Evidence for a static universe

In article , (Eric
Flesch) writes:

About 15 years ago I collected SNIa data with a view to testing for a
"static" universe also. At that time I found that all data had been
pre-processed with redshift dilation already removed, so it was
frustrating that the original raw data wasn't being reported.

I think that these days you can get all the raw data, or at least as raw
as you need (i.e. maybe not the completely unprocessed CCD readouts),
online. The Betoule et al. electronic supplement to their A&A article
is a good exercise in Fortran edit descriptors. :-)

What
struck me then was that the most distant SNIa were not the most
intrinsically brightest because with the redshift dilation removed,
they didn't have as wide a profile (that is, time-wide) as more nearby
ones -- in complete violation of the normal expectation that the most
distant ones should be the intrinsically brightest ones because only
those should be visible to us (at high redshifts).

Malmquist bias, and a normal expectation only if the brightness has a
relatively wide distribution and we miss the faintest objects at high
redshifts. But here, the distribution isn't that broad (supernovae are
still approximately standard candles) and even the weakest are above the
detection threshold, so this argument doesn't apply.

In article , jacobnavia
writes:

This has ABSOLUTELY NOTHING to do with the claim that the universe is
static. Nothing at all.

Yes, you are right. The fact that the accelerated expansion is wrong
doesn't imply immediately that the universe is not expanding. It could
be expanding normally, not accelerating.

Glad you agree, but it does demonstrate your tendency to trumpet
something you think supports your ideas without critically examining it,
but at the same time repeating criticism of ideas that don't, even if
said criticism has been thoroughly debunked.

But I have been arguing since several years that that viewpoint can be
very WRONG. I believe that data can be understood in several ways,

Science isn't about belief, though. Do you have an alternative theory
with quantitative, testable predictions?

and
our lack of advanced scopes precludes to definitively rule out space
expansion.

Not sure what you mean here. Scopes are pretty advanced. And don't you
mean "rule out space not expanding"?

I have philosophical (common sense) questions against any space
expansion since I do not see how that contre-sense space is "expanding".

Space itself can't expand. Into what would space expand into?

Into more space. Obviously.

And that new space is created out of nothing?

This is a FAQ. You're not the first to think about this, and there are
clear answers. It is even possible to understand cosmology without the
expanding-space picture.

I think cosmology is bound by the data that mankind has gathered about
our surroundings. Science can only speak about the observable universe
and not about the universe as such, that will always be unknowable by
definition.

The size of the observable universe increases with time. Yes, some
things we can never know, but that doesn't mean that things which we can
and do know are debatable. We already have post-truth ("word of the
year") politics, see Brexit and Trump. Science should stay
evidence-based.

Since scientists first proposed dark energy, no one's gotten any close=
r
to figuring out what it could actually be.

True, but irrelevant.

Interesting. You acknowledge then, that all this "dark energy" stuff is
really kind of suspect isn't it?

Who said it was suspect? We don't know what it is in the same sense
that we don't know why matter produces gravity. (Although there has
been recent progress on the latter.) According to Einstein, the value
of the cosmological constant is no more mysterious than the value of the
gravitational constant.

Why this "dark" adjective?

Why can't astronomers just name it "unknown", it would be better than
arbitrarily making something that until yesterday they said that was
making 70% or more of the mass of the universe, "dark".

Why paint everything that we have no idea of "black", "dark", whatever?

As I have pointed out here many times, "dark energy" is a bad name. But
a rose, by any other name, would smell as sweet. Whether we call it
"dark energy" or "the cosmological constant" or "George" doesn't really
matter. (The name was chosen in analogy with "dark matter", for which
there are good reasons for calling it so.)

Why not just open up and say the truth: We do not know what it is.

Because it is irrelevant here. General Relativity says nothing about
the source of gravitation. Why expect it to say something about the
source of the cosmological constant?

Science consists of finding explanations for things we didn't know
enough about before. There would be no progress if the answer were
always "We don't know what it is, so it therefore cannot exist".

Do astronomers have to propose some theory about "the universe" as such?

We find the simplest model which fits the data and is otherwise
believable.

They can only speak about their observations. From those observations to=

concluding "the universe is such and such" or even "the universe started=

13.7 billion years ago" there is a wide stretch of imagination I do not
follow.

Then read up on cosmology.

But now an international team of physicists have questioned the
acceration of the Universe's expansion, and they've got a much bigger
database of Type 1a supernovae to back them up.

