A layman's questions about universes

It's just an analogy. Cosmology (as with all physics) is about mathematical models that can explain all observational data, nothing more. The 2D balloon analogy should not be seen as anything more than an attempt to relate an obscure (to most people) model in laymen terms.Edit: Looks like someone beat me to it.This message has been edited by Beercules, 06-21-2004 11:36 PM

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But how, pray tell, can you analyze a 3d balloon with a 2d analogy and come up with the right answer?? If you do this with a sperical universe, you must begin from the surface of the sphere and we're not on the surface. We're in it which requires a 3d analogy to come up with any sense atol!

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Since we cannot visualize what curved space looks like (it's physically impossible to see anything but surfaces) we must drop down to lower dimensions for any meaningful analogy. There are 2 main ideas that this analogy successfully conveys. One, that the universe can be curved with no edges or center, as the 2D surface has none of either. Second, it relates how an object moving about in a finite, unbounded universe will eventually end up at it's starting point if traveling far enough. On a surface, any object only able to move about along the X,Y axis will meet this condition, so the analogy works.

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And how so are laymen, made of the same stuff upstairs as physicists incapable of understanding a 3d analogy/model? It does not take a doctorate degree for that, imo.

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But it takes an understanding of the math. That is something the vast majority of people lack. Fortunately, most people have the intelligence to understand the concept of an analogy and the application here does not go over their heads.

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That's what you may consider a subpoint to my point. Space/area is nothing but that, space/area into which things can be created or expand into.

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This is not correct as far as modern cosmology is concerned. One of the insights of Einstein's theory of gravity is that spacetime and the gravitational field are equivalent. If you were somehow able to switch off the gravitational field, "space" would disappear as well. The absolute background space of Newton simply does not exist as far as cosmology goes.

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There's gotta be more space/area beyond any imaginary bounds humans like to conjure up in the mind. We are temporal creatures who tend to think in terms of what we see on earth -- boundaries, and up in the sky, -- things/stars, etc. Modern science, imo, is trying to have it both ways. It wants all space/area to be inclusive in the term, "universe," but wants to call it a closed system which has bounds. By the nature of space/area, you can't have both.

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First of all, no one claims the universe (if finite) has boundaries. Your assertion that space must be infinite is merely an assertion. To be taken seriously you'll need to provide an actual argument for that claim.

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How do you know it works

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Because it conveys the idea of curved spaces without the need for mathematics to reasonably intelligent people. That success in conveying the idea is how we know it's a useful analogy. This isn't rocket science here.

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What proof does science have that curves somehow need to be involved an any theory about the universe??

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Science doesn't deal with proof, and it never has been. Shall I post a link that explains the scientific method? Scientists deal with models that have been very successful at making testible predictions about the observable universe. One such model is Einstein's theory of gravity, which is the basis of modern cosmology. This is the source of the curved universes being discussed in this thread.

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You use the phrase, "finite, unbounded universe." Say what?? How can an unbounded universe be finite??

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Again, this isn't rocket science and I just finished explaining this. The universe can be finite and unbounded in the same way a 2D surface can be finite without a boundary if it is curved enough. Oh wait, there's that tricky analogy again. Sigh.

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How can there be a surface to space?

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It's an analogy. Jesus Christ.

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I know modern physicists have this disdain for logic and common sense

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What a silly thing to say. Internal consistency is one of the minimum requirements a scientific hypothesis must have.

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They remind me of the dark ages when the bishops and popes of Vatican City insisted that the laymen couldn't be trusted with the Bible or to interpret it via their own common sense and the words in it. They MUST be explained by the educated and established heirarchy clergy. Thus the dark ages. Imo, we're there again when it comes to modern scienced in areas of origins and the universe, in spite of all the sophisticated equipment. As the Bible puts it for our time, "ever learning and unable to come to the knowledge of the truth."

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You are making the above comparison because you do not know the difference between theology and the scientific method. This is obvious when you post comments like that. Do a search on Google to learn about what science actually is. Otherwise, you simply cannot expect to contribute any intelligent discussion in threads about any field of science.

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I don't see how this pleudo analogy explains anything sensible or logical. Yah, it's something to throw out there to gullible folks who don't stop to analyze space itself. Yah, it's easy to say there's an end to space, a boundary if you will to it, but no model or analogy is going to make any sense when you hunker down and think about it's implications.

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That's funny, because the individuals who have spent the most time thinking about "space" have come to the opposite conclusion you have. That isn't to say that cosmologists claim the universe has a boundary (they don't, which a number of posters have explained to you), but they certainly won't insist the universe must necessarily be infinite.

