Why is the Law of Conservation of Momentum so important?

 (Asked on Quora)

The Laws of Physics are what they are - plain and simple. If they were otherwise the universe would look markedly different and indeed if sentient life had existence in such a hypothetical universe (in some form or another) the question of importance would hinge on the specific local reality.

The importance we assign to the Conservation of Momentum (COM), or any other physics law for that matter, is a value judgement of how it impacts us. We need to walk, run, swim or jump so we rely on Newton’s Third Law (which is an alternative way of stating COM), hence we value it.

We make use of rocket and jet propulsion for travel so we elevate the importance of COM again. Action-Reaction forces and collision physics have played a vital role in planetary and stellar formation so we highlight its importance. After all what we believe life to be requires these structures to function.

However this needn’t be the case. It is conceivable that superstructures may arise from systems that don’t adhere to COM. In which case those working off an alternative ‘Quora’ in a parallel world may be offering thanks to an obvious paradigm that subscribes to a non-COM truism.