A scientific theory is an explanation of aspects of the natural world that can be tested repeatedly, in accordance with the scientific method, using observed protocols and predefined experiments. Well-established scientific theories have persisted in strict supervision and realizing scientific knowledge.
The definition of scientific theory (often contracted for "theory" for the sake of brevity) as used in disciplines is significantly different from the use of the word "theory" in everyday language. In everyday conversations, "theory" can imply that something is unfounded and speculative, the opposite of its meaning in science. This different usage is proportional to the opposite use of "predictions" in science versus daily conversation, where it shows mere hope.
The power of scientific theory is concerned with the diversity of the phenomenon that can be explained and its simplicity. When additional scientific evidence is collected, scientific theories can be modified and eventually rejected if they can not be made according to new findings; in such circumstances, more accurate theories are required. In some cases, a less accurate and unmodified scientific theory can still be treated as a theory if useful (because of its simplicity alone) as an approach under certain conditions. The case example is Newton's law of motion, which can serve as an approach to special relativity at a relatively small velocity to the speed of light.
Scientific theories can be tested and make false predictions. They illustrate the causes of certain natural phenomena and are used to explain and predict aspects of the physical universe or certain areas of investigation (eg, electricity, chemistry, and astronomy). Scientists use the theory for further scientific knowledge, as well as to facilitate advances in technology or medicine.
As with other forms of scientific knowledge, scientific theories are deductive and inductive, aiming for a clear and predictive power.
Paleontologist Stephen Jay Gould writes that "... facts and theories are different things, not rung in the hierarchy of enhancement of certainty.The fact is the data of the world.Theory is the structure of ideas that explain and interpret facts."
Video Scientific theory
Jenis
Albert Einstein describes two types of scientific theory: "constructive theory" and "principle theory". Constructive theory is a constructive model for phenomena: for example, kinetic energy. The theory of principle is an empirical generalization like Newton's laws of motion.
Maps Scientific theory
Characteristics
Important criteria
Usually for any theory accepted in most academies there is one simple criterion. The important criterion is that the theory must be observable and repeatable. The criteria mentioned above are essential to prevent fraud and perpetuate the science itself.
The decisive characteristic of all scientific knowledge, including theory, is the ability to make predictions that can be forged or tested. The relevance and specificity of these predictions determines how useful the theory is. A candidate theory that does not make observable predictions is not a scientific theory at all. Predictions that are not specific enough to be tested are also useless. In either case, the term "theory" does not apply.
A group of knowledge descriptions can be called a theory if it meets the following criteria:
- This makes forged predictions with consistent accuracy across scientific areas of investigation (such as mechanics).
- This is well supported by much independent evidence, rather than a single foundation.
- This is consistent with pre-existing experimental results and at least as accurate in predictions as previous theories.
These qualities are certainly true of established theories such as special and general relativity, quantum mechanics, tectonic plates, modern evolutionary syntheses, etc.
Other criteria
In addition, scientists prefer to work with theories that meet the following qualities:
- This can be a small adaptation to take into account new data that does not fit perfectly, as they are found, thus increasing their predictive capabilities over time.
- This is one of the most stingy, economical explanations for the use of proposed entities or explanatory steps such as Occam razors. This is because for every explanation it receives from a phenomenon, there may be a large number of possibilities, and even more complex, possibly very complex alternatives, because one can always burden a failed explanation with an ad hoc hypothesis to prevent they are from forged ones; therefore, simpler theories are preferred over the more complex because they are more testable.
Definition of a scientific organization
The United States National Science Academy defines the following scientific theories:
The formal scientific definition of theory is very different from the meaning of everyday words. This refers to a comprehensive explanation of some aspects of nature that are supported by a large amount of evidence. Many scientific theories are so well established that no new evidence is likely to change them substantially. For example, there is no new evidence to suggest that the Earth is not orbiting around the sun (heliocentric theory), or living beings are not made of cells (cell theory), that matter is not composed of atoms, or whose surface is not divided into solid plates that have moved over geological time span (plate tectonic theory)... One of the most useful properties of scientific theories is that they can be used to make predictions about natural events or phenomena that have not been observed yet.
