Can Quantum Gravity Serve as a Theory of Everything?

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Discussion Overview

The discussion revolves around the potential of Quantum Gravity as a Theory of Everything (TOE), exploring whether combining Quantum Field Theory (QFT) with General Relativity (GR) can yield a comprehensive framework that explains both theories and possibly other phenomena like dark energy.

Discussion Character

  • Debate/contested
  • Exploratory
  • Conceptual clarification

Main Points Raised

  • Some participants propose that Quantum Gravity should be considered a candidate for a TOE, as QFT addresses all fundamental interactions except gravity.
  • Others argue that Quantum Gravity might only be a theory of 'almost everything', suggesting limitations in explaining certain phenomena, such as dark energy.
  • One participant asserts that Quantum Gravity is currently neither a TOE nor even a complete theory, indicating significant gaps in understanding.
  • Concerns are raised that any theory developed from the assumptions of QFT and GR may not be able to derive either theory, questioning the fundamental nature of the universe's quantum mechanical and relativistic characteristics.
  • There is a suggestion that string theory might be capable of rederiving GR, although this remains a point of contention.
  • A participant introduces the concept of causal fermion systems, speculating on its relationship with string theory and its potential to model fundamental aspects of physical systems.

Areas of Agreement / Disagreement

Participants express a range of views on the role of Quantum Gravity as a TOE, with no consensus reached. Disagreements exist regarding the sufficiency of Quantum Gravity to explain all aspects of the universe, particularly in relation to dark energy and the derivation of GR and QFT.

Contextual Notes

Limitations in the discussion include unresolved questions about the foundational aspects of Quantum Gravity, the definitions of a TOE, and the implications of various theoretical frameworks like string theory and causal fermion systems.

friend
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I'm wondering if Quantum Gravity is expected to be a Theory Of Everything (TOE)? Can we expect that if we combine QFT with GR to get Quantum Gravity, will that be a TOE that explains GR and QFT?
 
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I think is should be a candidate for a TOE, since QFT describes everything other than gravity.
It's as likely though that it could turn out to be a theory of 'almost everything', for example it might not adequately explain dark energy.
 
As of now, it's not only not a TOE, its' not even a T.
 
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It seems to me that any development of a theory assuming QFT and GR are true will not enable us to then derive either QFT or GR. We might be able to answer some questions about black holes and big bangs. But we still won't know why the universe is quantum mechanical or general relativistic. So what should we expect to find out with LQG or Stringtheory?
 
friend said:
It seems to me that any development of a theory assuming QFT and GR are true will not enable us to then derive either QFT or GR. We might be able to answer some questions about black holes and big bangs. But we still won't know why the universe is quantum mechanical or general relativistic. So what should we expect to find out with LQG or Stringtheory?
i thought string theory can rederive GR on its own?
 
black hole 123 said:
i thought string theory can rederive GR on its own?
Causal fermion system
Here's another possibility I literally just found. I see string theory as a theory of anything, so I wonder if string theory could be used to model this "causal fermion system" as well?

"Taking the concept seriously that the states of the Dirac sea form an integral part of the physical system, one finds that many structures (like the causal and metric structures as well as the bosonic fields) can be recovered from the wave functions of the sea states. This leads to the idea that the wave functions of all occupied states (including the sea states) should be regarded as the basic physical objects, and that all structures in space-time arise as a result of the collective interaction of the sea states with each other and with the additional particles and "holes" in the sea. Implementing this picture mathematically leads to the framework of causal fermion systems." - Putting the "darkness" of matter right in the core of its basis?
 

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