Strings Definition and 548 Threads

How small are those strings anyway ? Brian Green says in his book that they are a lot smaller than the particules we are used to deal with so, I mean, Is a quark the expression of one string or many, how many "actual" strings in a electron, a gluons etc ? Or is my conception ( yet again ! )...

Hello, I'm new here. Basically I have this practice excercise for my exam.: http://capa.hep.uprm.edu/msuphysicslib/Graphics/Gtype06/prob09_xph183f6pic2.gif My general problem is that I'm bad with separating forces into components, and I assume this excercise deals with that. Can...

Strings or LQG and why? Hi, I am currently studying LQG and i would like to have an idea on how opinions are devided between String Theory and LQG. I would like to use the outcome of this poll as a reference to the introductory text i am writing on LQG. View the Loop Quantum Gravity-thread...

I've sometimes heard that there are string theory results that are quite similar to some of non-commutative qft. What are these?

I was wondering if knotted topological strings can be asigned definite quantum charges apart from mass and angular mumentum. That would really be useful to glueball people who try to find candidate in the hadronic spectrum : they use only mass and angular momentum. If they had a mean to assign...

If I have heard correctly, models of the early universe predict the existence of macroscopic strings brought about by the enormous initial expansion of the universe. A way of proving string theory correct - among others - would be observing such macroscopic strings. My question lies with how one...

I just read the old thread on "What are strings made of?" https://www.physicsforums.com/archive/t-8995 and one member states that energy is just a property of the fundamental building block (string) just like momentum is a property of it. I wondered if that is the consensus, because I have...

To everyone, Being new to string theory (m-theory) this theory is not completely clear to me. I'd be like if some one please help me in understanding it. Thanks Aekansh

In laymans terms, what characteristic of a string do scientists use to determine the string's mass, spin, and charge? Are the three known families of particles at all analagous to musical octives? Can a given string simlutaneously have two different frequencies which are perpendicular to...

I play the violin, and I recently figured out that if I very gently touch my finger on a string, it produces a higher integer multiple of the frequency if I were to hold my finger down all the way. How does this happen?

Hey smart people! :smile: I want to learn string theory. First things first: My background is in medium energy theory (as in the kind of physics that is investigated at Thomas Jefferson National Accelerator Facility and at Brookhaven National Laboratory). As for my formal education...

String theory needs the graviton. But guess what. They would have to freely admit to gravity waves having not be proven, yet theorectially they have moved past this with the gravitons introduction. It would seem premature,:) yet this is the way of it that the mathematics have gone down this...

Assuming that string theory does not rule out point-like particles such as quarks, how can a group of one-dimensional objects be seen as having no dimensions at all?

how do strings exist in our reality? Let's just say, for the purposes of this argument, that a string was broken and stretched until it was perfectly straight (i understand this could never actually happen). That filament, then. Would it exist in one, two, or three dimensions?

Alright I swear that I read in scientific american that Loop Quantum Gravity is trying to put fouth a new toe to compete with string theory. However in discussion with Marcus he told me that they are not trying to have any sort of theory that would lead to toe. Part 2 I was reading in Pop...

Strings and Branes, a Turnabout ? When string theory came out, it was to add one dimension to the zero dimension of point-particles. Then it was realized that in order to make the theory consistent, six more dimensions must be added to space. Then M-theory needed one more space dimension...

I´ve just started to study superstrings and I´m working on Polchinski´s book problems. I come from other area and so I´m not used to work with group theory what makes a little difficult to me to understand the solution of exercise 1.5. The solution says that the states with m^2 =1/ \alpha ´ form...

I'm sorry, marcus, but as you well know, strings continue to dominate high energy theory, despite your efforts to fool people into somehow doubting this. In fact, marcus, strings have gone through a number of (relatively) barren periods, the last one ending when D-branes and dualities where...

Open strings and closed strings are the quanta of Type I string theory. If the rotational (vibrational) axis of a closed string coincides with another existing string, and this string is subsequently closed, can the new form of double loops of string be considered as a 2nd quantum structure of...

I was watching the Elegant Universe on PBS, and the show was talking about the string theory. there was one thing that i didnt really get though. It was the relation between strings and branes. I think i heard that if you were to add energy to a string, it gets bigger, and is stretched into a...

Most Fundamental Elements? Science continues to discover more fundamental elements with which to govern its predictions on and to unite a wider breadth of the universe. The latest, string theory, posulates, in laymens terms, that there are even smaller elements governing all aspects of our...

I have rebuilt my webpage with the aim of showing where vacuum stands in relation to string theory. This is a rough draught, but I hope, contains sufficient argument to get a debate going. Please note that I use real mass figures for fundamental particles demonstrating that the system can be...

Strings vs. Loops--Black Hole Metrics? You read a lot about how strings and loops can both derive the Bekenstein-Hawking entropy formula for black holes. String calculations only work for near extremal black holes, but they get the Immirzi-Barbero parameter right. Loop calculations work for all...

"The Duel: Strings versus Loops" by Rudy Vaas http://arxiv.org./ftp/physics/papers/0403/0403112.pdf it's a 10-page popular article about the Strings meets Loops conference last October written for Bild der Wissenschaft (translated into English by Martin Bojowald and Amitaba Sen) Part...

