- #1
Fra
- 4,177
- 618
The recent threads makse we want to as a simple question.
How many considers the notion of a _fundamental_ "diff invariant observables" as a clear and unquestionable requirement of the future theory of QG?
To me this far from clear from the conceptual point of view. It's not even clear what the physical basis of such a definition is. To start with, global manifolds are clearly abstractions. If this is to have any deeper plausability, shouldn't the structures be induced from some generic interaction picture?
I see two explanations to such a viewpoint.
- You have a realist idea of the existence of this symmetry. But isn't such things fundamentally disturbing the very intellectual foundation of a "measurement theory"?
- I can see the sense in it beeing a possible limiting (emergent) symmetry, in the sense that a large observer is simply unlikely to observe and breaking of this symmetry, in the sense that a broken symmetry with imply interactions between observers to restore their observed symmetry by internal transformations. But what about the physics between small systems, where the symmetry breaking is more probable? And what about non-equilibrium interctions? One might argue that these things are unlikely to be observerd except transiently which renders it indistinguishable from noise, but at least from a conceptual model-building point of view it seems severly disturbing to me.
Do you think that these questions even beyond the point (of physics)?
/Fredrik
How many considers the notion of a _fundamental_ "diff invariant observables" as a clear and unquestionable requirement of the future theory of QG?
To me this far from clear from the conceptual point of view. It's not even clear what the physical basis of such a definition is. To start with, global manifolds are clearly abstractions. If this is to have any deeper plausability, shouldn't the structures be induced from some generic interaction picture?
I see two explanations to such a viewpoint.
- You have a realist idea of the existence of this symmetry. But isn't such things fundamentally disturbing the very intellectual foundation of a "measurement theory"?
- I can see the sense in it beeing a possible limiting (emergent) symmetry, in the sense that a large observer is simply unlikely to observe and breaking of this symmetry, in the sense that a broken symmetry with imply interactions between observers to restore their observed symmetry by internal transformations. But what about the physics between small systems, where the symmetry breaking is more probable? And what about non-equilibrium interctions? One might argue that these things are unlikely to be observerd except transiently which renders it indistinguishable from noise, but at least from a conceptual model-building point of view it seems severly disturbing to me.
Do you think that these questions even beyond the point (of physics)?
/Fredrik