String Theory: Is an Atom Made of 1 or Millions of Quarks?

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Discussion Overview

The discussion revolves around the nature of quarks in string theory, specifically whether each quark is associated with a single string or composed of multiple strings. Participants explore various aspects of string theory, including its implications for the Standard Model, M-theory, and the relationship between different types of strings and particles.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants propose that all particles in the Standard Model can be explained as the behavior of a single string, typically in a loop.
  • Others discuss a construction where quarks are represented as open strings ending on branes, suggesting a geometric relationship to gauge groups.
  • A participant notes that quarks can be viewed in two ways: as fundamental quarks corresponding to strings and as dressed quarks that exhibit running masses influenced by scale, indicating a more complex structure.
  • There is a mention of the necessity of renormalization in quantum field theory to connect theoretical models with experimental observations of quarks.
  • Some participants express uncertainty about the nature of strings in M-theory, particularly regarding the existence and types of branes associated with different string theories.
  • Discussion includes the distinction between closed loops (gravitons) and open strings, with implications for their behavior and interactions.
  • Concerns are raised about the lack of experimental evidence for string theory and the challenges of proving or disproving it, with some expressing skepticism about its testability.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of quarks and strings, with no consensus reached on whether quarks are made of one or multiple strings. There is also disagreement on the implications of string theory and its testability, with some participants skeptical about its potential for empirical validation.

Contextual Notes

Participants highlight the complexity of string theory and its various models, noting that many aspects remain unresolved and dependent on specific definitions and assumptions. The discussion reflects the theoretical nature of string theory and its challenges in connecting to experimental physics.

clm321
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in string theory is it that each quark of an atom has one string or is it made up of millions?

i know this is a kinda silly question
 
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clm321 said:
in string theory is it that each quark of an atom has one string or is it made up of millions?

i know this is a kinda silly question

All of the particles of The Standard Model are explained as the behaviour of one string, usually in a loop.
 
There is a popular construction where quarks are open strings ending on two different stacks of branes. The topology of the stacks is supposed to build geometrically the gauge groups. It's cute.
http://arxiv.org/abs/hep-th/0502005v2
 
That does not really answer the first question by the way...

Already in the standard model, there are two ways to think of the quarks. The fundamental quarks (with current, small, masses) are directly in correspondence with the strings in different models as above. But there are also the quarks we probe in experiment, let me say phenomenological, or dressed quarks. They have a running mass which depends on the scale. Those are made up of more quarks and gluons if you look at them closer, just as strings are made up of more strings if you look at them closer. From this point of view, the question is far from trivial. In order to make contact with experiments dealing with quarks, you can not stay at the tree level, you need at least one, maybe two loops. So you need renormalization in QFT.
 
ok but in m theory there are not only looped strings but open strings right?
 
clm321 said:
ok but in m theory there are not only looped strings but open strings right?

I believe so, but definitely not loose; that would be type I I think.
 
In string theory, what is the key difference between bosons, fermions, and leptons?

Edit: let me rephrase. What is the difference in the strings that explains the observable differences?
 
Last edited:
In string theories, closed loops are gravitons which are free to go off in extra dimensions; open strings are bound on each end to a brane which we inhabit...

the detailed pattern of vibration executed by a string produces a specific mass, electric charge, spin and so forth. heavy particles vibrate faster, with more energy, than light ones.
spin 1 particles are messenger, spin 1/2 are matter particles.
 
I believe so, but definitely not loose; that would be type I I think.

Am not sure what "loose" means, but closed loops, gravitons, are not affixed to branes.

I am not sure if all the constitutent string theories associated with M theory have branes...and if they do which types, p and/or d...I just did a quick Wikipedia check...it says there are different types of d branes in different string theories...
http://en.wikipedia.org/wiki/Branes

Methinks we have too many theories, not enough experimental evidence so far...
 
  • #10
Naty1 said:
Am not sure what "loose" means, but closed loops, gravitons, are not affixed to branes.

I am not sure if all the constitutent string theories associated with M theory have branes...and if they do which types, p and/or d...I just did a quick Wikipedia check...it says there are different types of d branes in different string theories...
http://en.wikipedia.org/wiki/Branes

Methinks we have too many theories, not enough experimental evidence so far...

You're correct; not all STs rely on brane cosmology, and 'loose' means that they're not bound in a loop, but are under tension bound to at least one brane (I have no idea how this works for a theoretical entity with no basis in reality other than clever math).

String Theory is fascinating, but it's an intellectual exercise and a dart thrown at a VERY large board. As for how many... There's... 5 sub-types of string theory including M-Theory... I think. Some are obsolete or have parts that are now part of other string theories.
 
  • #11
So is it safe to assume that ST will never be proved or disproved?
 
  • #12
Dav333 said:
So is it safe to assume that ST will never be proved or disproved?

I think if you could make money betting that, you might stand to become rich. That said, it's never really safe to assume that a theory can't be proven or falsified (unless it's insane to begin with, and that is merely confirmed), but I can't imagine how String/M theory could be examined.

We're already unlikely to be able to observe a lone quark (undressed), but I would imagine that happening before anything like confirmation of strings, or fuzzballs inside BH event horizons. The theory itself doesn't really allow for much by the way of confirmation it seems.

I'm no expert however, that's just my opinion.
 

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