Originally Posted by Jerry

The answer is never that simple.

There are mainstream concepts that are jealously guarded: The Big Bang and the three pillars that support it: Metallicity evolution, expansion and the CMB. When the size of the universe became too great; a auxillary hypothesis, inflation, was added to the equation. Inflation required a reverbation signal in the the CMB; but in the Boomerang and WMAP measurements, the signature was much too small. Dark Energy was proposed as an auxillary hypothesis to an auxillary hypothesis. So was it a mainstream concept? It was a patch on a sinking raft, because without dark energy; the Big Bang was losing air and flying around backwards. Supernova researchers found more attenuation than they expected and there you have it: A bandwagon to reel-in the BB.

There has been no careful or critical examination of the assumptions made by supernova researchers as you imply: The explanation seemed to fit into the existing puzzle; so every other possible reason that supernova magnitudes are queer becomes an ATM issue. If you think about it dark matter is a very big patch: it is like floating all the pieces of a puzzle that do not fit on water and calling them islands. I guess since 70% of the earth is covered with water, 70% Dark Energy is a reasonable number, too.

So once again, observational evidence exists that comets are not the dirty snowballs they were predicted to be. Is the dirty snowball concept mainstream today, or ATM? Where do we discuss alternative hypothesis that attempt to explain why comets are made out of clay? How long should a discussion of alternative theories of comets last, and which theory should be allowed to be discussed on a mainstream discussion board?