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#31
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Hypothetical astrophysics question
"Jeff Root" wrote in message
om... "CeeBee" replied to Jeff Root: Yes, of course, but how the heck can you possibly know that light doesn't go between universes? What theory predicts that light doesn't go between universes, and what observations is that theory derived from? The big bang theory doesn't describe "universes". It just describes our universe, the development of it, and the phenomenon in it. Yes! Exactly! Since there is no "need" for such hypothesized universes to be "embedded into something" (are you quoting someone???) that is able to transmit information, it is therefore impossible for light to go from one such universe to another? I think that what you really mean to say is that it *might* be impossible for light to go from one such universe to another. The Big Bang theory "predicts" that. But you just said that the Big Bang theory doesn't say anything about other universes, only our own! In your next sentence you contradict that and say that it predicts what can and can't happen outside our universe! Which is it??? The BB theory applies onlyh to our own universe because it is the only one that we can possibly have empirical information about with which to test the theory. There is no way to know, for example, if the physical constants for another universe would be the same or different, or even if another universe was comprised of the same number of physical and time dimensions. The BB theory encorporates General Releativity, which deals with the geometry of space and the propagation of gravity and light in it. Light travels in space and, essentially by definition, follows space geodesics; it cannot leave space if it follows space geodesics, as space is continuous and boundary-free. It tells us that space and time were created simultaneously with the Big Bang, Actually, the Big Bang theory says nothing about the origin of space and/or time. It does say that at some time about 13.7 billion years ago everything in the Universe was squished real close together, was very hot, and was expanding real fast. It also says that a moment before that, something completely unknown happened, which no theory is yet able to describe in any way that makes sense. So, space and time *may* have been created at that time, or they may not have. There's no way to say, as yet. The current BB theory says that space and time were indeed created at some instant about 13.7 billion years ago. It further says that they were created in a very dense state; the whole universe would comfortably fit inside a breadbox for some tiny fraction of a second from the initiation. and all matter and energy in it. It predicts how the state of the universe was, is and will be. If observations are in accordance with the predictions of the theory, the theory gains validity. I fail to see the relevance between universes "embedded" into something conducting light and me quoting someone, but I might miss your point. I asked about your use of the term "embedded" because Greg used it prominently in a message posted less than two hours after yours; I don't think the term had been used previously; and I see no particular reason for its use here. The idea of universes being embedded in anything sounds goofy. I agree with you that there is no "need" for such universes to be "embedded" in anything, so I wonder why you brought it up. Why did you bring it up? If I may venture a guess, it is because the model that you apparently propose has the universe (and perhaps universes) being created and exploding into a pre-existing, all pervasive spacetime. In this sense you have our universe embedded in another. Of course we then need to modify our definition of the word "universe" to mean a local phenomenon that does not encompass all of existence, since the pre-existing space would then seem to be a better candidate for that. We would have to adjust our sites to theorize about the origin and geometry of this larger space (and presumably time). But, returning to current BB theory, our universe is considered to be a self-contained spacetime entity wherein space and time are evolving. [snip] I haven't seen any theory which predicts observed phenomenae and also predicts that light can't reach us from a "universe" other than our own. Or, at least, I haven't seen such a theory and been made aware that it was such a theory. That's because you fail to understand the Big Bang theory. It says that our universe comprises everything. You have said that it is possible that other universes could exist. In this post you have said that the Big Bang theory only describes *our* universe, not others. Now you say the Big Bang theory asserts that our universe comprises everything. Contradictions! Which statements should I believe? The Universe, referring to our universe, comprises everything that is connected by the spacetime which we inhabit. We speculate that other universes exist, and we can only speculate because by definition there can be no causal connection between separate universes, otherwise they'd be connected and part of the same universe. It says you won't meet a boundary with "space outside" because there isn't such. There certainly is no indication of any such boundary, and I'm quite sure that if one exists, neither I nor any other human will ever "meet" it, because it would be too far away. There is nothing outside, as there is no outside, How do you know that? What observations support the idea? I am not aware of any. Actually, the recent WMAP data appears to indicate that the space of our universe is geometrically flat. This means, from the field