Originally posted by: LongCoolMother
The problem is what is meant by the 'observable' universe. Well, there's a lot of info regarding this as well. To put it simply, early on after the big bang, photons scattered all over, and we had a hot, opaque universe. This opaque cloud of photons and energy expanded as some sort of shell, which is still moving outwards today. We can't see past this shell, since it acts as an opaque wall. Its what causes the well-known cosmic microwave background radiation that comes from all corners of the Universe.
You seem to be confusing recombination (or decoupling) with some sort of Earth-like explosion such as dynamite. There is no "shell" nor is there a wall which causes the microwave background. The microwave background radiation which permeates all space IS the remnant of the early universe.
After the big bang, the early universe was filled with a plasma of charged particles in which electromagnetic radiation could not travel very far without being absorbed and re-emitted. Thus, the process of proton + electron -> Hydrogen + photon and its inverse were in equilibrium. In this time, the universe was opaque to photons. Around 300,000 to 400,000 years after the big bang, space had expanded and cooled enough for stable atoms to form.
From Wikipedia: "This process is called recombination or decoupling (referring to electrons combining with nuclei and to the decoupling of matter and radiation respectively)."
Electromagnetic radiation present at that time could travel without being absorbed, i.e. it was no longer opaque. As space continued to expand and cool the wavelengths of these early photons expanded (extremely red-shifted). Again from Wikipedia: "[The radiation] has a thermal black body spectrum at a temperature of 2.725 kelvin. Thus the spectrum peaks in the microwave range at a frequency of 160.2 GHz, corresponding to a wavelength of 1.9 mm."