What is Theoretical: Definition and 1000 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. AW3Rgo0l

    Other Transition from theoretical physics to astronomy

    How easy to switch from research in theoretical physics to astronomy and is it possible to become a qualified specialist in this field after that?
  2. marce

    I Neutrinos and theoretical necessity

    - One of the most fascinating particles for me , have always been neutrino's because of them balancing between mass and massless properties. So the question 'why was this needed' in the context of the weak force has led me to the question : as with attempts to explain 3 generations of particles...
  3. billtodd

    PhD in theoretical physics and a PhD in Pure Maths at an old age

    I am approaching an old age of 40, and now pursuing an MSc in Engineering without a thesis nor project. Before that I pursued MScs in Physics and Maths, but never finished writing my theses. I have a sort of perturbed attitude towards both Maths and Physics, I mean something really pure in maths...
  4. AW3Rgo0l

    Studying How much chemistry do I need to know as a theoretical physicist?

    How much chemistry do I need to know as a theoretical physicist in order for this knowledge to be sufficient for research in any field of theoretical physics? It is also interesting to know how difficult the transition from theoretical to experimental physics is? Do experimental physics require...
  5. robotkid786

    Physics How important is python for theoretical physics?

    Hey guys, I'm a first year student studying theoretical physics in England. My physics modules include a fair bit of python programming and I want to apply to ICGs cosmology PhD in England. Can I escape learning python by choosing maths modules?
  6. matthieu1973

    Designing best theoretical sax/clarinet mouthpiece ligand

    Hey to all.. I am in the process of designing a ligand for a clarinet mouthpiece for my own use created only out of string material (braided kevlar). For those uninformed (like me a few weeks ago) saxophone/clarinets are instruments where the vibration of the standing wave through the...
  7. hdsfhsdf

    A "The Operation Combination Problem"

    "The Operation Combination Problem" In the "Operation Combination Problem," we explore the space of possible solutions, much like we explore the different possible topologies for the universe. The problem consists of finding all possible combinations of mathematical operations that, when...
  8. G

    I can't find a PhD in theoretical physics after 6 months of trying

    Hi, I am 25 years old living in EU. I am posting my experience with the objective of getting advice or opinions. I have a bachelor in physics with a thesis on the SM electroweak sector. I have a master again in theoretical physics with a specialization on Hadron Physics ( QFT ). Both of my...
  9. lforster02

    Calculating theoretical thickness while anodising aluminium oxide

    I am trying to calculate the theoretical thickness of an anodised coating. I know all values apart from I am unsure whether to use 2e or 6e for the amount of electrons. Anode reaction as follows: 2OH = H2O + O + 2e the aluminium reactions preferentially with the one O atom, using equation: 3O...
  10. L

    Measured Surface Resistivity Much Higher than Theoretical Value (Why?)

    I recently conducted a physics lab to measure the surface resistivity of a conductive sheet of a paper with a carbon filler. The theoretical Rs is approx. 5,000 Ω/☐ for this paper and yet we have calculated two Rs values: Rs when Varying Length and holding Width = 10100 +/- 83.07 Ω/☐ Rs when...
  11. R

    Computational, Theoretical, and Experimental Research: A Comparison

    Hi, I understand there is computational research as well as completely theoretical research compared to experimental research. I was curious about what they are like. Could anyone point out some good papers? Thanks.
  12. D

    I Theoretical pressure decay of a pressurised vessel

    I am looking to derive a method of plotting the theoretical pressure decay of a pressurised vessel. I would like to end up with a graph that plots internal vessel pressure against time. Is this possible? What assumptions would I need to make? The following inputs will be known. Gas: air...
  13. S

    Theoretical substantiation of the handicap principle

    https://en.wikipedia.org/wiki/Handicap_principleThe handicap principle is a controversial hypothesis, possible confirmed by Alan Grafen. I would like to understand his reasoning. A handicap is a harmful thing, like a peacock's tail, that attracts females precisely because it is harmful. Dawkins...
  14. Whitestar

    Exploring Theoretical Physics: Math Requirements and Resources

    Hello. I have been a member on this forum for quite some time and I came here because I've always had an interest in science, particularly physics. When I was in Junior High, I did very well in my science class but by the time I got to college, I wanted to make money. However, I realized that...
  15. S

    B Is there a theoretical size limit for a planet?

    Jupiter is huge. TrES-4 is 1.8 times the size. How big can planets actually get? is there a limiting factor? cheers.
  16. A

    Programs Advice for majoring in theoretical physics

    I am going into my senior year of hs next year and I am meditating on what I should major in. I have a keen interest in physics but also a love of math. The field in physics I would like to major in is theoretical physics/astrophysics, and the pure maths I am interested in are diff, algebraic...
  17. C

    How might plant life look different on other theoretical planets?