equations of General Relativity, that the universe may be infinite in extent (like a Euclidean plane is infinite in extent in 2D). Notice that I say "may be". It could be that the universe is simply so vast that the portion within our cosmic horizon is empirically indistinguishible from flat, although the universe as a whole may have some other geomety. hence nothing to travel _through_. One doesn't need to travel "through" anything in order to travel. One just needs to go from one place to another. If this were the case, then should expect light, gravity, and even matter to occasinally leak into unseen dimensions and disappear from our universe. As far as we can tell so far (and there are some interesting experiments on-going testing the very short-range behaviour of gravity in the search for extra, tiny dimensions -- see the work being done by Mike Varney), there is no leakage taking place. If you take a look at Maxwell's theory, you find that light propagation depends upon space having certain properties, namely permittivity and permeability. Space also, via General Relativity and the equivalence principle, is intimately connected with its contents in that its geometry is shaped by the mass and energy it contains. I don't see how anything from inside our universe could be removed from it and retain its properties (mass, inertia, charge, etc.). You can't seem to get yourself unhooked from the idea that there's _nothing_ outside the universe because there's _no_ outside. I'd like to know what observations support the assertion that there is no outside. I can certainly understand that there *might* not be any outside, but the assertion that there *is* no outside seems wildly beyond what is known. See above. Light can't reach the boundaries of the universe because there are no boundaries. It can't go outside, it can't go inside. It can't cross a boundary, because there is no boundary. Okay, okay. What observations support the assertion that there is no boundary? WMAP tentatively points in this direction, as does the recent observation that the universe seems to be not only expanding, but accelerating. If it is truly accelerating as we think, even within our little cosmic horizon, then on the grand scale the expansion rate must be phenomenal -- space would be growing at a rate that nothing interernal to the universe could ever approach a bounday, as that boundary would be receeding at untold multiples of the speed of light. You repeatedly suggest that "no theory predicts"; however it's more "I don't get the theory". I'm nearly certain that, as you said at the beginning of your post, the Big Bang theory describes our universe only, and predicts nothing about other universes or possible relationships between our universe and other universes. http://www.astro.ucla.edu/~wright/cosmology_faq.html I have read a significant chunk of it, and will continue to work through it as best I can. http://imagine.gsfc.nasa.gov/docs/as...s/961202c.html This basically just refers to the balloon model. I used the balloon model in a talk to my class in 12th grade. I snuck out of school during lunch hour to buy the balloons, and only had time to draw galaxies on a white balloon. If I had more time I would have glued white dots to a black balloon so the galaxies wouldn't expand along with the balloon. I think the balloon model is flawed in that the balloon is a material object which stretches and on which the galaxies are fixed, whereas there is probably nothing material between the real galaxies which stretches or expands or holds them in place. In reality, it is just the distances between galaxies which are increasing because the matter which comprises the galaxies has momentum, imparted to it early in the history of the Universe. This is where your theory departs from standard theory. Standard theory says that the BB is not a conventional explosion of matter into a pre-existing space, but an evolution of space itself. The balloon model is also flawed in that the surface of the balloon is strongly curved. The latest observations show the Universe to be indistinguishable from flat, overall. No indication of any overall curvature. Right. The balloon model has significant limitations. Of course, if you had a REALLY BIG balloon... :-) BTW the Big Bang theory isn't a religion. There are new idea's about the creation of our universe, handsomely called the "ekpyrotic" model: http://www.sciencenews.org/20010922/bob9.asp Thanks for the link to the Science News article! Ron Cowen always does an excellent job of explaining complex ideas of physics and mathematics. The article contradicts most of your above assertions. Of course, the main ideas of the article are an alternative to inflation and a way for the Big Bang to be initiated, which naturally contradicts those theories in many ways. I consider inflation, string theory, and brane theory all to be largely ad hoc and disconnected from observational evidence. That doesn't mean I reject them, but I doubt them very much. Inflation seems to be supported by the empirical evidence so far, or at least it is not contradicted. I have my own looney speculation which is far less developed than those theories, but which may be capable of answering some of the same questions far more simply. It has a serious failing which is exactly the same as those other theories have: A shortage of observational evidence. Two observations could be made to support or refute my speculation. One is astronomical, involving gravitational lensing. The math to quantitatively predict the effects of the lensing is beyond me, but in broad terms I would expect to see very faint radial lines where light of some distant galaxies or quasars has been smeared out by lensing galaxies. The opposite of the lensing actually seen so far, which is concentric and bright. The other observation is of the response of antihydrogen atoms to gravity. Experiments at CERN are now getting close to making this observation. It has the tremendous advantage that a good, clear result can totally demolish any possibility that my speculation is correct. It's a real make or break experiment for my pet notion. This, of course, is a very good position for any theory to be in -- an unambiguous test. Keep your fingers crossed! |
