Editing Causality (physics) (section)

== Macroscopic vs microscopic causality ==
Causality can be defined macroscopically, at the level of human observers, or microscopically, for fundamental events at the atomic level. The '''strong causality principle''' forbids information transfer faster than the [[speed of light]]; the '''weak causality principle''' operates at the microscopic level and need not lead to information transfer. Physical models can obey the weak principle without obeying the strong version.<ref>{{Cite journal |last=Cramer |first=John G. |date=1980-07-15 |title=Generalized absorber theory and the Einstein-Podolsky-Rosen paradox |url=https://link.aps.org/doi/10.1103/PhysRevD.22.362 |journal=Physical Review D |language=en |volume=22 |issue=2 |pages=362–376 |doi=10.1103/PhysRevD.22.362 |bibcode=1980PhRvD..22..362C |issn=0556-2821}}</ref><ref>{{Cite book |last=Price |first=Huw |title=Time's arrow & Archimedes' point: new directions for the physics of time |date=1997 |publisher=Oxford University Press |isbn=978-0-19-511798-1 |edition=1. issued as an Oxford Univ. Press paperback |series=Oxford paperbacks |location=New York}}</ref>