Theoretical Definition and 1000 Threads

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. B

    Theoretical Physics: What's the Point & How Is It Accurate?

    Is theoretical physics a real thing? What's the point of doing something that is relatively unknowable? How are such things researched, quantified, and calculated? And why is it accurate? Isn't it unknown until its actually applied?
  2. K

    Physics Theoretical Astrophysics - Still a route to go?

    Hey all, I've been reading tons of story on theoretical physicist not having a job, and end up going to other fields such as finance etc. While we do still earn a living, the situation is pretty hard: why bother to spend ~7 years for a phd to end up in somewhere else? I mean there're better...
  3. T

    Heat pump COP theoretical maximum

    Hello everybody. I have trouble of proving the theoretical maximum of heat pump Coefficent of Performance. The thing I'm trying to calculate is for heat pump pumping heat from colder reservoir to the hotter reservoir: COP=Qh/W Qh - heat supplied to the hot reservoir(output) W - mechanical...
  4. micromass

    Intro Physics The Theoretical Minimum by Susskind and Hrabovsky

    Author: Leonard Susskind, George Hrabovsky Title: The Theoretical Minimum: What You Need to Know to Start Doing Physics Amazon Link: https://www.amazon.com/dp/046502811X/?tag=pfamazon01-20 Prerequisities: Contents:
  5. J

    The Theoretical Minimum, Released today, January 29th 2013

    Leonard Susskind's the Theoretical Minimum was released today to go along with his Stanford Courseware lectures. Has anyone gotten there hands on a copy yet? I am very excited for this publication because I am very pro-self-education (if you could call it that). I am debating whether to order a...
  6. T

    Schools Theoretical vs. Lab Work: Evaluating Grad School Options

    As an undergraduate, I have a choice between working under two different professors in the Physics department at the university that I am enrolled in. One is theoretical, so my work would be in helping derive equations, and the other has a lab (not a super high-tech one, but a lab nonetheless)...
  7. schrodingerscat11

    Topic in Theoretical Materials Science

    Greetings! I just finished my bachelor's degree in physics. I am now applying for a master's degree in physics. My bachelor's thesis was an experimental study about aerosol. I am planning to shift to theoretical physics. However, I want my topic to be related to materials science...
  8. C

    Physics Theoretical physics or astrophysics

    I am soon to apply for university and I am not quite sure what I want to study. Theoretical physics and astrophysics/astronomy/cosmology all seem like very interesting fields of physics to me. How do I go about when I choose my career path? Which one of the fields has been more prospering than...
  9. D

    Courses What background courses is needed for doing MS in Theoretical Physics?

    I am a student from Electrical Engineering department and now at the end of 3rd year in my university.But I want to do MS in Theoretical Physics in my university at the end of 4th year.The Theoretical Physics department offers these courses (listed below) in their MS and I have to choose among...
  10. micromass

    Course of Theoretical Physics by Landau and Lifshitz

    Author: L.D. Landau, E.M Lifshitz Title: Course of Theoretical Physics Amazon Link: https://www.amazon.com/dp/0750628960/?tag=pfamazon01-20 https://www.amazon.com/dp/0750627689/?tag=pfamazon01-20 https://www.amazon.com/dp/0750635398/?tag=pfamazon01-20...
  11. C

    Which Pathway is Best for Theoretical Physics Grad School?

    I want to go to grad. school in theoretical physics after I'm done with undergrad (aiming quite high: Perimeter Institue, Cambridge's DAMTP, MIT, etc. I know it's hard but I want to keep optimistic about it). Which pathway would be more appropiate/realistic? route 1: I self study math courses...
  12. dbmorpher

    Can entropy be used to measure time?

    Hello dbmorpher here, I was looking at some articles on entropy and wondered, could this be used to calculate time? Entropy is known as the arrow of time, figurative I know but could actually be used to measure. If there was a device that calculated the entropy in a set system couldn't it...
  13. F

    I did theoretical physics now I will do pure maths

    Hi all, I am new to this forum =) I did physics and now I'm planning to apply for graduate studies in pure maths. I know it's relatively easier the other way (maths to physics). I never had any proof-based mathematics courses but I've been reading pure maths books (such as books of...
  14. W

    Quantitative way to compare theoretical values to experimental values

    I am looking at the cross-sectional shape of a sagging membrane. I have several theoretical models, neither of which fit perfectly. So rather than comparing values, I'm comparing shapes. One model fits fairly well, however I'm unsure of which quantity is correct to specify a 'goodness' of a...
  15. B

    Schools Should I go for theoretical physics in college?

    I'm in the 10th grade and i am trying to decide what to study in college. I am really good in physics, math, and chemistry. The thing is that i am very much interested in astronomy and stuff like quantum mechanics and string theory. A lot of people keep telling to study something more...
  16. E

    Theoretical or Experimental Applied Physics?

