String Definition and 1000 Threads

So a gluon in string theory may be an open string whose ends live on one or two branes? These strings have an orientation along the string? Does the orientation change direction if we reverse time, some where I thought I read that one can think of a flow along the string so if you reverse...

So I'm having a introductory study on waves and there's something that i can't understand when dealing with reflections on a fixed end. We have the general solution for the wave equation: ## y(x,t)=f(x-vt)+g(x+vt)## Supposing that the fixed point is in the origin we have the boundary condition...

Homework Statement Problem image: https://prnt.sc/gvhjso In this case I have to find the reaction forces at the point E (the Fx, Fy, and the Moment at point E) by using the given data. The 20kN forces at the load AC are concentrated, and are 1.8m far from each other. The tension of the cable is...

[Source] Both these masses are of 1kg each and the scale reads in Newtons. The intuitive answer for the reading of the scale is about 20N because it is being pulled by 10N from each side. However, this is clearly not true as the scale reads about 10N. Why is it so? I believe that I am...

My question is simply 'are all notes produced in a guitar produced by first harmonics?', but I will clarify what made me ask this question. Now, if you have a wave driver you can make several harmonics in a string by increasing the frequency of the machine. In a guitar string, however, it does...

Homework Statement A long, heavy rope hangs straight down from a high balcony on an apartment building. The lower end of the rope hangs about 1.0 m above the ground. If you grab onto the lower end and waggle it back and forth with constant frequency f, a wave travels up the rope. What would...

Hello, I am studing theoretical physics and i would like to focus my work in string theory, but my fellows say that is a waste of time. ¿Do you think that is worthwhile to spend my time and effort un string theory? Greetings

This is what I came up with but I keep getting segmentation fault whenever I run it in linux. Not sure why. Any help would be appreciated. Thanks #include <stdio.h> #include <string.h> #include <stdlib.h> int main(int argc, char** argv) { int i, childpid; for (i = strlen(argv[1]); i >=...

In the following diagram, a frictionless disc is supported by a massless string. This problem was given by the author of a book, and a solution was given to some questions that were asked about this diagram. One thing the author said in one of the solutions, was that the tension in the string...

Homework Statement Problem: ABC is a cable with length 5 m attached to both a and c. By neglecting the dimensions of the pulley, and if the pulley is stationary, Calculate: 1) x 2) Tension[/B] Homework Equations F net = 0[/B] The Attempt at a Solution I have two problems with this...

Homework Statement (Problem #1 on this page.)[/B] Homework Equations ##v=\sqrt { \frac { T }{ \mu } } =\lambda f## The Attempt at a Solution I don't think there is enough information, ##v=\sqrt { \frac { Mg }{ m/L } } ## m, the mass of the string is not given

I get a gist of how electric charge comes about in string theory here, https://physics.stackexchange.com/questions/5665/electric-charge-in-string-theory How much needs to be amended to the above answer to understand how color charge comes about in string theory? I assume there are interesting...

I know two essential points where General Relativity plays a central role in String Theory: i) definition of the theory using a target spacetime with some Riemannian background metric in the Polyakov action and ii) recovery of the Einstein field equations as conditions regarding conformal...

How can I find the potential energy of a string of mass m and length L that has a block of mass M attached to it? The string is uniform, so I know its center of mass is at L/2.

Homework Statement Two positively charged metal spheres are suspended from the same hook by light strings of equal length, making an angle of 10.0◦ with each other. The charges carried by the spheres are as shown in the diagram. After that, the spheres are brought in contact briefly, then...

1. The problem statement, all variables, and given/known data Consider a two-loop standing wave on a string. If we increase the tension without changing the frequency, what kind of standing wave can we obtain? (a) one-loop (b) three-loop Homework Equations Velocity = square root of(T/U)...

Homework Statement A 700g ball rotates around a vertical shaft supported by two strings. If the tension in the upper string is 20.0 N, determine (I have attached the file) a. The tension in the lower string. b. The rotation rate in rpm of the system. Homework Equations [/B] F=ma F= m...

Homework Statement A box slides on a smooth (frictionless) horizontal surface, 1.50 m above the floor, at a speed of 2.00 m/s. The box then slides down a ramp that makes an angle of 36 deg with the horizontal and has a coefficient of kinetic friction equal to 0.430. After reaching the end of...

Hello everbody! I found the following representation: F = 2ρdl(d²l/dt²) F - the maximum stretching force (force at which the string tears); ρ - density; dl - random differential section of the string; t - time. This is some kind of parallel between WAVE and STRING? I cannot find information...

General physical perturbations of string is derived by A.Larsen and V.Frolov (arXiv:hep-th/9303001v1 1March 1993). An arbitrary string configuration is in 4-dimensional gravitational background. Starting point is Polyakov action $$ S = \int d \tau d\sigma \sqrt {-h} h^{AB} G_{AB}$$. Here is...

