Shell structure topological defects as substitute for dark matter

In summary, the study explores the potential of shell structure topological defects as an alternative to dark matter in explaining cosmic phenomena. It posits that these defects, which can occur in various physical systems, might account for gravitational effects attributed to dark matter, offering a new perspective on the universe's mass composition and the behavior of galaxies. The research suggests that understanding these topological defects could lead to insights into the fundamental nature of matter and the structure of the cosmos.
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Ranku
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Recently a paper was published 'The binding of cosmological structures by massless topological defects' which proposes how 'massless' shells can bind galaxies in lieu of dark matter. There are a few basic technical details I am looking to clarify:

1. It is mentioned in the paper that an attractive force is exerted on a test particle riding a zero-mass shell. So, is the basic difference between Newtonian gravitational force and gravitational force in a shell, that in which the former propagates through spacetime, while the latter is entirely localized in spacetime?

2. The gravitational force decreases as 1/r in a massless shell. In order to produce a flat rotation curve in galaxies, does that therefore require each larger concentric shell to have greater mass, so that the gravitational force of the shells can act with the same magnitude upon stars at all distances in galaxies?

3. The paper seeks to offer an alternative to dark matter. But could it be also possible that dark matter particles are themselves miniature versions of massless shells?
 
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Link appears to go to a file on your desktop, not the paper.
 
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Ibix said:
Link appears to go to a file on your desktop, not the paper.
Oops: corrected.
 
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Ranku said:
Recently a paper was published 'The binding of cosmological structures by massless topological defects' which proposes how 'massless' shells can bind galaxies in lieu of dark matter.
This paper appears quite "hand wavy" to me. The proposed spherical shells are massless only because they combine shells of ordinary matter with shells of negative mass density, i.e., shells of exotic matter. Given the novel properties of gravitational systems incorporating exotic matter (stable wormholes, Alcubierre warp drive, etc.), it's no surprise that one can arrange to get a galactic 1/r potential this way. But as far as I can see, the author offers no explanation for the source of this exotic matter.
 
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FAQ: Shell structure topological defects as substitute for dark matter

What are shell structure topological defects?

Shell structure topological defects refer to specific configurations of matter that arise in certain physical systems, particularly in condensed matter physics. These defects can be visualized as irregularities or disruptions in the ordered arrangement of particles, which can occur in materials with a shell-like structure. They can take various forms, such as dislocations or vortices, and their properties can be studied to understand complex phenomena in material science and cosmology.

How do shell structure topological defects relate to dark matter?

Shell structure topological defects are proposed as a potential substitute for dark matter by suggesting that these defects could account for some of the gravitational effects attributed to dark matter. In this context, the defects may possess mass and interact gravitationally, thus influencing the motion of galaxies and galaxy clusters in a manner similar to dark matter. This idea stems from the need to explain the observed gravitational phenomena without invoking the existence of unseen dark matter particles.

What evidence supports the idea that topological defects could act as dark matter?

Evidence supporting the idea that topological defects could serve as a substitute for dark matter includes theoretical models that demonstrate how these defects can have mass and interact gravitationally. Additionally, certain astrophysical observations, such as the distribution of galaxies and the cosmic microwave background radiation, can be explained using models that incorporate topological defects. However, direct observational evidence is still limited, and further research is needed to validate this hypothesis.

What are the implications of using topological defects as dark matter?

If topological defects are confirmed to be a viable alternative to dark matter, it could significantly alter our understanding of the universe's composition and evolution. This could lead to new insights into fundamental physics, including the nature of gravity and the behavior of matter at extreme conditions. It may also impact cosmological models, potentially leading to a reevaluation of the structure formation in the universe and the dynamics of cosmic expansion.

What are the current challenges in studying shell structure topological defects as dark matter?

Current challenges in studying shell structure topological defects as dark matter include the difficulty in detecting these defects and distinguishing their effects from those of traditional dark matter models. Additionally, the theoretical framework surrounding topological defects is still being developed, and more empirical data is needed to establish their properties and interactions. Researchers are also working to reconcile these models with existing observations and to explore the implications for particle physics and cosmology.

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