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. G

    Schools Theoretical physics university climbing

    I'm a 4th year MPhys student currently finishing my undergrad. I will be attending a theoretical masters course next year at Kings. I have been declined by Imperial and Cambridge so I have started to get a little worried about my future. Even though I have been declined this year, is there any...
  2. H

    I How do you exactly calculate the theoretical maximum efficiency of an LED?

    Hi! I found interesting post here: https://electronics.stackexchange.com/questions/325762/how-efficient-are-leds However, it only gives the final results and not the steps he made. I tried to learn the formulas on wikipedia on my own but I couldn't figure out what variables need to have what...
  3. CarterTheSpaceman

    Math needed for graduate theoretical nuclear physics program?

    So, basically I need a roadmap of the math required for nuclear theory. I've completed Calc (1-3) and teaching myself ODE. My roadmap currently is PDE, Complex Analysis, Linear Algebra and Numerical methods. I'm going to work through Arfkens 2nd edition of math methods. Any thing else I should...
  4. Eucliwood

    Theoretical vs measured electrical resistance: Percent error relation

    Mentor Note -- Thread moved from the technical forums, so no Homework Template is shown. So, we've conducted an experiment on resistors in a circuit. The theoretical calculation was based of on E-24 series color band table and the measured resistance of the resistor was measured by a meter...
  5. Ellegal

    Schools Top School, Low GPA, Good CV -- Grad School for Theoretical Physics?

    Hey Everyone. So basically I'm having tonnes of anxiety about my future and would like a bit of a reality check on where I stand and what I will be able to achieve. I go to one of the best universities in the US for undergrad Physics, yet my GPA is on the lower side (3.1). This university was...
  6. P

    A Research styles in different branches of Physics

    Are the standards of studying/teaching methods same across different branches of theoretical physics like particle, astronomy and cosmology? For example we observe a lot of tours, events and conferences in institutes of astronomy and astrophysics, whereas particle and cosmologists are mostly...
  7. Ryu

    Theoretical Higher spatial dimensions question

    So I had a topic which I would like to fact check from an informed scientific source. Basically there is an argument about whether or not an object that naturally exists in a fourth dimensional space, would by default have more than countably infinite times the energy of a 3 dimensional Object...
  8. T

    I Data analysis for theoretical vs experimental results

    Hello, My question is what types of data analysis can I perform on a set of theoretical and experimental results? For example, I have v(x) = cos(x) and I plot my observed data to v(x). Thanks!
  9. S

    Courses Math courses for Theoretical Condensed Matter

    I'm a physics and math major, going into my 3rd year. Suppose I want to do research in theoretical aspects of condensed matter. What would be the mathematics I should be learning as an undergraduate? Here is a rundown of courses I'm considering taking next year: Abstract Algebra: it seems a...
  10. L

    Job Skills Theoretical vs Experimental Physics -- which is more glamorous?

    I am worried that I am passionate about physics and yearn for a career in physics(through theoretical physics), and by a career I mean a placement in a prestigious institute and then be part of leading physics, but would that require sacrificing my entire 20s and even 30s or can I can get all...
  11. P

    Bachelor's thesis: Theoretical vs Experimental

    Hey PF, In 1 month I am going to start my Bs.c thesis. I already "have" a mentor that is willing to supervise me and a topic. The topic is Bohmian Mechanics. I know its disliked, but that's not why I am asking this question. Tbh I'm not a great student, if I don't like something I will put...
  12. T

    Power output of a theoretical generator

    so, assuming that you know all of the aspects of your theoretical generator, apart from the voltage and current, how would you work it out. I know that it is possible, but i can't find anything that I understand, or is even valid online. There should be some equations i can use to work it all...
  13. A

    Other How did you find your reasearch area in theoretical physics?

    Hi guys, I find it hard to decide what to work on. To give some background, I am a bachelor student and I want to work in theoretical research. I talked with a professor (he is the chief of the theory department) at my uni about this and he expects me to find a topic or an area of research for...
  14. A

    Programs Medical physics vs theoretical physics

    Is medical physics as informative as normal physics in terms of the courses I'll do in the University and can it be used as a pathway into medicine and surgery?
  15. George Keeling

    News What do theoretical physicists do?

    I took great comfort reading a New Scientist article on the Perimeter Institute, Canada where top theoretical physicists pass the day. They asked four how they get through the day. Two replies gave me great comfort: Asimina Arvanitaki I spend most of my time being confused about things and...
  16. Taxi1337

    Sphere-with-non-uniform-charge-density ρ= k/r

    I am working on the same problem as a previous post, but he already marked it as answered and did not post a solution. https://www.physicsforums.com/threads/sphere-with-non-uniform-charge-density.938117/ I am curious as to a method of finding the ##k## and substituting into the electric...
  17. LilyWillows

    Physics Employability with a degree in theoretical physics vs physics

    Hi! I'm currently in my second year of a five year integrated masters degree in physics. When applying, I chose to study just plain physics as I didn't really know what I wanted to do and I didn't want to limit my options. However, for the past year and a half, and honestly before that too, I've...
  18. J

    Theoretical models of the Earth's Electric Field?

