Causal system
From Free net encyclopedia
A causal system is a system with output and internal states that depends only on the current and previous input values. This property is referred to as causality. A system that has some dependence on input values from the future (in addition to possible past or current input values) is termed an acausal system, and a system that depends solely on future input values is an anticausal system.
Classically, physical reality or 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. For an in-depth discussion, see causality (physics).