Strings Definition and 523 Threads

I'm obviously not going to ask how many strings there are in the universe. :wink: my question. To each quark how many strings are there? Just one unique one? Billions and Billions? Also does Brian Greene's book. "The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for...

I often think about this subject, would it be a fair assumption to say that our electronic bits are a equivalent and more simple "thing" of that we assume to be the more elementar "particle" of the universe, a string, acording to the theory, it is the vibrating state of certain string that...

If I attached a long string from the ground to a geostationary satellite in orbit, and plucked it, would the wave created by the string be affected by gravity? The particles in the string move sideways, so the wave itself should not be affected by the Earth's gravity, should it?

I probably won't be able to ask this question as well as I envision it in my mind. So please bear with me and try and decipher my babbling gibberish as best you can. :smile: According to my very limited knowledge of Strings and Branes...(theory) Strings are the smallest things in the...

Hello everyone, I'm a undergraduate student in the field of physics. I'm working toward a BS in Physics from University of North Carolina at Wilmington. I've been thinking about string modes of resonance lately and wonder if the theory allows strings to stop vibrating or change resonance...

If everything is made out of strings as described in string theory, or, M - Theory, then how do the strings know how to collect themselves to form an electron of the exact mass of 9.10939 x 10^-31 every time, and also form all the other particles (Proton, Positron, photon)? :rolleyes: You...

I am not really sure how to start this problem, and I have tried searching everywhere. If you could help me that would be great...just to know how to get started. I'm in 2nd Year, Intro to discrete mathematics, if it matters. Thanks Let G be a graph whose vertices correspond to the...

Hi, you have two strings, one has force constant K1, the other Force Constant K2. You hook the two strings together. I need to see a derived euqation using K1 and K2 to find KTOTAL (the force constant when he two strings are placed together). Please keep things as simple as possible...

Hey! Was just wondering if someone could shed some light on the whole stationary waves thing. I've done about them in my A-Level Physics course and I can't for the life of me figure out what it's about. I mean, why can you only have a certain number of nodes, hence certain frequencies...

Standing waves on strings... :smile: I understand how to produce standing waves on a string when we have a vibrator at one end, as you usually use in demonstrations in physics classes. ie - increase frequencies until we achieve the correct kind of interference to produce standing wave...

Is it possible to convert open strings to closed strings in string theory. Perhaps, we can convert out rest mass into gravitons, and appear in other dimensions. Is this a possibility? Or does string theory not predict this behavior?

In his book "the universe in a nutshell", stephen hawkings is discussing the possiblity of time travel to the past (ch. 5 How to protect the past). He introducted the concept of cosmic strings to explain that. would anyone here could explain this concept and it's relation to time travel...

Is there someone out there who could explain string theory and loop quantum gravity to me in plain English, please? I have no mathematical ability whatsoever, so I'm looking for an explanation of the concepts. Numbers leave me scratching my head. I am not suggesting that my numerical stupidity...

I'm not going to say anything about the anthropic principle (strong or weak form) because that's so clearly stupid that it speaks for itself. I'm also not going to say anything about the lack of observational evidence, because, let's be honest, we're all in the same boat on that one, probably...

Could any of you clever people answer me this.. Whenever I have read a 'popular' book on string theory, I get the impression that the strings themselves aren't nessecary. They are described as a vibrating string that wraps around a folded dimension, and so say an electron is particular type of...

Do physicists have any idea how much a string or brane would mass?

In a recent article in New Scientist Mag they are making claims of possible evidence of strings. Though I read the "The Elegant Universe" by Brian Greene and I once wrote to Greene with a question (his e mail address is on the web), I have pretty much looked the other way from strings because...

Ok about M-theory, are the P-branes or strings or closed and open loops suppose to be made out of matter/energy? if they are then how could that be possible if matter/energy is suppose to be composited out of particles to explain chemical reactions, that would mean for the strings to move they...

Two identical violin strings, when in tune and stretched with the same tension, have a fundamental frequency of 440.0 Hz. One of the strings is retuned by adjusting its tension. When this is done, 1.5 beats per second are heard when both strings are plucked simultaneously. -By what...

Do strings move in spacetime ? If at every Planck size point in spacetime there is a Calabi-Yau manifold. Do the manifolds move with the expansion of the universe so that the strings always have a constant vibrational pattern that determines their effect/elemental property or are the...

[FONT=Courier New]If string theory is based mainly on Minkowsi "flat" spacetime, then how do they account for the proven curvature of our spacetime? Thanks to all, - Alisa :bugeye:

how is it that some strings have mass (spin 1/2 particles) while others have no mass at all (spin 2 particles and force carrying particles)? all strings are the same, its just how they move and vibrate that they change from particle to particle, but wouldn't this mean that all strings either...

Help needed urgently! Question A string vibrates according to the equation: y=0.6sin px/4 cos 45pt p = pi , x and y = cm , t=s (i) what are the amplitude and velocity of the component wave given rise to this vibration? (ii) what is the distance between nodes? (iii) what is...

Q A 420 gm rock is whirled on the end of a string 44 cm long which will break under a tension of 21 N. a) What is the highest speed the rock can reach before the string breaks? (Neglect gravity.) For this I used F = mv2/r and calculated velocity in m/s which is correct. b) If two...

In Zwiebach's book "A First Course in String Theory", I read that the endpoints of an open string move at light speed. Do any of the interior points of a string also travel at light speed?

Q. 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 N. The angle between strings 1 and 2 is q12 = 130° and the angle between strings 1 and 3 is q13 = 120° with string 3 below string...

Problem : 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 = 2.5 N. The angle between strings 1 and 2 is q12 = 130° and the angle between strings 1 and 3 is q13 = 120° with string 3 below...

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...