Whither Goest CMB Isotropy?

[[Mod. note -- Due to a complicated chain of mishaps/mistakes on my
part, all References: headers are missing from this article. I apologise
to the author and other readers for this, and for the ensuing loss of
threading in many newsreaders.
-- jt]]

In article mt2.1-19091-1230581828@silver, Knecht
writes:

Typo in subject line corrected. Paragraph 2 gives some background
concepts relating to the issues under discussion.

I am reading a very new preprint (19 Dec 2008) put on the arxiv.org
site. It is designated arxiv:0812.3795v1 and it is written by F. K.
Hansen, A.J. Banday, H.K. Erikson and P. B. Lilje.

The basic issue is whether the observable universe is homogeneous
(appears isotropic) or whether the observable universe shows evidence
for discrete fractal organization from the smallest to the largest
observable scales.

I haven't yet read the paper (though I know and/or have met some of the
authors), but my guess is that they don't mention "discrete fractal
organization". You make it sound like a dichotomy: EITHER it's
homogeneous OR there is "discrete fractal organization".

Also, the universe can appear isotropic without being homogeneous if we
occupy a special position.

Conventional astrophysics has tended to favor the
assumption of strict large-scale homogeneity, and some theorists
insist that the Universe simply must be homogeneous (received
wisdom?). The Cosmic Microwave Background (CMB) has always been cited
as the gold standard proof of large-scale isotropy/homogeneity and
previous measurements were arguably consistent with the assumption of
large-scale homogeneity.

Ah, but deviations from isotropy in the CMB would indicate that
fundamental inhomogeneity, and the possibility of a fractal Universe,

Non-sequitur.

I wonder if fractal paradigms might be included in this search for an
explanation?

People might consider them had the discrete fractal paradigm made some
quantitative predictions which could in principle be falsified.

Phillip Helbig wrote:
Knecht writes:

The basic issue is whether the observable
universe is homogeneous (appears isotropic) or
whether the observable universe shows evidence
for discrete fractal organization from the
smallest to the largest observable scales.

I haven't yet read the paper (though I know and/or
have met some of the authors), but my guess is
that they don't mention "discrete fractal
organization". You make it sound like a
dichotomy: EITHER it's homogeneous OR there is
"discrete fractal organization".

There seems to be an issue ongoing for some number
of years here of a theory fuzzy in all its
details for which _every_ anomalous observation by
astronomers is seized upon as additional evidence
for that theory, without any attempt to integrate
it in any coherent way into that theory.

I'm fairly sure that's not a paradigm used by
successful scientists.

People might consider them had the discrete
fractal paradigm made some quantitative
predictions which could in principle be falsified.

Well, "discrete fractal organization" makes one
immediate prediction which is easily falsified.

"Fractal" means what it says, and if the universe
were "fractal", that would be observable at local
scales, and indeed down to atomic scales and below.

No such local observations exist, therefore
"fractal" is not an appropriate description of the
universe.

Pretending that "fractal" has some other meaning
than the one it has in mathematics doesn't seem
likely to lead anywhere useful.

We already know at what scales "discrete" would have
to hold, and that is at anything above the Planck
length.

Terminology that matches what the observations do
seem to support already exists and is in use, as
e.g. "anisotropic". There is not any obvious reason
to try to convey this direct observable and those
like it into some magical and unspecified realm
outside of math, physics, and astronomy.

xanthian.

On Jan 3, 1:33Â*pm, Phillip Helbig---remove CLOTHES to reply
wrote:

I wonder if fractal paradigms might be included in this search for an
explanation?

People might consider them had the discrete fractal paradigm made some
quantitative predictions which could in principle be falsified.

The Discrete Fractal Paradigm has made multiple definitive predictions
(defined as predictions that are unique, testable, quantitative and
nonadjustable) in peer-reviewed literature. Below is a sampling.

International Journal of Theoretical Physics, 12(12), 1503-1532
(1989): 9 definitive predictions.

