Originally Posted by
mal4mac
One should never make assumptions with this crazy stuff
Read what the crazy cosmologists write. The current favoured model is an
infinite, expanding space. The infinite space was created at the moment of the Big Bang... note it's now thought to be "flat", a nice 3D space, so nice and easy to visualise (?)
As infinite space was "just there" after the Big bang, I can't see matter had much to do with it. In any case, one could imagine a universe that is just flat and infinite without matter. Couldn't one?
What do you recommend that I read?
I see space or space-time as a coordinate system with a metric defined on it to measure distance between objects. So it is just a model, not the reality. If the model doesn't work to explain gravitation, for example, one changes it to claim that the model is now "curved". It makes the observations of the orbit of Mercury work better, but it is still a model. An infinite coordinate system does avoid the need to find an edge to the universe.
In looking for some validation for this, the Wikipedia article on the metric expansion of space somewhat helps: http://en.wikipedia.org/wiki/Metric_expansion_of_space The first paragraph makes sense to me although I don't think I understand what this "intrinsic expansion" of space really means. The rising bread image somewhat helps.
The metric expansion of space is the increase of the distance between two distant parts of the universe with time. It is an intrinsic expansion — that is, it is defined by the relative separation of parts of the universe and not by motion "outward" into preexisting space as, for example, an explosion of matter. The universe is not expanding "into" anything.
But later it talks about an infinite space to avoid the idea of an edge for which there is as yet no evidence:
At present, observations are consistent with the universe being infinite in extent and simply connected, though we are limited in distinguishing between simple and more complicated proposals by cosmological horizons. The universe could be infinite in extent or it could be finite; but the evidence that leads to the inflationary model of the early universe also implies that the "total universe" is much larger than the observable universe, and so any edges or exotic geometries or topologies would not be directly observable as light has not reached scales on which such aspects of the universe, if they exist, are still allowed. For all intents and purposes, it is safe to assume that the universe is infinite in spatial extent, without edge or strange connectedness.