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It might be philosophy, so I apologise in advance.

Does current understanding in cosmology or even general relativity itself rule out the existence of a larger empty space containing the expanding universe? I mean in such a case, nothing should change to the description and fate of the expanding and matter containing one... so it can be seen a redundant speculation and perhaps we might apply the razor of Occam.

I rephrase for clarity. On which bases we rule out (if we indeed do so, perhaps it just unnecessary and not giving any results, as I said above) that the Universe and its expansion are happening in existing space? Does GR prevent to conceive an empty space surrounding one in which matter dictates curvature? I don't think so. Perhaps the cosmological principle can be used, but it would implied an always infinite Universe.

I hope my question is clear enough. I think that the two situations might be mathematically and, of course, practically indistinguishable but yet conceived.

Alchimista
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    Possible duplicates: https://physics.stackexchange.com/q/7359/2451 and links therein. – Qmechanic Oct 28 '19 at 14:29
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    QMechanic◆ thx but I am fine with the fact that universe does not expand into something empty and at each moment bigger. I would like to know if still is possible. To me it seems yes but it is only concept. Our observation wouldn't change, and all theoretical achievements would be also the same. .. that is why I started to think if we can rule out that scenario – Alchimista Oct 28 '19 at 14:50
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    Physics uses Occam's razor as a key principle: one should not unnecessarily complicate the theory. There are no observations that require anything outside space-time, so assuming there is something there is unnecessary. Were one to start adding such possibilities there is no end to what one could imagine - but it makes rather bad physics. – Anders Sandberg Oct 28 '19 at 17:30
  • @Alchimista I don't understand the idea of a space containing a universe? The universe itself is the thing that contains everything. So the question does not make much sense. There's only one space-time. – seVenVo1d Oct 28 '19 at 18:50
  • The universe is "space + energy" ( or curvature and energy, which energy in the form of matter, radiation, etc). So your question implies "space + space + energy" which is same as "space + matter" (?) – seVenVo1d Oct 28 '19 at 18:50
  • To all, and perhaps I shall edit.... already writing the question I was oriented [....redundant. .] to Occam razor here. It is a sort of answer. To @Reign it is the core. I don't know GR but to me GR should be fine if contained in an empty space. But we again are at the limit of infinity etc.i would agree if the universe is finite, by definition we don't study the exterior. Butt if it is infinite, there could be a bigger empty infinite. I think Occam should be fine, but for me the situation is conceivable (at least if I don't crash my head with infinite).The situation would be that of a totall – Alchimista Oct 29 '19 at 08:25
  • ..Totally empty space in which our universe is contained. You can well call the resulting ensemble Universe, of course. – Alchimista Oct 29 '19 at 08:26

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