    Hello everyone, I'm considering becoming an Applied Physicist. I just need some help. Here are the questions I would like answered. -What would a Theoretical Applied Physicist research? -What would a Experimental Applied Physicist research? -Which one would have more of a likely...
  17. P

    Theoretical physics but worse in math

    I am planning to pursue my phD in theoretical physics. But my mathematics skill is not that good and physics concept is ok. So can it possible? Hope someone can give me some guidance. Thanks
  18. K

    Top 3 living theoretical physicists

    physics, of course, is a broad subject with many fields within it, but who do you consider your top 3 most influential/top living physicists in the world.
  19. S

    Geometrical algebra in theoretical physics

    Is geometric algebra and geometric calculus worth learning for a theoretical physicist? What are the advantages of this approach against the usual vector calculus ?
  20. K

    PhD in Theoretical Physics in the UK

    Hello everyone, I am a 4th year student in a UK undergraduate masters program (MPhys (Hons.)) in a russell group university. My grades are around 70% average as of last year (3rd year), and I am working really hard to improve my grades during the fourth year (i expect to graduate with an...
  21. mrspeedybob

    The maximum theoretical efficiency of a heat engine

    http://en.wikipedia.org/wiki/Heat_engine This is one of those threads where the OP proposed a device which will not work and hopefully by the end understands why. So here's the device... Air enters through a long intake tube. At the end of the tube it enters a combustion chamber where fuel is...
  22. N

    Is a vacuum balloon posible? Theoretical material?

    Homework Statement So, I was sitting in my algebra based college physics class and we were talking about buoyancy. According to Archimedes' Principal, "an object that is completely or partially submerged in a fluid experiences and upward force equal to the weight of the fluid displaced."...
  23. S

    Advancing Towards a Theoretical Physics Career: What's Next?

    Question: What's next for me? What should I learn next in physics and math? (I want a career in theoretical physics - phd route). I've learned: Physics: Newtonian Mech w/ calc, Griffith's Intro to Electrodynamics, Goldstein's classical mechanics, griffith's intro to quantum mechanics...
  24. P

    Schools Theoretical Physics at McGill University?

    Hi all, I still have a year of undergraduate studies left but I'm very, very interested in mathematical, theoretical physics. I would love to do research in string theory; does anyone know if McGill University is at least decent for this as a graduate school? It's probably a naive question to...
  25. S

    Theoretical gage factor for resistive wire strain gages?

    What model correctly predicts the sensitivity of a resisitive wire straing gage to applied strain? This question is motivated by an an old pamphlet found in a used book store, "Theory Of Strain Gage Flight Test Instrumentation" by Eugene Frank, 27 May 1946. The gage factor of a strain gage...
  26. J

    Potential Well - a theoretical question

    So imangine a potential well that looks like this: --_-- where the 1st and the third line have a potential U and the 2nd line has U=0. A wavefunction is coming from the left with E>U. When the wave function hits the first potential change(where the ΔU = negative), does some of the...
  27. O

    Theoretical impulse response and its normalization

    greetings, helpful people around the world, we all have heard once in our lives that the signal that is measure from your instrument, be it a spectrometer, optical microscope or an NMR machine, is not the real signal distribution, but the convolution of the real signal with an instrument...
  28. H

    Physics Which career path? Applied or theoretical physics?

    I am in the process of choosing the topic for my thesis. Originally I came from a more theoretical branch of physics but I realized that I do not see my future in university research, but more in the industry. I want to do research with more direct applications, but now I am not sure what my...
  29. N

    Programs After a Phd in Theoretical Physics

    Call me crazy, but am I right in thinking that people with a Phd in Theoretical Physics could take up a position in a university as an experimentalist? Is it a strange thing for a theorist to do? Or is it not that black and white? Is it more of a blur? Would theorists be viewed just as capable...
  30. F

    The theoretical max. speed in deep space

    Hello, Isn't the theoretical max. speed in deep space unlimited? There is no friction. Therefore, any energy we add to the spacecraft will increase its speed. So can't the speed of light be reached? Thanks.
  31. A

    Drop Test theoretical calculations & material selection

    Hello, I am currently assigned to perform a drop tests on a unit that we sell. Thing is that I am an Electronic Engineer so I am not best at mechanics. I am wondering whether you can calculate forces and required material strength to withstand the drop test. The reason I am asking is...
  32. C

    Physics Jobs for theoretical physicist outside academia

    Hello, I would like to know what can do theoretical physicist who don't get a job in academia, after a phd in theoretical physics or after a postdoc for example. I am thinking about people working in theoretical high energy physics, cosmology or things like that. If we compare the number of...
  33. A

    Theoretical pH of HOAc + NaOAc Solution

    Homework Statement Calculate the theoretical pH of each solution. The first solution was 30.00 mmol of HOAc (acetic acid) and 53.00 mmol of NaOAc. There was no water in this solution. Homework Equations We have to use this equation. The Attempt at a Solution I'm unsure of what...
  34. A

    Courses Math Courses for Theoretical Physicist to be (Hopefully)