From the American Association for the Advancement of Science:
A scientific theory is a well-proven explanation of some aspects of the natural world, based on a collection of facts that have been repeatedly confirmed through observation and experimentation. Such fact-supported theories are not "guesses" but credible reports about the real world. The theory of biological evolution is more than "theory". It is a fact of explanation of the universe as an atomic material theory or germ theory. Our understanding of gravity is still an ongoing work. But the phenomenon of gravity, like evolution, is an accepted fact.
Note that the term theory will not be appropriate to describe an untested but complicated hypothesis or even a scientific model.
Formation
The scientific method involves proposing and testing hypotheses, by deriving predictions from hypotheses about future experimental results, then conducting experiments to see if the predictions are valid. It provides good evidence for or against the hypothesis. When sufficient experimental results have been collected in a particular area of ​​investigation, scientists can propose an explanatory framework that contributes as much as possible to this. This explanation is also tested, and if it meets the necessary criteria (see above), then the explanation becomes a theory. This can take years, as it can be difficult or complicated to gather sufficient evidence.
Once all criteria are met, it will be widely accepted by scientists (see scientific consensus) as the best available explanation of at least some phenomena. This will make predictions of phenomena that previous theories can not explain or can not predict accurately, and it will reject counterfeiting efforts. The strength of the evidence is evaluated by the scientific community, and the most important experiment will be replicated by many independent groups.
The theory does not have to be very accurate to be scientifically useful. For example, the predictions made by classical mechanics are known to be inaccurate in the relatistivist realm, but almost true at relatively low speeds from ordinary human experience. In chemistry, there are many acid-base theories which give very different explanations about the basic nature of acid and base compounds, but they are very useful for predicting their chemical behavior. Like all knowledge in science, no theory is entirely certain, since it is possible that future experiments may be contrary to predictions of theory. However, theories supported by scientific consensus have the highest degree of certainty of any scientific knowledge; for example, that all objects are subject to gravity or that life on Earth evolved from the same ancestor.
Theoretical acceptance does not require that all of its predictions be tested, if supported by sufficiently strong evidence. For example, certain tests may not be feasible or technically difficult. Consequently, theories can make unconfirmed or proved predictions wrong; in this case, predicted results can be described informally with the term "theoretical". These predictions may be tested later, and if they are not correct, this may lead to a revision or rejection of the theory.
Modifications and improvements
If experimental results conflict with predicted theories observed, scientists first evaluate whether the experimental design is sound, and if so they confirm the results with independent replication. The quest for potential improvement on theory then begins. Solutions may require small or large changes to the theory, or none at all if satisfactory explanations are found within the existing theoretical framework. Over time, as successive modifications build on top of each other, theories consistently improve and greater predictive accuracy is achieved. Because every new version of the theory (or completely new theory) must have more predictive power and explanation than the last, scientific knowledge is consistently more accurate over time.
If modifications to theory or other explanations seem insufficient to account for new results, then a new theory may be necessary. Because scientific knowledge is usually durable, it happens much less frequently than modification. Furthermore, until such a theory is proposed and accepted, previous theories will be maintained. This is because it is still the best explanation available for many other phenomena, as verified by its predictive power in other contexts. For example, it has been known since 1859 that the perihelion precession of Mercury observed violates Newtonian mechanics, but the theory remains the best available explanation until relativity is supported by sufficient evidence. Also, while new theories can be proposed by one person or by many, the modification cycle ends up combining the contributions of many different scientists.
After the change, accepted theories will explain more phenomena and have greater predictive power (otherwise, change will not be adopted); this new explanation will be open for replacement or further modification. If the theory does not require modification despite repetitive tests, this implies that the theory is very accurate. It also means that accepted theories continue to collect evidence over time, and the length of time that theories (or principles) remain received often indicate the strength of the supporting evidence.
Unification
In some cases, two or more theories can be replaced by a theory that explains the previous theory as a particular approximation or case, analogous to the way the theory is a unifying explanation for many confirmed hypotheses; this is referred to as the union theory. For example, electricity and magnetism are now known as two aspects of the same phenomenon, called electromagnetism.
