The principle of causality (also called the law of cause and effect) is that which connects one process (cause) with another process or state (consequence), where the first partly is responsible for the second, and the second partially depends on the first. This is one of the main laws of logic and physics. However, recently French and Australian physicists have turned off the principle of causality in an optical system that they have recently created artificially.
In general, any process has many reasons that are causal factors for it, and all of them lie in its past. One effect, in turn, may be the reason for many other effects that all lie in its future. Causality has a metaphysical connection with the concepts of time and space, and a violation of the causality principle is considered a serious logical mistake in almost all modern sciences.
The essence of the concept
Causation is an abstraction that indicates how the world develops, and therefore is a basic concept more prone to explaining various concepts of progression. It is in a sense connected with the concept of efficiency. In order to understand the principle of causality (especially in philosophy, logic and mathematics), you need to have good logical thinking and intuition. This concept is widely represented in logic and linguistics.
Causality in philosophy
In philosophy, the principle of causality is considered one of the basic principles. Aristotelian philosophy uses the word “reason” to mean “explanation” or the answer to the question “why?”, Including material, formal, effective and finite “causes”. According to Aristotle, “reason” is also an explanation of everything. The theme of causality remains fundamental in modern philosophy.
Theory of Relativity and Quantum Mechanics
In order to understand what the principle of causality says, one must be familiar with the theories of relativity of Albert Einstein and the fundamentals of quantum mechanics. In classical physics, an effect cannot occur before its immediate cause appears. The causality principle, the truth principle, the principle of relativity are quite closely related to each other. For example, in Einstein's special theory of relativity, causality means that an effect cannot happen regardless of a cause that is not in the back (past) light cone of this event. Similarly, a cause cannot have an effect outside its (future) light cone. This abstract and lengthy explanation of Einstein, obscure to the reader, far from physics, led to the introduction of the principle of causality in quantum mechanics. One way or another, the restrictions formulated by Einstein are consistent with a reasonable belief (or assumption) that causal influences cannot move faster than the speed of light and / or the passage of time. In quantum field theory, observable events with a space-like dependence should commute; therefore, the order of observations or measurements of observable objects does not affect their properties. Unlike quantum mechanics, the causality principle of classical mechanics has a completely different meaning.
Newton's second law
Causality should not be confused with Newton’s second law related to the conservation of momentum, because this confusion is a consequence of the spatial homogeneity of physical laws.
One of the requirements of the principle of causality, valid at the level of human experience, is that the cause and effect should be mediated in space and time (the requirement of contact). This requirement was very important in the past, primarily in the process of direct observation of causal processes (for example, pushing a trolley), and secondly, as a problematic aspect of Newton's theory of gravitation (gravitating the Earth by the Sun through action at a distance), replacing mechanistic sentences such like the theory of vortices of Descartes. The causality principle is often considered as an incentive for the development of dynamic field theories (for example, Maxwell's electrodynamics and Einstein's general theory of relativity), which explain fundamental problems of physics much better than the above-mentioned Descartes theory. Continuing the theme of classical physics, we can recall the contribution of Poincare - the principle of causality in electrodynamics, thanks to its discovery, has become even more relevant.
Empirics and metaphysics
Empiricists 'aversion to metaphysical explanations (such as, for example, Descartes' theory of vortices) has a strong influence on the idea of ​​the importance of causality. Accordingly, the pretensions of this concept have been underestimated (for example, in Newton’s Hypotheses). According to Ernst Mach, the concept of power in Newton’s second law was "tautological and redundant."
Causality in equations and calculation formulas
The equations simply describe the process of interaction, without any need to interpret one body as the cause of the movement of another and predict the state of the system after this movement is completed. The role of the causality principle in mathematical equations is secondary in comparison with physics.
Deduction and nomology
The possibility of a time-independent view of causality underlies the deductive nomological (DN) view of the scientific explanation of the event, which can be included in the scientific law. In the DN approach, the physical state is considered explainable if, by applying the (deterministic) law, it can be obtained from the given initial conditions. Such initial conditions may include momenta and the distance from each other of the stars, if we are talking, for example, about astrophysics. This “explanation of determinism” is sometimes called causal determinism.
Determinism
The disadvantage of the DN view is that the causality principle and determinism are more or less identified. Thus, in classical physics, it was assumed that all phenomena were caused by earlier events (i.e., determined by them) in accordance with the well-known laws of nature, culminating in the statement of Pierre-Simon Laplace that if the current state of the world were known from by accuracy, his future and past states could also be calculated. However, this concept is usually called Laplace determinism (and not “Laplace causality”), because it depends on determinism in mathematical models - such determinism as is presented, for example, in the Cauchy mathematical problem.
The confusion of causality and determinism is particularly acute in quantum mechanics - this science is acausal in the sense that in many cases it cannot identify the causes of actually observed effects or predict the effects of the same causes, but it may still be determined in some of its interpretations - for example if it is assumed that the wave function does not actually collapse, as in the interpretation of many worlds, or if its collapse is caused by hidden variables or simply redefines determinism as s, which determines the probability, rather than specific effects.
