*From:* Joseph Brenner <mailto:joe.bren...@bluewin.ch>
*To:* Stanley N Salthe <mailto:ssal...@binghamton.edu> ; fis
<mailto:fis@listas.unizar.es>
*Sent:* Sunday, December 30, 2012 6:22 PM
*Subject:* Re: [Fis] dark matter
Dear Stan, Gordana, John, Bruno, Bob U., Yuri and All,
I think we have all been dancing around the obvious: Stan described the
situation we are in as a "remnant continuing expansion", but this
implies an expansion /relative/ to something or /against/ something,
some constraint. The model of the universe would be cyclical, but this
is accepted by some leading cosmologists.
For me therefore, we should not only be talking about what dark matter
/is /or dark energy /is/ but see them as inherent relational properties
which appear (already) to be in some sort of dynamic reciprocal
relation, in which one form of energy is primarily potential and the
other actual.
This is where Yuri and Bob U. come in: they both have some pretty
sophisticated mathematical tools which I hope might be applied not to
the theoretical entities but to the (equally theoretical, of course, for
the time being) relations between them.
Happy Western New Year!
Joseph
----- Original Message -----
*From:* Stanley N Salthe <mailto:ssal...@binghamton.edu>
*To:* fis <mailto:fis@listas.unizar.es>
*Sent:* Sunday, December 30, 2012 4:30 PM
*Subject:* Re: [Fis] dark matter
John -- You said:
There is no other evidence for a change in G, though it has been
postulated.
What is the compelling evidence for stable G? I would think that if
galaxies at known distances would be resolved without dark matter
using different values of G, that this would itself be the evidence
for change that would be required. But we would not be likely to
discover this if we hold G constant by fiat, or simply because it
simplifies calculations.
The dynamics to be explained apply to both near and far galaxies,
apparently in much the same way.
The near galaxies would have G much closer to our own value in the
case of evolving G.
Perhaps most important, they apply to our local group of galaxies.
These would be brought into the calculations as well, of course.
Overall we would expect that the most distant galaxies would require
the greatest G in order to explain their configuration, with G
getting smaller and smaller as we approach the present time. If so,
this would provide another evidence for the Big Bang.
I note that the evidence for "dark energy" is much weaker.
I have felt this as well. I have been wondering why our recent
discovery of current accelerating expansion could not simply be
interpreted as a remnant continuing expansion.
STAN
John Collier
On Sat, Dec 29, 2012 at 3:49 PM, John Collier <colli...@ukzn.ac.za
<mailto:colli...@ukzn.ac.za>> wrote:
Stan, there are several reasons that a change in gravity will
not explain the effects of supposed dark matter. I list them below.
*From:* fis-boun...@listas.unizar.es
<mailto:fis-boun...@listas.unizar.es>
[mailto:fis-boun...@listas.unizar.es
<mailto:fis-boun...@listas.unizar.es>] *On Behalf Of *Stanley N
Salthe
*Sent:* 29 December 2012 04:52 PM
*To:* fis
*Subject:* [Fis] dark matter
Gordana has said:
Information and Energy/Matter
What can we hope for from studies of information related to
energy/matter (as it appears for us in space/time)? Information
is a concept known for its ambiguity in both common, everyday
use and in its specific technical applications throughout
different fields of research and technology. However, most
people are unaware that matter/energy today is also a concept
surrounded by a disquieting uncertainty. What for Democritus
were building blocks of the whole universe appear today to
constitute only 4% of its observed content. (NASA 2012) [1] The
rest is labeled “dark matter” (conjectured to explain
gravitational effects otherwise unaccounted for) and “dark
energy” (introduced to account for the expansion of the
universe). We do not know what “dark matter” and “dark energy”
actually are. This indicates that our present understanding of
the structure of the physical world needs re-examination. [...]
Information and Energy/Matter
Gordana Dodig Crnkovic
Information 2012, 3(4),
751-755;
http://unam.us4.list-manage2.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=ae24f18d1e&e=d38efa683e
<http://unam.us4.list-manage2.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=ae24f18d1e&e=d38efa683e>
Special Issue "Information and Energy/Matter"
http://unam.us4.list-manage.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=ea193b9747&e=d38efa683e
<http://unam.us4.list-manage.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=ea193b9747&e=d38efa683e>
See it on Scoop.it
(http://unam.us4.list-manage.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=cdfa764e97&e=d38efa683e
<http://unam.us4.list-manage.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=cdfa764e97&e=d38efa683e>)
, via Papers
(http://unam.us4.list-manage.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=e23b9e2cd9&e=d38efa683e
<http://unam.us4.list-manage.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=e23b9e2cd9&e=d38efa683e>)
I would like to inquire whether any fis'rs might react to the
following notion:
Dark matter is postulated because the amount of matter
detectable in galaxies would be insufficient alone to explain
how they hold together given the value of the gravitational
constant.
However, the information we glean from galaxies represents their
condition as it was a very long time ago, in an earlier universe.
Is it not possible to resolve this puzzle less radically than by
inventing dark matter by supposing that the gravitational
constant has not been constant but has instead been changing,
and was much stronger in the past, which is when we detect these
distant clusters of matter? Perhaps G as been scaled to the
rate of expansion of space? Perhaps the rate of expansion was
greater then than now, even with current acceleration?
My response:
1. There is no other evidence for a change in G, though it has
been postulated.
2. The dynamics to be explained apply to both near and far
galaxies, apparently in much the same way.
3. Perhaps most important, they apply to our local group of
galaxies.
I note that the evidence for "dark energy" is much weaker.
John
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