    I am currently a sophomore majoring in physics in college. I also plan to major in math because I am very interested in theoretical physics. The math adviser that I spoke to could not give me much information on what math subjects are important for a career path in theoretical physics, so if...
  35. M

    Munich Theoretical physics (group theory and symmetries)

    I'm sorry if I'm posting this question here, but for some reason i can't add a new topic in the right section (i think it should be "Advanced Physics Learning Materials") ..I'm also sorry for my english... By The Way... Just one simple question: i'm looking for the note or the webpage for...
  36. B

    Theoretical Theorys of Magnetic Force and Origin

    Does anyone have a good theory for magnetic force? No need to talk about domain alignment or electron spin, (although if you have something deeper then just electron spin, id love to hear it)this much is known. I'm talking about the actual FORCE of magnetism. As in: If you are in a vacuum...
  37. B

    Programs Best courses to major in if I lean towards theoretical physics as a career goal?

    I'm not sure if anyone knows what I mean by saying my desire is to hypothesis and experiment, and build upon the basis of other theorems. I wonder if majoring in physics with a concentration on astrophysics are the proper choices in relation to my desired career path. I suppose I'm leaning...
  38. J

    Theoretical optimisation of foreign exchange strategy

    Hi everyone, I realize this is only loosely related to mathematics, but I didn't know where else to ask this question (if I post it in a finance forum I'll get 100 different answers from people who probably didn't really understand the question). I think mathematicians are the kind of people...
  39. L

    Theoretical situation - surface area vs. friction

    You are pushing a wooden crate across the floor at a constant speed. You decide to turn the crate on end, reducing by half the surface area in contact with the floor. In new orientation, to push the same crate across the same floor with the same speed, the force that you apply must be about: A)...
  40. H

    More theoretical questions about acceleration and velocity

    Homework Statement This question is from a theory stand point. I understand the definitions of velocity and acceleration separately. For some reason, I can not conceptualize them in equation form. How do you really know a*t= velocity or d/t=v ? Is there a proof for this or something? I need to...
  41. C

    Tricky Theoretical Probability Question

    Hey :) Homework Statement So, for a school assignment we had to create a carnival game and then calculate the empirical & theoretical probability of it. My game was called 'splat the rat;' basically, I put a computer mouse down a pipe and a contestant had to try and hit it with a little...
  42. S

    A very theoretical approach to diff eq

    Hi. I'm taking diff eq course this semester and the text is the latest Boyce DiPrima diff eq with boundary value problems. The first test is mostly proofs on theorems about continuity, like the Heine-Borel theorem, Bolzano-Weierstrauss theorem, etc. The book doesn't go into much details about...
  43. G

    Brains for Theoretical physics

    Does one need to be relatively super intelligent (to a human that is average) to make a significant contribution to the world of theoretical physics ie something on the same caliber as Relativity?
  44. Z

    Can I Pursue a PhD in Theoretical Physics with a Master's in Applied Physics?

    I have a very simple and straightforward question. This has been troubling me for quiet a long time now. Can i go for a phd in theoretical physics with a masters in applied physics ? I basically mean to say that: Will applied physics degree create any kind of hindrance for phd in...
  45. I

    Becoming a Great Theoretical Physicist by Gerard 't Hooft

    Hey, I came across (http://www.staff.science.uu.nl/~hooft101/theorist.html) in which Gerard 't Hooft has written a guide on becoming a good theoretical physicist and was wondering if anyone is using it, and if so d'you like it?
  46. J

    Good personal computer for a theoretical physicist

    Hi, I am a graduate physics student and I am looking to buy a new desktop. I was wondering if anyone had any opinion on a great desktop for a theoretical physicist. I mostly use mathematica for symbolic computations but from time to time I use C or C++ to write numerical programs. Any...
  47. M

    Programs Can I get on a theoretical physics PhD course?

    I have accepted an offer to study physics at Warwick University in England this September, however I have not decided yet as to whether or not I would like to proceed into an experimental or theoretical career and would just like to know whether or not it would be possible to get onto a...
  48. J

    Theoretical Aspects of Measurements

    I work for a drug company & they have a department of Metrology - "Metrology is the science of measurement. Metrology includes all theoretical and practical aspects of measurement." Anyways, so what exactly are the theoretical aspects of measurement? To me, they would be something like...
  49. perplexabot

    Calculating Theoretical Density of Single Crystal Silicon

    I posted this in the engineering section but no replies : ( ... Let us see if the physicists can help. Homework Statement Given: Density (D) of Si is 2.328 g/cm^3. Si has diamond crystal structure. Find: Theoretical density of a single crystal of Si. Homework Equations...
  50. P

    Assessment of JETP (Journal of Experimental and Theoretical Physics)

    On a scale of 1 - 10, where 10 means the journal is peer-reviewed, highly regarded, responsible and influential, and 1 means the journal is self-published junk science ... where does the Russian "Journal of Experimental and Theoretical Physics" (JETP) lie, in your opinion? Jeff
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