Difficult about the complex: causality, determinism and the causality principle in quantum mechanics
In modern physics, the concept of causality is still not fully understood. Understanding the special theory of relativity confirmed the assumption of causality, but they made the meaning of the word “simultaneous” dependent on the observer (in the sense in which the observer is understood in quantum mechanics). Therefore, the relativistic principle of causality suggests that the cause must precede the action in accordance with all inertial observers. This is equivalent to the assertion that the cause and its effect are separated by a time interval, and the effect belongs to the future of the cause. If the time interval separates two events, this means that a signal can be sent between them at a speed not exceeding the speed of light. On the other hand, if the signals can move faster than the speed of light, this will violate causality, because it will allow the signal to be sent at intermediate intervals, which means that at least some inertial observers will think that the signal moves backward in time. For this reason, the special theory of relativity does not allow different objects to communicate with each other faster than the speed of light.
General theory of relativity
In the general theory of relativity, the causality principle is generalized in the simplest way: the effect should belong to the future light cone of its cause, even if space-time is curved. New subtleties should be taken into account when studying causality in quantum mechanics and, in particular, in relativistic quantum field theory. In quantum field theory, causality is closely related to the principle of locality. However, the principle of locality is disputed in it, since it strongly depends on the interpretation of the chosen quantum mechanics, especially for experiments with quantum entanglement that satisfy Bell's theorem.
Conclusion
Despite these subtleties, causality remains an important and reliable concept in physical theories. For example, the idea that events can be arranged into causes and effects is necessary to prevent (or at least understand) the paradoxes of causality, such as the "grandfather paradox," which is the question: "What happens if a traveler in time will kill his grandfather before he ever meets his grandmother? "
Butterfly Effect
Theories in physics, such as the butterfly effect from chaos theory, open up possibilities like distributed parameter systems in causality.
A related way of interpreting the butterfly effect is to consider it as an indication of the difference between the application of the concept of causality in physics and the more general use of causality. In classical (Newtonian) physics, in the general case, only those conditions are considered (explicitly) that are necessary and sufficient for the occurrence of an event. Violation of the causality principle is also a violation of the laws of classical physics. This is only permissible today in marginal theories.
The causality principle involves a trigger that triggers the movement of an object. Similarly, a butterfly can be seen as the cause of a tornado in the classic example, explaining the theory of the butterfly effect.
Causation and quantum gravity
Caused by dynamic triangulation (CDT for short), invented by Renata Lall, Jan Ambierne and Jerzy Jurkevich, and popularized by Photini Markopoulo and Lee Smolin, is an approach to quantum gravity that, like loop quantum gravity, is independent of the background. This means that it does not imply any previously existing arena (dimensional space), but is trying to show how the space-time structure itself is gradually developing. The Loops '05 conference, organized by many loop quantum gravity theorists, included several presentations that discussed CDT professionally. This conference aroused considerable interest of the scientific community.
On a large scale, this theory recreates the familiar 4-dimensional space-time, but shows that space-time should be two-dimensional on the Planck scale and show a fractal structure on constant-time slices. Using a structure called a simplex, it divides space-time into tiny triangular sections. A simplex is a generalized form of a triangle in different dimensions. The three-dimensional simplex is usually called the tetrahedron, while the four-dimensional is the main building block in this theory, also known as the pentatope or pentachoron. Each simplex is geometrically flat, but simplexes can be “glued” together in different ways to create curved spaces. In cases where previous attempts to triangulate quantum spaces created mixed universes with too many dimensions or minimal universes with too few, CDT avoids this problem by allowing only those configurations where the cause precedes any effect. In other words, the time frame of all connected edges of simplexes, according to the concept of CDT, must coincide with each other. Thus, perhaps causality underlies the space-time geometry.
Theory of causation
In the theory of causal relationships, causality takes an even more prominent place. The basis of this approach to quantum gravity is the David Malament theorem. This theorem claims that the causal structure of space-time is enough to restore its conformal class. Therefore, knowing the conformal factor and causal structure is enough to know space-time. Based on this, Rafael Sorkin proposed the idea of ​​causal connections, which is a fundamentally discrete approach to quantum gravity. The causal space-time structure is represented as the initial point, and the conformal factor can be established by identifying each element of this initial point with a unit volume.
What does the principle of causality in management say?
To control production quality, in the 1960s, Kaoru Ishikawa developed a causal relationship diagram known as the Ishikawa diagram or fish oil diagram. The chart classifies all possible causes into six main categories, which it directly displays. These categories are then subdivided into smaller subcategories. The Ishikawa method identifies the “causes” of pressure on each other of the various groups involved in the production process of a firm, company or corporation. These groups can then be marked as categories in charts. The use of these diagrams is now beyond the scope of product quality control, and they are used in other areas of management, as well as in design and construction. Ishikawa schemes were criticized for their inability to distinguish between the necessary and sufficient conditions for the emergence of contradictions between the groups involved in production. But it seems that Ishikawa did not even think about these differences.
Determinism as a Worldview
A deterministic worldview believes that the history of the Universe can be exhaustively presented as a progression of events, which are a continuous chain of causes and effects. Radical determinists, for example, are convinced that there is no such thing as “free will,” since everything in this world, in their opinion, is subject to the principle of conformity and causality.