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. Smalde

    Programs Best Theoretical Physics Masters Degree in Continental Europe

    Dear All, I am sorry if you consider this question to be repetitive or too general but I have been unable to find sufficient answers on the web and thus I want to see what I can win from asking you guys. First my situation: I finished my Physics' Bachelor in the LMU Munich with good grades...
  2. bbbl67

    I What is theoretical minimum mass of neutronium?

    Not withstanding the fact that most neutronium is produced in neutron stars, what is the lowest mass required to keep neutronium stable? I've heard it could be as low as 0.1 solar masses. Could it be even smaller than that? Can you make an Earth mass neutronium ball and have it stay stable due...
  3. J

    Exploring a Career in Theoretical Physics

    First of all, I know it's a big field. But, currently, I don't know where exactly I would like working in it so I'm just asking like the most generalized explanation. I would probably prefer more in the theoretical part of the field (which might just be all of it [emoji23] ). A few major...
  4. assademre

    Where to start with Theoretical Physics?

    Firstly, I'm sorry if it is wrong part to start this thread. I'm new here and I can change the category if you let me know. Secondly, I want to learn something about theoretical physics. I am about to finish my study Mathematics in a semester. However, I consider to study physics either and I...
  5. N

    Studying Theoretical physics self-study curriculum

    Hey there, my name's Travis, I'm a high school graduate and prospective theoretical physicist. I started my post-school learning by looking into correspondence study and got hold of some material from a friend. However, despite the fact that I love calculus and physics, I completed the 1st year...
  6. JeffCyr

    A theoretical flotation device using a vacuum (for a novel)

    I'm writing a serialized Steampunk-fantasy story in which the cities float high in the planet's atmosphere using a combination of Magic and technology (sci-fi-ish steampunk technology) Though I want to bring it as close to real science as I can. From some google searches it seems that a vacuum...
  7. ISamson

    Theoretical interpretation to understand chemical recations

    Isn't this a breakthrough? Well, a base for a breakthrough? I have always wondered if a complete theory or accurate prediction of the formation of bonds and molecules is possible... I tried to think about this myself... :) What do you think...
  8. Hypercube

    Physics What do theoretical physicists actually do?

    Dear PF community, I was wondering, what do theoretical physicists actually do? Putting teaching and marking responsibilities aside, would you be able to describe to me your day-to-day activities when you do research? It is something that has been on my mind for a while. I suspect PF members...
  9. M

    Theoretical perfect Newton's Cradle (where does the sound really come from?)

    If the spheres of a Newton's Cradle were perfectly spherical I assume "contact" would be some minimal distance between the outer electrons of one atom of each sphere? Pulling one sphere back and releasing would result in a modest plastic deformation and subsequent minimal distance between more...
  10. K

    Special theory of relativity, theoretical problem

    Homework Statement Spaceship A, traveling past us at 0.7c, sends a message capsule to spaceship B, which is in front of A and is traveling in the same direction as A at 0.8c relative to us. The capsule travels at 0.9c relative to us. A clock that measures the proper time between the sending and...
  11. F

    Is There a Method to the Madness of Theoretical Physics?

    What exactly does a theoretical physicists do? Do they come up with hypotheses, and then do calculations to see how things would work if those hypotheses were true. If that is correct, how exactly do you come up with a hypothesis? Is there a lot of creativity involved? Also, when physicists...
  12. Greg Bernhardt

    A The Crisis in Theoretical Physics - Gian Francesco Giudice

    The Italian physicist Gian Francesco Giudice has come out with an article about the crisis in theoretical physics. Please read the paper before commenting. Thoughts? https://arxiv.org/abs/1710.07663
  13. S

    Latest Theoretical predictions to help guide my career choices

    Hello! I would like to follow a career in theoretical physics (mainly high energy). Can someone point me towards the most important theoretical predictions made in the last 50 years (basically after the QCD period, W, Z and Higgs predictions) that have been experimentally tested. By this I mean...
  14. L

    Courses What courses do I need for a Ph.D. in theoretical physics?

    Due to circumstances outside of my control, I couldn't go to college after high school. Physics is my passion however and I refuse to give up. I have a 5 month old so it would be in my best interest to start my schooling online. I'm only the 2nd person in my family to go to college. So, I don't...
  15. Lunct

    Has Theoretical Physics met a bit of a roadblock?

    I personally am undecided on the issue but it goes without saying that physicists have been stuck on the same problems for years. Sure they recently proved gravitational waves, but one could say that we knew they were they existed anyway with near certainty, if they weren' t there it would be a...
  16. A

    Help on Theoretical Physics Master's Application

    Hi everyone! I am currently in the process of applying for a masters degree in theoretical physics. I am having troubles on writing the personal statement part since I really need to make it shine (200 applications and 20 places:frown:) . Any definitely do's and dont's I should bear in mind? A...
  17. Gjmdp

    Physics What job is better Theoretical Physics or AI?

