Lee Smolin told me some neat stuff about MOND - that's "Modified
Newtonian Dynamics", which is Mordehai Milgrom's way of trying to explain
the strange behavior of galaxies without invoking dark matter. The basic
problem with galaxies is that the outer parts rotate faster than they
should given how much mass we actually see.

From
http://www.astro.ucla.edu/~wright/density.html#MOND
it seems MOND fails on the scale of galaxy clusters.
also I don't know if MOND can explain an accelerating universe,
predict correct elemental abundances, provide a good fit to CMB anisotropy
spectrum.

anyhow I think the fantastic fit of WMAP and SDSS,2DF to the standard
Lambda+CDM
is more or less a nail in the coffin for all alternative models.
Nevertheless the standard model requires BOTH non-baryonic
dark matter and dark energy
for which there is no laboratory evidence. So I guess as good scientists
it makes sense to think of alternatives and try to test them experimentally :-)

anyhow I have a question to experts on gravitation & cosmology on this forum.
what do you think about Conformal gravity which is cited in the paper by Aguirre
(mentioned by John above?) As far as I know unlike MOND this cannot be ruled
out at cluster scales. It also provides a natural explanation for an
accelerating universe. I however don't know if Conformal gravity is consistent
with predictions of GR at solar-system and binary pulsar distance scales.
Thanks

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