    I am doing some research into atmospheric energy harvesting. To design a proper feasibility experiment, I need to establish some theoretical baselines. I see a lot of values for the field strength for example, tossed about from various papers. However, there does not seem to be a standard...
  19. Brian Leist

    Admissions How to enter theoretical physics with astronomy background?

    Hi all, I am interested in advancing my education in theoretical physics, specifically topics concerning quantum field theories and quantum gravity. However, I have a somewhat rocky background as an early undergrad and while my Master's degree was achieved with great success in the classroom...
  20. T

    Courses Math as a substitute for theoretical physics

    I was watching a video about physics that said people who want to study theoretical physics but do not want to study things like electromagnetism, thermodynamics, experimental physics, etc, should study math, then take some classes in theoretical physics. This way, you could study your favorite...
  21. B

    MHB Calculating theoretical probability

    Hello All, I have the following question in one of my tutorials. I need some help in resolving this. Background: A manufacturing company developed 40000 new drugs and they need to be tested. Question The QA checks on the previous batches of drugs found that — it is 4 times more likely that a...
  22. T

    Programs Should I Major in AI or Theoretical Physics for a Lucrative Career?

    I am a 12th grader and I am having trouble choosing what I want to major in. My biggest interest is string theory/ quantum field theory/ theory of everything/ particle physics (math intensive theoretical physics). But the problems with getting a physics degree are 1) getting a phd takes a long...
  23. Auto-Didact

    A Taxonomy of Theories in Theoretical Physics

    It goes without saying that theoretical physics has over the years become overrun with countless distinct - yet sometimes curiously very similar - theories, in some cases even dozens of directly competing theories. Within the foundations things can get far worse once we start to run into...
  24. Hiero

    I Is there any theoretical basis for laws being 2nd order

    Hi, I’m just wondering about this: Are there any theoretical reasons why physical laws take the form of 2nd order (in time) differential equations? Or is it just observed to be that way? Are there ANY laws (even in a limited context) which are 3rd (or higher) order in time?
  25. K

    Physics Dark Matter theoretical research

    Hello! I am currently applying for graduate schools in the USA and during my undergraduate career I was mainly involved in Dark Matter research. However, my research focused on testing different models (experimentally or using numerical simulations) and doing some basic calculations, basically...
  26. astroman707

    How to get better at theoretical homework problems

    I’m having lots of trouble in my honors physics class with the theoretical homework problems that are assigned. The entire concept of learning to solve things theoretically, and then applying it is brand new to me. I’m decent at figuring out the applied problems, but pure theory stumps me. I...
  27. Quantum_Arcanium

    Physics Want to become Theoretical Physicist but don't know Coding

    Hi, I am an aspiring Theoretical Physicist. I've heard that you need to know many programming languages to become a Physicist, but I have never learned a single programming language in my life and I am 16-17 years old now. Is there any chance of me still becoming one? Is there anything I can do...
  28. I

    News There are no laws of physics theres only the landscape.

    In my post that I have been ranting on trying to figure out how to solve things on everyday occurrences. Which was titled "Mass of a Piston" That is to say, can you use physics on the spot to calculate a golf swing that projects a ball off a cliff that you have never seen before. You don't know...
  29. D

    Capacitor specification, doesn't exist maybe (theoretical)

    Need to come up with specifications for a capacitor that can hold 20,000 or more amps How many joules or watts or how much energy can this theoretical capacitor hold how many farads, what would the current be and how many volts could it tolerate, how to increase volt tolerance. how to increase...
  30. B

    Divergence of the E field at a theoretical Point Charge

    I've been thinking about this problem and would like some clarification regarding the value of the divergence at a theoretical point charge. My logic so far: Because the integral over all space(in spherical coordinates) around the point charge is finite(4pi), then the divergence at r=0 must be...
  31. S

    Other First year PhD in theoretical physics

    Hello! What can a first year PhD student (in an American university) do, research related, in the field of Theoretical (mainly high-energy) physics? I know in the USA you need to start research from the first semester of PhD (even if you formally choose a definite field of research at the end of...
  32. Robin04

    Physics How do theoretical physicists work?

    I always imagine them sitting in their room behind their desks and working on their new theory like Einstein. I suppose most theorists work in groups nowadays to be more efficient but do these lonely workers still exist and are they supported financially or they're working in their free time?
  33. S

    Other Math tricks for Theoretical Physics

    Hello! Is there a book (any kind of written collection) about mathematical tricks for complex problems (in both math and theoretical physics). Over time I have encountered several nice and impressive tricks to simplify apparently difficult problems and I was wondering if someone gathered them in...
  34. BadgerBadger92

    B A quick theoretical question on dark matter

    This is a theoretical question that may not be rooted in reality. I hope this was the right section. Please clear up all misunderstandings. Since dark matter can’t emit light, could it be possible that dark matter is ionized matter? I always thought you needed electrons to emit light. Then that...
  35. A

    Theoretical Physics should belong in the math department

    Theoretical Physics should belong in the math department to then collaborate with the physics department on new mathematical theories within physics. I can't accept that theoretical physics could really be considered a branch of just physics. I can only see theoretical physics being 95% math and...
  36. SJay16

    Courses Theoretical Physics or Optics?

