Facts against BB Theory

On Tuesday, April 29, 2014 4:17:10 PM UTC-4, Robert L. Oldershaw wrote:

What would have been truly spectacular
is if some theory had actually *predicted*
the vast filamentary cosmic web/void
structure before there were observations
that revealed this important cosmological
clue.

My impression is that observations and computer simulations of the
large scale void structure have developed concurrently over the past
10 years. While the simulations have improved, due to both faster
computers and improved algorithms, the input physics ingredients have
not changed and are not subject to a theorist's whim.

But if you would like a very clear example of a theoretical prediction
of standard cosmology followed by observational confirmation, then
look at the closely related topic of baryon acoustic oscillations.
Quoting from the discovery paper of Eisenstein et al (2005,
http://arxiv.org/abs/astro-ph/0501171 ) on the observed large-scale
galaxy correlation function:

"We find a well-detected peak in the correlation function at 100h^{-1}
Mpc separation that is an excellent match to the predicted shape and
location of the imprint of the recombination-epoch acoustic
oscillations on the low-redshift clustering of matter. This detection
demonstrates the linear growth of structure by gravitational
instability between z=1000 and the present and confirms a firm
prediction of the standard cosmological theory. "

These first observations have since been confirmed and much improved (
http://www.sdss3.org/surveys/boss.php ) and are in excellent agreement
with the oscillations observed in the microwave background. --Wayne

On Thursday, April 24, 2014 4:02:19 AM UTC-4, Robert L. Oldershaw wrote:


Matt Strassler's informed discussion of conventional
cosmological thinking provides an open-minded starting
point for useful discussions.
http://profmattstrassler.com/2014/03...-are-reliable/

I agree that this is an excellent discussion of the uncertainties in
big bang cosmology. In particular, what he classifies as "very high
confidence" results (green zone, 1 second after the big bang)
includes nearly all of classical big-bang cosmology, e.g. that the
universe is ~13.7 billion years old, that the light elements were
formed in primordial nucleosynthesis, that the cosmic microwave
background is a relic of the hot early universe that has since cooled
by expansion.

The orange zone (t ~ 10^-35 seconds) includes the period of cosmic
inflation and is more speculative. While the inflation models can
provide an excellent fit of the angular spectrum of the cosmic
microwave background, there are other models (e.g. the ekpyrotic
universe) that can also do this. But if the recent BICEP2 observations
are confirmed, then it may rule out all alternatives to inflation, and
this regime may be moved to the green zone.

Any theory discussing events before inflation are currently in the red
zone (scientific guesswork) both because that regime is currently
inaccessible to observations, and because we are not certain of what
physics applies. This includes ideas that the universe arose from
quantum fluctuations or a multiverse. Strassler notes individual
scientists may mean different things by the term "big bang" and some
don't consider the events before cosmic inflation as part of the big
bang. --Wayne

In article , wlandsman
writes:

What would have been truly spectacular
is if some theory had actually *predicted*
the vast filamentary cosmic web/void
structure before there were observations
that revealed this important cosmological
clue.

My impression is that observations and computer simulations of the
large scale void structure have developed concurrently over the past
10 years.

Right, although the filament-void structure was first seen in the real
universe, not in simulations.

While the simulations have improved, due to both faster
computers and improved algorithms, the input physics ingredients have
not changed and are not subject to a theorist's whim.

Right. Dark-matter simulations are well understood and there are really
no free parameters. Actually, what makes them relatively easy is the
lack of other interactions, i.e. only gravity.

