String Definition and 1000 Threads

1. Imagine two columns between which is hung a string. The hung string may be expressed graphically and mathematically as a parabola whose nature is exponential. If these columns are moved closer together or farther apart, the hung string becomes more loose or taut according to a trigonometric...

I'm watching a lecture by Edward Witten here: In it, he mentions that String/M-theory seems to be hinting toward a new kind of geometry where you don't talk about space/time points, but the interactions between quantum world sheets (around 37:00 minute mark.) Does this new geometry have...

Hello! (Wave) We are given $2$ strings $A=[1 \dots m]$ and $B[1 \dots n]$ and the following $3$ operations are allowed: Insert a charachter,with cost $c_i$ Delete a character,with cost $c_d$ Replace a character,with cost $c_r$ We are looking for the optimal sequence of...

Hi, I've been looking for a string theory review for a beginner graduate student. However, there is a vast number of reviews so it's easy to get lost. Does anyone know about a review article or any kind of material to begin with String Theory? Thanks.

Hello, Can anybody please explain me how magnetic monopoles, fine structure constant and string theory are related to each other? Thanks

Homework Statement Hi all! I was wondering what the tension is in the string of a pendulum, because I think sparknotes is wrong on this. Sparknotes says that: "Choose a coordinate system: We want to calculate the forces acting on the pendulum at any given point in its trajectory. It will...

Homework Statement An object with a mass of m = 4.80 kg is attached to the end of a string wrapped around a reel of radius R = 0.230 m and mass M = 3.00 kg. The reel is a solid disc. The suspended object is released from rest 1.90 m above the floor. http://imgur.com/ElfqPSX a) Determine the...

I have recently visited CERN, and in the Globe they showed an equation from string theory. My knowledge about it goes only as far as 'The elegant universe', so no mathematics, but i would say that the sketch beneath is about the string coupling constant. Could anyone please explain the...

Homework Statement Write a function called reverse that uses recursion to reverse any one-dimensional string array.Homework Equations The Attempt at a Solution function out = reverse(str) if length(str) == 0 out = str; else out = [str(end) reverse(str(1:end-1))]; end I am having...

Homework Statement A guitr player changes the frequncy of the note produced by a guitar string by pressing his fingers along the string. The fundamental frequency of the string is 264hz. What are the frquncies of the fundamental note if the player plucked the string at 1/4 of the way from one...

Hey guys, I would really appreciate some help for this question I'm stuck on at the moment: "A piece of 2 m long wire is to be cut into two pieces one of which is to be formed into a circle and the other into an equilateral triangle. How should the wire be cut so that the total area enclosed...

Homework Statement can someone teach me on this question? i really don't know how to start with it. the ans is 0.38m and 4.1N Homework Equations The Attempt at a Solution the working is in the second photo

I've heard that the strings in String theory are vacuums, is that right? And if so then how is it expected they form?

Just as particles move through the theoretical Higgs field and gain energy which gives them mass, do the strings in String theory get their energy to vibrate from the Higgs Field as well? And does that mean that the Strings have mass?

Homework Statement The figure below shows a snapshot of a standing wave on a composite string. It is a node in the composite point. If the aluminium string has a diameter of 1.50 mm, which diameter does the steel string have ...

We have had a heated debate at work and I feel we need to bring in a few outsiders into help clear things up. A co-worker of mine believes that if you had a string of bucky balls (small spherical neodymium magnets) held by only the top ball in the chain and allowed to hang such that you could...

Definition/Summary Take the case of a string with it's one end [which will refer to as the 'fixed end'] tied to a wall. The other end [which we will refer to as the 'free end'] is held by you. It is a common experience that if we move that free end, a 'bump' travels along the string. And if...

Hi all! I am currently conducting an investigation into the way in which frequency varies when you change the tension on a guitar string. I am aware of Mersenne's laws, and that frequency should vary in square root proportion to tension. I'm looking for an explanation that goes beyond simply...

Homework Statement Let S bet the set of all string's of 0's and 1's. define D: S --> Z as follows : for all s in S, D(s) = the numbers of 1's in s minus the number of 0's in s. a) Is D 1-1? Prove or give counterexample b) Is D onto? Prove or give counter example Homework Equations...

Homework Statement Hey everyone, I have a question regarding file IO in java. My assignment says: Extend program 2-add menu items Open(reads employees from a file),Save(writes employees to a file already specified), and Save As(writes employees to a new or different file than the one...

Question: Two pulleys of masses 12 kg and 8 kg are connected by a fine string hanging over a fixed pulley as shown. Over the 8 kg pulley is hung a fine string with masses 4 kg and M. Over the 12 kg pulley is hung another fine string with masses 3 kg and 6 kg. Calculate M so that the string over...

Homework Statement A uniform chain of length L hangs from an elastic string of natural length L. The upper end of the string is connected with the ceiling .When the system is in equilibrium , the string stretches by an amount L .At what distance from the lower end of the chain ,the chain...

Hi, if you remember back a decade ago we had a discussion on solutions to the first edition of Zwiebach's undergraduate textbook in string theory. (I have a copy of the solutions in my computer). Does someone have solutions to the updated second edition of the textbook? I tried looking for...

Can string theory explain dark matter and dark energy?

Homework Statement my question is on part b Homework Equations The Attempt at a Solution the period will be shorter due to smaller mass of oscillating system... but the amplitude is greater( ans from my book , in my opinion, the amplitude should be smaller because the string is...

