Chronos said:
Well, Mike, how else can you interpret it? No scientist I know of claims the BB as fact. It is merely our best approximation based on observation and physics. No one disputes our observations are incomplete and theories have error margins.
(snip -placed below-)
If something wrong with the pyramid of current theory, new observations will eventually cause it to collapse under its own weight. Furthermore, no scientist in his right mind would hesitate to attack the slightest inconsistency in any existing theory, however precious it may seem. This is how Nobel's are won.
It's true that nothing will stop the progress of science and sooner or later the data tells the tale. But there is a problem with new data. The CMB and the Super nova recession data are just about the only major new discoveries that have been made recently. And they are both corroborative of there universe having been very compact at some point in the past. So the BB is very attractive and has been for a century or so.
But the weakest part of the BB is not that things were compact some 15 billion years ago, but that
everthing in the universe was compact and that there was
nothing "outside" or "before" the BB. That is, the cosmological principle (CP) has been take as fact and is considered fact almost reflexively in most exminations of the new data and certainly in all conversations among the experts about the conventional models. But the CP is not only theoretical, it is unlikely.
Coversations about dark matter and dark energy are entirely predicated on the universe being homogeneous. The calculations of the total matter in the universe necessarily require uniformity throughout. And the CP is really an idealization of the locally visible universe and not a careful examination of the most probable disposition of the large scale universe.
All scales of the universe that we have ever examined shows a hierarchical structure, yet we humans always terminate that hierarchy with every new cosmology we devise. Currently the CP terminates the hierarchy by extending the largest visible scale out to whatever extent necessary. The CP is a very handy idealization that allows us to work backwards with all the local material to devise what I imagine to be a very accurate history, but it does not serve us to imagine so rigidly that it is universal. It is unlikely that the CP holds at, say, a million or a billion times the particle horizon.
Every physical phenomenon ever examined has proven to be finite in extent and multiply manifest (that is, for any given physical phenomenon we can find other examples in the universe). Why must the BB be unique. The CP is just as likely to be only a local idealization and if so, discussions about dark matter and dark energy are discussion about what an idealized homogenous universe would look like rather than a universe where larger structures and phenomonon dictated local matter/energy dispositions like they do at all the other scales of the universe we have examined so far.
Chronos said:
To couch every assertion with 'our best guess is' unnecessarily diverts attention from efforts to propose new ideas. This is the only way to shore up our more fundamental assumptions.
I don't see what you mean here. To me, the keeping everyone more apprised of the most presumptive aspects would be the better strategy in that it is probably the more presumptive aspects that will need modifying or replacing. I think that it wouldn't be too imposing for cosmologists, if only when talking to the public or the less cognizant groups, to add phrases like "the math suggests" or "the evidence suggests" or even "according to the model" before passages that deal with subject that are short on data, long on presumption or are projections beyond the existing data (eg dark energy, dark matter, curvature of the universe, etc). It would keep us more mindful of our own presumption.
-Mike
