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.
If there is a "theory of everything", a single equation that basically explains everything, why should be study Astrophysics, Condensed matter, or so?
I mean we should rather study String Theory, Quantum Gravity... So, am I wrong? Maybe I'm leaving some important details.
Homework Statement
I am reading Dummit and Foote, Chapter 13 - Field Theory.
I am currently studying Section 13.1 : Basic Theory of Field Extensions
I need some help with an aspect of Exercise 1 ... ...
Exercise 1 reads as follows:
Homework Equations
Relevant theorems for this exercise...
I am reading Dummit and Foote, Chapter 13 - Field Theory.
I am currently studying Section 13.1 : Basic Theory of Field Extensions
I need some help with an aspect of Exercise 1 of Section 13.1 ... ...
Exercise 1 reads as follows:
My attempt at a solution is as follows:p(x) = x^3 + 9x + 6 is...
Hi!
I'm struggling with these two problems:
1. If for whichever two vertices a and b in the graph G there is only one simple path from a to b, then the graph is a tree.
Eh... isn't this part of the definition for a tree? I really don't even know where to start with proving this statements...
in string theory, where strings are posited as fundamental entities, what is the relation between eletrons muons tau
how does string theory explain the increasing masses of leptons
how do these leptons other properties come about in string theory
what about the antiparticles of each? i.e...
This is no homework for me.
I am working as a teaching assistant in a lecture about logic and discrete structures for Informatics students. This should be a piece of cake, but I am not exactly sure of the logic behind.
1. Homework Statement
Translate into words
∃c . ∀a ∈ A . ∀b ∈ B . ¬(a =...
Homework Statement
I am solving a question that asks for, what's the minimum coefficient of friction required for a cylinder to roll without slipping? Where the cylinder has a force F acting on its center.
Homework Equations
And
The Attempt at a Solution
From the way I understand it, the...
For chemical experiments that involve gases as reactant and products, gas tube are used for their transport.
Q1. Why are there differences in length of gas tube when in a round flask. In most case, entering tubes are longer than exiting tubes? Why is that?
Q2. Why is sometimes the entering...
From time to time, I point to string theoretists that they should have considered more seriously to use Kaluza-Klein theory and they invariably answer me "we do", and move forward. So I am starting to thing that perhaps I am wrong and I have missed some developing of the theory the the XXIth...
1-Whats the relationship between entropy and İnformation ?
2-Can Entrophy always increases statement imply information lost ?
3-If it implies how its lost ?
Over the last couple of years there has been allot of traffic on youtube about the sum of all positive integers being equal to -1/12 as is explained in numberphile video. Some argue that their calculations are wrong and the sum really is infinity. In their original video numberphile shows a...
Hello friends.
I'm trying to compute an EoS to walecka model of barion interaction, but I'm having trouble to solve this equation by bisection.
M*=M-gs²*nb/ms²
where nb= (M*)*( kf*Ef- (M*)²* ln (kf+Ef)/M*) , using Ef= sqrt( kf²+(M*)²)
and Cs²= gs² M² / ms² = 267.1
I'm using J. D. Walecka...
Horgan: Do you still think string theory is “not even wrong”?
Woit: Yes. My book on the subject was written in 2003-4 and I think that its point of view about string theory has been vindicated by what has happened since then. Experimental results from the Large Hadron Collider show no evidence...
I'm fairly new to QFT and I'm currently trying to understand perturbation theory on this context.
As I understand it, when one does a perturbative expansion of the S-matrix and subsequently calculates the transition amplitude between two asymptotic states, each order in the perturbative...
Hello,
I am new to this.
As I understand it, the difference between the quantum field theory and string theory is that in the former, physical field is considered as the fundamental reality, while in the latter it is believed that everything comes out of strings. My question is, by everything do...
There seems to be a lot of conflicting research on nuclear winter theory, especially since the 1990s. Carl Sagan famously predicted that the Kuwaiti oil well fires from Operation Desert Storm would result in a small global winter, but the effects turned out to be more localized and less severe...
Hello! I read some stuff about "attempts" to test some aspects of string theory at LHC and I was wondering if there is any deep reason behind the conservation of energy in general or it is just based on the fact that it holds in all the experiments (excluding uncertainty principle arguments)...
This question is directed to all the professors who have supervised PhD students in high energy theoretical physics.
What attributes have you noticed (during your years as a supervisor) among PhD students who later went on to have great careers in high energy theoretical physics and made a name...
Homework Statement
STATEMENT
##\hat{H}=\int \frac{d^3k}{(2\pi)^2}w_k(\hat{a^+(k)}\hat{a(k)} + \hat{b^{+}(k)}\hat{b(k)})##
where ##w_k=\sqrt{{k}.{k}+m^2}##
The only non vanishing commutation relations of the creation and annihilation operators are:
## [\alpha(k),\alpha^{+}(p)] =(2\pi)^3...
Hi everyone,
So I recently read a chapter in a math book that vaguely describe how connections on bundles occur in particle physics, but they are very cryptic about the physics part and I just want to know a little bit more about it. So I'll tell you what I read and then follow up with some...
Homework Statement
hello, I have this graph and i have to figure out these so to speak characteristics.