#32
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Hypothetical astrophysics question
In message , Joseph Lazio
writes "GD" == George Dishman writes: "Joseph Lazio" wrote in message ... "JG" == John Griffin writes: JG stuff, with its own origin (big bang or whatever) occupying JG another part of the infinite space this one is in. This sounds like Martin Rees' Multiverse concept. He suggests that multiple universes may in fact exist. In this concept, though, universes are distinct. One cannot travel from one universe to another. GD Joseph, can you say if that is similar to the ideas in this paper GD by Alan Guth? GD http://www.arxiv.org/abs/astro-ph/0301199 It is certainly similar in spirit. The difference lies, I think, in that Guth's idea describes one "connected" Universe while Rees' idea describes "disconnected" universes. In Guth's idea, as I understand it, one begins with a single spacetime region. A small chunk of that inflates to form a "pocket universe." Sometime later, another small chunk inflates, etc. I think it would be possible, in principle, to travel from one pocket universe to another. (Though if this idea is correct, the size of each pocket universe is much larger than the size of our observable Universe.) Guth doesn't say this explicitly, but it seems to me that a consequence of this idea is that the same physical laws would apply everywhere. I've just bought a copy of Paul Davies' "The Last Three Minutes" which seems to ascribe this to Andrei Linde. Doesn't Guth's original idea describe one universe? -- "Roads in space for rockets to travel....four-dimensional roads, curving with relativity" Mail to jsilverlight AT merseia.fsnet.co.uk is welcome. Or visit Jonathan's Space Site http://www.merseia.fsnet.co.uk |
#33
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Hypothetical astrophysics question
Greg Neill replied to Jeff Root:
Not to mention the fact that if you're seeing it, it's *in* our universe and not a separate universe. Under *some* definitions of "universe". Not all. Clearly, this imaginary thing had no part in our Big Bang, and existed some time before our Big Bang occurred. I think that calling it a "universe" is entirely reasonable, and I think that such other universes could very well exist-- perhaps infinitely many of them, if space is infinite. Whether we would be able to see such a distant universe is a question I'm not sure anyone can answer until we understand the nature of our own Universe a bit better. The usual definition applied to our universe is that it contains everything. Obviously that definition doesn't apply to the scenario that John Griffin suggested. "Universe" is a reasonable term to apply to an entity which resembles our Universe, but which had a separate and independant origin. Not a new idea. A separate and independent origin implies no connection. So, two things which have separate and independant origins can never have any connection between them? Or what? Embedded means its part of our universe. So, if a thumbtack becomes embedded in my foot, the thumbtack is part of me? Or what? What is your point? CeeBee used the term "embedded" less than two hours before you did. Otherwise, I don't think it had been used in this thread. It seems an odd term to use, and I see no reason to mention it here, although I do see that you use it below. Did you use it because CeeBee did? If the BB scenario is taken to describe it, space itself was created and began evolving at the moment of the BB. If so, there is no space for this other universe to pre-exist in, in our frame of reference. But in some other frame of reference there *could* be space for this other universe to exist in? So whether such space exists or not depends on where you are? And whether the other universe exists or not depends on where you are? We can know nothing about something that does not exist inside our own universe and amenable to measurement. It must remain pure speculation. Fine. But irrelevant to the specific scenario we are talking about. It was hypothesized that light from another universe had reached us, and was visible and measureable. Certainly it could not exist in our universe and be a universe itself. It depends on what you consider a universe to be. The thing that John Griffin suggested is clearly something which had no involvement in the Big Bang which began our Universe. It is also just as big and as well-populated as our Universe. I'd say that qualifies it as a separate universe, even if there is some interaction (perhaps only one way) between the two universes. I see no profit in arguing semantics. When I say "universe" I intend it to mean all that is contained and connected by space and time in which we are embedded. It would seem that you are wishing to take the more old-fashioned view of the early astronomers who first recognized other galaxies for what they were, and referred to them as "island universes". The majority of words have multiple meanings. I'm using a reasonable definition of "universe" that is useful in discussing the scenario John Griffin suggested. Under my definition, our Universe encompasses everything that was involved in the Big Bang, and