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Have they changed the definition of 'space' since I was in school?

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When did you ever study physics, really?

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How do you define space so as for it to have the capacity to disappear?

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Who said it could disappear?

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I'm sure you've read and reread my statements that it is the area into which things can be created or expand into and nothing but just that, area. If area should disappear, what displaces the space area it occupied besides more space/area?? Big, big problem here!

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It's only a problem for those who rely on intuition and refuse to put any serious thought into the matter whatsoever. The universe (the gravitational field for simplicity) can exist without occupying any pre-existing background space. If you disagree, you must show how that stament suffers from self inconsistency.

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Actual argument? Maybe you need to reread my arguments already posted in that regard.

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I haven't seen arguments, I've seen assertions. The above claim about space is a perfect example.

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Again, how can space/area curve if it is nothing but area? To curve it must have something in it to define the curvature.

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There is much more to the gravitational field than area (which is 2D BTW, you're thinking of volume), but that's irrelevant because you're asking a question of geometry. Asking how it's possible for space to be curved is no more meaningful than asking how space can be Euclidean.

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But since nobody knows how immense the universe and the things in it are, how can one be so sure it curves. What part of the universe man can observe is likely, imo a partical of the universe. Puny little men on a tiny round dot in a round galexy of billions of stars, the galexy being itself a dot among the billions of galexies in the observable part of our universe, I say, puny men have established in their little minds that what the little human mind sees and comprehends of the universe has gotta be it and if every thing else is curved, the whole thing must be curved. How do we know what is beyond what is observable? The more powerful our instruments get, the more comes into view!

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The finite, unbounded universe is one possible solution when Einstein's theory of gravity is applied to the universe as a whole. No one is claiming we know whether this is correct, or if the universe is actually infinite. You on the other hand, seem to be arguing against the concept itself, no whether or not we know it to be true. But you haven't provided any arguments against the model - you've just made assertions.

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Yes, my friend, I'm afraid there's that rabbit in the hat tricky analogy. "Sigh." Ditto. Herein, imo, lies the lie modern science perpetrates.

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Your opinion doesn't mean shit if you can't even be bothered to learn what science is in the first place. Not understanding the actual physics also prevents you from forming an educated assessment of the situation. It would be like asking a shoe salesman his opinion about neuroscience.

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Again, my contention is that something with a surface is not analogous to something with no surface.

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I already pointed out 2 ideas that are successfully conveyed by the 2D analogy. If this goes over your head, I don't think we have much to discuss. Go to church.

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In 2d, your curvature argument works, but the universe is dimensionless if all space is included so a straight edge unbendable rod with the ability to extend forever, would, if extended in one direction protrude from any point in the universe forever out into endless boundless infinite space with the protruding end of it moving constantly further away from the beginning of it.

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That is simply incoherent.

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Even if scientists would allow some common sense a little say in explaining their concept of a circular 3d universe, they could easily figure out with a simple rubber ball and a straight darning needle protruded into it (the darning needle analogous to the third dimension of their ball which would be analogous to their 3d universe,) and the darning needle was unbendable as a straight edge with the ability to extend forever after disecting/crossing the surface of the 3d ball it would protrude out into space from there for ever with the with the protruding end going further and further away from the other end of the rod sticking into the ball. Why do they reject this model?

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The above demonstrates that you have completely misunderstood the point of the 2D analogy. As pointed out by others, the analogy only involves the surface, not the volume of the balloon or embedding space. Maybe the problem lies deeper? Perhaps an undertstanding of basic geometry would help.This message has been edited by Beercules, 06-23-2004 12:34 AM

Where did you go to school?

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I get the implication here that Rrhain has it in his mind that given the right conditions, space would have the capacity to disappear. Where'd I go wrong??

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That's not implied at all. The statement just shows that no gravitational field means no space.

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Well then, please define space

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You can define spacetime as a 4D coordinate system. To locate any event that takes place in the universe, you need this coordinate system. Finding this event requires 3 spatial dimensions, and one temporal. That is a simplified way to put it, but it gets the idea across.Moreover, this coordinate system is contingent upon matter/energy or any gravitational source. That means if all the mass in the universe were to disappear, spacetime would disappear with it. Note: I am not saying the mass can disappear.

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I'm not asking for understanding of how you define it. I'm asking for a statemnet defining space, the area in which things exist

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I just posted a simple definition. So have others.