But if you would like a very clear example of a theoretical prediction
of standard cosmology followed by observational confirmation, then
look at the closely related topic of baryon acoustic oscillations.
Quoting from the discovery paper of Eisenstein et al (2005,
http://arxiv.org/abs/astro-ph/0501171 ) on the observed large-scale
galaxy correlation function:

"We find a well-detected peak in the correlation function at 100h^{-1}
Mpc separation that is an excellent match to the predicted shape and
location of the imprint of the recombination-epoch acoustic
oscillations on the low-redshift clustering of matter. This detection
demonstrates the linear growth of structure by gravitational
instability between z=1000 and the present and confirms a firm
prediction of the standard cosmological theory. "

Essentially all of the features in the CMB spectrum were first derived
theoretically then observed. There are only about 6 free parameters.
One cannot fit anything with 6 parameters, so there is real constraint.
Also, the derived values agree with other methods of measuring the same
parameters.

In article , wlandsman
writes:

Matt Strassler's informed discussion of conventional
cosmological thinking provides an open-minded starting
point for useful discussions.
http://profmattstrassler.com/2014/03...-are-reliable/

I agree that this is an excellent discussion of the uncertainties in
big bang cosmology. In particular, what he classifies as "very high
confidence" results (green zone, 1 second after the big bang)
includes nearly all of classical big-bang cosmology, e.g. that the
universe is ~13.7 billion years old, that the light elements were
formed in primordial nucleosynthesis, that the cosmic microwave
background is a relic of the hot early universe that has since cooled
by expansion.

Right. So the various newsgroup pundits who claim that the big bang
never happened, that Eric Lerner is right and Ned Wright is wrong and so
on are disputing what Strassler (and practically everyone) considers to
be known with "very high confidence".

The orange zone (t ~ 10^-35 seconds) includes the period of cosmic
inflation and is more speculative. While the inflation models can
provide an excellent fit of the angular spectrum of the cosmic
microwave background, there are other models (e.g. the ekpyrotic
universe) that can also do this. But if the recent BICEP2 observations
are confirmed, then it may rule out all alternatives to inflation, and
this regime may be moved to the green zone.

At least this is a reasonably robust prediction of inflation and
confirmation of the BICEP2 result would dramatically increase confidence
in inflation. The scalar-to-tensor ratio R was firmly predicted long
before there were even any hints as to what it might be observationally.

On Thursday, May 1, 2014 8:11:54 AM UTC-4, Phillip Helbig---undress to reply wrote:
In a sense, this is what happened. The theory is Newtonian gravitation.
It just happened that observations were more advanced than computing
technology, so they were discovered before they were simulated and hence
predicted from the theory. You can be sure that Newtonian gravity was
not modified in any way in order to fit the observations.

-------------------------------------------------

In 1910 Newtonian gravitation had been
around for a long time. Ask yourself a
simple question: Did Newtonian theory
predict that matter would be organized
into "island universes" we call galaxies?

No! Not a chance!

Neither did Newtonian ever predict that
the larger scale distribution of matter
would be organized into a vast cosmic
web of filaments and huge voids.

I think the type of post facto reasoning
in the claims made above is common, but
unscientific.

Ask yourself another question: Was de Vaucouleurs'
Superclustering of galaxies welcomed with open arms?

Just the opposite! He had to battle to convince
people of the hierarchical organization of
galactic systems.

I am becoming increasingly aware of how
physicists deceive themselves, and yet
they seem virtually oblivious to the fact
that they are doing so.

This is why definitive predictions [prior,
feasible, quantitative, non-adjustable
and unique to the theory being tested] are
so important. It's a "lost art" but it is
the only thing that keeps us from deluding
ourselves.

Le 28/04/2014 22:13, wlandsman a ecrit :
For example, Sutter et al. (2013,http://arxiv.org/abs/1310.7155) find
nearly 1000 voids in the Sloan survey, and compare these with their
cosmological simulations, and conclude: "Our void abundances,
ellipticity distributions, and radial profiles all indicate that voids
in theory have the same sizes, shapes, and interior contents as
observed voids."

Thanks for this reference Mr Landsman. Sorry for the delay in answering
but it took me quite a few readings to start understanding this text and
its context. :-)

This paper has two parts. The first is a study of the voids as such, and
a method of finding those voids. This part looks ok to me, even if there
is a heated discussion between astronomers about Sutter's catalog
(Nadathur and Hotchkiss, ArXiv 1310.2791, and the answer of Mr Sutter in
ArXiv 1310.5067) There is also a web site about voids
(http://www.cosmicvoids.net).

