How can the universe be infinite, does it end, what is outsi

[shadow735]

Hello I am new here, I have a question that has always bothered me, I know parts of this have been discussed but not from my perspective so I hope some of you with more knowledge and opinions that I have can help me out. I am not a math wiz, I don’t know a lot of the complex theories discussed here. I am just a person trying to expand his mind with all the amazing sights, ideas, theories and knowledge about space time and the universe.<br /><br /> This Question freaks me out, maybe call it a phobia but it makes me sick to my stomach when I think about it. Maybe because its so outside of my ability to understand.<br /> When I think of this question I keep wondering, how can the universe be infinite? I am used to understanding things in the sense of the planet earth being contained, it has a start and finish point A leads to point B. Outside of the planet is space, our solar system then our galaxy, outside that is other galaxies, once I get past that point I get lost.<br /><br /> Outside of the expanding universe does it end? If it does what is outside. This is that part that freaks me out and I get lost.<br /> If lets say the universe is like a bubble then what is outside of a bubble. How can the universe be a contained bubble and have nothing outside of it. Is there nothingness outside the space bubble of the universe if so what contains that nothingness. I cant comprehend that outside the bubble is nothing, you cant go thru it, you cant see it. <br /><br />If the universe goes on forever, how can that be, how can something have no end even if its just empty space. How can something not be contained? This is the part the usually freaks me out most likely because I cannot comprehend this. That space cannot end. It makes me sick thinking about it because its means the universe is so big that we are not even a spot on the galactic windshield so to speak.<br /> I don’t know why but I get slightly paranoid/scared when I try to comprehend these ideas. <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

Well, firstly try considering that the universe is not infinite. A better description is that the universe is "finite but unbounded".<br /><br />So what does "unbounded" mean, in this context? Does it simply mean that the universe has no edge? If that is the case, then how can it be finite?<br /><br />Well, a simple example is <b>the surface</b> of a sphere. That surface is finite but unbounded. It has a finite area, but no edge or end. You can circumnavigate the sphere and end up where you started, so it has a finite size, but has no end.<br /><br />But that surface is only 2 dimensional. The inhabitants of that surface live in a 2 dimensional world, with no knowledge of the 3rd dimension that would allow them to understand the actual shape of their universe. They might work out that their universe is wrapped around another unseen dimension when they circumnavigate it, but they cannot see that other dimension.<br /><br />Now add a couple of dimensions to the above example and apply it to our own universe. Perhaps it has a finite size but resides within another unseen dimension that causes the universe to curve back on itself dimensionally, so in theory, if you could draw a straight line that was long enough, the line would end up back where it started.<br /><br />There are theories that our universe is like this, that space is ever so slightly curved. That a straight line may indeed be some supermassive loop, but the radius of that loop is larger than our observable universe, so we cannot see the same thing in different directions! <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[shadow735]

I understand what you are saying, I just keep visualizing it as a ball but what stumps me and make me think wait how is that possible it what is outside that ball, kind of like if I hold a basketball there is air outside that ball, when I try to apply that same example that the universe is a ball I cant comprehend that there is nothing outside of the ball.<br /><br />I dont know if I can explain my thinking on this in the right words. If space curves back on itself slightly to where you would end up back where your start of the line it would obviously mean space is curved so that its is like a sphere which I understand but what is outside that sphere?<br />if the universe is expanding what was previously occupying in the area that the universe has expanded to.<br />was it a void? was it nothingness? Its hard for me to understand the universe being able to expand into an area of nothingness, as well as a invisible wall that the universe pushes as it expands, whats behind the wall?<br /><br />I hope I am not losing anyone, I am just having a hard time trying to put this into words.<br /> <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

You forgot to "add another couple of dimensions" to the surface of a sphere. Visualising a ball won't help you here. In fact, visualisation of the possible shape isn't really possible (this is where the maths takes over, and where people who can see the beauty and simplicity in mathematical models have the advantage).<br /><br />Let's discuss <i>manifolds</i> for a moment.<br /><br />In a one-dimensional manifold, every point has a neighbourhood that looks like a segment of a line. So if you were an entity that lived in that manifold, you would only be able to see in one dimension, and you would see a line. Now, an example of a one-dimensional manifold is a <i>circle</i>, a 2-dimensional object. If you live on the line that defines that circle, all you see is a line in front of you and line behind you and you would only realise it was a circle once you travelled far enough along the line to get back to where you started (you cannot tell the line is curved as you can only see in 1 dimension).<br /><br />My surface of a sphere example earlier was an example of a 2-dimensional manifold. You can only see 2 dimensions, so all you see is a disk around you. Again, you might only work out that you live on the surface of a 3 dimensional object by circumnavigating it, as you cannot perceive that 3rd dimension.<br /><br />Now we come to a 3-manifold, which is getting closer to describing the universe (but we aren't there yet!). In a 3-manifold, you see in 3 dimensions, and your neighbourhood looks like a sphere. If you were able to travel far enough in one direction, you might come back to where you started, but, and here's the kicker - <i>the shape has one more dimension than you can perceive!</i> A 3-dimensional manifold is a 4-dimensional shape.<br /><br />Trying to visualise this shape will have you turning your brain inside out...<br /><br />Now, onto "nothingness", or void. This does not describe a volume of 3 dimensional space with nothing in it, it describes <i>no space</i> and no <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[johnrambo]