The first part is true, the second is not.

OK. Why is their database not bigger than the data base used then? Can
you really point out something here?

THEIR WHOLE POINT is that their analysis gives different results WITH
THE SAME DATA.

By applying a different analytical model to the 740 Type Ia supernovae
that have been identified so far, the team says they've been able to
account for the subtle differences between them like never before.

These are extremely fine details.

Details?

Yes.

This is the crux of the matter: the accelerated expansion was hanged to
those observations!

Yes, and the observations still support it. Give equal weight to the
numerous rebuttals to this new claim, all easily found online.

They say the statistical techniques used by the original team were too
simplistic, and were based on a model devised in the 1930s, which can'=
t
reliability be applied to the growing supernova dataset.

This applies to the statistical model.


Yes, of course this applies to their statistical model and they say it
is wrong.

They have not convinced the community that it is wrong and even if they
had, it is not wrong enough to say that "we don't have sufficient
evidence for an accelerating universe".

They also mention that the cosmic microwave background isn't directly
affected by dark matter, so only serves as an "indirect" type of evide=
nce.

This is a bizarre claim. One of the main pieces of evidence for dark
matter on cosmological scales is the CMB. And, yes, it is "directly"
affected by dark matter in any sensible meaning of the term. Even MOND
adherents concede that the CMB is evidence for dark matter. :-)

Why can't the CMB be the background emission of the sea of galaxies that=

we are inmersed in?

Because it's not. Because very precise details were predicted from
completely standard physics years or decades before they were observed.
That's how science work. An alternative claim needs quantitative,
testable predictions, otherwise it is not science.

Other explanations for the CMB are possible, within another frameworks.

See above.

First, the 5-sigma level is completely arbitrary. Second, 3 sigma is
still 99.7 per cent. So, they are saying that there is a chance of .03
per cent that the data are compatible with a non-accelerating (NOTE: no=
t
static) universe. The other 99.7 per cent indicate acceleration.

There you go. Not 5 but 3 sigma?

Do you understand the difference? They are splitting hairs, even if
their statistics are better. Look at that diagramme again. See the
sliver they are talking about.

Let's make an even bigger data base then.

Be my guest. Get the telescope time, the computing resources, the
people to work on it.

Look, if we are speaking about dark energy, it is not really a small
effect. The huge consequences that were hanged on that observation...
Nothing less than 70% of the universe's mass!

Yes, but the conclusion still holds up WITH NO INPUT FROM THE SUPERNOVAE
AT ALL, NONE WHATSOEVER.

I am convinced that we will never know. The universe will be always
bigger than anything any creature can imagine.

Maybe, but we can still understand parts of it.

In article , (Steve
Willner) writes:

In article ,
"Phillip Helbig (undress to reply)" writes:
... no-one has claimed that the supernova data prove the expansion
of the universe.

Are you sure about that?

This was in the context of someone confusing an accelerating universe
with an expanding universe; the supernova data (by which I mean the
stuff the Nobel Prize was awarded for in 2011, not supernova data in
general) were taken decades after the expansion of the universe was
consensus. Even that consensus didn't rely on supernova data, though.

I thought the SNe make up a key part of the
distance ladder for measuring the Hubble parameter.

Yes, they do today, and one can get a good estimate of the Hubble
constant from just them. My point was that the expansion (as opposed to
the acceleration) of the universe was consensus long before the recent
supernova projects came along.

There are, of
course, other distance measurements available over the distance range
the SNe cover, so it's not as though they are the only evidence for
expansion.

Right. Again, my main point was in reference to the confusion. Even if
the new statistical analysis manages to convince the community, the
issue is whether the supernovae demonstrate acceleration, not whether
they demonstrate expansion.

(There is even evidence for acceleration without the supernova: a nearly
flat universe from the CMB and the long-standing observational result
imply a low Omega and hence substantial cosmological constant. Yes,
this assumes GR, Friedmann-Lemaitre cosmology, etc, but no more than the
standard supernova analysis. In some sense, the supernova data might be
more direct, but they do not "measure the acceleration directly" in any
meaningful sense. As George Ellis and collaborators have pointed out,
some cosmological tests provide more model-independent information than
others, and the m-z relation is an example of one which does, but that
is not the issue here (nor even in most supernova-cosmology papers).)

On Wednesday, December 7, 2016 at 8:56:18 AM UTC+11, Steve Willner wrote:
In article ,
David Crawford writes:
The plot is shown in figure 2. These are the original observed
widths without Salt2 calibrations. As a function of redshift he
regression equation has a slope of (0.020 +/- 0.024).