This is quite interesting but nowhere are the explanations for the
questions I asked.

The second part (that you make reference as a proof for BB theory) is
that the catalog is very similar to orthodox cosmology simulations
realized in software.

And this is where I disagree with the author of the paper. I read
paragraphs like this, for instance:

quote
In Figure 7 we compare the number function of voids in the CMASS Mid
data sample to all our mocks. First, the unmasked N-body Mock simulation
hosts roughly three times as many voids per unit volume than the data,
even though they have similar galaxy populations. This occurs at all
scales, though there are approx 4 times as many small voids in the
unmasked mock as in the data.
end quote

So, the raw data doesn't at all fit with the simulation. Then, he
applies his mask, what is probably OK if the mask used is the SAME as
the mask he used with his data. But I did not find that sentence in the
paper and can't be sure of that fundamental fact.

Besides that, a few lines below, the paper says...
quote
As found in Sutter et al. (2013), the best match to voids in low-density
galaxy surveys comes from adjusting the "void parameter" Dv to -0.015.
end quote

There we start massaging the data so that it fits whatever we want it to
fit, sorry. Why is the simulation a low density survey? Maybe I did not
understand everything but the article is vague here.

Let's go on:

quote
While the number function roughly agrees with the order of magnitude of
the full N-body Mock void population, it overestimates the number of
voids in all size ranges considered here. It also does not fall off as
steeply as in the mocks, though this might be influenced by
finite-volume effects.
end quote

So, he must acknowledge that the data just DOESN'T FIT!

Next sentence after acknowledging that?

quote
Still, the correspondence of these curves shows that theoretical
modeling can qualitatively match unmasked void populations, but further
adjustments must be made to match void statistics from masked volumes.
end quote

Excuse but there is NO WAY that THIS can be presented as an exact
correpondence between the data and the BB models!!!
The two sentences: one that says the data doesn't fit, and the very next
one where he concludes that the survey supports BB theory just DO NOT
MAKE SENSE!

In the surface the conclusions of the paper are very "orthodox". The
devil is in the details however. And this repeats itself in each paper
that is supposed to "prove" BB theory.

Thanks again for your answer.

jacob

In article , "Robert L.
Oldershaw" writes:

In 1910 Newtonian gravitation had been
around for a long time. Ask yourself a
simple question: Did Newtonian theory
predict that matter would be organized
into "island universes" we call galaxies?

No! Not a chance!

The fact is that no-one had calculated it. Such computing power did not
become available until the late 1970s.

While a prediction is more emotionally satisfying than a postdiction,
one shouldn't put too much weight on historical contingency which
determined whether theory or observation was first.

This is why definitive predictions [prior,
feasible, quantitative, non-adjustable
and unique to the theory being tested] are
so important. It's a "lost art" but it is
the only thing that keeps us from deluding
ourselves.

Several have been mentioned in this thread, such as the features in the
CMB spectrum.

In article , jacob navia
writes:

The second part (that you make reference as a proof for BB theory) is
that the catalog is very similar to orthodox cosmology simulations
realized in software.

And this is where I disagree with the author of the paper. I read
paragraphs like this, for instance:

quote
In Figure 7 we compare the number function of voids in the CMASS Mid
data sample to all our mocks. First, the unmasked N-body Mock simulation
hosts roughly three times as many voids per unit volume than the data,
even though they have similar galaxy populations. This occurs at all
scales, though there are approx 4 times as many small voids in the
unmasked mock as in the data.
end quote

Excuse but there is NO WAY that THIS can be presented as an exact
correpondence between the data and the BB models!!!
The two sentences: one that says the data doesn't fit, and the very next
one where he concludes that the survey supports BB theory just DO NOT
MAKE SENSE!