only that which was involved in the Big Bang. Is your definition different from that? I think that your expression, "space and time in which we are embedded" implies more of a physicality to space and time than is warranted. It gives a mental image of space and time being a substance like clay, with stuff embedded in it. Very misleading. Space and time are only detected and measured by the behavior of things such as collections of atoms and beams of light. Whether space and time have any existence independant of matter is simply unknown. There can be no connection betwixt or between, so no path for light to follow. Why not? What observations support that idea? By my definition of universe, there can be no connection, no path between, or else they would be connected by the same space, thus all the same universe. Okay, that's using a reasonable definition of "universe". It just isn't a particularly useful one for the current discussion. But I'll go along with it. Unless someone comes up with a better term, how about referring to the object John Griffin hypothesized as a "monad"? Everything involved in the Big Bang, then, comprises our monad. There could be other monads in the Universe, but they might be impossible to detect, even theoretically. There could be monads in other universes, but they would definitely be impossible to detect, even theoretically, so there is no way we can ever have any idea whether or not they exist or what their properties might be. Are those statements satisfactory? (I see that George Dishman has used terms that are more in line with what I'm familiar with: "Cosmos" or "macrocosmos" for "everything" and "Universe" for our part of the Cosmos. Your definitions appear to conflict with that useage, so I didn't try to introduce it. I was going to use "subcosmos" instead of "monad", but the plural "cosmoses" was too grating for me. George is evidently stronger than I.) I intend to reply to the rest of your post soon. -- Jeff, in Minneapolis .. |
#35
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Hypothetical astrophysics question
"George Dishman" wrote in message ...
"John Griffin" wrote in message It turns out that the cosmologists have theories and some experimental data that say the other universe can't exist. Not true, at least two of the sources give you links to pages detailing ways in which other universes might exist The notion "exist" does not fit to describe validity of multiverse concept. --George |
#36
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Hypothetical astrophysics question
"Jeff Root" wrote in message
om... Greg Neill replied to Jeff Root: A separate and independent origin implies no connection. So, two things which have separate and independant origins can never have any connection between them? Or what? When speaking of universes, then that is so, barring some form of "collision" by way of motion through a higher dimension. I don't know if you've happened to read Abbott's "Flatland", but it is much the same scenario as the 3D sphere interacting with the 2D plane people. If two previously separate universes could somehow collide and happened to estabish an interface (it would be a lucky thing, them having compatible dimensions and physical constants), they would for all intents and purposes form a single, larger universe. Embedded means its part of our universe. So, if a thumbtack becomes embedded in my foot, the thumbtack is part of me? Or what? What is your point? If a thumbtack becomes embedded in your foot, in a sense it becomes part of you. Note, however, that the thumbtack was all along in the same universe with your foot, exchanging fields and generally interacting. The point is, if you can see it and it can interact causally with things in our universe, then it is part of the universe. It is connected. CeeBee used the term "embedded" less than two hours before you did. Otherwise, I don't think it had been used in this thread. It seems an odd term to use, and I see no reason to mention it here, although I do see that you use it below. Did you use it because CeeBee did? No. I use it because it was an appropriate term. [snip] We can know nothing about something that does not exist inside our own universe and amenable to measurement. It must remain pure speculation. Fine. But irrelevant to the specific scenario we are talking about. It was hypothesized that light from another universe had reached us, and was visible and measureable. And I suggest that if light can reach us from the object, and presumably light from us can reach the object, then there is a causal connection betwixt and between, and the object must perforce be part of the same overall universe. Certainly it could not exist in our universe and be a universe itself. It depends on what you consider a universe to be. The thing that John Griffin suggested is clearly something which had no involvement in the Big Bang which began our Universe. It is also just as big and as well-populated as our Universe. I'd say that qualifies it as a separate universe, even if there is some interaction (perhaps only one way) between the two universes. I see no profit in arguing semantics. When I say "universe" I intend it to mean all that is contained and connected by space and time in which we are embedded. It would seem that you are wishing to take the more old-fashioned view of the early astronomers who first recognized other galaxies for what they were, and referred to them as "island universes". The majority of words have multiple meanings. I'm using a reasonable definition of "universe" that is useful in discussing the scenario John Griffin suggested. Under my definition, our Universe encompasses everything that was involved in the Big