When the predictions of different theories contradict each other, this can also be resolved with further evidence or incorporation. For example, physical theories of the nineteenth century imply that the Sun can not burn for long enough to allow certain geological changes as well as the evolution of life. This is solved by the discovery of nuclear fusion, the main energy source of the Sun. Contradictions can also be explained as a result of a theory that approaches a more fundamental phenomenon (not contradictory). For example, atomic theory is an estimate of quantum mechanics. Current theories illustrate three separate fundamental phenomena in which all other theories are approximate; this unification of potential is sometimes called Theory of Everything.
Example: Relativity
In 1905, Albert Einstein published the principle of special relativity, which soon became a theory. Special relativity predicts Newton's principle alignment of Galilean invariance, also called Galilean relativity, by electromagnetic fields. By eliminating from the special relativity of the luminiferous ether, Einstein states that the time of widening and long contraction is measured in an object in the relative movement of inertia - that is, the object denotes a constant velocity, which is velocity with direction, as measured by the observer. Thus he doubled the Lorentz transformation and Lorentz's hypothesized contractions to solve the experimental puzzle and incorporated into electrodynamic theory as a dynamic consequence of the ether nature. An elegant theory, special relativity produces its own consequences, such as the equality of mass and energy that transform each other and the paradoxical resolution that the excitation of the electromagnetic field can be seen in a single frame of reference as electricity, but at another as an attraction.
Einstein attempted to generalize the invariant principle to all terms of reference, whether inertia or accelerated. Rejecting Newton's gravity - a central force acting instantly in the distance - Einstein assumes a gravitational field. In 1907, Einstein's principle of equality implies that free fall in a uniform gravitational field is equivalent to inertial motion. By extending the effect of special relativity into three dimensions, general relativity extends the contraction length into space contraction, understanding the 4D space-time as a gravity field that changes geometrically and defines all local object paths. Even the massless energies use the gravitational motion of local objects with the "curved" 4D space-time "surface" geometry. However, unless the energy is very wide, its relativistic effect in contracting slower space and time can be ignored when only predicting movement. Although general relativity is embraced as a clearer theory through scientific realism, Newton's theory remains successful only as a predictive theory through instrumentalism. To calculate the path, engineers and NASA still use the Newton equation, which is easier to operate.
Theory and law
Both scientific laws and scientific theories result from scientific methods through the formation and testing of hypotheses, and can predict the behavior of the natural world. Both are usually well supported by observation and/or experimental evidence. However, scientific law is a descriptive explanation of how nature will behave under certain conditions. Scientific theories are broader in scope, and provide a thorough explanation of how nature works and why it exhibits certain characteristics. Theory is supported by evidence from multiple sources, and may contain one or more laws.
A common misconception is that scientific theories are basic ideas that will ultimately turn to scientific law when enough data and evidence has accumulated. A theory does not turn into a scientific law with the accumulation of new or better evidence. A theory will always be a theory; the law will always be the law. Both theory and law are potentially falsified by conflicting evidence.
Theories and laws are also different from the hypothesis. Unlike hypotheses, theory and law may only be called scientific facts. However, in science, theory differs from fact even when they are well supported. For example, evolution is both theory and fact.
About theory
Theory as an axiom
The logical positivists think of scientific theories as statements in formal language. First-order logic is an example of a formal language. The logical positivists imagine a similar scientific language. In addition to scientific theories, languages ​​also include observation sentences ("sunrise in the east"), definitions, and mathematical statements. The phenomena described by the theories, if they can not be directly observed by the senses (eg, atoms and radio waves), are treated as theoretical concepts. In this view, the theory serves as an axiom: the observational predictions derive from theories such as the theorems derived in Euclidean geometry. However, these predictions are then tested against reality to verify the theory, and "axioms" can be revised as a direct result.
The phrase "accepted theoretical view" is used to describe this approach. The term usually associated with it is "linguistic" (because theory is a component of language) and "syntax" (because language has rules about how symbols can be strung together). The problem in defining this type of language appropriately, for example, is the objects seen in observed microscopes or whether they are theoretical objects, leading to the effective death of logical positivism in the 1970s.
Theory as a model
The semantic view of theory, which identifies scientific theories with models rather than propositions, has replaced the accepted view as the dominant position in the formulation of theory in the philosophy of science. The model is a logical framework intended to represent reality ("reality model"), similar to the way that a map is a graphical model that represents a city or state.
