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. M

    How can I solve for v(t) when given F=Fo and v(t=0)=0?

    Homework Statement Homework EquationsThe Attempt at a Solution See LaTeX[/B] given that $$v^2 = v_o^2 + \frac{2}{m}\int\limits_{x_o}^x F(x) \ dx\ $$ find the speed v(t) and the position x(t) given that $$F = F_o$$ and $$v(t=0)=0$$. I tried plugging in $$F=F_o$$ for $$F(x)$$ in the above...
  2. J

    Master of theoretical physics in Europe: ETH vs. ENS vs. LMU

    Could you please elaborate on their programmes and/or how they compare against one another ? I seem to be interested in the not-so-much-quantum part of theoretical physics, but any input will be very appreciated. *ETH Zurich *Ecole Normale Superieure *Ludwig Maximilian University
  3. erbilsilik

    Theoretical Particle Physics or Medical Physics?

    Hi everyone! I'm a newbie in this forum. And I need your help for making the right career path for my future. I've been graduated from Physics three months ago and I took some exams (like TOEFL and GRE) for applying master's degrees programs in Turkey. I'm from Kosovo and Kosovo is a developing...
  4. O

    Physics Vs Engineering for different careers?

    I've studied at an engineering course (1st year) for the last year at a decent UK university but due to some family matters, I'm having to move to another university closer to home( and starting from 1st year again). This is one of the London unis which is very highly ranked for electrical...
  5. M

    Confused on what degree to do for theoretical physics phd

    Hi guys :) I am in the uk and will be going to university to study physics and the aim is to go on to do a phd in fundamental theoretical physics either in the uk or in the usa However I am getting confused on what is better to study at undergrad between maths and physics as a lot of the phds...
  6. KylieVegas

    Physics Can an applied physics graduate be a theoretical physicist?

    Hello, can an applied physics graduate be able to be a theoretical physicist? Our school only offers applied physics major in instrumentation but they do send students to do interns/ojt (on the job training) to CERN and various universities all over the world. I know applied physics is more...
  7. chimath35

    Schools What are some good schools for graduate theoretical stats?

    Could you please list and elaborate as much as you can on schools that are heavy on the theoretical side of statistics? Thank you as I have to have my applications in by December-January for grad school (I plan to enter a PhD program and would like guaranteed funding).
  8. E

    MHB Random Graphs: Helping Paula Understand Discrete Math

    I am new to this, and not understanding discrete math very well. This is one of my week 4 discussion questions. If someone could help me apply this to a life situation so I could understand this question better, please? I am a CNC Mill machinist, and I understand programming a computerized...
  9. ClaireBear1596

    Choosing between Theoretical and Applied Physics

    Hi all, I'm going into my third year of university and up until this point I have been studying a little of everything in physics(my degree is a bachelors in Physics), for my third year however we have to select a stream of physics to focus on and I am stuck between Theoretical and Applied...
  10. B

    Calculus Theoretical Multivariable Calculus books

    Dear Physics Forum advisers, Could you recommend books that treat the multivariable calculus from a theoretical aspect (and applications too, if possible)? I have been reading Rudin's PMA and Apostol's Mathematical Analysis, but their treatment of vector calculus is very confusing and not...
  11. J

    Introductory book on theoretical physics

    I'm not necessarily looking for theory of any particular subject but rather a more general approach to how theoretical physics is actually done in practice: -What problem-solving strategies do physicists use? (Most important part for my interests, I'm getting back into math competitions and I...
  12. K

    Foundations Theoretical Books on Mathematics

    What are some rigorous theoretical books on mathematics for each branch of it? I have devised a fantastic list of my own and would like to hear your sentiments too. Elementary Algebra: Gelfand's Algebra Gelfand's Functions & Graphs Burnside's Theory of Equations Euler's Analysis of the...
  13. K

    Algebra What Theoretical Algebra Book Covers Advanced Topics Beyond High School Level?

    What is a good book on algebra that is highly theoretical and covers functions, the binomial theorem, sequences/series (basically all algebra topics in college) and if possible, elementary number theory? Most books on high school-college algebra today don't cover theory at all and when they do...
  14. DDH

    Is there a theoretical min. size/mass limit to a black hole?

    Normally a star with a mass several times that of the sun will become a black hole at the end of the lifetime of that star. Can black holes exist with a mass much smaller than that exist? In other words, are black holes with a mass of Jupiter or even Earth exist? Or even much smaller than that...
  15. Gvido_Anselmi

    How to apply in US to study theoretical physics?