Bang, and only that which was involved in the Big Bang. Is your definition different from that? Not essentially. The important difference is that I follow the standard theory line that space itself was created in the BB, and that this space is a connected manifold, containing all that can interact within itself. I think that your expression, "space and time in which we are embedded" implies more of a physicality to space and time than is warranted. It gives a mental image of space and time being a substance like clay, with stuff embedded in it. Very misleading. Space and time are only detected and measured by the behavior of things such as collections of atoms and beams of light. Whether space and time have any existence independant of matter is simply unknown. Sorry, I don't intend to imply a physical, "etherish" version of space or spacetime. Still, Space has a surprising collection of properties. For example, it exhibits specific values of permittivity and permeability (Maxwell's equations). It can embody stress energy (General Relativity), it can apparently have an intrinsic geometry modifiable locally and generally by mass-energy. It supports a background of virtual particles and energy modes. There can be no connection betwixt or between, so no path for light to follow. Why not? What observations support that idea? By my definition of universe, there can be no connection, no path between, or else they would be connected by the same space, thus all the same universe. Okay, that's using a reasonable definition of "universe". It just isn't a particularly useful one for the current discussion. But I'll go along with it. Unless someone comes up with a better term, how about referring to the object John Griffin hypothesized as a "monad"? Everything involved in the Big Bang, then, comprises our monad. There could be other monads in the Universe, but they might be impossible to detect, even theoretically. There could be monads in other universes, but they would definitely be impossible to detect, even theoretically, so there is no way we can ever have any idea whether or not they exist or what their properties might be. Are those statements satisfactory? I suppose, although I might have chosen "universe" and "multiverse", the latter capable of hosting multiple universes. Presumably it would involve adding one or more dimensions to the overall geometry of spacetime. I think that we still have a difference of detail that terminology might not be able to overcome. In my version of the universe and BB, space is created by the BB and comprises the entirety of the universe. There is no pre-existing space or framework in which our Bang took place, and there is no "outside". You seem to favour a creation of matter and explosion into a pre-existing space that can host many such bangs. I suspect that the viewpoints are not satifactorily reconcilable. (I see that George Dishman has used terms that are more in line with what I'm familiar with: "Cosmos" or "macrocosmos" for "everything" and "Universe" for our part of the Cosmos. Your definitions appear to conflict with that useage, so I didn't try to introduce it. I was going to use "subcosmos" instead of "monad", but the plural "cosmoses" was too grating for me. George is evidently stronger than I.) I intend to reply to the rest of your post soon. -- Jeff, in Minneapolis . |
#37
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Hypothetical astrophysics question
(George Buyanovsky) wrote
(John Griffin) wrote (George Buyanovsky) wrote (Matthew F Funke) wrote John Griffin wrote: Two tiny, fuzzy points of light are observed. Observations of each object indicate that it's a globular galaxy ten billion light years distant. The first one is exactly that, but the second one happens to be another entire universe. It's 100,000 times as far away as the galaxy, and it's emiting ten billion times as much light. Is there anything that would distinguish these objects from one another? Redshift. The universe is expanding, and there is more space in between us and the object 100,000 times as far away; it would appear to be more redshifted. Let me to reformulate it. Small star - 10 light years. Huge Quasar ? 10 billion light years. Huge Quasar moves toward us with exact speed to compensate redshift. For this arrangement, the redshift is not enough to distinguish them. I wish I had been more specific in my original question. In the hypothetical situation, the observations I mentioned were that radiation from the other universe had the same redshift as radiation from a galaxy ten billion light years from "here." (The cosmologists have me wondering if the word "here" is just some kind of strange idea.) The equal redshift would be purely coincidental, since the other universe's motion would It is not by chance I reformulated your question. The phrase like: "other universe's motion" makes no sense at all. That is, it makes no sense if we humans have learned everything. Your questions are based on one universe idea. That doesn't make sense. My hypothesis was that there are other instances of what the cosmologists call a universe. Since they say no information can be attained from anything other than our universe, it seems a bit hasty to say anything at all about a hypothetical "outside." People here have tried to explain you this. It is not a matter of complexity it is matter of natural perception of reality, which is, by the way, has been proven by natural selection ;o) It isn't "natural" to say that existence itself depends on the origin of the universe. If it were, there would be lots more than a few dozen people who can conceptualize it and formulate theories about it. The big bang was an event, so the natural thing