Can string theory and Penrose interpretation coexist?

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Discussion Overview

The discussion explores the compatibility of string theory, specifically M-theory, with the Penrose interpretation of quantum mechanics, which posits objective collapse due to gravity. Participants examine whether these frameworks can coexist or if fundamental differences prevent their integration.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants suggest that the Penrose interpretation modifies quantum mechanics rather than serving as a traditional interpretation, focusing on objective collapse due to gravity.
  • One participant argues that if string theory does not modify quantum mechanics, then it cannot coexist with the Penrose interpretation.
  • Another participant notes that Penrose's theory requires a classical spacetime, which cannot be entangled with the gravitational field, implying that theories of quantized gravitation, including M-theory and loop quantum gravity, do not qualify.
  • A participant references Smolin's "Principle of Maximal Variety" and discusses its superficial resemblance to Penrose's ideas, suggesting a connection between spacetime curvature and quantum mechanics.
  • There is a discussion about the implications of spacetime elasticity and how it relates to the interaction of systems in quantum mechanics, with references to specific metrics and dimensions.
  • Another participant quotes Penrose's interpretation, highlighting the distinction between macroscopic and microscopic systems in terms of their existence in multiple locations and the conditions under which collapse occurs.

Areas of Agreement / Disagreement

Participants express differing views on the compatibility of string theory and the Penrose interpretation, with no consensus reached. Some argue that the frameworks are fundamentally incompatible, while others explore potential connections and implications.

Contextual Notes

Participants highlight limitations regarding assumptions about spacetime, the nature of quantum mechanics, and the definitions of collapse and interaction, which remain unresolved in the discussion.

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Can the M theory/ string theory coexist with the penrose interpretation of quantum mechanics?
 
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Nav said:
Can the M theory/ string theory coexist with the penrose interpretation of quantum mechanics?
The "interpretation" of Penrose's is not really an interpretation of Quantum Mechanics; more of modifying Quantum Mechanics -- https://en.wikipedia.org/wiki/Penrose_interpretation -- to allow for objective collapse due to gravity.
 
StevieTNZ said:
The "interpretation" of Penrose's is not really an interpretation of Quantum Mechanics; more of modifying Quantum Mechanics -- https://en.wikipedia.org/wiki/Penrose_interpretation -- to allow for objective collapse due to gravity.
So is that a yes or no?
 
If string theory doesn't modify QM, then the answer is no.
 
It does remind me superficially of Smolin's "Principle of Maximal Variety", .
 
If I'm not mistaken, then Penrose theory requires a classical spacetime (or at least one that is very strongly superselected), as the gravitational field and the particle configuration cannot be entangled in any way. If they were, the linearity of the evolution would not allow for any form of collapse or state separation.

That means no theory of quantized gravitation qualifies, including Supergravity, M-Theory (strings), Loop quantum gravity, etc. The only framework that matches is in fact quantum field theory on curved spacetime, which is what practically all of Penrose's (and Hawking's for that matter) calculations are based on.

Cheers,

Jazz
 
As I understood it Smolin wasn't starting off talking about quantized QM Gravity per se. Though I think a unit of measure was implied in his attempt to connect QM and GR via the metric "similarity of views" a metric orthogonal to classical locality.

This seems consistent with Penrose' proposal that there is some maximum "elasticity" to space-time curvature? In what dimension is this elasticity defined? Smolin seems to be suggesting it is a function of the measure of distance across the non-space time dimensions. Or inverting that, the measure of difference in non gravitational dimensions is derivable from some specific sense of the elasticity of spacetime - as I understand it this is sort of Penrose.

From http://lanl.arxiv.org/pdf/1506.02938v1.pdf p3-4

"In the microscopic causal geometry underlying nature, two systems can interact if they are within a distance R in the metric hij . There are two ways this can happen. It can happen when they are nearby in the emergent macroscopic notion of spatial geometry. When two people stand next to each other and scan a landscape they see similar views. But two microscopic systems can also be very far apart in the macroscopic geometry and still have a similar view of their surroundings. When this happens there are a new kind of interactions between them
 
A brief quote from The wiki page on Penrose's interpretation, sounds a lot like Smolin, or vice versus.

"Accepting that wavefunctions are physically real, Penrose believes that matter can exist in more than one place at one time. In his opinion, a macroscopic system, like a human being, cannot exist in more than one place for a measurable time, as the corresponding energy difference is very large. A microscopic system, like an electron, can exist in more than one location significantly longer (thousands of years), until its space-time curvature separation reaches collapse threshold.[5][6]"
 

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