Ok, I know about the search for supersymmetric partner particles (sparticles) and the tests on gravity variance at small scales, but what other tests are there that can be used to add proof to superstring theory?

I just recently started studying the string theory and I don't understand one major part. I can't find anything about what the strings exactly are. I think I have an idea from what I've read but I'm not sure. Now if anyone is considering answering this you have to know that I'm just a high...

how serious is this theory? has it been used to define GR or SR yet or even parts of it? it is exciting, actualy, because as a student of Mathmatics with an interest in physics, I have come to think that a theory of the universe that allows for mathmatical solutions dealling with infinity are...

Hi all! I'm in serious need of some help. The question: How many binary strings of length 10 contains exactly two "01"? My idea was to weld together 4 bits to 2 "01". That way, there's \frac{8!}{2!} strings with at least 2 "01". But there are a bunch of strings with more than 2 "01" in...

A string has two parts: one with a very high mass density (per unit length), and the other with a very low mass density. A wave with amplitude A moves from the dense part toward the light part. What will be the amplitude of the wave which is transmitted to the light part? hhegab

Do different points along a string travel faster than others points along the same string?

After recently seeing Brian Greene's "Elegant Universe," I was struck by an idea - maybe not an original idea, but an idea nonetheless. If gravity is a weak force because it is not stuck to the "brane" of this universe, then gravity from our universe can influence others and vice versa from...

I don't know to much about the string theory or loop theory really. I have read a few books on it, but I want to know: Why do scientists think any extra dimensions take the form of strings? Is it that the formula say that is what the strings are, or is it just a way to explain why we can't see...

I have the following problem Pulling up on a rope, you lift a 4.25-kg bucket of water from a well with an acceleration of 1.80 m/s². What is the tension in the rope? What part exactly does the acceleration play in this scenario?

At one time, I read where strings were vibrating bits of space-time. In "The Elegant Universe" TV program, they were described as vibrating bits of energy. In "The Elegant Universe" book they are described as consisting of fundamental "string stuff" and that questioning their composition...

Check my math! I've derived a differential equation for strings starting from Stokes Theorems to show that energy is conserved along the world-sheet. These diff eq's involve connection coefficients. And I'm not really sure what it all meants yet. I would appreciate it if some who are more...

Pardon me. I claim ignorance. Where do strings 'exist'? Either? 'String Space'? If so, is there space between on string and the next? What, if anything 'fills' the 'void'(s)? How can strings be fundamental if they have to lay in (some) dimension(s)? Do strings define themselves? If not, what...

do string make time or does time make strings , since strings have varoius vibrations, do there have a decay rate? just a question maybe one of you might know an answer?

It is an old observation that both LQG and string theory are fundamentally built from 1-dimensional objects. This is no coincidence. In general, every gauge theory can be formulated in terms of Wilson loops and these can often be described by "a" theory of strings. This was discussed in detail...

A while back I created a web page to describe an infinetly long straight cosmic string. http://www.geocities.com/physics_world/cosmic_string.htm Does anyone know if an exact solution for such a string has been fount. The result in that page is based on a paper which seems to have been...

please excuse my ignorance, i have read much about strings sometimes i even get a glimmer of understanding, the problem is i can not find referance to what a string is ok an electron is a point particle so a string is?

I've included a picture. Three strings, in the horizontal plane, meet in a knot and are pulled with three forces such that the knot is held stationary. The tension in string 1 is T1 = 3.6 N. The angle between strings 1 and 2 is 130° and the angle between strings 1 and 3 120° with string 3...

[SOLVED] Strings: 1 Universe: 0 If you enjoy potentially stupid questions, read on. If strings vibrate in x dimensions and if all matter is made of strings, then why do we not share those dimensions? Why does the universe remain in four-dimensional spacetime? Chances are I'm missing the...

John Baez just posted this announcement and tentative schedule for a conference this month at the Albert Einstein Institute (Max Planck Institute for Gravitation Physics) on the outskirts of Berlin. We have had several threads at PF studying work by AEI people---Hanno Sahlmann, Martin...

Does anyone know of any good problem solving books on strings, branes and/or loop quantum qravity? I am looking for something that has a lot of actual solved problems, something in the spirit of Schaum's Outline Series, Zetteli's book on QM, or Peskin and Schroeder's book on QFT. Any...

Hello, I think it's interesting to post here some interesting publications or pre-publication links related to String and Brane. http://arxiv.org/pdf/hep-ph/0306136 Title: On Superplanckian Scattering on the Brane Authors: A.V. Kisselev 3 Transplanckian collision on the brane In the...

Pantheistic Strings & Mystical QM Einstein was cannonized as a saint by the Navaho nation for his theory of Relativity. The Navaho's have no future tense, no verb to be, in their language and their worldview is very relativistic. Much of native american religion shares the exact same artwork...

I've been looking into the possibility that "Solar Activity", flares, coronal mass ejections, magnetic fields, sunspots, coronal heating, etc, involve what might be called tachyonic states (I personally don't care for that name) with very long (by atomic standards) wavelengths. But I've also...

in fact if we have a classic hamiltonian. H=p**2/2m+V(x) to quantize it we would do.. p=-ihd/dx and H=ihd/dt (1st quantization) Or p=(a+)-(a) and x=(a+)+(a) in terms of creation and anhinilation operators (second quantization). But..if we would like to write it in a string theory...