Theory Definition and 1000 Threads

Hello ! I have just graduated from high school but I have a big interest in the strings theory. I am trying to understand its roots aka from where/ how did it come! To that I Need some references for my research, references to make me understand the bases only ! Thank you!

Hi I was hoping someone could advise me on a textbook/platform where I can learn more about the perturbation theory applied to helium and the perturbation theory time depedant. Thanks

Hey everyone ! I am trying to learn how to mathematically prove that a steel tube (with wall thickness of ~ 1mm and external diameter of ~ 15 mm) will have ... At any point along its length, the shaft must : 1) bend in such a way that the deflection is the same regardless of how the shaft is...

Hi , everyone! This is my first post/thread/anything on this forum so first I apologise if I slip up or make any mistakes. Anyway, my question is about recommendations for textbooks for Undergraduate Number Theory. So far, I have studied Calculus 1-3 (including things like line integrals...

ShayanJ submitted a new PF Insights post Entanglement Entropy – Part 2: Quantum Field Theory Continue reading the Original PF Insights Post.

If I place an insulated container of gas on the edge of a turntable and then rotate the container as a constant angular velocity, what happens to the gas? Does the temperature of the gas increase? If so, how was work done on the gas?

Hello everyone. Iam working on a course in multivariable control theory and I stumbled over the Identity Matrix. I understand what the identity matrix is, though the use of it is a mistery... I was reading about going from state space to transfer functions and I found this expressions...

I want to study Electromagnetic theory from Zero.Although i have basic knowledge of electrostatics and magnets but i do not feel confident about EM theory.I am undergraduate with Instrumentation and Control Engineering.I am preparing for National level exam in which question related to Emt...

I am reading Dummit and Foote, Chapter 14 - Galois Theory. I am currently studying Section 14.2 : The Fundamental Theorem of Galois Theory ... ... I need some help with Corollary 10 of Section 14.2 ... ... and the definition of $$\text{Aut}(K/F)$$ ... ... Corollary 10 reads as follows...

I am reading Dummit and Foote, Chapter 14 - Galois Theory. I am currently studying Section 14.2 : The Fundamental Theorem of Galois Theory ... ... I need some help with Corollary 10 of Section 14.2 ... ... and the definition of ##\text{Aut}(K/F)## ... ... Corollary 10 reads as follows: Now...

I need recommendations on literature to read. Basically i do not understand these section of Frank Harary's book on graph theory since the definition of what a boundary and a cycle vector is not clearly defined. I have googled literature on it but I am having a tough time finding the right...

I am reading "Abstract Algebra: Structures and Applications" by Stephen Lovett ... I am currently focused on Chapter 8: Galois Theory, Section 1: Automorphisms of Field Extensions ... ... I need help with Proposition 11.1.11 on page 560 ... ...Proposition 11.1.11 reads as follows...

I am reading "Abstract Algebra: Structures and Applications" by Stephen Lovett ... I am currently focused on Chapter 8: Galois Theory, Section 1: Automorphisms of Field Extensions ... ... I need help with Proposition 11.1.11 on page 560 ... ...Proposition 11.1.11 reads as follows: In the...

Hey, My question isn't exactly a problem,it's just a doubt which occurred in my mind,while studying current electricity.The potential difference across the emf of an ideal battery is considered to be constant,whereas if the battery has an internal resistance (the case for all real life...

I am reading "Abstract Algebra: Structures and Applications" by Stephen Lovett ... I am currently focused on Chapter 8: Galois Theory, Section 1: Automorphisms of Field Extensions ... ... I need help with Example 11.1.10 on page 560 ... ...Example 11.1.10 reads as follows: My questions...

Magnetic braking is a theory explains the loss of stellar angular momentum and is used extensively to describe the given rotation stars. However, on a smaller and more directly observable level, when we consider Jupiter's rapid rotation rate of less than ten hours and its accompanying powerful...

Hi All This is in relation to the folllowing paper: https://arxiv.org/pdf/1402.6562.pdf See section 3 on examples where standard probability theory is discussed. Is it valid? To me its rather obvious but I had had a retired professor of probability say probability theory doesn't have a state...

