Can a string have multiple simultaneous vibrations in different directions?

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Discussion Overview

The discussion revolves around the characteristics of strings in string theory, specifically focusing on how these characteristics relate to mass, spin, and charge. Participants explore the analogy between particle families and musical octaves, and whether a string can vibrate in multiple directions simultaneously.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants inquire about the characteristics of strings that determine mass, spin, and charge, suggesting that tension plays a crucial role in string physics.
  • One participant notes that strings do not have mass themselves but can generate massive particles through vibration, with higher frequencies corresponding to higher mass.
  • There is a suggestion that the three known families of particles are not analogous to musical octaves in a traditional sense, but rather relate to the group structure of the Standard Model and interactions between different forces.
  • Some propose that flavors of particles could be generated through topological features of higher-dimensional shapes, such as Calabi-Yau manifolds, which may allow strings to loop in various ways.
  • Participants discuss the possibility of a string vibrating in two different frequencies that are perpendicular to each other, with one asserting that a string can support complex vibrations analyzed into normal modes, similar to a violin string.
  • It is mentioned that in ten-dimensional superstring theories, there are multiple dimensions available for vibrations, allowing for the generation of multiple particles from a single string.

Areas of Agreement / Disagreement

Participants express a range of views on the characteristics of strings and their implications for particle physics. While some points are clarified, there is no consensus on the analogy between particle families and musical octaves, nor on the specifics of how strings vibrate in multiple dimensions.

Contextual Notes

The discussion includes various assumptions about string theory and its implications, with some participants referencing complex concepts such as the Higgs mechanism and chirality in the Standard Model without resolving the underlying mathematical or theoretical details.

Who May Find This Useful

This discussion may be of interest to those exploring string theory, particle physics, and the conceptual frameworks that underpin these fields, particularly in relation to the nature of vibrations in strings.

Glenn
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 each other? By this I mean that if we could view a string from the side, it would appear as a line. Along that axis could it also be vibrating?

Thanks,
Glenn
 
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Glenn said:
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 each other? By this I mean that if we could view a string from the side, it would appear as a line. Along that axis could it also be vibrating?

Thanks,
Glenn

http://a799.g.akamai.net/3/799/388/3d94d6b574ec9f/www.msnbc.com/news/wld/graphics/superstring.gif is for you Glenn :smile:
 
Last edited by a moderator:
Sol2,
Thanks for the link, however it doesn't work. It appears to be a GIF file on which I am unable to click the "Next" button.

Please repost the link if you have it available.

Thanks,
Glenn
 
Hmmmmmmm... that didn't tell me quite what I wanted to know.

Anyone have a more specific answer or perhaps another link?

Thanks,
Glenn
 
Glenn said:
In laymans terms, what characteristic of a string do scientists use to determine the string's mass, spin, and charge?

The basic parameter that controls string physics is tension. The string doesn't have mass itself, but can generate massive particles by its vibration, the higher the frequency of the vibration the higher the mass. But the massive string particles are not seen. Rather string phenomenology relies on low frequency massless particles which acquire mass in other ways at low energies (e.g. Higgs mechanism). Charge is imposed on the worldsheet or the branes as a separate step. Spin, or helicity, can be generated from multiple branes. Getting the correct chiral behavior of the standard model is something string physicists pay a lot of attention to. All the more important in that chirality in the SM is still generating new physics (neutrino mass, CP violation).

Are the three known families of particles at all analagous to musical octives?

Not in the Pythagorean vibration -> musical tone sense. The "flavors" as the three generations are now called are a feature of the group structure of the SM, specifically the interaction of the part that generates electroweak behavior and the part that does the strong force. Some intersecting brane models can reproduce this physics.

Another way to generate flavors has been suggested, a topological one. The higher dimensions of string physics are often thought of as compacted on tiny six dimensional shapes such as Calabi-Yau manifolds or higher tori. These may not be simply connected, meaning they have "handles" around which a string could loop, one, two, or more times. Then it is thought by some if two strings vibrate with different wrapping numbers it could generate particle families of different mass. This is certainly an attractive idea, but see my comments on particle mass above.

Can a given string simlutaneously have two different frequencies which are perpendicular to each other? By this I mean that if we could view a string from the side, it would appear as a line. Along that axis could it also be vibrating?

Thanks,
Glenn


Yes. a string can support complex vibrations which can be analyzed into an infinite set of normal modes - just like a violin string. The vibrations happen in the transverse dimensions, the ones not entrained by the two dimensional world sheet. In ten dimensional superstring theories there are 8 dimensions to vibrate in. Each normal mode can generate a particle, so multiple particles can come out of one string. In the case of closed string you also have left moving and right moving excitations which interact, forming particles. The graviton is one particle formed this way.
 
Last edited:
Thank you for the in depth reply!

-Glenn
 

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