What is Theories: Definition and 485 Discussions

A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may either be scientific or other than scientific (or scientific to less extent). Depending on the context, the results might, for example, include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several related meanings.
In modern science, the term "theory" refers to scientific theories, a well-confirmed type of explanation of nature, made in a way consistent with scientific method, and fulfilling the criteria required by modern science. Such theories are described in such a way that scientific tests should be able to provide empirical support for it, or empirical contradiction ("falsify") of it. Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge, in contrast to more common uses of the word "theory" that imply that something is unproven or speculative (which in formal terms is better characterized by the word hypothesis). Scientific theories are distinguished from hypotheses, which are individual empirically testable conjectures, and from scientific laws, which are descriptive accounts of the way nature behaves under certain conditions.
Theories guide the enterprise of finding facts rather than of reaching goals, and are neutral concerning alternatives among values. A theory can be a body of knowledge, which may or may not be associated with particular explanatory models. To theorize is to develop this body of knowledge.The word theory or "in theory" is sometimes used erroneously by people to explain something which they individually did not experience or test before. In those instances, semantically, it is being substituted for another concept, a hypothesis. Instead of using the word "hypothetically", it is replaced by a phrase: "in theory". In some instances the theory's credibility could be contested by calling it "just a theory" (implying that the idea has not even been tested). Hence, that word "theory" is very often contrasted to "practice" (from Greek praxis, πρᾶξις) a Greek term for doing, which is opposed to theory. A "classical example" of the distinction between "theoretical" and "practical" uses the discipline of medicine: medical theory involves trying to understand the causes and nature of health and sickness, while the practical side of medicine is trying to make people healthy. These two things are related but can be independent, because it is possible to research health and sickness without curing specific patients, and it is possible to cure a patient without knowing how the cure worked.

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  1. C

    What are unified theories trying to match at lower energies?

    What do the phenomenologists of unified theories (strings, loops etc) try to match at lower energies when there are so many conflicting theories lying around at these energies? I understand that certain things should be there in any model - like chiral matter, three generations etc - but a lot...
  2. B

    Time Dilation/Gravitational Theories Needed for Short Film

    Hi Everyone, I hope everyone had a very enjoyable holiday season. Currently I'm developing a short film to shoot later this year. Being ever fascinated with the natural universe and also theoretical physics this film will be a welcome new approach to the science fiction genre. The goal is...
  3. Q

    Why are personal and crack theories not allowed?

    Why are personal and "crack" theories not allowed? I always wondered about this rule. This is a skeptics section of the forum and if you have something to say, well wouldn't it be reasonable to question it and take it apart than to rather disown it? I asked a question earlier about Forces by...
  4. S

    How can I publish my own Physics Theories ?

    How can I publish my own Physics Theories ? or Where can I Publish my theories ? Officially to the scientific community ??.. so, that they can accept it.if it's correct and than give me copy right ?? How 2 get my theory registered ? I have lot of awesome ideas that can change our world of...
  5. Q

    Exploring the Possibilities of Integrating Cosmological Theories

    Hi! This is my first post. I have a question of cosmological importance - literally and figuratively. The Standard Model is the most accepted theory of (almost) everything, yet is unable to make sense of gravity. String Theory can explain it all theoretically through quantitative...
  6. L

    Why do we need particles in our theories?

    One thing I don't understand is that most of our theories include particles...the oversimplified analogy is, of course, balls on a billiard table. Even the "theory of everything" or String Theory/M-theory tries to explain everything with one particle and one force. My question is this...why do...
  7. L

    How do we deal with theories that are hard to prove or falsify?

