BB Isometric?

[aguy2]

Why is it assumed that the pre and post-inflationary epoch BB event expanded 'isometrically', when most other energenic mass expulsions take the form of 'jets' or 'pulses'?

 

I have heard that an isometric expansion is assumed because our mathematical 'toolkit' can only express this type of expansion. Is this true?

 

aguy2

[Snake_Arts]

Current indications from the cosmic microwave background are that the universe is spatially flat. That implies that the sum of all of the energy (density) in the universe equals the critical density, i.e. the total Omega is 1. This is quite interesting because as the Universe expands the value of Omega changes. In fact the value 1 is unstable, and the Universe would prefer to evolve towards one of the two natural values: 0, if the expands forever further apart until the Universe is almost totally empty ; and infinity, if the matter recollapses to a state of higher and higher density. Then the observation that Omega is fairly close to 1 today, means that it must have been even closer to 1 in the past. It is unsatisfying to believe that we just happen to live at the time when Omega is just starting to depart from 1 by a small factor. It is much more appealing to consider that we do not live at a special epoch, so that Omega is still close to 1 today. But then we need to explain why Omega started out very close to 1 in the early universe. The theory of inflation provides just such a justification - most versions of inflation predict that the early Universe was driven extremely close to flat, and that it is still very close to flat today. If this is so, then at least 90% the energy of the Universe is dark! Note that although the universe may be flat, that does not mean that matter makes up the crtical density. In addition to dark matter there is dark energy, e.g. a cosmological constant, that needs to be included in the accounting.

[aguy2]

Current indications from the cosmic microwave background are that the universe is spatially flat.

 

The most current CMB data seems to indicate that the visible universe may have a 'perferred' orientation. I agree with you that the visible universe is pretty close to being 'flat', but by in large your response really did not address the questions I posed. Insofar as 'flatness' goes if a 'jet/pulse expansion' had a reasonably large 'conic projection', it would be acting much as an 'isometric expansion ' would.

 

aguy2