[[Mod. note -- This citation appears to be incorrect: the IJTP web
site says that volume 12 was published in 1975, and did not contain
a page 1503. scholar.google.com suggests that the correct reference
might be to volume 35 number 12 (December 1996), pages 2475-2481.
Alas, Springer doesn't believe in Open Access, so an institutional
subscription (or $$$) is needed to read this paper.
-- jt]]

Fractals, 10(1), 27-38 (2002): Dark matter predictions, results:
stellar-mass black holes = many, dark matter particles = 0.

arXiv:astro-ph/0102285, currently being reviewed, discusses a critical
and definitive prediction of the DFP that the lowest mass M-dwarf
stars will have an anomalously low incidence of planetary companions.

The website www.amherst.edu/~rloldershaw discusses these and many more
quantitative predictions by which the Discrete Fractal Pradigm may be
unambigously tested.

I am still hopeful that FGST, and further microlensing surveys, will
give us new information on stellar-mass black holes in the Galaxy. I
eagerly await LHC start-up and predict no discovery of dark matter
particles, beyond the usual false-positives.

Yours in science,
Knecht
www.amherst.edu/~rloldershaw

On Jan 4, 1:19Â*pm, Knecht wrote:
International Journal of Theoretical Physics, 12(12), 1503-1532
(1989): 9 definitive predictions.

[[Mod. note -- This citation appears to be incorrect: the IJTP web
site says that volume 12 was published in 1975, and did not contain
a page 1503. Â*scholar.google.com suggests that the correct reference
might be to volume 35 number 12 (December 1996), pages 2475-2481.
Alas, Springer doesn't believe in Open Access, so an institutional
subscription (or $$$) is needed to read this paper.
-- jt]]



Alas, we are both wrong, I copied a typo from my website and you cited
a different paper.

The correct reference is, I hope, IJTP, vol.28, No.12, 1503-1532
(1989). It is a companion piece to Part 1 (IJTP, 28(6), 669-694 (1989)

Both papers are PRINTED IN FULL in the "Selected Papers" section of
www.amherst.edu/~rloldershaw . NO CHARGE; AVAILABLE 24/7.

Sorry about that incorrect vol. #,
Knecht
www.amherst.edu/~rloldershaw

On Jan 4, 1:00=A0pm, Kent Paul Dolan wrote:

"Fractal" means what it says, and if the universe
were "fractal", that would be observable at local
scales, and indeed down to atomic scales and below.

No such local observations exist, therefore
"fractal" is not an appropriate description of the
universe.


Perhaps the term "fractal" is off-putting to you, so let's switch to
the synonymous concept of self-similar structure. Self-similarity
strictly implies hierarchical organization and for the moment we do
not need to worry about whether the self-similarity is discrete or
quasi-continuous.

Please go to www.amherst.edu/~rloldershaw, click on "Selected Papers"
and choose the essay "Nature Adores Self-Similarity". As you read this
informal essay, jot down a list of the specific examples of physical
self-similarity observed in nature and reported in scientific books
and journals by other scientists.

When you are done with the essay, you will have a written list of
about 80 examples of self-similar structures in the local observable
universe. When your intuition tries to tell you that nature is not
fractal, this list and nature will help to improve your vision.

Note also that nonlinear dynamical systems are ubiquitous in nature.
Fractal phenomena (see period-doubling, strange attractors, etc.,
etc.) are inimately linked to NLDS.

It's a fractal world, my friend. Enjoy!

Yours in science,
Knecht
www.amherst.edu/~rloldershaw

Thus spake Knecht
On Jan 4, 1:00=A0pm, Kent Paul Dolan wrote:

"Fractal" means what it says, and if the universe
were "fractal", that would be observable at local
scales, and indeed down to atomic scales and below.

No such local observations exist, therefore
"fractal" is not an appropriate description of the
universe.


Perhaps the term "fractal" is off-putting to you, so let's switch to
the synonymous concept of self-similar structure.

That is not synonymous. Classical space time is self similar, but not
fractal, whereas a fractal universe can be mooted to apply on very small
scales on which the scale of discreteness cannot be observed, but not on
large scales where it is observably false.



Regards

--
Charles Francis
moderator sci.physics.foundations.
charles (dot) e (dot) h (dot) francis (at) googlemail.com (remove spaces and
braces)

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