Causality describes the relationship between causes and effects, is fundamental to all natural science, especially physics, and has a basis in logic. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Logic is the study of the principles of valid demonstration and Inference. It is also studied from the perspectives of philosophy, computer science, and statistics. Philosophy is the study of general problems concerning matters such as existence knowledge truth beauty justice validity mind and language Computer science (or computing science) is the study and the Science of the theoretical foundations of Information and Computation and their Statistics is a mathematical science pertaining to the collection analysis interpretation or explanation and presentation of Data.
In classical physics, it was assumed that all events are caused by earlier ones according to the known laws of nature, culminating in Pierre-Simon Laplace's claim that if the current state of the world were known with precision, it could be computed for any time in the future or the past. (see Laplace's demon)
According to classical physics, the cause simply had to precede its effect. In the History of science, Laplace's demon is a hypothetical "demon" envisioned in 1814 by Pierre-Simon Laplace such that if it knew the precise location In modern physics, the notion of causality had to be clarified.
The insights of the theory of special relativity confirmed the assumption of causality, but they made the meaning of the word "precede" observer-dependent. Special relativity (SR (also known as the special theory of relativity or STR) is the Physical theory of Measurement in Inertial Consequently, the relativistic principle of causality says that the cause must precede its effect according to all inertial observers. In Physics, an inertial frame of reference is a Frame of reference which belongs to a set of frames in which Physical laws hold in the same and simplest 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. SpaceTime is a patent-pending three dimensional graphical user interface that allows end users to search their content such as Google Google Images Yahoo! YouTube eBay Amazon and RSS In Special relativity, a light cone (or null cone) is the pattern describing the temporal evolution of a flash of Light in Minkowski spacetime Equivalently, special relativity has shown that it is not only impossible to influence the past, it is also impossible to influence distant objects with signals that travel faster than the speed of light.
In the theory of general relativity, the concept of causality is generalized in the most straightforward way: the effect must belong to the future light cone of its cause, even if the spacetime is curved. General relativity or the general theory of relativity is the geometric theory of Gravitation published by Albert Einstein in 1916 SpaceTime is a patent-pending three dimensional graphical user interface that allows end users to search their content such as Google Google Images Yahoo! YouTube eBay Amazon and RSS New subtleties must be taken into account when we investigate causality in quantum mechanics and relativistic quantum field theory in particular. Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons In quantum field theory (QFT the forces between particles are mediated by other particles In quantum field theory, causality is closely related to the principle of locality. In Physics, the principle of locality is that distant objects cannot have direct influence on one another an object is influenced directly only by its immediate surroundings 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. An interpretation of quantum mechanics is a statement which attempts to explain how Quantum mechanics informs our Understanding of Nature. Quantum entanglement is a quantum mechanical Phenomenon in which the Quantum states of two or more objects are linked together so that one object Bell's theorem is a theorem that shows that the predictions of Quantum mechanics (QM are not intuitive and touches upon fundamental philosophical issues that relate to modern
Despite these subtleties, causality remains an important and valid concept in physical theories. For example, the notion that events can be ordered into causes and effects is necessary to prevent causality paradoxes such as the grandfather paradox, which asks what happens if a time-traveller kills his own grandfather before he ever meets the time-traveller's grandmother. Time travel is a common theme in Science fiction and is depicted in a variety of media This article refers to the Time travel paradox In novels based on the television series Doctor Who, "Grandfather Paradox" is the semi-mythical See also Chronology protection conjecture. The chronology protection conjecture is a Conjecture by the Physicist Professor Stephen Hawking that the Laws of physics are such as to prevent
Distributed causality
Theories in physics like the Butterfly effect from chaos theory open up the possibility of a type of Distributed parameter systems in causality. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. The butterfly effect is a phrase that encapsulates the more technical notion of sensitive dependence on initial conditions in Chaos theory. In Mathematics, chaos theory describes the behavior of certain dynamical systems – that is systems whose state evolves with time – that may exhibit dynamics that A distributed parameter system (as opposed to a lumped parameter system) is a System whose State space is infinite- dimensional. The butterfly effect theory proposes:
"Small variations of the initial condition of a nonlinear dynamical system may produce large variations in the long term behavior of the system. "
This opens up the opportunity to understand a distributed causality.
References
- Green, Celia (2003). The Lost Cause: Causation and the Mind-Body Problem. Oxford: Oxford Forum. ISBN 0-9536772-1-4. Includes three chapters on causality at the microlevel in physics.
See also
External links
- Causal Processes, Stanford Encyclopedia of Philosophy
- Caltech Tutorial on Relativity — A nice discussion of how observers moving relatively to each other see different slices of time. Causality (but not causation) denotes a necessary relationship between one event (called cause and another event (called effect) which is the direct consequence Retrocausality (also called retro-causation, backward causation and similar terms is any of several hypothetical phenomena or processes that reverse Causality The causal structure of a Lorentzian manifold describes the causal relationships between points in the manifold The causal sets programme is an approach to Quantum gravity. Its founding principle is that Spacetime is fundamentally discrete and that the spacetime points are related In Physical cosmology, particle horizon is the maximum distance from which particles could have traveled to the observer in the Age of the universe Philosophy of physics is the study of the fundamental philosophical questions underlying modern Physics, the study of Matter and Energy Two entities are in causal contact if there may be an event that has affected both in a causal way
- Faster-than-c signals, special relativity, and causality. This article explains that faster than light signals do not necessarily lead to a violation of causality.
- by John G. Cramer:
- EPR Communication: Signals from the Future? "In this column I want to tell you about this causality-violating communications scheme and its possible consequences. "
- The Transactional Interpretation of Quantum Mechanics "3. 10 The Arrow of Time in the Transactional Interpretation - The formalism of quantum mechanics, at least in its relativistically invariant formulation, is completely even handed in dealing with the "arrow" of time, the distinction between future and past time directions. "
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