Drakkith said:
Sorry, unless you can provide a solid reference that space is fluidic then we cannot discuss it. And no, the article you linked is not saying that.
The following article "reduces to GR coupled to an incompressible fluid."
'Empty Black Holes, Firewalls, and the Origin of Bekenstein-Hawking Entropy'
http://arxiv.org/abs/1212.4176
"But why an incompressible fluid? The reason comes from an attempt to solve the (old) cosmological constant problem, which is arguably the most puzzling aspect of coupling gravity to relativistic quantum mechanics [13]. Given that the natural expectation value for the vacuum of the standard model of particle physics is ∼ 60 orders of magnitude heavier than the gravitational measurements of vacuum density, it is reasonable to entertain an alternative theory of gravity where the standard model vacuum decouples from gravity. Such a theory could be realized by coupling gravity to the traceless part of the quantum mechanical energy-momentum tensor. However, the consistency/covariance of gravitational field equations then requires introducing an auxiliary fluid, the so-called gravitational aether [14]. The simplest model for gravitational aether is an incompressible fluid (with vanishing energy density, but non-vanishing pressure), which is currently consistent with all cosmological, astrophysical, and precision tests of gravity [15, 16]:
__3__
32πGN Gμν = Tμν − Tα gμν + Tμν ,
Tμν = p (uμ uν + gμν ), T μν;ν = 0,
where GN is Newton’s constant, Tμν is the matter energy momentum tensor and Tμν is the incompressible gravitational aether fluid. In vacuum, the theory reduces to GR coupled to an incompressible fluid."
The following article describes a 'back reaction' associated with the "fluidic" nature of space itself.
'An Extended Dynamical Equation of Motion, Phase Dependency and Inertial Backreaction'
http://arxiv.org/abs/1208.3458
"We hypothesize that space itself resists such surges according to a kind of induction law (related to inertia); additionally, we provide further evidence of the “fluidic” nature of space itself."
The following article describes the "space-time ideal fluid approach from general relativity."
'Fluidic Electrodynamics: On parallels between electromagnetic and fluidic inertia'
http://arxiv.org/abs/1202.4611
"It is shown that the force exerted on a particle by an ideal fluid produces two effects: i) resistance to acceleration and, ii) an increase of mass with velocity. ... The interaction between the particle and the entrained space flow gives rise to the observed properties of inertia and the relativistic increase of mass. ... Accordingly, in this framework the non resistance of a particle in uniform motion through an ideal fluid (D’Alembert’s paradox) corresponds to Newton’s first law. The law of inertia suggests that the physical vacuum can be modeled as an ideal fluid, agreeing with the space-time ideal fluid approach from general relativity."
The following article describes a modification of gravity which includes an incompressible fluid.
'Phenomenology of Gravitational Aether as a solution to the Old Cosmological Constant Problem'
http://arxiv.org/abs/1106.3955
"One proposal to address this puzzle at the semi-classical level is to decouple quantum vacuum from space-time geometry via a modification of gravity that includes an incompressible fluid, known as Gravitational Aether. In this paper, we discuss classical predictions of this theory along with its compatibility with cosmological and experimental tests of gravity. We argue that deviations from General Relativity (GR) in this theory are sourced by pressure or vorticity."
This is not correct. I have already linked to you what the halo is. By your definition the Milky Way's arms are curved spacetime, as is everything since curved spacetime exists everywhere. They may be in curved spacetime, but it itself does not make up objects or regions. (Other than possibly a black hole)
The matter which the Milky Way's arms consist of is not curved spacetime. The matter which the Milky Way's arms consist of curves spacetime, as does all of the matter the Milky Way consists of.
