Space Forum / Astronomy / November 2007

In article <mt2.0-20741-1195551259@hercules.herts.ac.uk>,
eric@flesch.org (Eric Flesch) writes:

Wrong.  Flatness, or near-flatness, is something which is DEDUCED from
observations, not an assumption.  Of course, someone else might think
that this is so well established that he assumes it when calculating
something else (e.g. galaxy formation), but it is NOT assumed when
determining the cosmological parameters.

No.  There was a time, about 15 years ago, when the Einstein-de Sitter
model was assumed without good evidence.  Some people just assumed it as
a working hypothesis, but the assumption was so widespread that many
people thought there was evidence for it.  However, that was back in the
days when there were only 9 facts in cosmology.  Now, cosmology is a
data-driven science, and the current "standard model" is a result of
observations.  Note that for many people it was quite difficult to
accept the current standard model, a flat model with a positive
cosmological constant.

No, this is simply wrong.  Can you point to one example of such circular
reasoning in the literature?

One assumes arbitrary lambda and Omega, which allow for all types of
curvature, and deduces the parameters from fits to observational data.

Again, if someone is interested in, say, the equation of state of the
universe, then he might assume flatness and present his results for the
case of the flat universe, but this is because he believes that the
flatness has already been established.  However, it is not assumed for
any determination of cosmological parameters for which flatness is a
derived conclusion.

This is true for a specific redshift.  However, acceleration and
negative curvature are not degenerate.  By looking at the dependence on
redshift, one can differentiate the two, and also differentiate from
other effects which lead to faintness, like dust.  In particular, in the
flat accelerated case, above a certain redshift the objects become
brighter than "expected".

First, no-one can seriously claim that it is exactly flat, but rather
quite near flat.  There is a HUGE amount of evidence for this.  In
particular, of all the various cosmological tests, once one combines 2
or 3 to derive joint constraints, non-flat models start looking
improbable.

Like you, I find a  flat universe unappealing.
Assuming your question is rhetorical,  try:
http://xyz.lanl.gov/abs/0709.0886
"The scale and the substructure, i.e. 30 degree-radius rings and
voids in the distribution of the excursion sets around the
antipodes, reveal features of mirroring which cannot be
explained either via global (integrated Sachs-Wolf effect)
or local inhomogeneities of matter. The anomaly is also
not close to the apex of the CMB dipole arisen due to the
motion of the Earth i.e. of the detector. This mirroring
effect can be the first empirical signature of a Universe
with compact topology, potentially of either curvature."

and
"The mirrored structures cannot be explained simply via inte-
grated Sachs-Wolf effect or via nearby matter anomalies10, i.e.
either by means of global or local inhomogeneities. Mirrored fea-
tures however, would be expected in a Universe with a compact
topology; for examples of hyperbolic and other spaces see e.g.
ref.[11,12]. If we, indeed, deal with the first empirical signature
of a compact space, this result and this method of analysis can
open a new path towards overcoming the curvature/topology de-
generacy and revealing the genuine shape of the Universe."

These references were originally intended as a response to a Sam
Wormley post:
http://groups.google.com/group/sci.physics/msg/3a3b73bb43d99816

John

That's an _extremely_ strange thing to believe about
mathematics and mathematical models. Any old piece
of nonsense most likely can be mathematically
modeled in a self-consistent way. For example a
model could possibly be created under which
Burroughs Barsoom stories were on a planet that had
breathable air, perhaps by earlier events colliding
most of the Oort cloud with Mars leaving only the
current remnant of snowballs.  That model does not
make the real Mars "habitable" as usually
understood.

More than that, probably (almost certainly) a
countable infinity of "valid mathematical models"
could be created, of which the ones
realizable/realized in the physical universe would
be a subset of measure zero.

You certainly shouldn't let such a mindset drive you
to speculate that the received wisdom of cosmology
considered together with all its supporting evidence
is incorrect _merely because_ other arrangements for
some universe somewhere can be mathematically
modeled. That way lies madness.

xanthian.

Thus spake Eric Flesch <eric@flesch.org>

There is more to it than that. The spectrum of the "wrinkles" can be
analysed. The result can be related to the curvature of the universe.
There are a few anomalies, but basically this is a solid bit of work
based on gtr as we understand it.

