Could Dark Energy be concentrated inside galactic bubbles?

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Discussion Overview

The discussion centers on the hypothesis that dark energy could be concentrated within galactic bubbles, potentially influencing the structure and expansion of the universe. Participants explore the implications of this idea in relation to observed cosmic structures, such as galactic filaments and voids, while referencing existing cosmological models and theories.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that bubble regions devoid of galaxies may contain localized concentrations of dark energy, which could push matter out and contribute to the universe's accelerating expansion.
  • Another participant cautions against assuming that qualitative similarities imply the same underlying physics, emphasizing that dark energy is typically considered uniform in the standard cosmological model.
  • A different viewpoint is presented that acknowledges the possibility of inhomogeneous dark energy, referencing scalar fields and their potential variability in space and time.
  • Some participants discuss the lambda-CDM model, arguing that it can adequately explain the formation of large-scale structures without needing to invoke localized concentrations of dark energy.
  • There is mention of the cosmological constant as a geometric property of spacetime, with some participants expressing skepticism about the idea of dark energy as a form of energy similar to electromagnetic radiation.
  • Concerns are raised regarding the predictions of the cosmological constant's value, with a call for future observational efforts to determine the nature of dark energy.

Areas of Agreement / Disagreement

Participants express differing views on the nature of dark energy, with some supporting the idea of uniformity while others propose inhomogeneity. The discussion remains unresolved, with multiple competing perspectives on the implications of dark energy in relation to cosmic structure.

Contextual Notes

Some participants reference the Millennium Simulation as evidence for the formation of galactic filaments from an initially homogeneous universe, while others highlight the complexities of dark energy and its characterization within cosmological models.

skeleton
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Bubble regions devoid of galaxies are seen giving structure to the universe; this is coincident with the observed filament structure of super-cluster complexes of galaxies.

Similar filamentation is seen in the concentration of fluid boundaries when a (soapy) foam is filled with pressurized bubbles (of air). Note, it is the internal pressure of those bubbles that maintains the bubble boundaries. Further, three or more mutual bubbles will see an accumulation of fuild along the common linear boundary (ie: a filament develops).

Could it be possible that the bubble regions between the galactic filaments are filled with localized concentration of dark energy?

As such, the dark energy would push matter (visible and dark) out of the enclosed bubble regions. Collectively the amalgam of bubbles would lead to the accelerating expansion of the the universe.

What this conjecture may serve is to explain the curious mechanism for the formation of the galactic filaments.
 
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Hi skeleton,

skeleton said:
Bubble regions devoid of galaxies are seen giving structure to the universe; this is coincident with the observed filament structure of super-cluster complexes of galaxies.

Maybe just semantics, but I wouldn't say that the great voids and walls in the distribution of galaxies "give" structure so much as they ARE the structure. In other words, the term structure here refers to inhomogeneity: matter overdensities and underdensities.

skeleton said:
Similar filamentation is seen in the concentration of fluid boundaries when a (soapy) foam is filled with pressurized bubbles (of air). Note, it is the internal pressure of those bubbles that maintains the bubble boundaries. Further, three or more mutual bubbles will see an accumulation of fuild along the common linear boundary (ie: a filament develops).

Ok, interesting, but beware of assuming that things that share some qualitative similarities are governed by the same physics.

skeleton said:
Could it be possible that the bubble regions between the galactic filaments are filled with localized concentration of dark energy?

In the standard cosmological model, dark energy is considered to be uniform (i.e. the same density everywhere). So I don't think that there are really "clumps" of dark energy.

skeleton said:
As such, the dark energy would push matter (visible and dark) out of the enclosed bubble regions. Collectively the amalgam of bubbles would lead to the accelerating expansion of the the universe.

What this conjecture may serve is to explain the curious mechanism for the formation of the galactic filaments.