    Got interested on how plants (and other things such as fungi) could evolve on other planets along with how plant life may flourish depending on the position of the planet to the sun, moon etc. I'm looking for any article talking about this or something similar.
  18. DavidBalut

    I The Theoretical Minimum: Length Contraction and Time Dilation

    Hello, My name is Dave and I'm a physics major at UIUC. It looks like I will be taking the special relativity course (phys 225) this fall. I've always been fascinated by the theory so I decided to get a head start with Lenny and Art's perspective on it. My first head-scratching moment came in...
  19. modellatore

    Studying Theoretical Physics Study Path (it's about tetrads....)

    I'm a graduate theoretical physics student at the (almost) end of his master's degree with a fairly varied curriculum, as I attended both QFT (and sub-courses on qed qcd etc) and GR courses. However in my latest intro to quantum gravity classes I familiarised with tetrads and, after a lot of...
  20. A

    Other Transitioning from Theoretical Physics to Software Dev: Steps & Difficulties

    I'm going into my final year of undergraduate theoretical physics. I have had a bit of a deviation in what I want to do and would really like to work in software development in the future. How difficult would it be for me to deviate from my current position and what steps should I take to to...
  21. Admiralibr123

    Physics Quantum Computing masters with Theoretical physics background

    I want to do a masters related to quantum computing from a physics background and my criteria for the place is: 1. A quantum computing group with experimental realizations and industrial ties. 2. A strong theoretical physics department with research in fundamental physics 3. A good chance of...
  22. N

    Finding theoretical impedance of acoustic transducer

    Hi all If we have an acoustic transducer and values of its two parameters are known, i.e conductance and capacitance, is it possible to calculate impedance using these two parameters? Thanks
  23. M

    Hypothetical stable isotope of Promethium?

    Say one was to create an artificial stable isotope of Promethium as it has predicted applicable properties. What would it’s number have to be? I know Promethium-147 is semi-stable.
  24. Jamestein Newton

    Can one do mathematical physics and theoretical physics at the same time?

    I finished my 1st-year physics, took analysis, linear algebra, mathematical logic, classical mechanics, quantum mechanics(I was exempted from intro phy and took some 3rd-year physics courses) I internal transferred to pure maths. The reason is that the curriculum of the physics programme in our...
  25. Jamestein Newton

    Courses Is it necessary for theoretical physics students to take a course in PDE?

    By PDE. The book written by Walter Alexander Strauss perfect described a typical undergraduate PDE course I have in my mind. It should at least include: Laplace equations, waves and diffusions reflection, boundary problems, Fourier series The content of the book I mentioned can also be found...
  26. Arman777

    A How to express the agreement between experiment and theoretical observations?

    Let us suppose I have a value measured from experiment and given by $$V_{\text{exp}} \pm \sigma_{V_{\text{exp}}}$$ and a theoretical value given as $$V_{\text{the}} \pm \sigma_{V_{\text{the}}}$$ Is there a statistical way to measure how well ##V_{\text{the}}## matches with the...
  27. S

    Quantum 'Quantum mechanics the theoretical minimum' book

    I want to know about the book 'quantum mechanics: the theoretical minimum' book by Leonard Susskind. Is it a book worth buying
  28. M

    Theoretical question about a new Energy and implications of using it

    Toady we use energy sources like fossil fuels which in turn cause global warming, which is a slow process in which our planet changes its habitat to a hostile one for humans. For a science fiction book idea I would like to know if there is a theoretical source of energy that using it would...
  29. ergospherical

    Increasing confidence in theoretical calculations

    How can one maximise one's confidence in the results of a theoretical calculation? After long and fiddly calculations I often encounter an uneasy feeling where I find it difficult to confirm whether the fruits of all that labour are actually correct. The first ports of call are always: -...
  30. A

    Grant for Research in Theoretical Physics

    Suppose there is a nonprofit that wants to order a piece of research in theoretical physics. The research is rather small; it consists in considering an issue and writing a 8-10 pages article. The physicist to do the research will be from a high income country; he/she should be an experienced...
  31. CyclicAvatar

    PhD in condensed matter theory or theoretical cosmology

    Hi all, I just graduated from my master's program in theoretical physics. I did 60% of the coursework in high energy physics and rest in condensed matter theory plus a few experimental physics courses. I did my master's thesis in what can be called as theoretical cosmology, studying particle...
  32. OscarV

    Calculus Should I read Spivak's Calculus as an undergrad in theoretical physics?

    I am about to start a physics with theoretical physics major, I've taken calculus before but I've not been satisfied with the "memorization of formulas" type books. I started to read Spivak and found it enjoyable, but since it's a major undertaking I am also concerned for the practical value...
  33. Joel_Entrup

    Is it possible to become a theoretical physicist with a 120 IQ?

