Infinite Space

[spacekud]

What I can not grasp is how is something infinite? I know dumb question but it just boggles my mind how it can be so big and never end. <br />How does something do that, there is no picture in my mind that shows how this is possible. <br />How is the universe expanding when there is no end in the first place?<br />I'm sorry I just wanted to see what everyones view is on this thank you for your time.

 

[vogon13]

Big.<br /><br />Really, really big.<br /><br /><br />No, bigger than that.<br /><br /><br /><br />Big, big, big.<br /><br /><br /><br />Really stupendously big.<br /><br />Much, much bigger than that, actually.<br /><br /><br />What we are trying to get across here is way bigger than what you are used to, way, way, bigger.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[origin]

<font color="yellow">How is the universe expanding when there is no end in the first place?</font><br /><br />Space is not infinite. What is your specific question?<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[juliemac]

Reading Vogon13's post I kept expecting him to emerge from a fridge in tail and start to sing "Just remember..."<br /><br />(Juliemac added nothing intelligent to the thread.....)

 

[owenander]

Space is infinite<br />Infinite nothingness<br />Nothingness can't just 'end', think about it.

 

[SpeedFreek]

Einstein considered it may be possible that space is finite, but <i> unbounded. </i><br /><br />What does unbounded mean? Well it may not simply mean that space goes on forever. Some people hear the word unbounded and <i> infer </i> from it that space goes on forever, when all unbounded may <i> actually </i> mean is that it has no end, no edge, no bound. This is not necessarily the same as infinite, though.<br /><br />It might be the case that the dimensions of our universe curve back on themselves, meaning that there is no edge. If this were the case there might come a time when you would be looking at the same region of space when you look in opposite directions - but the region you are seeing would be showing how it looked in different epochs and thus may not be recognisable as the same <i> place. </i><br /><br />In general relativity, space-time is modelled as a four dimensional manifold, or 4-manifold. The 'shape' of this object is not something we can easily visualise.<br /><br />Let's look at some examples of expanding boundless manifolds. <img src="/images/icons/smile.gif" /><br /><br />A 1-manifold is a place where all you can see is one dimensional space. An example of a boundless 1-manifold is a circle. Anywhere an observer in this space looks, their neighbourhood looks like a line, for they can only see one dimension. If they travel along the line they might eventually end up back where they started, unless the circle is expanding faster than they can circumvent it.<br /><br />An example of a boundless 2-manifold is a sphere, or a torus. Anywhere an observer in this space looks, they see a disc shaped plane, for they can only see in two dimensions. Again, if they can beat the rate of expansion they may eventually circumvent it.<br /><br />So now try to imagine what kind of object a boundless 4-manifold might be. Is it possible to visualise this object? If we are living in a universe that acts like a 4-manifold, we would see 4 dimensional space (space-time) all around us <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[bdewoody]

Finite......Infinite. It doesn't really matter to me since we can't even get out of our solar system (at this time). <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[spacekud]

I was just asking how does something not end or have any sort of edge, like a circle if it was a circle would there just be more emptiness on the outside of that? Sorry for my ignorance I keep thinking about this lil subject.<br />okay lets say if it was a circle if we started in the middle and went straight out any direction and got to the "edge" I guess I know there is none but lets just say the edge of the universe would it just "pop" us back on the other side of the universe of some sort?

 

[origin]

Space is finite. Space is NOT nothingness. Our universe is a 4 dimensional space time continuum. There is no edge of space. Space does not expand 'into' something.<br />If it were somehow possible for an observer to be outside of our universe he might look at the universe and see that Spacekud is one inch away from the 'edge' of the uiniverse, but we are bounded by the universe and so we would not detect any edge at all. In our universe you can have a section of space that has no matter or energy - but this area is still space, it is not nothing. Matter and energy can only exist in space which is our universe. <div class="Discussion_UserSignature"> </div>

 

[spacekud]

Sorry did not mean to say nothing

 

[origin]

Lets look at space as something 3 dimensional instead of 4 dimensional. Imagine an ant that is walking on the surface of a balloon. As the balloon is blown up it is expanding so the ants 'universe' is expanding. The ant cannot leave it's universe it continues to walk around on it's expanding universe and it never encounters an edge.<br /> <div class="Discussion_UserSignature"> </div>