    Hi, In this other thread https://www.physicsforums.com/showthread.php?t=354424" I was hoping to get a scientific answer to my question. Apparently this was not an easy question or hypothesis that was easily falsified. I was sorry to see the subject turned into a unpleasant debate which ended up...
  8. A

    New Unified Theories: Current Research

    Is anyone currently working on new theories unifying matter and fields that differ from string theory?
  9. J

    To easily describe complex theories

    Interpretation of gravity and others. Aids for explaining the phenomena of the universe. Take the mental image of Hawking's universe, I mean, surface of a sphere where latitude (vertical axis) is the time and longitude (horizontal axis) is the space. If we imagine that the sphere has a...
  10. E

    What are the differences between Volovik & Wen theories?

    Both purport to make use of condense matter- models to model fundamental physics. What are the differences and which seems more promising?
  11. G

    Level of Learning Theories: String Theory & Loop Quantum Gravity

    At what level (graduate, PhD, etc...) do people start learning theories, such as String Theory and Loop Quantum Gravity?
  12. Pattonias

    Origin Theories: Evolution, Intelligent Design & More

    Apart from evolution and intelligent design what other serious origin theories are there?
  13. D

    What are some theories of the creation of the universe?

    Hi, I'm new to this forum and I thought I'd ask for some help with my research paper. Well I am a Senior in Highschool and I take IB (International Baccalaureate [Google it]) courses which are basically super advanced courses. Anyway, one of the requirements is that I write a 3,500-4,000 word...
  14. C

    History of theories of motion; the role of inertia

    In physics there has been a sequence of three theories of motion, each superseding its predecessor: Newtonian dynamics, SR and GR. Insights from GR cast the predecessors in new light. With the new insights the predecessors can be reframed in such a way that the transitions between them become...
  15. O

    Any proof about the equivalance of between theories of R^4 x M and R^10?

    Here R^4 is a flat 4-dimensional space, and M is a 6-dimensional Calabi-Yau manifold; and the other side, R^10, is a flat 10-dimensional space. Is there any careful talk and reference about the equivalence of theories in those two spaces above? Great thanks.
  16. R

    Black holes and theories of gravity

    In the perception of General Relativity a Black hole can form in which anything (including light) is trapped inside the horizon of the Black hole and can never escape, because nothing can exceed light speed. However, still something escapes the Black hole, which is the presence of the...
  17. MTd2

    How many string theories with more than one supersymmetry?

    With one, we have 5, what about more than one? What are they? What are the importance of these, phenomenologicaly saying?
  18. Adrian59

    LHC - the last chance for all theories of everything?

    The LHC is probably the last of the large accelerators so should the main contenders for the title of the theory of everything (if such a thing exists) now, at the dawn of the LHC start up, clearly state what findings would a) prove their theory b) support their theory & c) eliminate their...
  19. J

    Physics Theories which have been found to be incomplete

    I need a topic for a physics research paper on Physics Theories that have been found to be incomplete/inaccurate. Anyone out there that can throw an idea to me? Thank you for your time! Justin
  20. H

    Logic behind theories and perception.

    Jun3-03, 03:02 PM C0mmie "... logic is not an attribute of the universe, but instead is our means of understanding the universe, while the universe itself has nothing to do with logic. For expample, imagine a person who for the first time in his life is exposed to Heisenberg's...
  21. S

    What is the underlying connection between geometry and matter in string theory?

    Would it be sufficient for the validation of a string theory if it could make the same predictions as those already validated under QM and GR? Would it be necessary for such a theory to make additional predictions that could be tested at available energies?
  22. D

    Hardy's Paradox: Exploring Copenhagen & Bohm's Theories

    Can someone explain how Hardy's Paradox is resolved? As well, what could someone infer from this regarding both Copenhagen Interpretation and Bohm's theory?
  23. LaserMind

    Renormalizable quantum field theories

    In Quantum Field Theory, there are 'infinity' problems: At extremely short distances the energy quanta increase so much that infinities would occur. In order to overcome this a cut off is imposed that postulates that quanta cannot possess energy above some arbitary high value. This works...
  24. L

    Theories of relativity and the resulting E = MC^2

    Einstein"s theories of relativity and the resulting E = MC^2, although extremely important to physics, was not his greatest insight. His idea that time is not fixed, that it can run infinitely slow or possibly infinitely fast was the most important. If there was a Big Bang, that suggests at...
  25. L

    Is Geography a science? It is comprised of theories, Laws and rules

    Is Geography a science? It is comprised of theories, Laws (well Rules realy), hypothesis, some Math equations, aspects of Physics Chemistry and Biology. Also there is still much to be learned from it.
  26. C

    Origins of the universe theories?

