 Update for DAMA and SABRE)
Dark Energy
Parallel Universes, Multiverse - the Unobservable Universe
Quantum Cosmology and Pre-Big Bang Theories

The Observable Universe

The observable universe is the space around us bounded by the event horizon - the distance to which light can have traveled since the universe originated. This space is huge but finite with a radius of about 10²⁸ cm. There are also finite total numbers of everything: about

		10¹¹ (2x10¹², according to the 2016 update) galaxies, 10²¹ stars, 10⁷⁸ atoms, 10⁸⁸ photons. There is a hierarchy of structure: Everything is composed of smaller things and is a part of something larger as shown in Figure 02-01a (See also "Map of the Universe" for a different perspective) and Figure 15-01. The characteristics of structures in different scale changes according to the interplay of various physical forces. Quantum phenomena control the small scales, while gravity dominates on large scales, and both come into play at the beginning of the universe. On each scale of size there is a corresponding scale of time: processes tend to happen quickly on small scales and slower on the larger ones.
Figure 02-01a The Observable Universe [view large image]	Figure 02-01b Inflationary Cosmology

Note that according to inflationary cosmology, the entire universe is much bigger than the observable one (see Figure 02-01b, not to scale), and the confine of observable universe depends on the location. Observers in the Andromeda galaxy and beyond have their own observable universes that are different from but overlap with ours.