Theoretical physics
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena.
The advancement of
Overview
A physical theory is a model of physical events. It is judged by the extent to which its predictions agree with empirical observations. The quality of a physical theory is also judged on its ability to make new predictions which can be verified by new observations. A physical theory differs from a
The equations for an Einstein manifold, used in general relativity to describe the curvature of spacetime
A physical theory involves one or more relationships between various measurable quantities.
are not continuously variable.Theoretical physics consists of several different approaches. In this regard,
Theoretical advances may consist in setting aside old, incorrect
Physical theories become accepted if they are able to make correct predictions and no (or few) incorrect ones. The theory should have, at least as a secondary objective, a certain economy and elegance (compare to mathematical beauty), a notion sometimes called "Occam's razor" after the 13th-century English philosopher William of Occam (or Ockham), in which the simpler of two theories that describe the same matter just as adequately is preferred (but conceptual simplicity may mean mathematical complexity).[10] They are also more likely to be accepted if they connect a wide range of phenomena. Testing the consequences of a theory is part of the scientific method.
Physical theories can be grouped into three categories: mainstream theories, proposed theories and fringe theories.
History
Theoretical physics began at least 2,300 years ago, under the
The great push toward the modern concept of explanation started with
Among the great conceptual achievements of the 19th and 20th centuries were the consolidation of the idea of
The pillars of
All of these achievements depended on the theoretical physics as a moving force both to suggest experiments and to consolidate results — often by ingenious application of existing mathematics, or, as in the case of Descartes and Newton (with
Modern theoretical physics attempts to unify theories and explain phenomena in further attempts to understand the Universe, from the cosmological to the elementary particle scale. Where experimentation cannot be done, theoretical physics still tries to advance through the use of mathematical models.
Mainstream theories
Mainstream theories (sometimes referred to as central theories) are the body of knowledge of both factual and scientific views and possess a usual scientific quality of the tests of repeatability, consistency with existing well-established science and experimentation. There do exist mainstream theories that are generally accepted theories based solely upon their effects explaining a wide variety of data, although the detection, explanation, and possible composition are subjects of debate.
Examples
- Big Bang
- Chaos theory
- Classical mechanics
- Classical field theory
- Dynamo theory
- Field theory
- Ginzburg–Landau theory
- Kinetic theory of gases
- Classical electromagnetism
- Perturbation theory (quantum mechanics)
- Physical cosmology
- Quantum chromodynamics
- Quantum complexity theory
- Quantum electrodynamics
- Quantum field theory
- Quantum field theory in curved spacetime
- Quantum information theory
- Quantum mechanics
- Quantum thermodynamics
- Relativistic quantum mechanics
- Scattering theory
- Standard Model
- Statistical physics
- Theory of relativity
- Wave–particle duality
Proposed theories
The proposed theories of physics are usually relatively new theories which deal with the study of physics which include scientific approaches, means for determining the validity of models and new types of reasoning used to arrive at the theory. However, some proposed theories include theories that have been around for decades and have eluded methods of discovery and testing. Proposed theories can include fringe theories in the process of becoming established (and, sometimes, gaining wider acceptance). Proposed theories usually have not been tested. In addition to the theories like those listed below, there are also different interpretations of quantum mechanics, which may or may not be considered different theories since it is debatable whether they yield different predictions for physical experiments, even in principle. For example, AdS/CFT correspondence, Chern–Simons theory, graviton, magnetic monopole, string theory, theory of everything.
Fringe theories
Fringe theories include any new area of scientific endeavor in the process of becoming established and some proposed theories. It can include speculative sciences. This includes physics fields and physical theories presented in accordance with known evidence, and a body of associated predictions have been made according to that theory.
Some fringe theories go on to become a widely accepted part of physics. Other fringe theories end up being disproven. Some fringe theories are a form of protoscience and others are a form of pseudoscience. The falsification of the original theory sometimes leads to reformulation of the theory.