is to think it had to have some "place" to occur. It could have occurred somewhere else, and an infinite number of them could have occurred. Even in the balloon analogy, someone could stick a pin in the balloon, whether or not a bug or a weasel walking around on its surface can perceive anything beyond it. I wonder what the "creation scientists" think about this. They created "God" to explain everything, so they probably agree with the hypothesis of a universe within an infinite empty space. By the way, you didn't exactly reformulate my question. The first guy who observed a quasar thought it was a star with lots of heavy atoms. Anyway, I don't know what you mean by "compensate redshift." Moving toward us, its radiation would be shifted the opposite way. If it shows no redshift or blueshift, it's at rest relative to us, isn't it? I guess that could happen if it's orbiting the center of a galaxy (on the approaching side) at whatever rate corresponds to the recession velocity of a galaxy ten billion light years away...but then when it completes half a revolution, it would be receding at twice that velocity...? |
#38
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Hypothetical astrophysics question
"George Buyanovsky" wrote in message om... "George Dishman" wrote in message ... "John Griffin" wrote in message It turns out that the cosmologists have theories and some experimental data that say the other universe can't exist. Not true, at least two of the sources give you links to pages detailing ways in which other universes might exist The notion "exist" does not fit to describe validity of multiverse concept. What word would you use instead? George |
#39
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Hypothetical astrophysics question
"George Dishman" wrote in message ...
"George Buyanovsky" wrote in message om... "George Dishman" wrote in message ... "John Griffin" wrote in message It turns out that the cosmologists have theories and some experimental data that say the other universe can't exist. Not true, at least two of the sources give you links to pages detailing ways in which other universes might exist The notion "exist" does not fit to describe validity of multiverse concept. What word would you use instead? Probably "manifestation" is good to describe the logical consequences of multiverse construct. --George |
#40
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Hypothetical astrophysics question
(Jeff Root) wrote in sci.astro:
But you just said that the Big Bang theory doesn't say anything about other universes, only our own! In your next sentence you contradict that and say that it predicts what can and can't happen outside our universe! Which is it??? Note the semicolons. As the Big Bang describes nothing but our own universe, it can't tell us anything about another universe. If a photon from another universe would be visible here, it would be subject to the same laws as a photon from our universe. The Big Bang theory leaves a photon no room to "leave" our universe. Actually, the Big Bang theory says nothing about the origin of space and/or time. It does say that at some time about 13.7 billion years ago everything in the Universe was squished real close together, was very hot, and was expanding real fast. It also says that a moment before that, something completely unknown happened, which no theory is yet able to describe in any way that makes sense. So, space and time *may* have been created at that time, or they may not have. There's no way to say, as yet. During the Big Bang our current space and time were created. The theory tells us nothing what happened before, and it's quite interesting, but not very relevant for the questions raised. I asked about your use of the term "embedded" because Greg used it prominently in a message posted less than two hours after yours; I don't think the term had been used previously; and I see no particular reason for its use here. "Embedded" is a perfect description of one medium existing in another medium. Like "embedded software" in a chip. Or the inside of a house is a space. It is embedded in the outside space. The idea of universes being embedded in anything sounds goofy. I agree with you that there is no "need" for such universes to be "embedded" in anything, so I wonder why you brought it up. Why did you bring it up? In one of your previous posts you suggested that that other universe could be traveling towards us at high speed. What does it travel through if there's nothing to travel in? You also suggested that there is something "outside" our universe that the light travels through. You told us it was "space". How does a photon travel from one universe to our universe? What happens between the moment that photon "leaves" the other universe and "enters" the other universe? In a further posting you told us that the light traveled through space: You brought it up yourself with your idea of a space medium outside the universe. You have said that it is possible that other universes could exist. In this post you have said that the Big Bang theory only describes *our* universe, not others. Now you say the Big Bang theory asserts that our universe comprises everything. Contradictions! Which statements should I believe? Sorry, but this is playing with words, and it has little to do with your understanding of the universe. The Big Bang theory tells us nothing about other universes. It supposes the universe encompasses all space-time there is, as it created space-time. It was not created "in" something, it's self- contained. There are also new theories about other universes. They suppose the universe is not all there is. These theories can be true. They tell nothing about light