    I was just wondering which out of the 2 courses would be more beneficial for me as I am interested in Astronomy, Astrophysics, and Cosmology: A senior level course in Optics or a Senior Level course in Methods of Theoretical Physics (Presumably mathematical methods). Course Descriptions...
  37. Alex Petrosyan

    Physics Getting into theoretical Physics after multiple setbacks

    Hi all, I'm a theoretical physics hopeful, and I've had a couple of major setbacks in my undergraduate studies. I'm thinking of whether I should pursue a career in TP, or reconsider doing physics entirely. My background: I've always had an interest in Physics. I got a bronze medal from...
  38. Kiwimaster76

    Calculations for a theoretical planet + a little biology

    So I'm attempting to write a scientifically accurate story and i need some help with the planets characteristics. I have a few things set up already and need some educated guesses and ideas for how the rest will work. So to start with what i have: Planet name: Remvale Radius:~8370 miles Gravity...
  39. L

    Programs SISSA theoretical particle physics

    I have thought about taking the enterence exam for theoretical particle physics at SISSA this coming July. I was hoping someone here took it in a previous year and could give me some advice. By looking at the old written exams, it seems they are mainly made up from QFT and QM. So my plan was...
  40. Highwire

    [The Theoretical Minimum] Can closed systems exist?

    Homework Statement The first exercise in Susskind and Hrabovsky's The Theoretical Minimum is one that, in the words of Susskind, "is designed to make you think, more than it is designed to test you." The exercise asks: Homework Equations In the prior paragraph, the authors define the notion...
  41. G

    Quantum Dr Susskind: Theoretical Minimum Quantum Field Theory?

    Does anyone know if or when Dr Susskind is coming out with a “ Theoretical Minimum Quantum Field Theory “ ?
  42. Jordan M

    Theoretical ξr of a molecule from the absolute configuration

    I am wondering if anybody knows how to calculate the theoretical relative permittivity of a molecule (1) using the theoretical configuration and values that are easily accessible (2). I am also wondering what the technique would be. In my pharmaceutical reaction class and also O-chem 2 we have...
  43. F

    Platform for theoretical physicists?

    I’m a young very ambitious student who would like to embrace a project. As a third year undergrad I feel pretty alone. My fellow colleagues are not very forward thinking nor want to do anything besides pass the exams. Are there any platforms/associations for young theoretical physicists...
  44. Orangeator

    B Theoretical Question On The Twins Paradox and Heart Rate

    Okay, so if two identical twins put on a heart rate monitor that after let's say 400 million beats were detected (at 80bpm that's about 10 years) the monitor killed them. Now one gets in a spaceship and the other stays on earth. The one in the spaceship travels at say 95% of the speed of light...
  45. H

    Courses PhD in theoretical physics vs material science?

    Hello PF, I am currently pursuing my Masters in Physics with specialisation in material science. But I am interested in quantum mechanics and want to do PhD and then research in quantum mechanics. But in today's date is it good to go for theoretical physics rather than going for some...
  46. EnigmaticField

    Programs Apply for a PhD in theoretical condensed matter physics?

    I did research on theoretical formulations in general relativity during my MSc studies. I look forward to pursuing PhD and have searched many universities and some research institutes for suitable research themes, but haven't found many research groups undertaking research consistent with my...
  47. Jianphys17

    I Relation between statistics and theoretical physics

    Hi at all, maybe it's a bit trivial. However, the question that i ask myself is ; that relation there is between statistics-probab theory & theoretical physics. What role does it play in theoretical research ? (apart from the probabilistic amplitudes encountered in qm) Thanks for the answers
  48. O

    I Theory of Acceleration: Is There a Limit?

    Is anyone aware of any theory which includes a theoretical limit on acceleration in the same way C is the universal speed limit? [[By this I do not mean some sort of practical limit set by energy density and known systems of propulsion.]]
  49. T

    Vector Notation in Nolting Theoretical Physics 1

    On pg. 60 of Nolting Theoretical Physics 1 for the definition of a vector multiplied by a scalar the book shows two little up arrows if the scalar is greater than zero and an little up arrow and then a little down arrow if the scalar is less than zero. Then again on pg. 61 for definition 1.139...
  50. Greg Bernhardt

    Insights Interview with Theoretical Physicist Clifford Johnson - Comments

    Greg Bernhardt submitted a new PF Insights post Interview with Theoretical Physicist Clifford Johnson Continue reading the Original PF Insights Post.
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