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Is frame dragging in GR the same as torsion in curved spacetime?
tom.stoer said:No.
The mathematical setup for GR is Riemann geometry with Levi-Cevita connection and vanishing torsion. Frame-dragging does exist in GR.
Einstein-Cartan gravity is an extension of GR with non-vanishing torsion, especially relevant when coupling gravity to fermions.
I doubt that this can be a general result. Reading the paper I can't see any hint how they rule out torsion.bcrowell said:Experimentally:
Searches for torsion have given negative results
bcrowell said:Frame dragging has been confirmed by Gravity Probe B: http://en.wikipedia.org/wiki/Gravity_Probe_B
No; I think it's fine.A.T. said:Are they inaccurate? Misleading?
But how should they be interpreted? What does it mean physically, when the radial lines and the circumferences are not orthogonal? Would radially falling photons be diverted tangentially, and "spiral down" instead of going straight down?tom.stoer said:No; I think it's fine.
Nothing. At least not directly b/c what is shown are coordinates = reference frames. And they are unphysical i.e. cannot be observed.A.T. said:What does it mean physically, when the radial lines and the circumferences are not orthogonal?
Yes! But this does not follow from the reference frames but from the geodesics.A.T. said:Would radially falling moving photons be diverted tangentially, and "spiral down" instead of going straight down?
Hm, perhaps I was wrong ;-(tom.stoer said:No; I think it's fine.
Frame dragging is a phenomenon in which the rotation of a massive object, such as a planet or a star, causes the space-time around it to twist and drag along with it.
Torsion is a concept in physics that refers to the twisting or rotation of an object around an axis. In the context of general relativity, torsion is a theoretical concept that describes the twisting of space-time.
No, frame dragging and torsion are not the same thing. While they both involve the twisting of space-time, frame dragging is a specific phenomenon caused by the rotation of a massive object, while torsion is a theoretical concept that describes the twisting of space-time in general relativity.
Frame dragging and torsion are related in the sense that frame dragging is considered to be a manifestation of torsion in general relativity. However, they are not the same thing and have different origins and implications.
One example of frame dragging is the Lense-Thirring effect, in which the rotation of the Earth causes the orbits of satellites to precess. Torsion, on the other hand, is a more abstract concept and has not been directly observed. Some theories propose that torsion could manifest in the behavior of spinning particles, such as electrons, but this has not been confirmed.