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!

I just found out about the lectures, are there any interesting or profound ones. https://www.youtube.com/channel/UCFeW8O-DWElfT436yuivT6g/videos

First, sorry if there's grammar mistakes,english is not my native language. 1. Homework Statement Find the normal modes of a string of length L with a massles ring ,free to move on the y-axis ,attached to each end. Homework Equations General wave solution: u(x,t)=A·e(kx-wt)i+B·e(-kx-wt)i...

Homework Statement A string prq which is fixed at p and where q is vertically below p. r is a smooth ring threaded on the string which is made to rotate at an angular velocity ω rad/s in a horizontal circle centre q, the string being taut. If |pq| = 0.12 m, |pr| + |rq| = 0.18 m, show that...

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...

On page 5 of the notes (https://arxiv.org/abs/1501.00007) by Veronika Hubeny on The AdS/CFT correspondence, we find the following: Nevertheless, already at this level we encounter several intriguing surprises. Since strings are extended objects, some spacetimes which are singular in general...

Hello All, I was performing an experiment in which the perod of oscllation of a pendulun at different lengths is measured using a light gate. while performing the experiment i noticed that the string was slightly elastic, differing from the perfect pendulum. I was attempting to figure...

Speed of a wave in a string is given by √(τ/μ) . But this speed is with respect to which reference frame? Since, the speed depends on τ and μ( which are independent of reference frame ), I can consider speed of wave independent of reference frame. But this is not so. From experiment, we know...

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...

Homework Statement This is a common massless string and pulleys problem. I'd just like to understand why, according to the solution, l_2 + 2l_1 = constant. It doesn't seem to me that two times the l_1 length is equivalent to l_2. Can somebody explain? Homework EquationsThe Attempt at a Solution

The blue and red lines represent a very stiff string The blue section is plucked and oscillates. The vibration energy is carried through to the red section. This is what I don't understand. A) Is the red section a forced oscillation at the resonant frequency of the blue section? B) Will the...

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?

Homework Statement There's two blocks of mass m_{A} and m_{B} which are linked by an ideal string. The block of mass A descends at constant speed. There's no friction. If the pulley is ideal, which one of the following is true[/B] Homework Equations Newton laws and trigonometry I...

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.

I have the following program that moves a wave on a string with fixed ends. The program solves the wave equation given a initial condition wave. The initial condition is a triangle wave splitting into two pulses. Here is the code written in Python: from numpy import * from matplotlib.pyplot...

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...

When we pluck a string and a triangle is formed. Why does this triangle form into two opposite moving pulses? If we have reflective edges the two pulses will reflect, invert and superposition into the same triangle wave on the under side of the string. Let's say we have no dampening. I think...

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...

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...

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...

A box suspended by a rope is pulled to one side by a horizontal force. The tension in the rope increases! Why is it so?

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...

Homework Statement In our physics course, we were studying one dimensional waves in a string. There, our teacher stated that the kinetic energy in a small piece of a string is dK=\frac{1}{2}μdx\frac{\partial y}{\partial t}^2 were μ is the linear density of the string, so he claimed that...

Homework Statement The A string on a violin has a fundamental frequency of 440Hz. The length of the vibrating portion is 32.4cm and has a mass of 0.340g. Under what tension must the string be placed? Homework Equations V = Fλ Vs = √t/μ The Attempt at a Solution I plugged in my info to...

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)...

Homework Statement I'm going through the derivation here starting on page 16. This image adds some context: . Generalizing their result to the i'th particle they find the extended distance between two masses being ##\Delta l= \frac{(y_i-y_{i-1})^2}{2a}## Then since the potential energy is...

Homework Statement (I have dropped the hats on the ##\alpha_{n}^{u}## operators and ##L_{m}##) ##[\alpha_{n}^u, \alpha_m^v]=n\delta_{n+m}\eta^{uv}## ##L_m=\frac{1}{2}\sum\limits_{n=-\infty}^{\infty} : \alpha_{m-n}^u\alpha_{n}^v: \eta_{uv}-\delta_{m,0}## where : denotes normal-ordered. Show...

Homework Statement A 1.5 kg ball is tied to a string that is .75 m long and whirled in a verticle circle. A) Find the tension in the string at the top of the circle B) Find the tension in the string at the bottom of the circle Homework Equations Fc=mac ac= v2/r The Attempt at a Solution A)...

Homework Statement I'm having trouble understanding an example given in K&K's Intro to Mechanics textbook. 'A string with tension ##T## is deflected through an angle ##\theta_0## by a smooth fixed pulley. What is the force on the pulley'. I don't understand how (in the first picture) they...