    Hello, everybody. I'm an undergraduate student interested in QFT (especially CFT, String theory, quantum gravity etc). I have already worked through several serious books in QFT and related topics of mathematics (including all problems from books). Of course I don't mean I'm an expert for now...
  16. F

    A theoretical question about forces

    Hello, Imagine the following scenario: a person is lying in bed, straight on the back. A second person passes the bed and accidently hits the edge with it's knee. The created force results in a fast head movement of the person on the bed, towards the direction where the impact was. Is it...
  17. Gvido_Anselmi

    Analytical methods in theoretical physics

    Hi everybody! I'm very interested in the methods of complex analysis in theoretical physics. By these methods I mean such things (tools) as (for example) analytical properties of scattering amplitudes (or S-matrix) in QFT, regge calculus in QCD, analytical continuations of Einstein's equations...
  18. Y

    How to become a theoretical physicist

    Hi , I'm currently a high school student and aiming to be a theoretical physicist but before I go any further I'd like to know what it takes to be a theoretical physicist based on some basic questions revolving around my head all this time.Eventhough I searched for any information pertaining to...
  19. P

    What do TAs and RAs for theoretical physics do?

    do they also work with mathematics or do they do something different
  20. M

    MHB How Does Complexity Theory Enhance Quantum Computation?

    Hey! :o I want to begin with my master thesis and now I have to choose a topic. I am thinking about a topic that is related to theoretical computer science and more specific to Computability or to Complexity Theory. Could you give me some examples of topics that are related to Complexity Theory?
  21. Zeedr

    Is this idea remotely possible in the distant future?

    Hello, I was just brainstorming for futuristic inventions with context for a sci-fi, high fidelity game (because I'm too cool to revise for exams) - and I thought of one, but my physics and engineering knowledge is at best sketchy when it comes to gravity and nuclear fusion combinations, I was...
  22. Joshua McAnaney

    My Theoretical Fusion Reactor- Looking For Feedback

    Ok, so before I begin, I'd like to point out that I'm a 16-year-old GCSE student from the UK. Therefore all of my physics knowledge above high school level is self-taught, so I am by no means an expert. Anyway, I plan on building a deuterium reactor this Summer as a personal project, and I've...
  23. M

    Schools University in England to study theoretical physics

    Hi, I'm from Norway and I'm planning to go to university in England in 2016 to study theoretical physics, but I can't decide which ones to apply for. I have never been to England so I don't know the best places to live, how's studying in London for example? Which schools rank the highest in...
  24. M

    Mandatory (online) courses for theoretical physics

    Hello, I am a master student in physics. I have come to realize that I will probably not work in a highly theoretical field in the future as I do not believe I stand a real chance in this world. However I want to learn as much as I can "on the side". Which set of courses would you recommend to...
  25. C

    Best Undegrad course in theoretical physics

    Hi all, My long term goal is to become a theoretical physicist, General relativity being my field of interest. I am not sure about the university I should choose for my undergraduate course. I am from India, but I want to pursue my undergrad, graduate and PhD from a US or UK university( In case...
  26. D

    Theoretical vs Experimental Physics

    I was watching a sixty symbols video on Stephen Hawking: , and it got me thinking. Is there any practical value for theoretical physicists, if what they are doing is simply speculation not backed by any data? I understand observing a physical phenomena, and from understanding it predicting new...
  27. A

    Photon as a Mathematical Concept in Theoretical Physics

    I always have some interesting on the photon. after I read the oscillator expansion of the electromagnetic field in a finite volume, I find photon is more a mathematical concept in theoretical physics than real particle. not like electrons, number of photon is a representation of the energy...
  28. Adrian Silaghi

    On Becoming a Theoretical Physicist

    Hello everyone.First of all let me introduce myself.My name is Adrian I'm 20 years old I'm a freshmen in college and I live in Romania.My story is kinda short.After I got my Highschool final exam from Physics I started liking it.Now I study Systems Engineering cause it was my only option due to...
  29. D

    Nuclear physics or theoretical physics?

    From which branch of physics like nuclear physics or theoretical physics the PhD will be more beneficial for career?
  30. J

    Burst/Rupture Disk Capacity - Experimental vs. Theoretical

    We have built a cold gas cannon that utilizes burst disks as the means to quickly release the built up pressure with maximum flow. The bore for the burst disk is 2" and the material is Brass 260 H02 (1/2 Hard). The disks are solid and flat (i.e. no scoring or features to promote a certain type...
  31. N

    Programs Should You Pursue a Minor Alongside a Double Major in STEM?

    Hi everyone, I have a question about the intricacies of Majors and Minors. Not sure if the topic/prefix is correct, any mod that thinks it should be under something else please go ahead and change it. But my question is regarding the specifics and impacts of majors and minors. I plan on...
  32. yeshuamo

    Engineering How satisfying is engineering for a theoretical brain?

    After a degree in business and literature and a few years as a science writer in advertising, I'm going back to school for a second bachelor's. My idea is to go into a physics-related field. Ideally, I'd be an astrophysicist. I love physics and plan on graduate school, but knowing how many...
  33. N

    Mathematical Physics vs Theoretical Physics

    Hello PF, pardon me if this isn't the wrong place but I just had a quick question. So I have always wanted to do Theoretical Physics (particular interests are Quantum Gravity, Cosmology, QFT and Quantum Optics, but those are subject to change), but recently I have started to look into...
  34. H

    Is This Theoretical Physics Book Easy to Learn?

    Hello everybody, I have see Theoretical Physics Book from amazon... This contain is easy to learn See the pic : https://www.amazon.com/dp/0486652270/?tag=pfamazon01-20 http://flgopics.science/10/o.png
  35. L

    Physics Is doing top-end theoretical physics hard?

