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View Full Version : With out gravity, would there be no space?



Chunky
2008-Dec-29, 03:01 PM
so, space is a vacuum. and gravity holds all things together(i guess) so if there was no gravity, wouldn't all of space be polluted with matter?

it makes me think of something, the universe was created from gravity!... because... idk.

EDIT: a better way to pose the question. without gravity would space still be a vacuum?

Chunky
2008-Dec-29, 03:05 PM
what if there was no big bang.. and the universe was filled, no void. then gravity(this oddity) formed, for what ever reason. it started pulling all the matter from the universe into separate pieces, all forming differently..

yeah.. maybe there wasnt a big bang.. No thrust from an explosion. only gravity pulling bits of the universe into itself.


Meh.

Chunky
2008-Dec-30, 02:38 AM
nothing?

WayneFrancis
2008-Dec-30, 03:20 AM
so, space is a vacuum. and gravity holds all things together(i guess) so if there was no gravity, wouldn't all of space be polluted with matter?

it makes me think of something, the universe was created from gravity!... because... idk.

EDIT: a better way to pose the question. without gravity would space still be a vacuum?

Vacuum is a bad term to use. Space has a given energy density. If the physics of our universe was different and there was no gravity then matter would be more evenly spread out. Even so at the current size of the universe space would still be pretty empty. Even the Vacuum has real particles zipping through it all the time.

Ken G
2008-Dec-30, 02:18 PM
In our best model of gravity (Einstein's), what it does is to induce curvature into spacetime. So if there were no gravity, then spacetime would be flat. Matter would be spread out all over, that's true, but as WayneFrancis said, most of the universe would not be much different. Most of the known matter in the universe is in the form of hot hydrogen gas in between galaxies, and the unknown matter may be "dark matter", and both of these are very spread out anyway. So not having gravity wouldn't be a huge difference for either of those, they would just be less clumped into galaxy clusters. There would simply be no galaxy clusters, and no galaxies, and no stars, so it would not be a universe conducive to intelligent life, but most of the matter in it would probably experience little difference.

Cheap Astronomy
2008-Dec-30, 10:02 PM
what if there was no big bang.. and the universe was filled, no void. then gravity(this oddity) formed, for what ever reason. it started pulling all the matter from the universe into separate pieces, all forming differently..

yeah.. maybe there wasnt a big bang.. No thrust from an explosion. only gravity pulling bits of the universe into itself.


Meh.

This view is at odds with all the evidence of expansion. However, the idea that 'without gravity there would be no space' is somewhat supported in theories of early symmetry breaking (http://en.wikipedia.org/wiki/Planck_epoch) where it is suggested that the deunification of gravity from the primordial singularity was what started the whole ball game.

... although 'without gravity there would be no space-time' is better :-)

EvilEye
2008-Dec-31, 01:40 PM
In inflationary cosmology, there is the Inflaton Field (http://en.wikipedia.org/wiki/Inflaton).

It causes space to be filled with repulsive gravity. When the field in an area reaches near zero, energy can become massive, and you get a "big bang"... (a universe) ...an expansion bubble of matter and spacetime.

Chunky
2008-Dec-31, 05:23 PM
... although 'without gravity there would be no space-time' is better :-)

even if i stand motionless, time will pass.

EvilEye
2008-Dec-31, 06:32 PM
even if i stand motionless, time will pass.

If you were the only object in a void, there would be no frame of reference with which to count time.

Not only that, but you also could not move. Move in reference to what?

Chunky
2008-Dec-31, 06:36 PM
If you were the only object in a void, there would be no frame of reference with which to count time.

Not only that, but you also could not move. Move in reference to what?


i could count in my head still. have a watch on my arm tick.


and i could move my arms still. in reference to my body ill move.

cosmocrazy
2008-Dec-31, 07:26 PM
i could count in my head still. have a watch on my arm tick.


and i could move my arms still. in reference to my body ill move.

The fact that you exist and are conscious of your existence creates your own personal reference frame. But if there is nothing else to use as a reference then your motion and position in that void are undefined.

Although regarding the OP you would not exist as you do now if there was no gravity from the outset at the beginning of the universe as we know it (at least certainly when gravity was thought to have become independent very shortly after the BB).

tommac
2008-Dec-31, 08:59 PM
I actually believe that space is a byproduct of gravity.

That is that gravity fully creates the topology that we call space-time.


so, space is a vacuum. and gravity holds all things together(i guess) so if there was no gravity, wouldn't all of space be polluted with matter?

it makes me think of something, the universe was created from gravity!... because... idk.

EDIT: a better way to pose the question. without gravity would space still be a vacuum?

cosmocrazy
2008-Dec-31, 09:03 PM
I actually believe that space is a byproduct of gravity.

That is that gravity fully creates the topology that we call space-time.

You know, its funny that you posted this, cause i personally thinks its the other way round, gravity is a bye product of space-time warped by the presence of mass, a sort of displacement effect.

Durakken
2008-Dec-31, 09:22 PM
let's see...

as we know it gravity is caused by those things with mass...
all things with mass are in the universe...
could the thing needed to create the universe exist outside the universe? As far as we know...no, so the answer is no, is not responsible for the universe...

would there be space without gravity? mass distorts space creating gravity. Does it make sense the other way? mass distorts gravity creating space... no.

Assuming the universe or multiverse or whatever had no gravity what so ever it wouldn't effect space...at least not it's existence property. Nothing is predicated on gravity existing other than things being held together, but if i were to push something it would still move and bangs would still happen.

tommac
2008-Dec-31, 09:29 PM
You know, its funny that you posted this, cause i personally thinks its the other way round, gravity is a bye product of space-time warped by the presence of mass, a sort of displacement effect.

OK ... I think I agree. I mean what i mean by gravity ... is energy. e=mc^2
So gravity is part of what beeing mass is all about.

Now space-time just exists because there is energy to create its landscape.

cosmocrazy
2008-Dec-31, 09:57 PM
Now space-time just exists because there is energy to create its landscape.

In sense i see what you mean, if you consider the BB theory space-time was created along with/by the initial energy contained in the primordial atom / singularity or what ever was at the beginning. :)

EvilEye
2008-Dec-31, 11:38 PM
My reply fits within the Multiverse theory (which is real science).

The void is not void of energy, but there is no mass or time. As areas of it cool to near zero, a bubble begins to inflate as energy becomes mass.

Think of a block of Swiss-cheese. Universes are the holes in the cheese, and the cheese are the inflatons.

You need not ask where the cheese comes from.... it is just pure energy. The proof that it is energy is that it had the ability to do work, which it did. It created the universe we live in.

Cheap Astronomy
2009-Jan-01, 07:15 AM
even if i stand motionless, time will pass.

Well sure, your heart beats and you use up valuable oxygen ;-)