The existence of the filaments (or, more precisely, the nature of the large scale structure of the universe) can be explained perfectly well within the framework of lambda-CDM cosmology, without the need to invoke localized "concentrations" of dark energy. See, for instance, something like the Millennium Simulation.
 
Thanks for your comments.

cepheid said:
In the standard cosmological model, dark energy is considered to be uniform (i.e. the same density everywhere). So I don't think that there are really "clumps" of dark energy.

I thought one accepted proposal was that dark energy could be inhomogeneous:
http://en.wikipedia.org/wiki/Dark_energy

Two proposed forms for dark energy are the cosmological constant, a constant energy density filling space homogeneously,[5] and scalar fields such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant is physically equivalent to vacuum energy. Scalar fields which do change in space can be difficult to distinguish from a cosmological constant because the change may be extremely slow.

I could imagine, in regard to my conjecture, that dark energy (concentrated inside a galactic bubble) might be a vector field that is related to the surrounding galactic filaments of visible and dark matter. The more matter aggregates along the filaments, the more dark energy (field) occurs within the coincident bubble regions.

If the dark energy (field) can act on the matter, then the matter can influence (counter reaction) the energy field. Such influence could be that the filaments of matter are, in-turn, confining the energy field into the void bubble regions. This develops a self-perpetuating mechanism that foster the evolution of larger bubble regions and large galactic filament structures.


cepheid said:
The existence of the filaments (or, more precisely, the nature of the large scale structure of the universe) can be explained perfectly well within the framework of lambda-CDM cosmology, without the need to invoke localized "concentrations" of dark energy. See, for instance, something like the Millennium Simulation.

Thanks for the tip on the Millennium Simulation. So, if I understand correctly now, that: galactic filaments can naturally form from an initial homogenous early universe (Big Bang) that had uniformly distributed matter and energy.
 
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skeleton said:
Thanks for your comments.
I thought one accepted proposal was that dark energy could be inhomogeneous:
http://en.wikipedia.org/wiki/Dark_energy

Maybe. I don't know much about this.
skeleton said:
Thanks for the tip on the Millennium Simulation. So, if I understand correctly now, that: galactic filaments can naturally form from an initial homogenous early universe (Big Bang) that had uniformly distributed matter and energy.

Yes, simulations like this show that the growth of large scale structure that is quantitatively very similar to what we observe at the present day can be explained within the framework of the Lambda CDM model (a model in which dark energy takes the simplest form of a cosmological constant). Structures like this can arise in a universe that began in a state very close to homogeneous, but with tiny fluctuations to the spacetime metric that were seeded by Inflation (or caused by something else, although Inflation is a leading theory for how they arose). Inflation took quantum fluctuations and expanded them to macroscopic size. Some of these perturbations to the metric corresponded to variations in the matter density that grew under self-gravitation with time, leading to the growth of structure.
 
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The concept of dark energy as a form of 'energy' [e.g., such as EM radiation or kinetic energy] is disfavored by most cosmologists, who prefer the term cosmological constant. The cosmological constant is a geometric property of spacetime itself and often referred to as 'curvature' to capture the geometric flavor of the idea. This is not dissimilar to the GR picture of gravity, which is the geometry, or curvature, of spacetime in the vicinity of a massive object.
 
Chronos said:
The concept of dark energy as a form of 'energy' [e.g., such as EM radiation or kinetic energy] is disfavored by most cosmologists, who prefer the term cosmological constant. The cosmological constant is a geometric property of spacetime itself and often referred to as 'curvature' to capture the geometric flavor of the idea. This is not dissimilar to the GR picture of gravity, which is the geometry, or curvature, of spacetime in the vicinity of a massive object.

I don't think most cosmologists disfavour the idea of a dynamical dark energy as opposed to a cosmological constant, mainly due to the fact that predictions of the constant's value from fundamental physics is many, many orders of magnitude higher than that observed in the universe. A lot of future observational power will be put in determining the equation of state of dark energy, and testing for a deviation from w=-1.
 

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