1) find incidence matrix
2) arrange peak according to rank and layers
3)draw new arranged graph
4) find new connection matricies of peaks and arcs
Homework EquationsThe Attempt at a...
so this is the question:
let a and b be real numbers such that 0<a<b. Suppose that a3 = 3a -1 and b3 = 3b -1. Find the value of b2 -a.
initially my line of thinking was that just solve the equation x3 - 3x +1 = 0
and take the roots which are more than 0 and then after that i got stuck
ok that...
Firstly an apology...I don't know what level my question should be aimed at and what forum it should be set in and I think that level A and Quantum Physics are as good as guesses as any. Moderator please moderate if necessary.
It's about constructor theory, something that I wouldn't normally...
Let us consider a classical field theory with gauge fields ##A_{\mu}^{a}## and a scalar ##\phi^{a}## such that the Lagrangian is gauge-invariant under the transformation of
1. the gauge fields ##A_{\mu}^{a}## in the adjoint representation, with dimension ##D_{\bf R}##, of the gauge group...
Hi all,
I am struggling the question, please see attachments.
Thanks a lot
Devise an algorithm which, given a (directed) friendship graph (in the xkcd format), finds the optimal seating arrangement. Your algorithm should include the following:
a description of the required input format...
Homework Statement
I have an exercise that I do not know how to solve. ##N## is a nucleon field, in the fundamental representation of ##SU(4)##. We want to classify operators by their ##SU(4)## transformation properties, bearing in mind that the nucleon is a fermion and we need antisymmetric...
Hello! I read several books and took courses on quantum mechanics and particle physics and I understood the topics. However I feel that I have only pieces of informations without a global image of what is going on. For example in the particle physics classes we were given Feynman rules without...
Hello people,
I'm really interested in non-mainstream physics but so far i can't find a place./forum where i can discuss or share theories. I've tried doing it in the Quantum Physics section, but my thread was rejected because personal theory developments are not allowed here. So far it's ok...
Homework Statement
The problem consists of 2 parts,the first one(I have done it) is on the following website:
https://www.physicsforums.com/threads/transition-probability-from-two-states.804343/
Q1: I calculated the desired result p(t) = sin^2(Ut/h). However,I don't understand why <1,t | 2 >...
What happened to the membrane bound organelles that were present in the eukaryote that gulped the primary endosymbiont (that is, the eukaryote that gulped a prokaryote), after the secondary endosymbiosis.
The textbook proves that ##x^a x^b = x^{a+b}## by an induction argument on b. However, is an induction argument really necessary here? Can't we just look at the LHS and note that there are a ##a## x's multiplied by ##b## x's, so there must be ##a+b## x's?
In classical field theory, translational (in space and time) symmetry leads the derivation of the energy-momentum tensor using Noether's theorem.
From this it is possible to derive four conserved charges. The first turns out to be the Hamiltonian, and thus we have energy conservation.
The...
I have been attempting to unravel Abbe’s theory, of the role of diffraction in microscopic vision, in a ‘nuts and bolts’ sort of way, meaning in terms that I can understand: diffraction, interference and so on. While Fourier transforms are clearly at the heart of the process the assertion that...
Instead of the 10,11, and 26 dimensions proposed by various theories, could there be, let's say 10 positive dimensions, existing of 9 of space and one of time, but also 1 negative dimension? This is just a random theory. I have no idea what a negative dimension would hold, but I think it would...
Good afternoon people; recently I decided to give a study break from control engineering; now I'm back. I'm studying again control theory and I see some good results. By the way I got stuck in a topic called root locus method. Now my issue is not about how to sketch the root loci graph (BTW I...
Lightcone gauge is ##X^u=\tau=1/\sqrt{2}(X^0+X^{D-1})## (1)
The mode expansions are:
My book says 'it is possible to solve for one of the oscillators in terms of all the others' with this relation.
What is a oscillator? Is this any of the ##X^{D}## coordinates, what exactly does ##n##...
In mechanical engineering we have various courses in strenght of materials, and I've noticed that graduate students learn the Theory of Elasticity. I've researched a little bit about it, and I know that the Theory of Elasticity is more general than strenght of materials. But I have some doubts...
The question is about to derive an approximate expression by regular solution theory, It is difficult for me to find relevant source on this question. However, the question to me is so vague that I do not know how to answer.
What I have tried is to search what the interaction parameter is...
So I did this lab on momentum on jets and the theory is that "a force is applied on the plate due to change of momentum" the jet both impacted on a flat plate and on a hemispherical plate; now i understand that the greater the angle of deflection of the water jet, the greater the change of...
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...
Homework Statement
Hi,
In some of the diode analysis examples that we did in class, we often end up with circuits like the ones shown here. I'm quite confused because sometimes I understand them and other times I just don't know how these voltages are coming from. It really makes me question...
Homework Statement
[/B]
Use Max Planck's quantum theory to explain the following behavior of photoelectrons.
i) Low-intensity light does not release any photoelectrons. What will happen if the light is made brighter? Explain your reasoning.
ii) Low-intensity light releases photoelectrons...
I have an acquaintance who maintains that in quantum field theory, primarily the cgs system is used. OK, I know it's not really important, but I was under the impression that everyone had switched to SI. (My book on quantum field theory has very few actual quantities with units outside of GeV...
I am looking for an accessible textbook in group theory. The idea here is to use it to learn basic group theory in order to take up Galois Theory.
My background includes Calculus I-IV, P/Differential Equations, Discrete Mathematics including some graph theory, Linear algebra, and am currently...