Im also new to this forum but thats the best explanation i have read so far about how the universe is build.

 

[falkor]

Haha, speedfreek explained that one perfectly! <img src="/images/icons/smile.gif" /> Hey speedfreek, how much for private tuition? <img src="/images/icons/tongue.gif" /> What about all my problems; help me out mate... <img src="/images/icons/wink.gif" />

 

[SpeedFreek]

Well, we must remember that the way I described it is just one of the possibilities. It can help you get your head around the concepts involved and still be able to sleep at night! <img src="/images/icons/wink.gif" /><br /><br />In the end, the final picture could be very different, and beyond our current meagre understanding. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[shadow735]

I have to review your explanation when I get home from work. I think I am understanding it. I just have to mull it over in my head.<br />I will post later what I dont understand <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[mytheory]

Hi speedfreak, I understand your description just fine! The thing I can't get my head around is the theory that the universe will eventually collapse in on itself. If this were to happen, where would space and time go and wouldn't that prove that space isn't and never was infinite? not that anyone would be around to discuss it haaa... any thoughts? <div class="Discussion_UserSignature"> <span style="font-weight:bold" class="Apple-style-span">@LEX</span> </div>

 

[shadow735]

speedfreak I hope this doesnt sound like a stupid question but what is a manifold? Sorry I am pretty new to the different terms that are used. <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

Which theory is it that has the universe eventually collapsing in on itself? I thought we discounted those types of scenarios years ago.<br /><br />The way I understand it, with the recently discovered acceleration of cosmic expansion, the opposite will happen - the universe might continue expanding at an accelerated rate until one day in the distant future even atoms are pulled apart. Google "big rip" to see what I mean. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[SpeedFreek]

Not a stupid question at all. There are no stupid questions, only stupid answers - I try to make sure my answers aren't stupid <img src="/images/icons/smile.gif" /><br /><br />A manifold is simply an abstract mathematical space in which every point has a neighborhood which resembles Euclidean space, but in which the global structure may be more complicated.<br /><br />A 1-manifold describes a structure where every point has a neighbourhood that looks 1 dimensional, but the structure is actually 2 dimensional. (your surroundings look like a line, but the overall shape is actually a circle)<br /><br />A 2-manifold describes a structure where every point has a neighbourhood that looks 2 dimensional, but the structure is actually 3 dimensional (surroundings look like a disc, but shape is actually a sphere)<br /><br />A 3-manifold describes a structure where every point has a neighbourhood that looks 3 dimensional, but the structure is actually 4 dimensional! (surroundings look like a sphere, but the shape is actually a 4 dimensional object).<br /><br />In all these cases, if you somehow mark your starting point, you can move in (what seems to you to be) a staight line, but you end up back where you started, so you might be able to work out the shape of the overall structure without being able to actually see that structure.<br /><br />Of course, when it comes to our universe, the furthest parts we can see are receding from us at speeds faster than light, so that theoretical straight line might loop round and meet itself, but we could never actually circumnavigate it. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[shadow735]

Speedfreak can you recommend some reading material for me that discusses the theories on the universe and its expansion, origin and demise? <br />Most of the info I got that has put me on the path of intense interest has been from documentaries.<br /> <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

Well I would start with:<br /><br />A Brief History of Time - Stephen Hawking<br />The Elegant Universe - Brian Greene<br />The Fabric of the Cosmos - Brian Greene<br /><br />Some websites:<br /><br /> The Distance Scale of the Universe and after that, go back to the main page of that site for other good stuff!<br /><br /> Misconceptions about the Big-Bang is a good article, which is based on this paper.<br /><br /> A Review of the Universe <br /><br /> Evidence for the Big-Bang <br /><br />For something a little less formal, the book "The Elegant Universe" was made into a set of documentaries. All 3 hours of it is watchable online <img src="/images/icons/smile.gif" /> There are interviews with Brian Greene too, all here - The Elegant Universe <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[weeman]