In this approach, theory is a specific category of the model that meets the required criteria (see above). One can use language to describe a model; However, theory is a model (or similar set of models), and not a model description. A model of the solar system, for example, may consist of abstract objects representing the sun and planets. These objects have associated properties, such as position, velocity, and mass. The model parameters, for example, Newton's Gravity Law, determine how position and velocity change over time. This model can then be tested to see if it accurately predicts future observations; astronomers can verify that the position of the model object over time matches the true position of the planets. For most planets, predictions of Newtonian models are accurate; for Mercury, it's a bit inaccurate and a general relativity model should be used instead.
The word "semantic" refers to the way the model represents the real world. Representation (literally, "re-presentation") describes certain aspects of a phenomenon or mode of interaction between a series of phenomena. For example, the scale model of a house or solar system is definitely not the actual house or the actual solar system; the actual aspect of the actual house or solar system that is represented in the scale model, only by certain limited means, representative of the actual entity. The house scale model is not a house; but for someone who wants to learn about a house, analogue to a scientist who wants to understand reality, a fairly detailed scale model might be enough.
Difference between theory and model
Some commentators have argued that the distinguishing characteristics of the theory are that they are explanatory and descriptive, while the model is only descriptive (though still predictive in a more limited sense). Philosopher Stephen Pepper also distinguishes between theories and models, and says in 1948 that general models and theories were based on "root" metaphors that limited how scientists theorized and modeled phenomena and thus came to a testable hypothesis.
The engineering practice makes the distinction between "mathematical models" and "physical models"; the cost of fabrication of a physical model can be minimized by first creating a mathematical model using a computer software package, such as computer-aided design tools. The parts of each component are modeled, and the fabrication tolerances are determined. The exploded view image is used to compile a fabrication sequence. The simulation package to display each sub-assembly allows the section to be rotated, zoomed in, in realistic detail. The software package for making material bills for construction allows subcontractors to specialize in assembly processes, which deploy machine manufacturing costs among many customers. View: Computer-assisted techniques, computer-aided manufacturing, and 3D printing
Assumptions in formulating theory
The assumption (or axiom) is a statement received without evidence. For example, assumptions can be used as places in logical arguments. Isaac Asimov described the following assumptions:
... it is not right to talk about assumptions either right or wrong, because there is no way to prove it to be good (If anything, it is no longer an assumption). It is better to regard assumptions as useful or useless, depending on whether the deductions made from them are in accordance with reality... Since we must start somewhere, we must have assumptions, but at least let's have as little assumptions as possible.
Certain assumptions are required for all empirical claims (eg the assumption that reality exists). However, the general theory does not make assumptions in the conventional sense (statements are accepted without evidence). While assumptions are often included during the formation of new theories, these are either supported by evidence (as from previous theories) or evidence generated in the process of validating theory. It may be as simple to observe that the theory makes accurate predictions, which is evidence that any assumptions made at the beginning are true or approximately right under the conditions under test.
Conventional assumptions, without evidence, can be used if the theory is only intended to apply when such assumptions are valid (or less valid). For example, the special theory of relativity assumes an inertial frame of reference. This theory makes accurate predictions when such assumptions are valid, and does not make accurate predictions when such assumptions are invalid. Such assumptions are often the point at which older theories are replaced by new theories (the general theory of relativity works in non-inertial reference frames as well).
The term "assumption" is actually broader than the standard use, etymologically. The Oxford English Dictionary (OED) and Wiktionary online indicate its Latin source as assumere ("accept, to take it upon yourself, adopt, seize"), which is a composite of ad - ("to, towards, at") and sumere (to fetch). Roots survive, with meaning shifting, in Italian sumere and Spanish sumir . The first feeling of "assuming" in OED is "taking (self), accepting, accepting, adopting". The term was originally used in religious contexts such as "to receive to heaven", especially "the reception of the Virgin Mary into heaven, with a body preserved from corruption", (1297 AD) but it is also used only to refer "accept into association" or " adopted into partnership ". In addition, other feelings of assumptions include (i) "investing in (attributes)", (ii) "to do" (especially in the Act), (iii) "to appear only alone, to pretend to have," and (iv) "to assume something to be" (all senses of the OED fit in "assume"; OED entries for "assumptions" are almost perfectly symmetrical in the senses). Thus, the "assumption" connotes to other associations rather than the notion of contemporary standard "assumed or taken for granted, a presumption, postulate" (only 11 of the 12 sense "assumptions", and 10 of 11 senses "assume").