In the surface the conclusions of the paper are very "orthodox". The
devil is in the details however. And this repeats itself in each paper
that is supposed to "prove" BB theory.

In EACH paper? In EACH AND EVERY PAPER? This seems to be an
exaggeration on your part.

You seem to be throwing the baby out with the bathwater. What is "the
big-bang theory"? It is the idea that the universe is expanding from an
earlier state which was very hot and very dense. During this expansion,
structure evolves. This is a complicated process and not all details
are understood. When there is a discrepancy between theory and
observation, you a) automatically conclude that the theory is wrong
(observations can also be wrong, misinterpreted, misunderstood
etc---witness all the wrong measurements of the Hubble constant, for
example) and b) don't think that just the details of structure formation
are wrong but want to chuck out the entire big-bang theory, essentially
ignoring all other evidence in support of it.

In article , Phillip
Helbig---undress to reply writes:

In article , "Robert L.
Oldershaw" writes:

In 1910 Newtonian gravitation had been
around for a long time. Ask yourself a
simple question: Did Newtonian theory
predict that matter would be organized
into "island universes" we call galaxies?

No! Not a chance!

The fact is that no-one had calculated it. Such computing power did not
become available until the late 1970s.

While a prediction is more emotionally satisfying than a postdiction,
one shouldn't put too much weight on historical contingency which
determined whether theory or observation was first.

Let me give another example. QED is one of the most successful theories
ever. I don't know what the current state is, but theory and
observation agree to 20 digits or whatever. When studying
electrodynamics, the professor mentioned that, at that time, the
agreement was 12 places or whatever. I asked whether the observations
weren't more exact or whether the theory broke down at that level. The
answer was neither, but rather that one hadn't CALCULATED more digits
yet. These calculations are straightforward (i.e. everyone agrees on
how to do them and there are no free parameters) but quite expensive
numerically. Now, someone could calculate, say, 100 digits and this
would be a prediction and perhaps some day g-2 will be measured to this
precision and the prediction will be confirmed. However, what has
usually been the case in the past is that more digits are calculated
after experimental precision has correspondingly increased. Is this
somehow worse for the theory? Should experimentalists always
intentionally measure less accurately than the current prediction? Is
it OK to calculate measure something as long as the theorists don't know
about it?

Of course, if the theory is amended IN ORDER TO get a particular
experimental result, this makes a bad impression, especially if it is
the case that, or is at least unclear whether, the theory could
reproduce ANY experimental result. However, that is definitely not the
case with QED.

So, in summary, you seem to be setting the bar too high. My claim is
that with something like QED, where it is clear that there is NO WAY to
amend the theory to get an arbitrary result, a postdiction is just as
valid a test of the theory as a prediction is. In this sense, n-body
dark-matter simulations are like QED. The fact that voids and filaments
were first observed then calculated is an accident of history.

On 5/2/2014 10:23 AM, Phillip Helbig---undress to reply wrote:
In , "Robert L.
writes:

In 1910 Newtonian gravitation had been
around for a long time. Ask yourself a
simple question: Did Newtonian theory
predict that matter would be organized
into "island universes" we call galaxies?

No! Not a chance!

The fact is that no-one had calculated it. Such computing power did not
become available until the late 1970s.

While a prediction is more emotionally satisfying than a postdiction,
one shouldn't put too much weight on historical contingency which
determined whether theory or observation was first.

There are "dictions" with several levels of strength:

1) The theory predicts it and later it is observed.
2) The theory *predated* the observation but only
afterwards the postdiction is made (case above!)
3) The theory is formulated *after* the observation
and is able to postdict the observation without
effort.
4) The theory predated the observation but needs to
be extensively fitted to match one new observation.
5) The theory is formulated after the observation and
still needs to be extensively fitted to match it.

It sounds reasonable to say that cases 1 and 2 are
actually equivalent (and 4 and 5 are suspicious..)

--
Jos