    Recently, I've been struggling with this issue. I really really love theoretical physics and mathematics, but at some point, I feel like it has now become into a mix of speculation and super advanced mathematics. The fact that some physicists say some areas like String Theory or Quantum Loop...
  18. J

    Generating Audio Signals from Lasers: Theoretical Possibilities?

    Say you have a red laser and pointed it at a ~175 nm antenna, then amplified the signal into a speaker. Would you then theoretically get a very high frequency audio signal (in the terahertz range, i realize this isn't practical)? My question is really on the nature of the light emitted from...
  19. R

    Career advice -- What can I do with a Master's in Theoretical Physics and a Bachelor of Computer Science?

    Hi everyone, What can I do with a master's in theoretical physics and a bachelor of computer science ? I am in Canada, I had to do a master's before a PhD. I just decided to do something else than physics afterwards. I had the opportunity to do a PhD in computer science, in medical imaging...
  20. T

    Theoretical question about wingless flight with a flight pack

    What is the power to weight ratio required from a wingless augmented portable flight pack (jetpack) so that it can enable flight horizontally? Assume that the jetpack and the user both weigh 300 pounds combined.
  21. C

    Programs To pursue a masters degree in theoretical physics

    Hello, I'm about to start my last year of bachelor degree in physics, and in a few months I would like to have a clear idea of where I want to go for my master degree. My dream since I started university is to pursue theoretical physics, in which specific field, that remains for me to...
  22. A

    Physics Theoretical Physicist Career Guidance

    what is the academic route to become a theoretical physicist?
  23. Vanadium 50

    Jack Smith: A Life in Theoretical Physics

    Jack Smith, professor emeritus of physics at SUNY Stony Brook passed away Sunday. His colleague George Sterman writes " Jack Smith joined the Institute for Theoretical Physics at Stony Brook as research associate in the Institute’s second year, 1967, and he subsequently joined the faculty of...
  24. B

    Physics Where Can I Study a Master in Theoretical Physics in Europe?

    Hi, I am finishing the grad in physics and i would like to study a master in theoretical physics the next year. Anyone know or have studied any master in theoretical physics preferably in Spain but also in other countries in Europe. I would like to know your opinion Regards
  25. Eslam100

    What are the topics in theoretical and mathematical physics?

    I'm a rising physics sophomore at a Japanese university. I've studied general physics, linear algebra, and analysis (actually, calculus of single and several variables with emphasis on analysis, everything was proven and the theoretical background was well explained) Other than that, I've...
  26. upigdir

    Physics Theoretical HEP or neuroscience?

    ever since my first year in undergraduate, I wanted to pursue a degree on theoretical high energy physics. so I took a lot of theoretical classes and started a double major in math (I dropped it after I took some classes I was interested in). however now I have only one year left, I began to...
  27. P

    Theoretical physics -- where does spin 1/2 come in

    How did they figure out that particles have spin.where does spin 1/2 come in...how was that detected?
  28. dextercioby

    Studying Gerardus 't Hooft receipe for a self-learner of physics

    Stumbled upon 't Hooft's receipe for the self-learner. Perhaps some of the readers could find it useful https://www.staff.science.uu.nl/~gadda001/goodtheorist/index.html
  29. lawlieto

    Studying Should a theoretical physicist learn maths like a mathematician?

    I'm currently doing my undergraduate physics course at university, and I'm quite confident I'd like to be a theorist in the future. We have separate maths lectures from maths students, and most people have an attitude towards maths which could be summed up as "only learn what you need to know...
  30. Jhelf

    Programs Are there any Engineering Majors that deal frequently with theoretical physics?

    Hi, quick question. Are there any Engineering Majors that deal frequently with theoretical physics? Thank you
  31. P

    Nuclear Theoretical Nuclear Physics Textbook

    Hello, I am interested in getting into low-energy experimental nuclear physics. I have studied quantum mechanics and a few introductory nuclear science textbooks (e.g. Shultis + Faw: Introduction to Nuclear Science and Engineering). I found the textbook Theoretical Nuclear Physics by Blatt...
  32. P

    Programs Amsterdam vs Utrecht Theoretical Physics

    Hello everyone! I have been admitted in Utrecht and UvA (University of Amsterdam) for the Theoretical Physics masters. I am having a hard time deciding between the two and I was thinking that someone might have an opinion on one or the other (or even better on both). Any kind of information is...
  33. Nathan Warford

    I Theoretical Models for Sizes of Fundamental Particles

    I am aware that according to the Standard Model of Particle Physics, fundamental particles such as electrons and quarks are treated as point-like particles. However, if fundamental particles are indeed 0-dimentional points with no spatial extent, it creates problems (i.e. fundamental particles...
  34. S

    Studying How Do You Evaluate Theories and Physicists in Theoretical Physics?