    Hi, I am a enthusiastic student (not yet in University) but am mature for my age so please read on... I am deeply passionate about Theoretical Physics (Practically fell in love with it) but also I am concerned about future, as much as I do want to pursue Physics in University I feel a lot of...
  36. B

    How to perform theoretical vibro transporter analysis?

    I am working on a vibrating section containing serrated plates which transports and aligns longitudinal parts. I have come up with model modification but I have no theory to back it up. How could I perform some vibro analysis, maybe determining frequency, optimum vibration path etc.? Can you...
  37. TheFloppyFIsh

    Time Dilation Effects of Warp Travel | 65 Characters

    I was looking at Time Dialation a bit today and some of the experiments with it. Considering time goes approximately 1/3 as fast as normal, under 100% the speed of light, what would happen if you went past the speed of light with a craft capable of warping. Would it have no effect due to the...
  38. N

    Physics The Future of "Lone Physicists" - Researching Physics Alone?

    Hello everyone, just a quick question: I have heard that it is impossible to do research in physics by yourself anymore. I heard that "The days of Einstein are gone" and that nowadays in physics, especially string and quantum relativity research, everyone publishes in groups. I feel like this is...
  39. S

    What Is the Smallest Integer c for LCM(a, b, c) to Equal L?

    Recently I have faced the following problem. I'm given 3 integers a,b and L where LCM(a,b,c)=L and c is another integer. It is worthy of mentioning that the value of c will be smallest i.e if there are many possible values of c then we have to choose the one which is smallest. I myself solved...
  40. P

    Can I become a theoretical physicist?

    With an undergrad degree in Applied Mathematics and Meteorology (school has no quantum field theory; didn't to study it and its extensive lab classes). And then do a masters degree in Mathematical Physic afterwards do a PhD in Mathematical Physics? Will I then be a theoretical physicist or a...
  41. S

    Calculus Calculus 10th Ed by Salas enough for theoretical physics?

    I am currently reading Calculus Volume 1 by Tom Apostol, I find it very good but hard. I often get stuck and it took me very long time to move from page to page (mostly pages with theorems). I am done reading till half of chapter 2. I just want to know if reading apostol is really a MUST for...
  42. P

    Courses Can a computer illiterate graduate in theoretical physics?

    I have recently taken up mathematics at home and found that it does not pose any problems for my future aspirations in becoming a physicist. However, I am not mechanically inclined and can't use a computer to any sophisticated degree. It's all about abstract thinking for me. I fear mechanical...
  43. S

    Admissions Admission to Europe for PhD in theoretical physics

    I finished my Bachelors in Physics with second class. After that I did my Masters in Physics securing 4 out 6 (G.P.A) in 2011. From 2012 to 2014 I was a Junior Research Fellow at one of the top most theoretical physics groups in India and worked on a project in String Theory. I completed my...
  44. gfd43tg

    Theoretical number of plates for distillation column

    Homework Statement Homework EquationsThe Attempt at a Solution With my solution, I think cold feed means ##q = \infty##, which is seen from my xy diagram. I have some issue understanding the statement "for each mole of feed 0.15 mol of vapor is condensed at the feed plate". I assumed that...
  45. B

    Self-Studying: Theoretical Calculus vs Analysis

    Dear Physics Forum advisers, I am a sophomore in US with double majors in mathematics and microbiology; my current computational/mathematical biology research got my interested in the mathematics, particularly the Analysis and Algebra, and led me to start with calculus II (computational aspect)...
  46. T

    Find angular acceleration using theoretical values

    Homework Statement I'm doing a coursework where I must find the angular acceleration of a rolling tin can using theoretical values. I have its mass and radius. I actually have experimental data so i have access to the actual values of angular velocity and angular acceleration, as well as time...
  47. C

    How to calculate theoretical values for a ride?

    Hi, I've done a prac at school where we had to take an accelerometer onto a ride and obtain a graph in at duration. However, the data I've obtained (Acceleration in X, Y Z and resultant) is experimental data. I need to calculate theoretical data for certain segments of the ride. Assuming that I...
  48. hideelo

    Should I do undergrad experimental research if my goal is theoretical physics?

    I'm currently an undergraduate double majoring in physics and math and hoping to go into theoretical physics. It seems to me that there is very little I can do now in terms of research on theoretical physics, simply because of the knowledge required (please correct me if I'm wrong). I can get...
  49. B

    Can I Pursue Careers in Both Nuclear and Theoretical Physics?

    So I'm in Grade 9 and I have been thinking about careers and I've found myself to most interested in Nuclear and Theoretical Physics. I was wondering if I could do both as a career without dying from exhaustion. Also if I could work it out how many additional years of schooling is it after Grade...
  50. M

    How do people obtain the math for theoretical physics?

    I'm confused about how people learn the required math for theoretical physics. Do they take the math during undergrad or is it taught during grad school or do they just learn it on their own time? The physics undergraduate program here requires calc 1-3, linear algebra, odes, pdes but that's...
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