String Theory: Background Dependence & Complaints

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Discussion Overview

The discussion centers on the concerns regarding background dependence in string theory, particularly in relation to competing theories like loop quantum gravity. Participants explore the implications of these concerns and the broader context of foundational physics.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants inquire about the reaction of string theorists to the criticism of background dependence and why it may not be a significant concern for them.
  • Others assert that background dependence is indeed a concern for string theorists, but they lack solutions, suggesting that this does not warrant the rejection of string theory in favor of loop quantum gravity.
  • One participant emphasizes that string theory encompasses more than just a quantum theory of gravity, which may not necessarily align with established physics expectations for a theory of quantum gravity.
  • Another viewpoint suggests that the discussion should not be limited to just string theory and loop quantum gravity, proposing that there are potentially more options to consider in foundational physics.
  • A participant expresses a desire for a rethinking of the fundamentals of physics, integrating concepts from evolutionary models and complex systems, indicating that string theory may not be the most relevant framework for their perspective.

Areas of Agreement / Disagreement

Participants express differing views on the significance of background dependence in string theory, with some acknowledging it as a concern while others argue for a broader exploration of theoretical options. The discussion remains unresolved regarding the implications of these concerns and the relevance of string theory compared to other approaches.

Contextual Notes

Participants mention various papers and responses related to background independence, indicating a complex landscape of ongoing discourse without clear resolutions or consensus on the issues raised.

Ratzinger
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What actually is the reaction of string theorists to the complaints that their approach is not background independent? Why is it not such a big concern to them?
 
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It IS their concern. Unfortunately, they do not know how to solve this problem. Nevertheless, that is not a reason to reject string theory and accept loop quantum gravity. This is because string theory is MUCH MORE than a quantum theory of gravity. String theory and loop quantum gravity are NOT too different approaches to the same problem.
 
On "The case for background independence", Smolin
http://arxiv.org/PS_cache/hep-th/pdf/0507/0507235v1.pdf

I've seen at least one response from some string theorist
"The case for background independent theories and formulations with background",
http://mathphys.iu-bremen.de/~robert/background.pdf

I'm sure there are lots of string responses to Smolins paper though.

/Fredrik
 
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"string theory is MUCH MORE than a quantum theory of gravity."

For a physicist that's not neccessarily a good thing of course. We have good reason from established physics to expect a theory of QG to exist in reality, we don't have any physical reasons whatsoever to believe that anything else that ST is exists.
 
Demystifier said:
It IS their concern. Unfortunately, they do not know how to solve this problem. Nevertheless, that is not a reason to reject string theory and accept loop quantum gravity.

I don't think we need to narrow it down to just two options do we? Perhaps the are other options.

To me at least, there is sufficient issues all over the place for me to motivate a rethinking of the fundaments of physics and it's methods, and and that point I think the options are more than the two mentioned. Part of my motivation is that the foundational physics touches the scientific method and is thus to me at least more than just the traditional physics. Natural extensions I want integration in foundational physics is generic evolutionary models, touching also highly complex physical systems such as the human brain. We may well end up dynamically modelling the models to an even larger extent. In that perspective, string theory is not what comes to my mind. But then that's just a single opinion.

/Fredrik
 

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