A perturbation is a disturbing influence upon the stability of a system. It disrupts and agitates the system that it intrudes upon to a degree that depends upon the magnitude of the intruding influence, as well as the effectiveness of the control mechanisms the system has in place. It is metaphysically tempting to suggest that every entity and phenomenon in the universe has the capacity to perturb every other, but the everyday realities of observation suggest that such at assertion would not be of cosmic significance. A perturbation is an energy intrusion... usually random... that is sufficient to cause a deviation in the form or behaviour of a system. The cosmic events of comets impacting a planetary satellite are substantial perturbations. These events, perhaps in conjunction with other gravitational influences, may well be sufficient to even initiate an instability in the equilibrium of the orbit. The pigment discolorations in a few of the cells of a living organism may be a corruption of no consequence, but it may also be evidence of a virus intrusion against which the defence systems of the plant are quite inadequate. Whilst the growth pattern of a leaf structure may conform in some broad manner to a conceptual simplification, the number of irregular deviations from any such pattern would be considerable.

It has always been a mistake to assume that by designating certain selected parameters as significant, and designating others as less significant, any behavioural patterns so revealed in the simplified system would thereby indicate some sort of 'law'. Conceptualizing form or pattern is a process of ignoring as much supposedly irrelevant detail as possible in order to simplify the infinite complexities of reality. To suppose that such a procedure would reveal deterministic laws is always unjustified. The universe is a complexity of systems being continuously subjected to chaotic interacting disorder. It is not existentially possible to isolate any aspect of it. Any behavioural pattern observed by protecting a system from the influences of indiscriminate intrusions may well function quite adequately in controlled conditions for the purposes of engineering and design. If however, sporadic disturbances occur when the system is near a critical balance, and a positive feedback is able to also reinforce a magnified effect of the instability, then the system will alter its behaviour to one which is unpredictably influenced by the disturbances. Perturbations ensure that it is not possible to simplify cosmic patterns into 'laws'. Force = mass x acceleration may be a convenient simplification in some circumstances... when various factors and circumstances are either ignored or deemed to be irrelevant... but in the universe we find ourselves in, mass, distance and time are all subject to uncertainties of estimation and measurement, so that supposing such a relationship to be an intrinsic and absolute 'law' is quite misplaced.