Every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.
– Newton’s First Law of Motion, translated from the Principia‘s Latin
“A body that is acted on by no net force moves at a constant velocity (which may be zero) and zero acceleration.” http://physics.about.com/od/classicalmechanics/a/lawsofmotion_2.htm
1. If the action of any body of matter is static in the absence of the introduction of an outside force, original matter would maintain stasis apart from a new force acting upon it, since only the original forces would also be present to act upon the original mass.
2. The proposition of the ‘big bang’ theory is that the original ‘singularity’ (sometimes referred to as a ‘cosmic egg’) built up such internal force that its matter was propelled outward to create the universe. If the singularity represents all matter and energy from which the universe was developed, there could be no other energy source or applied force than what was contained in the ‘singularity’ itself, preventing the possibility of a change in “net force”, and therefore preventing the unlimited expansion of the ‘universe’ produced by such a process.
2b the original singularity would have contained a specific amount of energy with particular characteristics. In the absence of an outside influence, there would be no change to either the quantity or the characteristics of the contained energy – preventing the occurrence of the “big bang” in the first place.