A causal system is a system that depends only on the current and previous inputs. This property is referred to as causality. A system that gets values from the future is termed acausal.
Classically, nature has been considered to be a causal system. Though causality is still thought to be found in nature, discoveries in modern physics have challenged the view that nature is strictly causal. See Causality (physics).
Causality describes the relationship between causes and effects, and is fundamental to all natural science, especially physics.
This is equivalent to the statement that the cause and its effect are separated by a timelike interval, and the effect belongs to the future light cone of its cause.
A careful analysis of the phenomena is needed, and the outcome slightly depends on the chosen interpretation of quantum mechanics: this is especially the case of the experiments involving quantum entanglement that require Bell's Theorem for their implications to be fully understood.
Causality is the centerpiece of the universe and so the main subject of ontology; for comprehending the nature, meaning, kinds, varieties, and ordering of cause and effect amounts to knowing the beginnings and endings of things, to uncovering the implicit mechanisms of world dynamics, or to having the fundamental scientific knowledge.
Representing the current understanding of causality as the relation of cause and effect, this covers the modern definitions of "cause" as either the agent or agency or particular events or states of affairs.
Destiny might be considered reverse causality in that a cause is predated by an effect, i.e.