Re: Astronomical Software
- From: Charles Francis <charles@xxxxxxxxxxxxxxxx>
- Date: Wed, 04 Jan 2006 09:03:03 GMT
Thus spake Phillip Helbig---remove CLOTHES to reply <helbig@xxxxxxxxxxxx
LOTHESvax.de>
>In article <mt2.1-32679-1136285772@xxxxxxxxxxxxxxxxxx>, Charles Francis
><charles@xxxxxxxxxxxxxxxx> writes:
>
>> Thus, any theory which
>> >indicates that the supernova results should result in different
>> >cosmological parameters would have to explain why combinations of other
>> >data sets lead to the result they do.
>>
>> It gets very difficult at this point. These analyses get very technical
>> and complex.
>
>Indeed. Doing fits to the m-z relation is trivial compared with the
>analysis of CMB data, of galaxy-redshift surveys etc.
>
>> In practice these measurements determine cosmological parameters rather
>> than test consistency, and they depend on the distance scale found from
>> redshift. One can argue that a distortion in the distance scale will
>> alter acceleration in a definite way, so that, if the standard model is
>> consistent, the optical distortions due to the square redshift law can
>> be expected to give consistent values in different tests at least to
>> first order. At the moment I can't prove it.
>
>Keep in mind that the result that Omega_matter = 0.3 or so has a) been
>around for about 35 or 40 years,
This is true. But challenges to the affine connection date from at least
65 years ago, and come from Einstein himself
Einstein A., 1930, Auf die Riemann-metric und den Fern-Parallelismus
gegründete einheitliche Field-Theorie, Math Ann., 102, 658-697.
A translation can be read on A Unzicker's site. Quite a few theorists
have thought that this is the way towards unification, but the real
subtleties, imw, involve reconciling a change in cosmological redshift
to geodesic motion and the equivalence principle. The reconciliation is
to do with the collapse of the wave function, and only makes any sense
in a strict orthodox, Dirac-Von Neumann interpretation of qm.
>b) has never been seriously challenged
>based on observational data
It doesn't alter observational data at all. It doesn't even require that
we change direct measurements of local density, or local distance
scales, or the amount of baryon matter generated by BBN. If the
teleconnection is correct it merely means we have to reinterpret
Hubble's law as meaning that galaxies are receding at adot = H0a/2. It
follows at once for an FRW cosmos that the universe only requires 1/4 of
the density for closure. The teleconnection model renormalises Omega, so
critical mass Omega=1 is roughly the same absolute density as in the
standard theory.
>and c) doesn't depend on measuring anything
>as a function of redshift, since it is a "local" measurement (at most
>one would measure distance as a function of redshift to first order,
>where the cosmological model, or even (within reason) the underlying
>cosmological framework, doesn't matter).
We can't actually do a direct measurement of the velocity of a receding
galaxy. However we can measure a related effect which is genuinely
local. The model predicts an anomalous blue-shift in pioneer directed
towards the Earth - current measurements do not determine direction that
accurately, but there is a planned mission which will. And we can
measure the same effect in the galaxy rotation curves. Using the
teleconnection model these require neither CDM nor a modification to
Newtonian dynamics, though it does predict that the MOND law appears in
the analysis of redshift.
> The supernova data and the
>analysis of the CMB deliver confidence regions which are elongated in
>the lambda-Omega plane and roughly orthogonal to each other. The
>combined best fit is consistent with the "directly observed" Omega of
>0.3 or so.
As I say, I cannot analyse the CMB as yet. The first order analysis will
be unchanged as far as I can see. However it is worth remarking that
Spergal comments on discrepancies in the data, and that reports of
anisotropy have even reached scientific American. My remark was to point
out that to get a figure for Omega we have to compare the WMAP data with
the 2dGFS analysis, which depends on the redshift-distance relation. So
any figure for acceleration is going to be changed in the same way,
according to the change in the red-shift distance relation. We should
expect the same correspondence between Omega_standard~.3 and
Omega_teleconnection~1 whether it is measured by Supernova or by WMAP-
2dGFS.
>
>> But they say it
>> never gets converts from the establishment - practitioners of the old
>> theory die off, they do not change their ideas. Certainly that was said
>> of Priestley who continued to believe in phlogiston even though he
>> discovered oxygen. How many things will it be necessary to establish by
>> comparison with data before I can get people to look at it seriously?
>
>I think you're being a bit pessimistic here. Several cosmologists have
>"bowed down to the data" and changed their ideas about what the universe
>is really like. A prominent example: Philip Morison was a vocal
>supporter of the steady-state theory for many years and later became a
>vocal advocate of the big-bang theory. With less famous people and
>smaller paradigm shifts, it happens more often. Of course there are a
>few people who stick with their guns no matter what, but it would be
>wrong to say that, influential though they might be, they control the
>field to the point of hindering real progress. Also useful are people
>who play devil's advocate, i.e. they might not REALLY BELIEVE in their
>favourite cosmological model, but regularly write papers in support of
>it, the real motivation being to challenge contemporary thinking with
>the goal of determining what is really accepted without question, what
>looks like a current best guess, what is speculative etc.
I am sure you are right about this.
Regards
--
Charles Francis
Please reply by name
.
- Prev by Date: Re: Astronomical Software
- Next by Date: Re: Astronomical Software
- Previous by thread: Re: Astronomical Software
- Next by thread: Re: Astronomical Software
- Index(es):
Relevant Pages
|