Description
From the philosophers of science
Karl Popper describes the characteristics of scientific theory as follows:
- It's easy to get confirmation, or verification, for almost every theory - if we're looking for confirmation.
- Confirmation should be counted only if it is the result of a risk prediction; that is, if, not enlightened by the theory in question, we should expect an event inconsistent with theory - an event that would disprove the theory.
- Every "good" scientific theory is a prohibition: it prohibits certain things from happening. The more theories that prohibit, the better it is.
- A theory that can not be denied by imaginable events is unscientific. Uncertainty is not the kindness of the theory (as people often think) but a lie.
- Any original test of theory is an attempt to falsify it, or deny it. Testability is falsifiability; but there is a level of ability: some theories are more testable, more open to argument, than others; they take, as it were, a greater risk.
- Confirming evidence can not be counted unless it is the result of the original test of the theory; and this means that this can be presented as a serious but unsuccessful attempt to fabricate the theory. (I am now speaking in such cases "corroborating evidence".)
- Some really testable theories, when proven wrong, may still be supported by admirers - for example by introducing post hoc (after the fact) some hypotheses or additional assumptions, or by reinterpreting the post hoc theory in a way it escapes disclaimers. Such a procedure is always possible, but it saves the theory from rebuttal only by destroying prices, or at least lowering, its scientific status, by damaging evidence. The temptation to damage can be minimized by first taking the time to write the test protocol before starting a scientific work.
Popper sums up these statements by saying that the main criterion of the scientific status of the theory is "forgery, or refutability, or test ability". Along with this, Stephen Hawking states, "A theory is a good theory if it meets two requirements: It should accurately depict a large class of observations on the basis of a model containing only a few arbitrary elements, and it should make a definite prediction about the outcome observation of the future. "He also discussed the" unproved but false "nature of the theory, which is an important consequence of inductive logic, and that" you can disprove the theory by discovering even one observation that is inconsistent with theoretical predictions ".
However, some philosophers and historians of science argue that the definition of Popper's theory as a set of false statements can be wrong because, as Philip Kitcher has pointed out, if one takes the Popperian view of "theory," Uranus's observations when first discovered in 1781 would " "Newton's sky mechanics. Instead, people suggest that other planets affect the orbit of Uranus - and this prediction is finally confirmed.
Kitcher agrees with Popper that "There must be something right in the idea that science can succeed only if it can fail." He also said that scientific theories include statements that can not be falsified, and that good theories must also be creative. He insists we look at scientific theories as "a complex set of statements," some of which can not be faked, while others - what he calls "supplemental hypotheses," are.
According to Kitcher, good scientific theories must have three features:
- Unity: "A science must be put together.... A good theory consists only of a problem-solving strategy, or a small family of problem-solving strategies, that can be applied to a variety of problems."
- Fecundity: "A great scientific theory, like Newton, opens up new fields of research.... Since a theory presents a new way of looking at the world, it can lead us to ask new questions, and thus to begin on the path of inquiry the new and fruitful.... Usually, the evolving science is incomplete.At any time, this raises more questions than can be answered today, but incompleteness is not the opposite.Instead, incompleteness is the mother of fertility.... Theory is good should be productive, it should lead to new questions and assume those questions can be answered without giving up a problem-solving strategy. "
- Additional hypothesis that can be independently tested: "An additional hypothesis should be tested independently of the specific problem introduced to be solved, regardless of the theory designed to be stored." (For example, evidence of Neptune's existence does not depend on anomalies in Uranus's orbit.)
Like other definitions of the theory, including Popper, Kitcher explains that theory should include statements that have consequences of observation. But, as observations of irregularities in Uranus's orbit, forgery is but one of the consequences of observation. The production of a new hypothesis is a possible and equally important outcome.