    An IQ of 120 is plenty good, but the average IQ of Physics and Astronomy majors is higher. It's even higher for brilliant theoretical physicists and Physics PhD holders. So is it possible, with enough hard work and dedication, that someone with a 120 IQ could become a theoretical physicist? Or...
  34. ergospherical

    Applied Lectures on the geometric anatomy of theoretical physics

    I stumbled across this series of 28 lectures by Dr Frederic Schuller of the university of Twente whilst searching for lectures about Lie theory. Having watched through lectures 13 to 18, I think they are simply superb (of course I'm assuming the rest are of similar quality). I only wish he would...
  35. George Jones

    Exploring Chris Isham's Work in Theoretical Physics

    An interesting article about theoretical physicist Chris Isham (by Michael Duff) has been posted on the arXiv, https://arxiv.org/abs/2112.13722 Combine this with (from "Group Theory for the Standard Model of Particle Physics and Beyond" by Ken Barnes) Isham has written two books that I quite...
  36. E

    Theoretical reaction rate for water electrolysis

    So I'm designing a proces where carbondioxide is converted into methane using the Sabatier reaction. For this reaction hydrogen is required which I'm planning on producing using the electrolysis of water. But I'm having a problem where I need the speed of this reaction to determine the size of...
  37. K

    I Theoretical maximum efficiency of a heat engine without Carnot

    Through an intriguing fictitious dialog between Sadi Carnot and Robert Sterling, Prof. Israel Urieli of the Ohio University shows that it is not required to invoke entropy, the second law of thermodynamics, and the Carnot cycle with the [ideal] adiabatic processes in order to find out the...
  38. laserdan

    A Rate and function to fill a theoretical vacuum

    I am trying to find a way to determine the rate and function that would describe how a theoretical vacuum (let's say a cubic centimeter) would repopulate with air if surrounded by ambient air at STP. Any suggestions? I am not very good with thermodynamic or kinetic theory. My current work...
  39. Monsterboy

    Do you agree with Jeff Bezos on theoretical physics?

    I recently watched a video of Jeff Bezos explaining his journey from Princeton to Amazon. (watch from 24:39) He said when it comes to theoretical physics, if you are not in the top 50, you are probably just wasting time. How accurate is this opinion ? Are most theoretical physicists just...
  40. M

    Programs Maths vs Physics degree for theoretical physics

    Hi, I'm interested in doing research in theoretical cosmology (the kind or work hawking did). Should I do an undergraduate degree in mathematics or physics? I'm in the UK so I can't do a double major. I'm well aware of the fact that interests change a LOT later on, but ideally which one is...
  41. Solitron

    Battery - theoretical specific energy

    I want to learn how to calculate maximum theoretical specific energy of various battery combinations consisting of a single metal and single oxidant, like for example Sodium - Sulfur, Potassium - Sulfur or even crazy stuff like Rubiddium - Iodine. I asked this question on stackexchange but I...
  42. Hamiltonian

    Relativity Advanced Theoretical Physics: a book on SR & GR for Undergrad Students?

    I recently came across a book called advanced theoretical physics -nick lucid. chap6 covers tensors and chap 7&8 cover SR&GR. I have studied a bit of SR before but never GR. At this point in life I don't want to read huge books on the subject. this book covers relativity entirely in three...
  43. T

    A Radius of the Sun: Can We Accurately Predict It Through Theoretical Models?

    Basically, I'm wondering if there have been any attempts to calculate/model what the radius of the sun should be based on gravitational, thermal, and electromagnetic pressures. If there has, where can I find the calculation/model, and how closely does it match the actual radius of the sun...
  44. T

    Programs PhD Theoretical Physics - Part 2

    Hello, I have several questions around the application process as well as the organization. 1. Are you aware of any reference website centralizing PhD offers by countries? 2.When it comes to the organization/management/ supervision of a PhD program, I wonder if there are differences by...
  45. Hacker Jack

    What do theoretical physicists actually do?

    What are they employed to do most of the time? I read that Albert Einstein was working at a patent office when he came up with his theories. So do theoretical physicists work on stuff they are interested in their free time as opposed to when they are at work?
  46. E

    Other Your thoughts about "International Journal of Theoretical Physics"

    A year ago, I asked a question about two journals, both of which were predatory ( https://www.physicsforums.com/threads/are-open-access-journals-legit-for-my-cv.990744/ ). Thanks to the overwhelming advice I have received, I did NOT publish in either of those journals. Right now I am asking a...
  47. Falgun

    Studying Computational Skills for Theoretical Physics

    I am currently learning to code by auditing Harvard's CS50 course on edx. I am mainly interested in pursuing a theoretical physics major in the future. What I would like to know which scientific computing software/language (as in OCTAVE, SCILAB, FORTRAN, JULIA, etc ) can I learn alongside which...