Not really, but it does rest on an untested assumption in gtr and one we
already know is wrong because Einstein pointed out an inconsistency.
Classical electromagnetism does not mesh with gtr, in that our
description of a classical e.m. wave from a distant source is not
consistent with the description of the same e.m. wave as given by an
observer close to that source. We also know that e.m. waves are more
accurately treated in the quantum domain. We ought to assume that the
interpretation of all measurements based on redshift from distant
sources is likely to be wrong. I have done a number of tests within the
galaxy which show that this is in fact the case, so I do not think much
weight should be put on the analysis of WMAP.

As far as I know, WMAP is the only evidence.

Regards

Thus spake Eric Flesch <eric@flesch.org>

You are wrong. Before the WMAP/Boomerang data, and before the Supernova
data, there was no reason to assume a flat universe. FRW models come in
nine major types, with a couple of subcategories thrown in for good
measure. If it had not been for the missing matter problem, and the
timescale problem, I would think theoretical prejudice was most strongly
in favour of a closed positive curvature model.

Shouting does not work. You have at least to start with a rigorous data
analysis in the context of a valid cosmological model. At the moment the
only models which are even reasonable are the FRW models based in
standard gtr. The outcome of the data analysis in those models is quite
clear, and gives a flat model with accelerating expansion, dark matter
and dark energy.

Of course that does not mean that those are the only possible models. We
know that gtr needs a fix to make it compatible with quantum theory and
even with classical electromagnetism. We also know there are a range of
astronomical measurements, e.g. MOND, Pioneer, lensing profiles, which
do not make sense in the standard model. Imv the only place where any
sort of fix or adjustment is reasonable, or perhaps even possible is the
connection. That was also Einstein's view. The result of replacing the
affine connection with the teleconnection is a closed universe, no
missing matter, no accelerating expansion, no dark matter, no dark
energy, no MOND, and an explanation for Pioneer acceleration.

[Mod. note: can I remind posters of the speculativeness criterion for
s.a.r. postings -- it would be preferable not to assert that
non-standard models explain phenomena without some qualification (or
at least a reference to publications where these claims can be
examined). Thanks -- mjh]

Regards

Thus spake Oh No <NotI@charlesfrancis.wanadoo.co.uk>

The fact that Einstein pointed out the inconsistency between gtr and
classical electromagnetism nearly eighty years ago should need no
reference, even if it has been studiously ignored in standard cosmology.
This being the case you might perhaps consider that standard models are
at least as speculative at any based on the removal of that
inconsistency, and remember your own guideline that argument from
authority, in this case the authority being peer reviewed publication,
is not a proper scientific criterion. Mathematical rigour, otoh is.

[Mod. note: a criterion might be to consider whether a reader new to the
newsgroup could be expected to figure out what you're talking about
and what its status is. They can do that for the standard model by
picking up an undergraduate cosmology textbook: non-standard ideas
require more explanation and perhaps more caveats -- mjh]

I have previously given reference to papers which can be examined.

gr-qc/0508077
A Relational Quantum Theory Incorporating Gravity

gr-qc/0604047
Does a Teleconnection between Quantum States account for Missing Mass,
Galaxy
Ageing, Lensing Anomalies, Supernova Redshift, MOND, and Pioneer
Blueshift?

I will not say they are perfect, and am working on a new and more
accessible account. Publication will depend on such things as finding a
reviewer who does not think, for example, that if a curve has the same
gradient as its tangent at a point, then that curve has that gradient
everywhere, and is thus a straight line.

More strictly, I should say, that if a manifold has the same metric as
its tangent space at a point, then the manifold has constant metric and
is flat; for a one dimensional manifold, this reduces to the previous
statement. This appears to be a case of that disease in applied
mathematics where people glibly write down, "let f=f(x)" instead of "let
f:x->f(x)", not realising that they have just said, let a function be
equal to one of its values. Similarly general relativists typically talk
of tensor fields (being tensor valued functions on coordinate space) as
tensors. This being so prevalent these days, I am starting to despair of
finding anyone who actually understands the subject.

Likewise peer reviewed publication of the empirical evidence appears to
depend on finding a reviewer who does not confess that he doesn't know
the difference between radial velocity and the component of velocity
parallel to an axis, or one who doesn't say the results must imply that
systematic errors on Hipparcos were more than four times greater than
published statistical errors, or other similar nonsense.

