# Assume that empty space have mass

Simplex0
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Topic 194046

Just wondering.

How would the universe look like if empty space had grater density \ mass the the part of space occupied by mass as wee know it like stars and galaxies?

Chipper Q
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### Assume that empty space have mass

Quote:

Just wondering.

How would the universe look like if empty space had grater density \ mass the the part of space occupied by mass as wee know it like stars and galaxies?

Well, greater density means more mass (or energy) per unit volume ... hmm, since mass is attracted to mass because of gravity, then wouldn't the mass of so much empty space between (and in) galaxies keep the universe from expanding? What would prevent it all from collapsing in upon itself, the way regular matter does (into a 'black hole') when enough of it accumulates in the same volume of space?

Anything in particular that made you wonder about empty space having (non-zero) density?

Have a look at Recipe for the Universe â€“ Just Six Numbers â€“ there's not much leeway for varying any of the more fundamental properties observed in nature â€“ not that it couldn't or doesn't happen, but more that things just wouldn't function in a manner conducive to the reality that we all know and love, er, the one we love to endeavor to know, anyway ... :)

Simplex0
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### Thank you Chiper. Just

Thank you Chiper.
Just something that is always on my mind after reading GÃ¶del, Escher, Bach: an Eternal Golden Braid

Sometimes it is easy to mix up what is foreground and background :).

Just to clarify. I meant that space was like water and what we normally relate to mass was like gas bubbles in the water and different kind of mass was like different kind of gas.

Now assume that space have a quality that prevent it from collapsing to a singularity, it can only reach a defined maximum density. In that case the mass in a given area of universe occupied by stars and galaxies will gain density and mass as the universe expand.

Simplex0
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### I have give it some more

I have give it some more thought and have 2 more questions.

1. If space have mass and is infinite there is no central point.
Would that fact alone keep it from collapsing to a singularity?

2. And if empty space have a grater mass than space occupied by stars and
galaxies would not that cause stars and galaxies to fly apart instead of
collapsing to a singularity?

Chipper Q
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### RE: 1. If space have mass

Message 88598 in response to message 88597

Quote:
1. If space have mass and is infinite there is no central point.
Would that fact alone keep it from collapsing to a singularity?

Good question, Tomas .... the early distribution of regular matter seems to have been quite even, with no central point, ('isotropic' is a better term), and yet after billions of years of evolution, what started out as mostly hydrogen has eventually clumped to form stars and galaxies â€“ so one question would be, does â€œdense spaceâ€? behave similarly? There would have to be other factors involved, like is space connected to adjacent space (like a giant molecular lattice of sorts), and how much can it warp/bend/compress/stretch before it â€œbreaksâ€? or collapses?

Quote:

2. And if empty space have a grater mass than space occupied by stars and
galaxies would not that cause stars and galaxies to fly apart instead of
collapsing to a singularity?

It's hard for me to see how that would be possible â€“ two galaxies flying apart would be flying apart from each other, but flying towards other adjacent groups of galaxies that are also flying apart? â€“ from observations it looks more like the whole universe is expanding, doesn't it?

Simplex0
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### RE: It's hard for me to see

Message 88599 in response to message 88598

Quote:

It's hard for me to see how that would be possible â€“ two galaxies flying apart would be flying apart from each other, but flying towards other adjacent groups of galaxies that are also flying apart? â€“ from observations it looks more like the whole universe is expanding, doesn't it?

Exactly Chipper Q!
But is not that what the galaxies in the universe seems to do?

The question is if it can be calculated and verified if space in fact have mass.

Chipper Q
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### I'm guessing there are

I'm guessing there are several theories/models that are based on the idea that space is like a fluid, and here's a quick for-instance: The universe is a string-net liquid (although I think this has to do with Loop Quantum Gravity where spacetime is a granular 'spinfoam' of networks of loops â€“ it's a bit beyond the basics [which is the part I'm still learning :) ] )

Regarding the universe and expansion, and in addition to dark matter and dark energy, there may also be â€?dark flowâ€? to take into account ...

mikey
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### RE: from observations it

Message 88601 in response to message 88598

Quote:
from observations it looks more like the whole universe is expanding, doesn't it?

So if the Universe is expanding, and from all indications it is, what is it expanding into? AND why is it expanding? I think it is expanding because of the initial propulsion in the beginning and the fact that gravity is having less and less of an impact on each cluster of matter. Also from gravity itself propelling us, in some cases, away from objects instead of always toward something else. Now what caused the initial propulsion? Whew, what a question...but what if we are the product of a black hole? Matter goes into a black hole and some law says matter can not be lost, but it can be changed. Maybe the output of a black hole is another universe and we are it. Maybe that is where all the stuff that black holes "eat" is going, into another universe? May be impossible to prove but an interesting idea none the less, at least to me. With the speed that black holes "eat" what goes into it, the matter inside must have some kind of impetus behind it when it comes out the back side, assuming that it does come out.