Message from John Collier -------- Original Message -------- Subject: Re: [Fis] [Fwd: Fw: dark matter]--J.Brenner Date: Fri, 04 Jan 2013 16:12:54 +0200 From: John Collier <colli...@ukzn.ac.za> To: Pedro C. Marijuan <pcmarijuan.i...@aragon.es>
Dear folks, I agree that there is nothing of special interest to information about dark matter insofar as we understand it so far. When we know more about it there might be much more of interest, e.g., what exactly are the constraints that keep it from interacting more strongly with normal matter. I have some comments below, as it seems to me that this discussion has got out of hand and needs to be tied back to the historical roots of the concept of dark matter. > *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. In any case it isn't. Dark matter of our own galaxy is the same as for others. There is no consistent spatial or temporal variation. Without going into a lot of detail, I will say that indeed varying G has been investigated, and there is so far no evidence against it. The issue is still open, as we also have no theoretical reason to think that G is constant. G is not held constant by fiat. Even if G were variable, it wouldn't explain dark matter. Galaxies at all distances show the same effects of dark matter, so it can't be due to G varying with either time or distance. That was my point. If that were not the case, I am sure that I would know about it. As Newton says, for the same effects, we should assume the same causes. Note that dark matter was first postulated in 1932. It isn't like it is a new fangled idea that hasn't been examined. There have been several attempts to modify gravitational theory to account for observations, but all have failed so far to fit the evidence or have empirical support. None of them is remotely like your idea, which is a non-starter. > > 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 compatible with Leibniz, Mach's and perhaps Einstein's view of matter in general. If there is a general field theory ever invented, then everything would have this nature. We argue for this in /Every Thing Must Go/. There is nothing special here about either dark energy or dark matter as far as I can see. With obligatory respect to information, informational closure would require that both dark matter (it definitely exists) and dark energy (not so clear) act as sources and/or sinks of information for "normal" matter and energy. One source is the influence of dark matter in holding galaxies together: they would fly apart if just the gravity of normal matter mattered. This means it imposes a constraint, and as Shannon said, a constraint is a kind of information. (if you are careful enough you can represent all information as constraint and vice versa, but that can be misleading.) Of course there might be much more going on, but the necessity of dark matter has been known since Jan Oort proposed it in 1932 to explain the dynamics of galaxies (again, irrespective of their distance). Cheers, John > > 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 > > > _______________________________________________ > fis mailing list > fis@listas.unizar.es > https://webmail.unizar.es/cgi-bin/mailman/listinfo/fis ------------------------------------------------------------------------ Professor John Collier colli...@ukzn.ac.za Philosophy and Ethics, University of KwaZulu-Natal, Durban 4041 South Africa T: +27 (31) 260 3248 / 260 2292 F: +27 (31) 260 3031 http <http://web.ncf.ca/collier> ://web.ncf.ca/collier <http://web.ncf.ca/collier> -- _______________________________________________ fis mailing list fis@listas.unizar.es https://webmail.unizar.es/cgi-bin/mailman/listinfo/fis