Regards

Thus spake Eric Flesch <eric@flesch.org>

Perhaps, but it seems extraordinarily speculative to postulate inflation
during a time of the universe when we have every reason to believe, from
gtr, from quantum theory, and even from observation of isotropy, that
the very idea of spacetime structure had broken down and ceased to make
sense.

Regards

Thus spake Kent Paul Dolan <xanthian@well.com>

The ordering I use is one of logic, not of time or causality. Before we
can talk of spacetime we must be able to talk of the possibility of
carrying out measurements of time and position. At the very least, there
must exist the kind of physical process which enable us to discuss time
and position coordinates, repeating processes from which clocks can be
made, exchange of photons and so forth. The processes which give rise to
spacetime structure clearly break down at a singularity; that is the
very meaning of a singularity. What we cannot say with any level of
certainty is when or where, in the vicinity of a singularity it becomes
meaningful to talk of space-time structure.

Spacetime is a four dimensional structure. One cannot have one time in
the universe without the existence of all other times. It is no more
logically correct to say that one time results from another than to say
the second results from the first.

Efforts today are largely directed against understanding the foundations
of physical theory. Nothing comes of thinking about measurement the way
Einstein did, or Von Neumann did, they say. Perhaps nothing comes of it
because effort is directed away from it. Without first understanding
foundations we have little prospect of understanding fundamental
physical processes, and we then have little prospect of understanding
the processes in the big bang. What we are left with is positivism and
efforts in metaphysics in the strange hope that if you invent a
mathematical structure it might produce physical results.

Regards

Thus spake Kent Paul Dolan <xanthian@well.com>

Please study Einstein's thought and work.

You have no empirical basis for such an assertion. You should study
Einstein's thought and work.

Certainly we have to have a clock to measure time before we can even
think of measuring spacetime, but I suspect you are talking of
discussing time in the absence of a clock. That may be done quite
regularly, but it is metaphysics.

I can only ask you to think deeply about the assertion, in the manner in
which Einstein did. It is an empirical fact, with vital consequences
shown in the 1905 paper, and has no need of further support.

Spacetime is what we observe. Your response is itself metaphysics and
muddle talk.

Science says neither. It does say that logical deduction about what
exists should be based on observation, not on metaphysics.

Please distinguish your own lack of understanding from my confusion.

Please study the mathematical definition of a singularity.

Regards

Thus spake Eric Flesch <eric@flesch.org>

If you do not understand the math, you are in no position to laugh.

Not. A flat universe is only one possibility among FRW cosmologies.

Not. Inflation is a break from a straight FRW cosmology, one which I
don't even think makes sense within the context of gtr and FRW
cosmology.

The edifice, as you call it, has been constructed by mathematicians
whose interest and strange mental abilities mean that constructing
things with extreme accuracy is what they do. If you don't follow the
maths, you are in no position to knock it.

Not. It is based on general and for the most part, almost undeniable
principles. If you wish, for example, to throw away the general
principle of relativity, that local laws of physics are universally the
same, then you throw away our ability to do science at all.

Actually, given how difficult it is to produce a black body spectrum
from physical processes, it is quite a big deal.

Those are not papers which build up the FRW cosmology, but ones which
derive results assuming results from the particular FRW cosmology which
fits observation.

Everyone, I would say. Mostly they understand it.

If you don't understand the maths, you are in no position to make such
an accusation. It is quite unfounded. FRW cosmology is based on the
general principle of relativity, together with assumptions of
homogeneity and isotropy (the matter distribution is everywhere roughly
the same and shows no directional preferences), plus Weyl's postulate,
we can model the motion of galaxies in the manner of a perfect fluid.
There is not a lot there which you can meaningfully change, though
people do make changes, and sometimes manage to show that the changes
conflict with observation.

The only things I can think of reasonably open to change are

a) whether the cosmological constant is actually constant. This is
subject to empirical testing by quite a number of groups using different
methods. So far no indications that it is not constant.

b) the affine connection, which Einstein tried to change. So far no
accepted results have come, but I believe my own research does change it
successfully. The result is still an FRW cosmology, but one which is not
flat, and in which inflation has no part.

Regards