# space curviture

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#### mandy_sgra

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How can space be curved and expanding when there is nothing outside of space to be expanding into? and everything that has a shape has a solid form outside of it holding it into that shape. so how can space be cuved with nothing outside of it holding it into that shape? now i understand that the big bang theory pushed everything outward. but space is the black stuff. space had to be there in order for the big bang to happen. the molecules and atoms had to have somewhere to go so i think that space existed before the big bang. but i still dont see how space itself can be expanding and in a curved shape...

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#### Saiph

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the big bang is the explosion of space as well, it created space.<br /><br />One way to visualize all this is to nest our space into a "higher" dimension.<br /><br />Say you have a balloon, that you inflate. The surface of this balloon is 2 dimensional, and is curved back onto intself, giving it shape. Now, it expands, but into what? Well, nothing but the 3rd dimension.<br /><br />So our 3d space expands into a 4th or 5th dimension, mathematically.<br /><br />However, that doesn't mean anything is there. Go back to the balloon, and tell me where the edge of the surface is. Remember, you can't leave the surface, as that's our universe, our space. In that 2d surface there is no edge, there is no center. But it is expanding. The points on the balloon (you can draw them on if you'd like) all spread apart, the surface area of the balloon increases. But nowhere will you find an edge moving into something else.<br /><br />So from our 3d perspective, the universe isn't expanding into anything. From a mathematical sense, in a 4d or higher perspective, it's expanding into a 4th or 5th dimension, but is entirely contained in itself, having no edge or center, just like the surface of the balloon has no edge or center. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

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#### paintwoik

##### Guest
The balloon and raisin bread analogy has never cut it, and never will.

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#### Saiph

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They have thier uses. They aren't supposed to be all inclusive and one hundred percent accurate.<br /><br />They do, however, serve to point out a few physical processes and demonstrate what exactly someone means when you have expansion, but no center.<br /><br />Now, within those limits, you can use them to help people visualize how some things work, and why some things are not required, like an edge to the universe, or a center, and yet still have expansion.<br /><br />Or do you care to elaborate on your protest? <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

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#### lewcos

##### Guest
A balloon has an edge, it is the point at which the balloon surface meets the air - I think what people mean when they ask the question (at least I mean this) is, what is the "air" made up of in our universes example? (the air on the outside of the balloon) (the "air" outside of our universe)

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#### mandy_sgra

##### Guest
exactly what i mean. . the rubber that makes the balloon is made in a curviture shape. there are also long balloons, round balloons, oval balloons even dolphin shaped balloons. It doesn't just get it's shape by expansion it is a premade shape. so, for the balloon theory to be 100% correct, then the universe had to have been premade in a curviture shape and blown up with air persay to take on the shape. And just as you said, what "air" can be out of space?

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#### Saiph

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Mandy: the balloon is only an illustration, an analogy, not a complete theory. Many of the properties related to balloons do not have an analogous property in the current model of the universe (premade shapes for instance).<br /><br />That's why I only talk about a few specific properties in a general sense. I talk of the surface as a 2 dimensional plane, it has no depth, just as a 3 dimensional object has no extension into a 4th dimension. Of course a balloon does have thickness, but I say don't worry about it, it's thin enough, use the balloon only to anchor your thoughts.<br /><br />Lewcos: Any movement in a direction perpendicular to the surface of the balloon is into the third dimension. To scale the analogy to the 3rd dimension being the surface fo the balloon, that means we're expanding into a 4th or 5th dimension, and yet there is no edge, or center to the 3d universe of space and time. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

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##### Guest
We will never know for sure. We're stuck in our abilities to see the real picture.<br /><br />My answer is; If space is still expanding how can you reach/ see the edge of the universe if the edge is moving at light speed away from us.<br /><br />To see the edge of space is impossible. Even if the univers is contracting, we'ld be contracted by the time we view the edge. <br /><br />

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#### alokmohan

##### Guest
Just a way to explain.

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#### bobw

##### Guest
Mandy, this might help.<br /><br />Flatland: A Romance of Many Dimensions<br />Edwin A. Abbott (1838-1926. English scholar, theologian, and writer.)<br /><br />With Illustrations by the Author, A SQUARE (Edwin A. Abbott)<br /><br />http://onlinebooks.library.upenn.edu/webbin/gutbook/lookup?num=201<br /><br />This is a really funny little story about how different dimensional creatures would appear to each other. 213 kilobytes for the text version, less for the zip. A fun read, I recommend it for people trying to get a handle on the balloon analogy and for those who understand all about it. Free download from project Gutenberg with great ascii illustrations, too! <div class="Discussion_UserSignature"> </div>

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