The Elegant Universe is definitely a good one, I would recommend that. Brian Greene covers a lot of topics in his book, including a history of Einstein and his views through General Relativity.<br /><br />Greene gives awesome examples of how 1-dimensional beings, 2-dimensional beings, 3-dimensional beings (and so on) experience the world around them. As hypothetical situations, Greene gives visuals to explain how our universe may exist in more dimensions than we can perceive. A 1-dimensional being lives in "Lineland", where all known directions are left and right. "Lineland Beings" are infinitely thin worms, who have eyes only on the ends of their bodies. Linebeings can only see their neighbors to their immediate left or right; all they know of the world is the eye of the Linebeing directly beside them! Then you have 2-dimensional beings, who live on a garden hose-like surface. They can travel left and right, and around (front and back). Then you have 3-dimensional beings, who are essentially, us! They can travel left-right, forwards-backwards, and up-down. Greene states that the Beings in each universe know only the dimensions that they can perceive, however, what Greene is trying to say is that the universe in which the Beings live actually has higher dimensions that they are completely oblivious to. <br /><br />Wouldn't these be similar to the manifold examples?<br /><br /><font color="yellow"> A 3-manifold describes a structure where every point has a neighbourhood that looks 3 dimensional, but the structure is actually 4 dimensional! (surroundings look like a sphere, but the shape is actually a 4 dimensional object). </font><br /><br />It sounds to me that our universe can best be described by the 3-manifold model. Of course, just as Brian Greene implies, things aren't always what they seem in the universe. <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]

Yes, that's correct, Greene was indeed describing manifold spaces in the same way that I was doing in my examples. <img src="/images/icons/smile.gif" /><br /><br />A 3-manifold is a good model to help us understand the way the universe might work as a static model. But to be accurate, you need an even more complicated "shape" in order to factor in things like expansion and time. For instance, general relativity models space-time using a 4 dimensional Pseudo-Riemannian manifold <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[qso1]

shadow735:<br />This Question freaks me out, maybe call it a phobia but it makes me sick to my stomach when I think about it.<br /><br />Me:<br />Rather than get sick, it might be more useful to just be amazed at such a gigantic structure.<br /><br />Bottom line as to how big and what the Universe is...we don't really know structurally beyond that which you mentioned with galaxies being the largest known structures within the confines of what we call the Universe.<br /><br />I used to understand Universe to be all encompassing and probably eternally ongoing. But when I researched what scientists thought...it turned out they had theories ranging from infinite Universe to multiverses, omniverses, you name it.<br /><br />However, their data is largely mathematical based on observations of certain objects. An example being the boundries of the Universe are defined by the farthest observable object. And the object would only occupy a very tiny portion of the Universe in whatever direction it is observed.<br /><br />To my knowledge, we have never observed anything that could be said to lie outside the Universe going by the generally accepted definition of the Universe. I try to grapple with it by thinking of the Universe as eternal...the void of empty space that all else occupies. That void being uncontainable because it stretches into infinity.<br /><br />We see about 20 billion light years out...that is the farthest observable object detected. What lies at 200 billion light years or 530 trillion light years? Did the collection of matter we know start as a big bang within the eternal void...other big bangs taking place too far for us to see? Or is it one big bang starting within the confines of nothing. No dimension, no time...no surrounding. We will probably never know.<br /><br />shadow735:<br />If the universe goes on forever, how can that be, how can something have no end even if its just empty space.<br /><br />Me:<br />The only answer I can give would be that if it is...its because it <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[shadow735]

Dont get me wrong I am completely amazed with the universe; I wish I could get on a ship that provided all my needs and for my protection from the dangers of space so I could go out and explore it.<br /><br />I get the sick feeling because when I think of the universes size and scope and how it may have formed it hits a childhood phobia.<br /><br />I dont know what it could be called but I was once deathly ill and had dreams about things being so tiny and small becoming huge and gigantic kind of like a tiny flea becoming instantly huge like a elephant right before your eyes.<br /><br />my uneasy feeling when I try to comprehend the universe is tied to that. Trying to imagine something smaller then and atom expanding to become the universe, all that matter confined and compressed into something smaller then an atom and becoming something so huge. It just is scary, the power and forces involved. And then trying to comprehend the scope of how big the universe is.<br /><br />Dont get me wrong I am amazed but it also scares me, who knows maybe its because I am human and trying to comprehend something like this makes our world and un as a species so small and unimportant in the scheme of the universe.<br /> <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