I don't know what "figure 2" you mean, but if you are claiming time
dilation is not observed, you are doing something wrong. What do you
get for SN1995E in B-band compared to 1997ek in I-band? Even a
cursory glance at the SN data shows clear time dilation.

Clearly figure 2 in my paper! I think it shows strong evidence for no time dilation.

SN light curve widths depend weakly on wavelength but are nowhere
near proportional to wavelength. (Widths can be measured for SNe
near zero redshift.) If time dilation weren't present, the standard
analysis would show that. You can show that by running mock data
through the standard analysis, if you are unconvinced by anything
else. Just make sure your mock data fit the z=0 light curves rather
than something you've invented.

It is the template light curves that show the wavelength dependence which
is due to the Salt2 calibration. It is NOT the intrinsic widths.

As to the supernova data supposedly not requiring dark energy, my
comments are in sci.astro at Message-ID:

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In article ,
"Phillip Helbig (undress to reply)" writes:
Malmquist bias, and a normal expectation only if the brightness has a
relatively wide distribution

One thing to keep in mind is that the nearby samples are just as
likely to suffer Malmquist bias as distant samples. Nearby objects
are found in wide but shallow surveys such as ASAS-SN:
http://www.astronomy.ohio-state.edu/...in/index.shtml

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In article ,
David Crawford writes:
Clearly figure 2 in my paper! I think it shows strong evidence for
no time dilation.

Then you've made a mistake. The thread 12 years ago identified at
least two possibilities, maybe more, but there are lots of ways to go
wrong.

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In article , Steve Willner
writes:

In article ,
"Phillip Helbig (undress to reply)" writes:
Malmquist bias, and a normal expectation only if the brightness has a
relatively wide distribution

One thing to keep in mind is that the nearby samples are just as
likely to suffer Malmquist bias as distant samples. Nearby objects
are found in wide but shallow surveys such as ASAS-SN:
http://www.astronomy.ohio-state.edu/...in/index.shtml

As Sandage liked to point out, Malmquist was not a cosmologist; he was
interested in stellar statistics. :-) (Another of Sandage's heroes,
Wolfgang Mattig, was a solar physicist, but well known in cosmology for
the Mattig formula. It used to be the case that for the German
Habilitation one had to "minor" in a completely unrelated subject, which
is why and how he came upon his formula.) But for a given magnitude
limit, of course nearby surveys will be more complete than distant ones,
if they are otherwise the same and if the fainter, distant objects drop
below the detection limit.

In article ,
"Phillip Helbig (undress to reply)" writes:
But for a given magnitude limit, of course nearby surveys will be
more complete than distant ones,

Yes, of course. The point is nearby surveys have to be wider to find
many objects and therefore have shallower magnitude limits because
the available exposure time at a given position is less. It is
possible to find nearby objects in deep surveys, but as a practical
matter, there are very few.

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On Thursday, December 8, 2016 at 9:12:18 AM UTC+11, Steve Willner wrote:
In article ,
David Crawford writes:
Clearly figure 2 in my paper! I think it shows strong evidence for
no time dilation.

Then you've made a mistake. The thread 12 years ago identified at
least two possibilities, maybe more, but there are lots of ways to go
wrong.

What do you think is wrong. Maybe you don't trust my width measurements or there is something wrong with my interpretation. Surely a plot of raw (No Salt2 corrections) verses redshift show show time dilation if there is one?

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In article ,
David Crawford writes:
Surely a plot of raw (No Salt2 corrections) verses redshift show
show time dilation if there is one?

Indeed. See the upper plot of Fig 3 of
https://arxiv.org/abs/astro-ph/0104382
No doubt current data are much better.

I don't know what you are doing wrong, but 12 years ago, two of the
problems were mixups between flux density and magnitude and also
trying to base light curve widths on the time of maximum. Time of
maximum is ill-determined because the light curve is flat at maximum.
Instead one has to measure decay rate or do a template fit (which
amounts to the same thing).

The idea that the standard analysis would "put in" time dilation when
it's not present is also mistaken. Time is scaled by 1+z for
convenience, but if the true widths didn't scale that way, the
stretch factor would systematically decrease with redshift. That
doesn't happen, as shown in the bottom panel of the same figure
mentioned above.

I've already suggested several ways you can look for your mistakes
and won't repeat those suggestions.

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