 

[deapfreeze]

That makes sense to me. Good explanation. <div class="Discussion_UserSignature"> <p><font size="2" color="#0000ff"><em>William ( deapfreeze ) Hooper</em></font></p><p><font size="1">http://deapfreeze-amateur-astronomy.tk/</font></p><p> </p> </div>

 

[kelvinzero]

furthermore, the expansion of space is allowed to move objects in distant locations away from us at greater than the speed of light, so we will never even be faced with the confusion of traversing the balloon and returning to the same spot.. if the universe really is twisted into a balloon. Even if it isnt we are still trapped in a spherical region we will never reach the edge of for the simple reason that its boundary is receding from us at the speed of light.<br /><br />It is an interesting philosphophical question: is something really there if the same theory that predicts it also explains that it will never interact with us in any slightest way. Regions beyond this boundary might as well be different universes.

 

[portercc]

My opinion? Space/nothingness goes on forever in all directions...at least until it hits the wall, then the wall goes on forever. No, no wall, infinite emptiness and universes.

 

[Kalstang]

origin: <font color="yellow">Space is finite.</font><br /><br />Really? How do you know this to state it as such a hard core fact? Please show me the proof that you have that makes you so sure of yourself. <div class="Discussion_UserSignature"> <font color="#ffff00"><p><font color="#3366ff">I have an answer for everything...you may not like the answer or it may not satisfy your curiosity..but it will still be an answer.</font> <br /><font color="#ff0000">"Imagination is more important then Knowledge" ~Albert Einstien~</font> <br /><font color="#cc99ff">Guns dont kill people. People kill people</font>.</p></font><p><font color="#ff6600">Solar System</font></p> </div>

 

[SpeedFreek]

The ant on the balloon is a very good model, but it is only a model of a 2 dimensional manifold. It works well describing the edgeless but finite space of a universe whose inhabitants only ever experience 2 dimensions (seeing or moving across the surface of the balloon). In that model, there is no <i> inside </i> or <i> outside </i> the balloon. Those are part of the extra dimension <i> we </i> use to model the system.<br /><br />But our universe works as modelled by a 4 dimensional manifold - we see and move through 4 dimensions. A 4-manifold is also edgeless but finite. But the shape of it is not something as simple as a sphere. If we follow my example above (and in my previous post) we find that to visualise the shape of a universe we need to add an extra dimension to those that the inhabitants observe - and we observe 4 already!<br /><br />With a finite but edgeless manifold, there does not actually have to be <i> anything </i> outside it, as there is no edge where the outside might begin. But it is not infinite, as it contains a finite amount of space.<br /><br />The way we observe the universe is consistent with a 4-manifold which is how relativity works. So this means the universe <i> might </i> be finite but edgeless.<br /><br />But we do not know for sure. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[lukman]

In short, finite space in 3D seems like infinite. <div class="Discussion_UserSignature"> </div>

 

[spacekud]

Okay so I'm guessing you can't put that in model terms??? If you could unless the ant thing is about as close as we get but if there is another way you could put that then please do.

 

[SpeedFreek]

Yes, that's right, you can't visualise this model. The closest you can get is a stipped down model using less dimensions.<br /><br />We model the ants on a balloon universe as a 3d sphere, but they can never see it as that, they only see the surface of the sphere (and they don't look <i> up </i> as they only see in 2 dimensions!).<br /><br />So if we see a universe in 4 dimensions (3 spacial dimensions, plus time) we need another dimension in which to model it, which you can do with mathematics, but not with pictures.<br /><br />So you have to work on the principle that the concept of a finite but boundless object, like a circle (which is 1 dimensionally edgeless) or a sphere (which is 2 dimensionally edgeless) would work for a similar object that had more dimensions, which leaves open the possibility that the universe is a 4 dimensional edgeless object.<br /><br />General relativity is based on this concept. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[spacekud]

Okay still a lil confusing but I understand now, thanks alot sorry for the trouble

 

[lukman]

Cant we map our universe in 3D? Funny, although we can map galaxies, know the exact position one to another. <div class="Discussion_UserSignature"> </div>

 

[weeman]