At times like these, I usually find solace in the writings of Douglas Adams. This issue reminds me of his "Total Perspective Vortex"<br /><br />From the wiki entry:<br /><br />The Total Perspective Vortex, in the fictional world of Douglas Adams's The Hitchhiker's Guide to the Galaxy, is the most horrible torture device to which a sentient being can be subjected. Located on Frogstar World B, it shows its victim the entire unimaginable infinity of the universe with a very tiny marker that says "You Are Here" which points to a microscopic dot on a microscopic dot.<br /><br />The machine was originally invented by one Trin Tragula in order to annoy his wife. Because she was forever nagging him for having no sense of proportion, he decided to invent something that would show her what having a sense of proportion really meant. Unfortunately the shock of being placed in the Vortex destroyed her brain, but Trin Tragula's grief was tempered by the knowledge that he had been right and she had been wrong. The Total Perspective Vortex had proved that in an infinite universe the one thing sentient life cannot afford to have is a sense of proportion.<br /><br />The machine produces a virtual reality model of the entire universe by means of the axiom that any piece of matter is affected by all other matter. The Vortex reconstructs the universe through computer processing of a high-resolution scan of a small object. In the words of the Hitchhiker's Guide,<br /><br /> "...since every piece of matter in the Universe is in someway affected by every other piece of matter in the Universe, it is in theory possible to extrapolate the whole of creation - every Galaxy, every sun, every planet, their orbits, their composition, and their economic and social history from, say, one small piece of fairy cake."<br /><br />Only Zaphod Beeblebrox is reported to have survived the Vortex unscathed (and to then have eaten the small piece of fairy cake). When it showed him the "You Are Here" marker, Zaphod cor <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[MeteorWayne]

Thanx for the reminder!!!!!<br /><br />It makes much more sense than many of the ideas floating about lately. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[Anonymous]

Consider-- 1:<br />Earth has no end, has it?<br />Earth is round and "infinite.<br /><br />Consider-- 2:<br />Most of the things in unverse, including universe has unpteen things in common.<br /><br />Consider--3:<br />Some theories propose an expanding universe.<br /><br />Consider--4:<br />There is not much proved information about Black holes.<br /><br /><br />It may be that universe is something like earth.<br /><br />For an expanding unverse, maybe Black holes form some edge of the universe, they swallow things, which allow others to take its place,maybe<br /><br />Or, possibly, universe is a part of much more bigger things and we are to that thing, as electrons are to universe.<br /><br />I am not sure that my answer will please you or not. I have tried the idea. <div class="Discussion_UserSignature"> <strong><font size="2"><p align="center"><br /><img id="a9529085-d63d-481e-9277-832ea5d58917" src="http://sitelife.space.com/ver1.0/Content/images/store/9/2/a9529085-d63d-481e-9277-832ea5d58917.Large.gif" alt="blog post photo" /><br /><font color="#339966">Oops! this is my alien friend.</font></p><p align="center"><font color="#ff6600">╬→Ť╠╣є ’ M€ ’<br />╬→ Ðôŵņ2Ëãřŧĥ ๑<br />╬→ ЙДm€ :Varsha<br /></font></p></font></strong> </div>

 

[siarad]

Your maniflod description seems to be a simple integration, has this been done to produce a fourth dimension ?

 

[SpeedFreek]

I'm not sure I understand your question, in the way you worded it. I am not much of a mathematician, I'm afraid. If you are asking if there are four-dimensional manifolds, the answer is yes.<br /><br />I must admit that whilst I can describe the principles, I will not pretend to understand the mathematics involved. My explanations are based on what I understand of the four-dimensional pseudo-Riemannian manifolds which model space-time in general relativity, specifically the Lorentzian manifold, and the concept that a manifold can be described as a surface or volume "wrapped" around a separate dimension. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[siarad]

Sorry not too plain, I had 30 seconds left to post before cutoff.<br />However you've answered it, thanks <img src="/images/icons/smile.gif" />

 

[shadow735]

"Consider-- 1: <br />Earth has no end, has it? <br />Earth is round and "infinite. "<br /><br />The Earth is not Infinite, if you start at point a and move fwd you end up back where you started, the earth is finite no matter which direction you go.<br /><br />The universe seems to go on forever at least we dont know for sure about this. Outside the earth is space an other planets, stars and galaxies. <br />If the universe is a sphere like the earth then what is outside it? <br /> <div class="Discussion_UserSignature"> </div>