goredsox wrote:astro_uk said:
Is there any scientific reason why a two phase universe should be preferred?
No, but there isn't any reason that a one phase universe should be preferred either. It is arbitrary because empirical evidence does not apply at all to what came before BB. I think preferring one phase over all other possible numbers of phases represents a bias, and more phases are statistically more likely.
You said that choosing more phases is choosing the more complicated solution, but I think that changing BBT so that it creates all matter in the universe in one place at one time with no prior phase is the more complicated solution.
This contains several, rather common, fallacies.
For example, 'statistically more likely' is an (unconscious?) inference drawn from experience of the observable universe; there is,
a priori, no scientific reason to expect it to apply to realms for which we have neither theory nor observation to guide us.
Second, the LCDM cosmological models ('big bang theory') is silent on the origin of the universe, for the very good (scientific) reason that we have no quantum theory of gravity (or, if you prefer, theory of quantum gravity). So, within the domains of the current best theories, all we can say is that the observable universe seems to have been very hot and very dense ~13.7 billion years ago.
If you'd like to choose one string theory, or loop quantum gravity, or ... i.e. one of the several current theories which contain both general relativity (GR) and quantum theory, then you can begin to construct models of the universe prior to t = some tiny fraction of a second. However, I think you'd be stuck in at least one place - there is no 'tie-breaking' observational support for any of these theories (yet).
harry said:
Reproducing acceleration of expansion. Of what?
Expansion of the universe. Everything is observed to be expanding all the time, and it is accelerating. Dark matter can explain this. So my question to you is whether you consider the existence of Dark Matter to be sufficiently well grounded to be considered fact, or it really just a theoretical model? I ask because we are trying to establish what the facts really are, and where the theoretical model begins.
I think you mean dark energy, not dark matter.
Your question begs a deeper one, for example: do you consider the existence of atoms (quarks, neutrinos, ...) to be considered fact, or is it really just a theoretical model?
Or, putting this another way, show me a 'fact' that is not so intricately bound with theory that it can stand on its own two feet. Qualification: any such 'facts' go beyond that which you can experience directly with your own senses (esp sight).
makc said:
astronomers have not come up with a one yet that would make at least equally good predictions
It would help to catalog all the observations that have been made over the years that were inconsistant with the prevailing BBT of the time. It seems that BBT has been modified to fit the observations after the fact. It would be more convincing if BBT was right before the next observation.
Hmm ... what do you think science is? some kind of dogma?
What you have just (briefly) described is a core aspect of science, and one reason why we do experiments and make observations!
Of course, it is entirely possible there is a better way to understand the universe, than the present methods used by astronomers - perhaps you have such a method? - but until one comes along and is accepted, then I guess we'll just keep using the same methods that brought you your PC, the internet, most of the the medicinal drugs you (or your friends and relatives) take, your car/bicycle/motorbike, etc.