Examples
Thought experiments vs real experiments
"Thought" experiments are situations created in one's mind, asking a question akin to "suppose you are in this situation, assuming such is true, what would follow?". They are usually created to investigate phenomena that are not readily experienced in every-day situations. Famous examples of such thought experiments are
See also
- List of theoretical physicists
- Philosophy of physics
- Symmetry in quantum mechanics
- Timeline of developments in theoretical physics
- Double field theory
Notes
- ^ There is some debate as to whether or not theoretical physics uses mathematics to build intuition and illustrativeness to extract physical insight (especially when normal experience fails), rather than as a tool in formalizing theories. This links to the question of it using mathematics in a less formally rigorous, and more intuitive or heuristic way than, say, mathematical physics.
- ^ Sometimes the word "theory" can be used ambiguously in this sense, not to describe scientific theories, but research (sub)fields and programmes. Examples: relativity theory, quantum field theory, string theory.
- Johann Balmer and Johannes Rydberg in spectroscopy, and the semi-empirical mass formulaof nuclear physics are good candidates for examples of this approach.
- Ptolemaic and Copernican models of the Solar system, the Bohr model of hydrogen atoms and nuclear shell modelare good candidates for examples of this approach.
- ^ Arguably these are the most celebrated theories in physics: Newton's theory of gravitation, Einstein's theory of relativity and Maxwell's theory of electromagnetism share some of these attributes.
- ^ This approach is often favoured by (pure) mathematicians and mathematical physicists.
References
- .
- ^ "The Nobel Prize in Physics 1921". The Nobel Foundation. Retrieved 2008-10-09.
- ^ Theorems and Theories Archived 2014-08-19 at the Wayback Machine, Sam Nelson.
- ^ Mark C. Chu-Carroll, March 13, 2007:Theorems, Lemmas, and Corollaries.[permanent dead link] Good Math, Bad Math blog.
- ISBN 9780471771715
- ISBN 9780691125268
- ^ Bokulich, Alisa, "Bohr's Correspondence Principle", The Stanford Encyclopedia of Philosophy (Spring 2014 Edition), Edward N. Zalta (ed.)
- ^ Enc. Britannica (1994), pg 844.
- ^ Enc. Britannica (1994), pg 834.
- ^ Simplicity in the Philosophy of Science (retrieved 19 Aug 2014), Internet Encyclopedia of Philosophy.
- ^ See 'Correspondence of Isaac Newton, vol.2, 1676–1687' ed. H W Turnbull, Cambridge University Press 1960; at page 297, document #235, letter from Hooke to Newton dated 24 November 1679.
- ^ Penrose, R (2004). The Road to Reality. Jonathan Cape. p. 471.
- ^ Penrose, R (2004). "9: Fourier decompositions and hyperfunctions". The Road to Reality. Jonathan Cape.
Further reading
- Physical Sciences. Vol. 25 (15th ed.). 1994.
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ignored (help) - Duhem, Pierre. La théorie physique - Son objet, sa structure, (in French). 2nd edition - 1914. English translation: The physical theory - its purpose, its structure. Republished by ISBN 2711602214.
- Feynman, et al. The Feynman Lectures on Physics (3 vol.). First edition: Addison–Wesley, (1964, 1966).
- Bestselling three-volume textbook covering the span of physics. Reference for both (under)graduate student and professional researcher alike.
- Landau et al. Course of Theoretical Physics.
- Famous series of books dealing with theoretical concepts in physics covering 10 volumes, translated into many languages and reprinted over many editions. Often known simply as "Landau and Lifschits" or "Landau-Lifschits" in the literature.
- Longair, MS. Theoretical Concepts in Physics: An Alternative View of Theoretical Reasoning in Physics. ISBN 978-0521528788
- Planck, Max (1909). Eight Lectures on theoretical physics. Library of Alexandria. ISBN 9781465521880.
- A set of lectures given in 1909 at Columbia University.
- Sommerfeld, Arnold. Vorlesungen über theoretische Physik (Lectures on Theoretical Physics); German, 6 volumes.
- A series of lessons from a master educator of theoretical physicists.