<font color="yellow"> With a finite but edgeless manifold, there does not actually have to be anything outside it, as there is no edge where the outside might begin. But it is not infinite, as it contains a finite amount of space. <br /> </font><br /><br />Spacekud, Speedfreek usually has a very good way of explaining things <img src="/images/icons/smile.gif" /> <br /><br />That statement above, in yellow, describes our universe to the best of our knowledge to this day. The universe may not be infinite by most definitions, but the universe is all that there is, it is everything.<br /><br />Many people ask, "If the universe is expanding what is it expanding into?" The answer to this is: itself. Since the universe is everything, it can only expand into itself, there isn't anything that it expands into. <br /><br />The thing to keep in mind is that the universe hides many things that we have yet to learn. There could very well be extra dimensions to our universe that we cannot perceive, some of which may hold more answers to these mysteries.<br /><br />Take this example into consideration. Lets say you draw a stick figure on a piece of paper and draw him a house, lets name him Frank <img src="/images/icons/wink.gif" /> Frank lives in an entirely 2D world, to him, that's all there is. 2 dimensions is all he knows, it's all he can see and perceive. However, we know that there are more than 2 dimensions since you and I live in a 4 dimensional world. Frank might be able to hear you talking, but he will never be able to see you unless he steps out of his 2D world, and into our 4D world. <br /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[SpeedFreek]

<i> Cant we map our universe in 3D? Funny, although we can map galaxies, know the exact position one to another. </i><br /><br />Yes, we can map our universe in 3D, but only from the <i> inside! </i> <img src="/images/icons/wink.gif" /> And in 3D, it would be a static map, a moment in time frozen for us to view.<br /><br />But we have to ask what we would be looking at. <i> When </i> is the map accurate? Seeing as the further we look the more out of date our information is, the only place that our map would be accurate for is the local cluster of galaxies. Anything else further away isn't actually where we see it any more and won't look like it does any more either. So we don't know their <i> exact </i> position relative to each other, or it depends on your definition of exact.<br /><br />So, if we take the observable universe and map it in 3D, where do we put the most distant objects? Do we put them where they look like they are right now? They look like they are something over 13 billion light years away. But they aren't.<br /><br />But that's just what they looked like over 13 billion years ago, when the light left them. This point in space was only around 40 million light years away from them when that light was emitted, but the expansion of space means it has taken over 13 billion years for their light to reach us. The light has been stretched to make them look 13 billion light years away but we see them as they looked when they were only 40 million light years away, but a lot smaller and sometimes distorted by gravity.<br /><br />How <i> exact </i> a map of <b> "you" </b> would I have, if I took a photo of you as a baby and looked at it through the wrong end of a telescope, making you look far further away than you were when the picture was taken, when you are now married with 2 kids and emigrated to the other side of the planet? <img src="/images/icons/wink.gif" /><br /><br />It is theorised that those distant objects would now be something like 46 billion light years aw <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[Kalstang]

speedfreek: <font color="yellow">Seeing as the further we look the more out of date our information is, the only place that our map would be accurate for is the local cluster of galaxies. Anything else further away isn't actually where we see it any more and won't look like it does any more either. So we don't know their exact position relative to each other, or it depends on your definition of exact.</font><br /><br />Actually we could make an accurate map of the position of any place. Just use extrapolation. We can tell the direction they are going and we know how far away they are. We can even tell their relative speed. Take those and you can figure out where they would be right now. Couldnt see it of course but you could tell where it is at this moment. <div class="Discussion_UserSignature"> <font color="#ffff00"><p><font color="#3366ff">I have an answer for everything...you may not like the answer or it may not satisfy your curiosity..but it will still be an answer.</font> <br /><font color="#ff0000">"Imagination is more important then Knowledge" ~Albert Einstien~</font> <br /><font color="#cc99ff">Guns dont kill people. People kill people</font>.</p></font><p><font color="#ff6600">Solar System</font></p> </div>

 

[nexium]

If we spend incredible amounts of money we can make a sort of accurate computer map in 3D where we can select the date to see how it changes with time for our galaxy, our local group of galaxies, perhaps most of the known universe. The latter would require millions of world class telescopes to produce details about the farthest galaxies. Neil