Aside from micro organisms the dead body rots because of its own chemical processes and enzymes. Edit: This thread may better fit the Biology & Genetics subforum.
I have Neptune in the 7th opposing my Jupiter with Gemini rising This causes physical Decay as astro substances are depleting and taking things with them at the speed of light as seen on Fast forward tapes.
decomposition is an increase of entropy or dissociation of materials to a greater area/volume. Decomposition does not just happen because molecules bind and unbind with other molecules without need of catalysts because of enough time for these reactions to occur...decomposition happens not just because of presence of oxygen and thus oxydation...decomposition occurs from the universal preference of entropy and dissociation of matter.
its my bad choice of wording here...Universe laws are such that particles in greater concentration move to occupy area/volume with lesser concentration...such arrangement favors lower energy requirements associated between such particles. Universe favors entropy.
bacterial activity oxydation digestive enzymes oportunistic insects (flesh flies, blowflies, wasps, beetles, and their larvae) http://www.deathonline.net/decomposition/index.htm
yes even with solids in vacuum. After sometime even those molecules will not stay together forever and loose the energy.
People like to be heard, anything including ridiculous nonsense works as well...because life is boring...and when the slow ticking time finally hits us we realize that saying normal things we all know is just not fun anymore...and so we make up gibberish trying to peace logic out of thin air, because...because...we are bored and we want to be heard. Enmos, you do understand that, don't you?