Why are stings only one dimension?

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Discussion Overview

The discussion centers around the dimensionality of fundamental particles in string theory, specifically why they are conceptualized as one-dimensional strings rather than three-dimensional objects like oscillating balls. The conversation explores theoretical implications and the nature of string theory itself.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants question why fundamental particles are modeled as one-dimensional strings instead of three-dimensional shapes, suggesting that one-dimensional strings could allow for more complex abstractions.
  • Others note that string theory has evolved to include extended objects like branes, indicating a shift in understanding beyond just one-dimensional strings.
  • A participant references a technical argument from Green, Schwarz, and Witten's book, stating that higher-dimensional objects face significant challenges in quantum field theory, which may explain the preference for one-dimensional strings.
  • Another participant emphasizes the hypothetical nature of string theory, asserting that it remains uncertain whether fundamental particles are indeed strings.

Areas of Agreement / Disagreement

Participants express differing views on the dimensionality of fundamental particles, with some supporting the one-dimensional string model and others highlighting the existence of higher-dimensional objects. The discussion remains unresolved regarding the definitive nature of fundamental particles.

Contextual Notes

Participants acknowledge the technical challenges associated with higher-dimensional objects in quantum field theory, but do not resolve the implications of these challenges for the validity of string theory.

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Why are strings only one dimension?

Why is the fundamental particle a one dimensional string as opposed to,for example, a three dimensional ball that oscillates?
 
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Pjpic said:
Why is the fundamental particle a one dimensional string as opposed to,for example, a three dimensional ball that oscillates?

Answer that and I predict a Nobel Prize for you.
 
Hm. I'm highly uneducated on the matter but it seems to me that with one dimensional string you could build more complex and convoluted abstractions including a sphere as a posed to a bunch of little spheres rotating to reach the same goal but with less accuracy.
 
But nowadays string theory is no longer just a theory of string, there are extended objects like branes.
 
From Green, Schwarz and Witten's book on String theory:

"Membranes and objects of still higher dimensionality have another glaring problem, as follows. Eq (the action for such objects) defines a n+1 dimensional quantum field theory, which by power counting is renormalizable for n = 1 and unrenormalizable for n > 1. Making sense of Eq() as a quantum theory is as hard as making sense of general relativity as a quantum theory. Thus membranes and higher dimensional objects would hardly be a promising start toward quantum gravity"

There are other reasons for it too, outlined in that same book next to this quote (it's on page 60). So it's not arbitrary, and we have some ideas why it might be that way, but as far as I know they're all technical. You can imagine though that strings "spread out" interactions, avoiding the kinds of divergences you get in QFT.
 
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Pjpic said:
Why is the fundamental particle a one dimensional string as opposed to,for example, a three dimensional ball that oscillates?

Nobody knows if the fundamental particles are strings or not. String theory is still very much hypothetical.
 

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