Analogy and metaphors
The concept of scientific theory has also been described using analogies and metaphors. For example, logical empirical Carl Gustav Hempel likened the structure of scientific theory to "complex spatial networks:"
The terms are represented by nodes, while the connecting threads are final in part, in part, by definitions and, in part, on the fundamental hypotheses and derivatives included in the theory. The whole system floats, as it were, over the field of observation and anchored to it by the rules of interpretation. This can be seen as strings that are not part of the network but connect certain points from the last with certain places in the observation field. Based on this interpretative connection, the network can serve as a scientific theory: From certain observational data, we can rise, through interpretive strings, to some point in the theoretical network, from there continued, through definitions and hypotheses, to another point, from which other interpretive threads lets it down to the field of observation.
Michael Polanyi made an analogy between theory and map:
Theory is something other than myself. This can be set on paper as a rule system, and it is a theory that is really more than it can be fully laid out in such terms. Mathematical theory achieves the highest perfection in this regard. But even geographical maps fully embody a rigorous set of rules to find their way through uncharted areas of experience. Indeed, all theories can be regarded as a kind of expanded map of space and time.
A scientific theory can also be regarded as a book that captures basic information about the world, a book that must be studied, written, and shared. In 1623, Galileo Galilei wrote:
Philosophy [i.e. Physics] is written in this ledger - I mean the universe - which stands constantly open to our view, but can not be understood unless the first learns to understand the language and interpret the written character. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures, without which it is impossible for man to understand a single word from him; without this, someone roams in the dark labyrinth.
Book metaphors can also be applied in the following sections, by contemporary science philosophers Ian Hacking:
I myself prefer the Argentine fantasy. God did not write the Book of Nature as envisioned by the ancient Europeans. He wrote the Borgesian library, each of the shortest books possible, but each book was inconsistent with each other. No excessive book. For each book there are some Nature that can be accessed humanely so that the book, and nothing else, allows understanding, prediction and influence what is happening... Leibniz says that God chooses a world that maximizes various phenomena while choosing the simplest law. Just the way it is: but the best way to maximize phenomena and have the simplest laws is to make laws inconsistent with each other, each applicable to this or that but not applicable to all.
In physics
In physics, the term theory is generally used for mathematical frameworks - derived from a small set of basic postulates (usually symmetry - such as location equations in space or time, or electron identity, etc.) - capable of generating experimental predictions for a particular category of physical systems. A good example is classical electromagnetism, which includes results derived from the measuring symmetry (sometimes called invariant measurement) in the form of several equations called Maxwell's equations. The specific mathematical aspect of classical electromagnetic theory is called "the law of electromagnetism," reflecting the level of consistent and reproducible evidence that supports it. In general electromagnetic theory, there are many hypotheses about how electromagnetism applies to a particular situation. Many of these hypotheses have been considered fairly tested, with new ones always in the making and probably untested. The last example may be the reaction force of radiation. In 2009, the effect on the charge periodic motion was detected in synchrotron, but only as an effect of average from time to time. Some researchers now consider experiments that can observe this effect at an instantaneous rate (ie not averaged over time).
Example
Note that many fields of inquiry do not have a specific named theory, e.g. developmental biology. Scientific knowledge outside named theory can still have a high degree of certainty, depending on the amount of evidence that supports it. Also note that since the theory draws evidence from various fields, categorization is not absolute.
- Biology : cell theory, evolution theory (modern evolution synthesis), germ theory, particle inheritance theory, dual inheritance theory
- Chemistry : collision theory, gas kinetic theory, Lewis theory, molecular theory, molecular orbital theory, transition state theory, valence bond theory
- Physics : atomic theory, Big Bang theory, Dynamo theory, perturbation theory, the theory of relativity (the successor of classical mechanics), quantum field theory
- Other : Climate change theory (from climatology), tectonic plate theory (from geology), Moon origin theory, Moon illusion theory
Note
References
Further reading
- Seller, Piers (August 17, 2016). "Space, Climate Change, and the Meaning of Theory". The New Yorker . Retrieved August 18 2016 . , an essay by the British/American meteorologist and NASA astronaut about antopogenic global warming and" theory "
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