    Hi everyone.. I'm supposed to find the pros and cons of major and minor theories on how the universe began. The only things i have so far are the big bang and creationisme..but i can't think of anything else! Help ! =(
  27. B

    Gribov Ambiguity: Non-Abelian Theories & Solutions

    Im looking for a good resource that clearly explains the problem of Gribov ambiguity. In particular, I want to know 1. Why the problem only arises for non-abelian theories 2. Why restricting the functional integration to field configurations where the Faddeev-popov determinant is postive...
  28. DrChinese

    How do deterministic Bohmian/Pilot Wave Theories Handle These?

    How do "deterministic" Bohmian/Pilot Wave Theories Handle These? We are fortunate to have Demystifier and several others on this board who are very involved in research into Bohmian Mechanics/dBB/Pilot Wave theory. I have a couple of questions I am hoping someone can discuss. (I will use...
  29. Q

    Programs PhD Scholar Leave and Research: Physics Theories and Data Analysis

    How much leave do phd scholars in physics get annualy? Is it it not possible to do research work at home,incase the student is ill and wants to be in his comfort zone during bad times? Btw if i choose a theoretical physics topic will i be free from learning computer related stuff with...
  30. D

    Completeness of finite first order theories

    Is every first order theory with finitely many axioms automatically complete? An axiom schema like that of ZFC's separation counts as an infinite number of axioms.
  31. B

    Instantons in non-abelian theories

    Im trying to learn about instantons at the moments from Cheng and Li's book. It seems to suggest that instantons only occur in theories that are non-abelian. Why is this so?
  32. K

    Medical Aspiring author looking for theories

    Aspiring author looking for theories... Hi :) I'm looking for some information / theories for a sci-fi book I'm working on. I have no medical or biology background so I'm kind of starting from scratch with this. I'm specifically looking for theories regarding parasites, virus's, things of...
  33. MTd2

    Fermi (GLAST) almost kills all Lorentz violating theories.

    http://www.symmetrymagazine.org/breaking/2009/02/19/most-extreme-gamma-ray-blast-also-probes-quantum-gravity/Fermi%20Observations%20of%20High-Energy%20Gamma-Ray%20Emission%20from%20GRB http://www.nasa.gov/mission_pages/GLAST/news/high_grb.html...
  34. V

    Grand unified theories and quantum mechanics

    Why is it that general relativity and quantum mechanics are so different and that physicists are having difficulty combining them. Please give me a simple answer. I scoured the whole net and each website has its own opinion.
  35. S

    Chiral theories and matter gauges

    Is it true that classical theories tend to treat matter 'in the limit' of large N, or it encodes matter in N_A as N_A(m_e,e) say, and chiral theories need to include \hbar which classicality sees as \{G(h),c\} ? We use 'mass-free' theories that treat charge and spin momentum in circuits =...
  36. wolram

    Weighing Public Opinion vs. Global Impact: Examining Unproved Theories

    How much weight if any, should be given to public opinion to scientific theories that are, let's say difficult to prove, and could have significance effects globally.
  37. ThomasT

    Eternalism and Presentism - theories of time

    Eternalism and Presentism -- theories of time The topic of this thread emerged from this thread, A problem with time travel Originally posted by Maxtm How do I know that you're not just a closet presentist masquerading as an eternalist? :smile: Your statements don't make any sense to me...
  38. R

    String Field Theory: Will It Outshine String Theories?

