MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Dark Matter results when gravity is not modified. (pure Newtonian)
IMO John Moffat has a much better mod-gravity theory http://arxiv.org/pdf/gr-qc/0506021.pdf wiki-Moffat: He proposes a variable speed of light<http://en.wikipedia.org/wiki/Variable_speed_of_light> approach to cosmological <http://en.wikipedia.org/wiki/Physical_cosmology> problems, which posits that *G <http://en.wikipedia.org/wiki/Gravitational_constant>*/ *c* is constant through time, but *G* and *c* separately have not been.in the early universe, in which the speed of light was 1030 times faster than its current value. Richard: That would say that the fine structure constant was different in the early universe, which agrees with observations of the Keck telescope. However, more recent observations in the southern hemisphere indicates the the fine structure constant varies monotonically north to south and not as a function of time. I have used those observations to hypothesize that the Calabi-Yau compact space particles are numerable and a basis for computationalism in my string cosmology papers. But he has done much more- read his wiki. On a personal note John Moffat was a consultant one summer in the MIT Lincoln Lab group that I worked in in the late 1960s. But I am not sure it's the same John Moffat. On Sun, Dec 1, 2013 at 9:44 PM, LizR <lizj...@gmail.com> wrote: > I should have said that by ad hoc I mean with no, or little, theoretical > justification. That is, adjusting the threoy to fit the data, but with for > no compelling theoretical justification. > > > On 2 December 2013 15:42, LizR <lizj...@gmail.com> wrote: > >> Ad hoc modifications to our existing theories. Although it looks like >> it's actually bolt-on extras to Newtonian gravitation... >> >> http://en.wikipedia.org/wiki/MOND >> >> >> >> On 2 December 2013 14:33, Richard Ruquist <yann...@gmail.com> wrote: >> >>> Can you explain what you mean by 'bolt-on extras to GR'? >>> >>> > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to everything-list+unsubscr...@googlegroups.com. > To post to this group, send email to email@example.com. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to firstname.lastname@example.org. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.