What is k-Minkowski spacetime, and is it a tool in a theory of quantum gravity?

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Discussion Overview

The discussion revolves around the concept of k-Minkowski spacetime and its potential role in theories of quantum gravity. Participants explore its definition, characteristics, and comparisons to other spacetime models, particularly focusing on the differences in metric signatures and the relationship to kappa-Minkowski spacetime.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the definition of k-Minkowski spacetime and its application in quantum gravity theories.
  • One participant describes k-Minkowski spacetime as a generalization of Minkowski spacetime with a change in the metric tensor's signature.
  • Another participant questions the difference between Minkowski and Lorentzian signatures, seeking clarification on the terminology.
  • There is a discussion about whether k-Minkowski is synonymous with kappa-Minkowski, with one participant suggesting that the use of "k" instead of "κ" may be a typographical choice.
  • Some participants express uncertainty regarding the existence of a Lorentzian metric, indicating a lack of consensus on this point.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and uncertainty regarding the definitions and implications of k-Minkowski spacetime, with no clear consensus on the relationship between k-Minkowski and kappa-Minkowski or the existence of a Lorentzian metric.

Contextual Notes

Some statements rely on specific definitions of metric signatures, which may not be universally agreed upon. The discussion includes assumptions about the dimensionality of spacetime and the implications of generalizing Minkowski spacetime.

nomadreid
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What is k-Minkowski spacetime, and...

In http://www.physorg.com/news157203574.html, k-Minkowski spacetime, which decreases down towards zero at small scales, is mentioned as a possible tool in a theory of quantum gravity and spacetime. But it is very, very vague. First, how is k-Minkowski space-time defined, and where precisely would it enter? Is the "k" here the same as the "q" in the description of the quantum group given in http://en.wikipedia.org/wiki/Quantum_group#Drinfel.27d-Jimbo_type_quantum_groups? Roughly what role would such fractional spacetime play? An explanation for a non-physicist (but with a mathematical background) would be greatly appreciated.
 
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K-Minkowski spacetime is a generalization of Minkowski spacetime in which the signature of the metric tensor is changed from the standard signature of Minkowski spacetime to the signature of the Lorentzian metric. It is often sufficient to use this model for background geometry when working with curved spacetimes.
 
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Thanks, Greg Bernhardt!
 
Greg Bernhardt said:
the signature of the metric tensor is changed from the standard signature of Minkowski spacetime to the signature of the Lorentzian metric.
What's the difference between Minkowski and Lorentzian signature?

A bonus question, is k-Minkowski the same as kappa-Minkowski?
 
Greg Bernhardt said:
the standard signature of Minkowski spacetime to the signature of the Lorentzian metric.
From https://mathworld.wolfram.com/MetricSignature.html
"For n-dimensional Lorentzian space Rn-1,n , the metric signature is (n-1,n) , e.g., (3,1) (as above) for the Minkowski space of special relativity."
So if I understand correctly (wishing to be corrected), perhaps by "changing" the signature one means that in generalizing the Minkowski to more dimensions than 4, one generalizes the signature as well to the Lorentzian.

Demystifier said:
A bonus question, is k-Minkowski the same as kappa-Minkowski?
I am presuming that the author of the article (first link in my original post) used k instead of κ (kappa) out of typographical reasons. (Which may or may not be a euphemism...:rolleyes:)
 
Demystifier said:
What's the difference between Minkowski and Lorentzian signature?

A bonus question, is k-Minkowski the same as kappa-Minkowski?
For your first question, I am not sure there's even such a thing as a Lorentzian metric.
There's a Lorentz transformation and Minkowski metric or space-time.
Before I learned GR from Schutz's book I didn't think to myself that the global spacetime metric may be flat, i.e. Minkowski.
 
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