    Sifting through ArXiv and other sources, I've found many documents on the topic of String Field Theory, perhaps the most extensive being by Thorn, 1989*. This brings up the question: Will String Field Theory evolve in popularity and perhaps outshine the more traditional String Theories? With...
  39. P

    Advanced published papers regarding valid unification theories?

    Questions: Where can I obtain the most advanced published papers regarding valid unification theories? If there are none, which published papers will get me closest when combined in their respective categories? Comment: It is obvious to me through speculation, physical laws have yet to...
  40. MTd2

    Request to String Lovers: Classify theories by critical dimensions.

    Topological Strings = 3 Superstrings = 10 Bosonic strings 26 Tensionless strings = arbitrary Do you know of any others that could fit in other dimensions not listed above?
  41. H

    The math behind a couple of theories

    I was just wondering, what math is needed to fully understand the mathematics of general relativity, quantum mechanics, and string theory? Can you be specific in naming them? For example General Relativity Algebra Calculus I know there has to be more than that but that was an example...
  42. R

    Question on parallel multi. theories

    Ok, I haven't studied the subject at all (yet), but a professor of mine was explaining some of the theories behind string, brane, etc. to me. So bear with me here; I'm confused by this idea that came into my head earlier: If there are an infinite number of universes where every possible...
  43. thenewmans

    Examples of accepted theories once rejected?

    Can any of you think of examples of physics theories that were at one time rejected by the scientific establishment but later were accepted? Can you beat these examples? • Heliocentrism (Galileo in particular) - I don’t count this since he was primarily rejected by less scientific groups. •...
  44. G

    Theories of personal/communication compatibility?

    What theories do exist that predict compatibility between two people? Sometimes I talk to people and I think there is just no connection. Or they are just too boring. I recently read something about transaction analysis. It's not quite communication theory, but it seemed to sort of grasp why...
  45. I

    The Stephan's Quintet and Arp's Theories

    What about the Arp' s theories? I' ve seen the photos of the Stephan's quintet. What about them? Seems that the quasars are near other objects that look to be nearer to us than the quasars.
  46. edward

    News What are the dangers of spreading and believing in extreme conspiracy theories?

    The online version of my local paper, as do many, has a place to post an opinion addressing most of the days articles. People make posts and then argue back and forth. It doesn't take long until the conservative wing nuts begin going off of the deep end. From todays article about Obama...
  47. T

    Gauge Boson Propagators in Spontaneously Broken Gauge Theories

    The propagator for gauge bosons in a spontaneously broken (non-abelian) gauge theory in the R_\xi gauge is (see Peskin and Schroeder eqn. 21.53) \tilde{D}^{\mu\nu}_F(k)^{ab}=\frac{-i}{k^2-M^{ab}}\left[g^{\mu\nu}-(1-\xi)\frac{k^\mu k^\nu}{k^2-\xi M^{ab}}\right]\,, where M^{ab} is the gauge...
  48. H

    The Cause of the Big Bang: Proven Theories

    Hey there Why did the big bang happened? what made it happen? what is the cause of the big bang? Could be vacuum fluctuations? Or a collision between different branes or universes? Could be some sort of a creator? What is the most proved and most appropriate theory that talks about...
  49. M

    Quantization of Gauge theories ?

    Quantization of Gauge theories ?? Hi , i am trying to learn the math formalism of Gauge Theories as far as i know they begin with the 1-form A= \sum_{i} T^{i}A_{\mu}^{i} where 'T_i ' are the generators of the Lie Group then we define the 2-form F= dA + (1/2)[A,A] and the...
  50. A

    What is the effect of gravity on light?

    hey everyone, My names aaron and I am a year 12 student studying physics. We have to learn about both the wave and particle theories of light, and i just have a few questions. I have read that light behaves as if it has a mass, and although we can't actually 'weigh' the light we believe its...
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