Is there a guide, based on existing evidence, that I could use to infer realistically how color would be affected on alien worlds due to factors like star class, luminosity, atmospheric composition, etc? I'm planning to develop a not-too-too-distant future scenario where all the stars in...

Double field theory [1] is an attempt to realize T-duality of string theory at the level of field theory. For instance, if a field in ordinary field theory lives in 4 non-compact spacetime dimensions, then a field in double field theory lives in 8 non-compact spacetime dimensions. I don't...

Hi all, Clarification question: I've read that string theory is manifestly Lorentz invariant - however, I'm confused about this being true in 4D spacetime or in the full 10D setting of the theory (well, one version anyway). At some point I'd also read in a paper that 4D Lorentz invariance...

just below eqn 3.25, it is said: At any given time, Ex is constant for all values of x, but of course, this possibility cannot therefore correspond to a traveling wave advancing in the positive x-direction. Why can't Ex be a constant?

I'm sure you are familiar with Le Sages physics and how it predicts gravitational drag. But what if no velocity vector matters except the direct line between the two gravitational objects? Does this fix Le Sages theory?

Hey guys I figured out something new about color theory in additive color mixing. So, the primary colors in additive color mixing are R, G, and B (Red, Green, and Blue). The secondary colors are C, M, Y (Cyan, Magenta, Yellow). Using basic knowledge we know that R + G = Y R + B = M G + B = C...

I just want to verify from physicists whether what I have read in this article is true: http://www.astro.ucla.edu/~wright/infpoint.html It says: The Universe was not concentrated into a point at the time of the Big Bang. But the observable Universe was concentrated into a point

I know that mie theory is used to analyze the absorption/scattering/extinction of a homogeneous sphere within a homogeneous dielectric medium. However, if I wanted to perform the same analysis on a sphere enclosed by two different media, is there an analytic solution to this?

So I've been reading David Bohm's original paper on the alternative interpretation of quantum mechanics in terms of hidden variables, just out of interest. In the 4th section he presents a complex function ψ in terms of R and S, and then (using the time dependent schrodinger equation, TISE)...

Homework Statement this problem came out in the math olympiad i took today and i got completely wrecked by this consider the following equation where m and n are positive integers: 3m + 3n - 8m - 4n! = 680 determine the sum all possible values of m: Homework Equations not sure which The...

Where is the electron-nucleon interaction? On the surface of the nucleus, or at the origin (R-0) ?

I am a cosmologist/theoretical astrophysicist, and so far my research (all 2 years of it) has focused on quantum cosmology. However, I have become interested in string cosmology recently, and wish to do some work in that field. Obviously though, there is a minor problem with that idea. Learning...

Hi , in the classical course " nuclear reactor theory we treated neutrons as particles. can we treat neutrons as waves when it comes to diffusion or transport equation ? neutrons flux/ cross-sections ? I googled it and I didn't find enough info. Like there a lot of common terms between quantum...

Homework Statement [/B] 1) Is the order paramter ##\phi(x)## intensive or extensive? 2) Is ##M## intensive or extensive? With the following definitions : Homework Equations The Attempt at a Solution 1) Free energy is extensive, however I don' think I can use this to deduce whether...

In string theory, particles is vibrating strings. However, QFT treats particles as excitations in a quantum field. Can both of these theories be correct? If so, how does them fit together?

I have known: (1) A Hamiltonian, say, H(k), where k is the crystal momentum. (2) An appropriate complete basis set {a_1,a_2,a_3…}. (3) Some symmetric operators {A,B,…} which commute with H(k), i.e. [A,H]=[B,H]=...=0. Of course, by calculation, I can get any matrix element of H(k), i.e...

How do I show that the payoff function πi isn´t continuous? Why do best replies not always exist?

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.

I'm looking for a recommendation for an up to date, introductory String Theory text and an overview of the prerequisites. Thanks in advance.

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 +...

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...

Hi, i would be curious to know what would be the prerequisites for learning the classical field theory !