Homework Statement the answer is a for this question. but i don't understand how to get the solution. Homework Equations The Attempt at a Solution mg-k(l-a+b)=ma since mg=k(l-a) -kb=ma a=-(k/m)b k/m=a/b so my ans is sqrt root( a/b)

Homework Statement The length of a stretched string is 1m. Its mass per length is 2x10-3kg/m. The string resonates at its 4th harmonic at 400Hz. (a) Calculate the velocity of the string wave. (b) Calculate the string tension. Homework Equations fn = nv / 2L v² = F / μ The...

Homework Statement A mass of 3.50 kg is suspended from a 1.59 m long string. It revolves in a horizontal circle as shown in the figure. The tangential speed of the mass is 2.99 m/s. Calculate the angle between the string and the vertical. Homework Equations a_c = v^2/r F = m*a_c...

What are you thoughts about Laura Mersini Haughton´s theory of the multiverse? She predicted a CMB cold spot, power suppression at low multipoles, preferred direction associated with the quadrupole octupole alignment, dark flow, and the deviation of the CMB amplitude. While dark flow remains...

I have been given a project in my ap physics class where I am to explain how Bose-Fermi equivalence, tachyon, dilaton, green-schwarz anomaly cancellation and kahler manifolds relate with string theory. After an hour of research, I realized that I could not find even the slightest information on...

Homework Statement A light string is wrapped around a solid cylinder and a 300g mass hangs from the free end of the string. when released, the mass falls a distance of 54cm in 3.0s. a) Calculate the tension in the string. b) Calculate the mass of the cylinder. Homework Equations...

Hello, Is string theory or M theory wrong ? Isn't it the theory of everything ? Should we continue our research to reach the true theory of everything ? If so, why physicists still research on string theory ?!

through the string? I'm at a point in a program I'm making where I have a string representation of a valid decimal representation of a double. By "valid representation" I mean that it contains only characters in the set {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.'} with no more...

Homework Statement a 4-kg block is attached to a string 2 m in length rotates on a horizontal surface. (a) If the co-efficient of friction between the block and the surface is .25, find the work done by the force of friction in each revolution of the block. Homework Equations Wnc=...

I am looking for literature on a certain topic in mathematics inspired by string theory of which I have heard bits and pieces. Since I am not at all familiar with string theory and haven't found anything online, I was hoping someone more knowledgeable might recognize some of the keywords I...

Are there any solutions (ways to avoid/get rid of) to the string theory landscape besides the anthropic principle and comological natural selection?

a wave pulse on a string has the dimension shown in figure (see attachment) the wave speed is v=1 cm/s. point o is a free end, the shape of wave at time t=3s is? someone please explain why would the answer to this question differernt if the point O was a fixed end? how does it make a difference...

Anything that exists has to exist/interact with at least 4 dimensions, right? Stuff existing/interacting with other dimensions too (even if they can't be/haven't been observed) have to exist/interact with our 4D as well, right?

Homework Statement See attachment (stuck with part b at the moment)Homework Equations The Attempt at a Solution \phi=D(x)T(t) so (1+bx)D''(x)T(t)-D(x)T''(t)=0 (1+bx)\frac{D''(x)}{D(x)}=\frac{T''(t)}{T(t)} let \frac{T''}{T}=\sigma (1) use trial solution T=be^{rt} subbing into (1) and solve...

Hello. I'm learning about high power LED's. I would like to design a high power LED driver for a DIY project I'm working on. I'm planning on using an LED driver to provide constant current and have dimming control through PWM. I'm going to be using 3W high power LED's in a series configuration...

Hello everybody. I have a BSc in physics, I tried hardly recent two years to get high scores in GRE/TOEFL exams to get accepted in U.S. and continue my education in physics,however, I rejected badly. First I thought by myself to leave physics, I gambled whole my future for physics and now I'm...

How does where you pluck a guitar string affect the pitch of the note? Does it or does it not? Can you explain this in terms of harmonics? Does where you pluck it simply change the harmonic content and not the frequency? Thanks. Also how is resonance and standing waves on a string and...

Homework Statement A light elastic string on a smooth horizontal table has one of its ends fastened. The other end is attached to a particle of mass m. The string of force constant ##k## is stretched to twice its natural length of ##l_0## and the particle is projected along the table at right...

Homework Statement Uniform rod AB with end B resting against rough vertical wall. Coefficient of friction between wall and rod is μ. Rod is 2m long and has mass 3kg. Rod is kept in limiting equilibrium by a light inextensible string, one end of which is attached to the end A of the rod and...

Homework Statement A yo-yo of mass M is composed of two disks of radius R separated by a shaft of radius r. A massless string is would on the shaft, and the loose end is held in the hand. Upon release the yo-yo descends until the string is unwound. The string the begins to rewind, and the...

I am trying to understand the connection between eternal inflation and the the string theory landscape of 10^520 possible universes Where is the original scientific article that proposed so many false vacua solutions If anyone can point me to the underlying equation and article that...

Hi, if I have a mass on a string and I swing it around my head at a constant speed, what is the resultant force on the mass (I'm looking for a qualitative rather than quantitive answer)? My inital thoughts were towards the centre of rotation, due to the tension on the string (and since the...

Homework Statement The displacement, y(x; t), of a tight string of length, L, satisfies the conditions y(0, t) = \frac{\delta y}{\delta x}(L,t) = 0 The wave velocity in the string is v. a) Explain what is meant by a normal mode. Give the form of the displacement, y(x; t), for the normal...

If dark energy is caused by quantum fluctuations, where does this energy come from? Also according to string theory mass is determined by the sum of a string's positive, vibrational energy and its negative energy from quantum fluctuations. Could it be possible to create a particle with negative...

When do these two fields of physics overlap other than when we discuss entropy of supersymmetric black holes? Does statistical mechanics or statistical physics support any aspect in string theory or vice verse? I have read some place that the string theory reduces to the standard model by doing...