Comments about "Fractal Cosmology" in Wikipedia

Introduction

Introduction

The document starts with the text:

In physical cosmology, fractal cosmology is a set of minority cosmological theories which state that the distribution of matter in the Universe, or the structure of the universe itself, is a fractal across a wide range of scales

A better sentence would be:

Within cosmology, fractal cosmology is a minority theory which states that etc

The issue is the word the word fractal in this sentence. What do they mean that the distribution of matter is a fractal. They should mean that it forms a certain pattern, but that is not mentioned.
They also indicate that the structure of the universe is a fractal. What do they mean.
Next is written:

A central issue in this field is the fractal dimension of the Universe or of matter distribution within it, when measured at very large or very small scales.

Within cosmology the distribution (and evolution) of matter is an issue. But this has nothing to do with fractals.
In principle this distribution could be a fractal, but than you should explain clearly what you mean. This is dot done in the article.

1. Fractals in observational cosmology

The word observational should be removed. This section starts with:

The first attempt to model the distribution of galaxies with a fractal pattern was made by Luciano Pietronero etc. Pietronero argues that the universe shows a definite fractal aspect, etc.

The same problem as before: the details are missing. What is the fractal pattern. Next is written:

The universe has been observed to be homogeneous and isotropic (i.e. is smoothly distributed) at very large scales

That is all correct. This subject is studied by cosmology. It has nothing to do inpriciple with fractals even if the universe is non-homogeneous and non-isotropic.

2. Fractals in theoretical cosmology

In the realm of theory, the first appearance of fractals in cosmology was likely with Andrei Linde’s "Eternally Existing Self-Reproducing Chaotic Inflationary Universe" theory, in 1986. In this theory, the evolution of a scalar field creates peaks that become nucleation points which cause inflating patches of space to develop into "bubble universes," making the universe fractal on the very largest scales.

All of this is not very clear. Again what does he mean with fractals.

Since 1986, however, quite a large number of different cosmological theories exhibiting fractal properties have been proposed.

What are fractal properties? Again not clear.
At the end of the paragraph:

Both approaches suggest that the fabric of space itself is fractal, however.

You can write such a sentence, but what do you mean? It is not clear.

3. Publications

The book Discovery of Cosmic Fractals by Yurij Baryshev and Pekka Teerikorpi gives an overview of fractal cosmology, and recounts other milestones in the development of this subject. It recapitulates the history of cosmology, reviewing the core concepts of ancient, historical, and modern astrophysical cosmology

The second sententece describes the realm of cosmology and has nothing to do with fractal cosmology.
More is written about this book.

In addition, they document the work of de Vaucoleurs, Mandelbrot, Pietronero, Nottale and others in modern times, who have theorized, discovered, or demonstrated that the universe has an observable fractal aspect.

When you look to pictures of switserland covered in snow it also shows some fractal aspects. However only at a certain scale. If you go to more detail this fractal aspect disappears. The same with snow cristals.

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Comments about "Talk page:Fractal Cosmology" in Wikipedia

In this document "Fractal Cosmology" is discussed by the Wikipedia community i.e. Jonathan Dickau
To order to read the document select: http://en.wikipedia.org/wiki/Talk:Fractal_cosmology

1. Creation

The document starts with the sentence:

I have created this page as a summary of the subject, to replace the re-direct to Infinite Hierarchal Nesting of Matter, which is only one of the many examples of what can be called Fractal Cosmology. Scale Relativity, for example, has an equal claim to be the right re-direct, in my opinion. Both are limited examples as there have been so many appearances of Fractals, and Fractal-like structures, which have appeared in the study of Cosmology.

Again no detailed information about what fractals are. There is a hugh difference between fractals in mathematics (which are very specific defined) and fractal-like structures. The coast line of England is fractal like, so are the branches of a three.

16. Largest scale structure discovered by Clowes, Campusano, et al

Recent discovery by a team led by professor Roger Clowes was published in the Monthly Notes of the Royal Astronomical Society. A Press release describes the study and the paper A structure in the early Universe at z approx. 1.3 that exceeds the homogeneity scale of the R-W concordance cosmology

The document mentioned is extremely interesting but has no relation with fractals in general.
In the document twice word fractal is mentioned in relation with the concept of fractal dimension. The issue is: is the universe uniform. IMO (strictly IMO) if you observe the Univese at further and futher distances the universe should not be uniform because of evolution in galaxy creation etc. In fact when you observe you get an image of how the universe was, in the past. Strictly speaking we humans can not make any claim if you position yourself at a different position in the universe (at present) if the overall apearance will be identical.
Secondly it is also observed that there are certain structures in the universe. There are galaxy clusters en voids, which indicate non uniformity. To call those structures fractals is a misnomer.
More about this issue in:Fractal dimension as a measure of the scale of homogeneity and: On the Fractal Dimension of the Visible Universe

Next in that same paragraph:

A structure so big as the Large Quasar Group discovered by Clowes and his team, implies that Pietronero and his group were right all along, to assert that there was no reason to assume that fractality disappears at some arbitrary distance. This in fact shows that things are NOT homogeneous and isotropic beyond 100 MPc as the article currently claims, calls the veracity (accuracy,truth) of the new SDSS result into question, and affirms that Fractal cosmology is more realistic than lambda CDM.

Specific the last sentence is highly misleading.

Reflection

Physics and cosmology starts by observations, performing measurements and defining a model. This modelling is the mathematical part. The concept of fractals is purely mathematics.

The following search fractal dimension galaxy shows 4 hits.

The overall conclusion is that the importance of the concept "Fractal Cosmology" is slim.

To get an image of a fractal galaxy go here: VB FGalaxy.htm

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