Avril and Michael, (01)
A few comments: (02)
> the Dynamic Universe model... is infinite in all directions
> in the sense that if you could go far enough in any direction,
> you would come back to where you left. (03)
You could say that about a circle or a sphere. If its volume
is finite, it's misleading to say that it's infinite. (04)
> 4D-space - usually infinite in all directions if one of
> its roles is to explain the finite 3D-volume. (05)
You have to distinguish the model from the thing you're modeling.
We could, in theory, embed a curved N dimensional space in an
infinite Euclidean space of N+1 dimensions. But that infinity is
in the theoretical model. The universe itself could be finite. (06)
> Would an eternal heat death count as nothingness? (07)
The term 'heat death' is used for a state of maximum entropy.
In such a state, all the stars have burnt out, and there is
a state of thermal equilibrium in which all material bodies
(planets, stars, etc.) are unchanging lumps at a uniform
That would not be nothingness, but no life could survive.
It would be incredibly boring to observe, but there would
be no life forms to observe it (or be bored by it). (09)
> There can be a first state but no last state too. Isn't this
> what people usually assume today? (010)
Since space, time, matter, and energy are intimately related
by all known theories of physics, the concepts of 'before'
and 'after' apply only for events within the universe.
Those terms might be meaningful in some theoretical model,
but they would have no meaning within the universe itself. (011)
> What would be the best objective criterion in selecting between
> two models whose predictions match the observations equally
> accurately? (012)
Simplicity is an important criterion. But simplicity (like
beauty, taste, elegance, etc.) is in the eye of the beholder
(or the theorist who is trying to defend a dissertation). (013)
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