    Hello! I have one more year in undergraduate and I would like to go for a grad school in USA and do theoretical physics. I am a bit confused about particle physics. From what I saw most of the theoretical models today aim to extend the standard model and yet most of them are proved to be wrong...
  35. Physicsphysics

    Courses MMath vs. MPhys Theoretical Physcs

    At this point I have no idea how to look at this situation, so I'm really hoping I can get a little help here. I have an offer for Mathematical and Theoretical Physics which leads to an MMath, and eliminates all lab. I also have an offer for straight Physics, leading to MPhys with no extra...
  36. Work Hard Play Hard

    David Suzuki and Applied Physics vs. Theoretical Physics

    Another thread reminded me of this. Sometime, probably in the 70's Suzuki said something like this, for something to be "real" it has to have a least one piece of retrievable information. One example he gave that I remember was a point in space. I remember this example because of his...
  37. Greg Bernhardt

    Insights Interview with a Theoretical Physicist: Sabine Hossenfelder - Comments

    TheAdmin submitted a new PF Insights post Interview with a Theoretical Physicist: Sabine Hossenfelder Continue reading the Original PF Insights Post.
  38. TheFlyingGandalf

    Physics A few questions about a theoretical physicist career

    Hello, I'm Michael, am 17 and uncertain about my future (as I'm sure anyone my age is). you see, I aim to be a theoretical physicist in the future and I am worried a bit: Yes, I know, you shouldn't pick a job just for the money, but I do worry about how much does a theoretical physicist make. do...
  39. bananabandana

    MSc in Theoretical (Mathematical) Physics,KCL vs Edinburgh

    Hi all, I have an offer to do an MSc in QFFF at Imperial or an MSc in Mathematical Physics at Edinburgh, or (with luck) an MSc in Theoretical Physics at Kings College London (KCL). Technically, QFFF is the best (i.e most reputable) course - but I have heard very bad things about how it's...
  40. S

    A Are there experimental proofs for modern theories

    Quantum theory, although hard to understand with intuition has a lot of experimental proof. Do the more modern theories e.g. String theory, or black hole theories have any experimental proof, or are they theories that the mathematics have led to? Without proof, do they deserve so much credit...
  41. D

    Theoretical model for damped harmonic oscillation.

    Homework Statement Hello all, I have a question regarding the damping constant for a model of a vertically oscillating mass on a spring. I have read through one or two similar questions on this site but I think I can manage to be a little more specific about what I'm asking. I am in a physics...
  42. smodak

    Classical Found a great resource on Theoretical Mechanics (free)

    Classical mechanics: a minimal standard course by Sergei Winitzki. It is not probably going to help you if you already did not know the subject but is a great refresher nonetheless. He also includes a differential equations refresher that I found invaluable. Looks like he has a ton of other...
  43. P

    A little rant about theoretical physics....

    Not sure where to put this discussion, so please feel free to move it... Ok, so here I go... I understand why theoretically time travel cannot exist before the moment it was created, cause one fellah would have to take one end of a wormhole on a fast ship and fly about a bit. I understand...
  44. M

    Admissions Yes, another post about theoretical physics

    I apologize for perhaps seeming redundant with my post. Please forgive me, I'm looking for more specific advice orientated towards my situation. First and foremost, I am a second year student studying physics. Currently, I am also pursuing a double major in mathematics. To me it's either theory...
  45. jamalkoiyess

    Schools How to search for the best Theoretical Physics Schools

    Hello PF, I was wondering how could someone search for a graduate school while being a theoretical physicist (expl : String theorist). I mean someone working in an applied area can search for schools with the best labs or latest technologies but not the Theoretical Physicist. Thanks.
  46. smodak

    Relativity Susskind's Third book on the Theoretical Minimum Listed

    Amazon now lists Susskind's third book on the theoretical minimum series Special Relativity and Classical Field Theory https://www.amazon.com/dp/0465093345/?tag=pfamazon01-20
  47. E

    Fluid Mechanics Theoretical Pipe Diameter

    Homework Statement I need to find the pipe diameter or mean velocity. Q= 0.01m^3s Density= 960kg m^3 Viscosity = 0.081 Pa s Max Velocity = 1.8 m s Homework Equations Mean velocity= 4Q/pi.D^2 The Attempt at a Solution I have two unknowns in this equation so I'm unable to find D or Mean...
  48. BL4CKB0X97

    Physics Is Theoretical Physics a Saturated Field for Aspiring Scientists?

    I am 19 and have always been interested in being a theoretical Physicist, but I am worried that the field seems to have a great amount of people also taking this road. I'd imagine jobs are running short in this field, do it begs the question: should I choose another path? Or do I follow the...
  49. Hypercube

    Schools PhD in theoretical physics at “prestigious” university

    Hi! I want to (eventually) do PhD in theoretical physics, and although universities like MIT, Harvard, Cambridge, Oxford, etc. are incredibly competitive, I was wondering if being self-funded student makes things any easier? My current situation is following: I am nearly 29 years-old student...
  50. J

    Quantum Theoretical Physics course textbooks

    Hello, I will be attending an undergraduate course called "Theoretical Physics" and I want to borrow some books from the library that cover the material of this course. I would appreciate any suggestions. The syllabus of the course is the following(I will be translating so I am sorry If...
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