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Causality is the relationship between causes and effects. [1] [2] While causality is also a topic studied from the perspectives of philosophy and physics, it is operationalized so that causes of an event must be in the past light cone of the event and ultimately reducible to fundamental interactions. Similarly, a cause cannot have an effect ...
The idea that the output of a function at any time depends only on past and present values of input is defined by the property commonly referred to as causality. A system that has some dependence on input values from the future (in addition to possible dependence on past or current input values) is termed a non-causal or acausal system , and a ...
Causality is not inherently implied in equations of motion, but postulated as an additional constraint that needs to be satisfied (i.e. a cause always precedes its effect). This constraint has mathematical implications [45] such as the Kramers-Kronig relations. Causality is one of the most fundamental and essential notions of physics. [46]
Even though () does not cause () and vice-versa, one can write an equation relating () and (). This equation may be used to successfully calculate the number of hibernating bears (), given the surface area of the lake covered by ice. However, melting the ice in a region of the lake by pouring salt onto it, will not cause bears to come out of ...
The causality violating set is the set of points through which closed causal curves pass. The boundary of the causality violating set is a Cauchy horizon . If the Cauchy horizon is generated by closed null geodesics, then there's a redshift factor associated with each of them.
In quantum mechanics and quantum field theory, the propagator is a function that specifies the probability amplitude for a particle to travel from one place to another in a given period of time, or to travel with a certain energy and momentum.
Causal analysis is the field of experimental design and statistics pertaining to establishing cause and effect. [1] Typically it involves establishing four elements: correlation, sequence in time (that is, causes must occur before their proposed effect), a plausible physical or information-theoretical mechanism for an observed effect to follow from a possible cause, and eliminating the ...
The weaker the causality condition on a spacetime, the more unphysical the spacetime is. Spacetimes with closed timelike curves, for example, present severe interpretational difficulties. See the grandfather paradox. It is reasonable to believe that any physical spacetime will satisfy the strongest causality condition: global hyperbolicity.