traveling from one universe to another universe, or other universes visible from our universe, which was the starting point. There certainly is no indication of any such boundary, and I'm quite sure that if one exists, neither I nor any other human will ever "meet" it, because it would be too far away. You don't understand it. The universe has no need for a boundary. It has nothing to do with "too far away", it has to do with never being able to reach it. It's like walking the surface of the Earth and never reach the edge. The edge of the earth is not "too far away", there _is_ no edge. Before you take it too literally again: traveling the universe and never reaching a boundary is _not_ the same as walking the surface of the Earth. Walking the surface of the Earth is an _example_ of the possibility of traveling endlessly and never encountering or even observing a boundary. One doesn't need to travel "through" anything in order to travel. One just needs to go from one place to another. Why is that so? How do you do that? How does that happen with a traveling photon? What mechanics are you referring to? How does that travel happen? How can you determine that there is travel if there are no reference points? At what theories about travel are you reffering? What happens when one goes from one place to another? Is this spontaneously? Is this sequentially in time? What time is that? Is there time without space? How does that time exist without space? How can we separate those places from each other, to determine that the photon has "traveled"? I'd like to know what observations support the assertion that there is no outside. I can certainly understand that there *might* not be any outside, but the assertion that there *is* no outside seems wildly beyond what is known. There are no observations. We weren't talking about observations, we were talking about theories. If theories predict or describe actual observations, the theory gains value. If it has gained value, it is used to describe phenomenon which are not visible. Black holes are not visible. Yet they were predicted before we even had a first glimp at a point in space where one might be. Now we know for sure that they are there. Do they exist or don't they exist? Your have a notion of inside and outside which is really confined to our own universe, our own space-time. There's no inside our universe and outside our universe, there's just universe and no universe: space-time and no space-time in current theory. We haven't got a clue if no-space-time is, is something, and if it is something, what the properties of that something is. However we do have a notion of what a photon is, and how it propagates, how it behaves. Let's assume there is another universe. Let's assume there is an in- between able to conduct a photon, even if we don't know how to describe it. Let's forget to ask ourselves how a photon - an element of space- time - can propagate when there's nothing to propagate in. We can see it and distinguish it as a photon, so it obeys the same laws as photons in our universe. Let's assume the photon can - by some non-space-time magic find its way to our galaxy. Let's assume that photon gets to our universe without having a 'space- time road' to it - however that might happen. It just arrives at our universe. Now the problem diminishes, as we know something about the properties of our universe, our space-time. Where is the outside? Current theory leaves no room for such an outside. An outside like that presupposes a boundary, and there's no boundary. Let's skip that point. Let's assume that there's an _outside_ without the need of a boundary. Now the photon hits that outside. It now has contact with our universe, and has to obey the rules of our universe. That universe has no boundaries from the _inside_. How will it _find_ a non-existent inside boundary? How will it _pass_ a non-existent boundary? What will happen when it passes a non-existent boundary? What will happen if you cross two space-times with each other? Will they mix? Will they merge? How do they exchange information? What happens to the energy balance in our own universe? Will somewhere else energy disappear? How or where does that disappear, as at least nothing in our universe can _leave_ it, given the fact that _outside_ for _our_ energy is non-existent? As soon as that extra-universal photon interferes with our space, it has to obey the rules of our space. And our space tells a photon it can not cross a non-existent boundary. Okay, okay. What observations support the assertion that there is no boundary? There are no observations necessary. You are limited to "I only believe it when I see it". Theory can predict what will happen, even if it hasn't happen yet, even if you don't see it - even if you _can't_ see it. I think the balloon model is flawed in that the balloon is a material object which stretches and on which the galaxies are fixed, whereas there is probably nothing material between the real galaxies which stretches or expands or holds them in place. In reality, it is just the distances between galaxies which are increasing because the matter which comprises the galaxies has momentum, imparted to it early in the history of the Universe. No. Space between galaxies expand. The fabric of space itself expands. The balloon model is also flawed in that the surface of the balloon is strongly curved. The latest observations show the Universe to be indistinguishable from flat, overall. No indication of any overall curvature. A _flat_ universe has nothing to do with it's actual 3D-form: it means that the rules of Euclidian geometry apply to it. It means it has the _geometry_ of a flat surface, not that it _is_ a flat surface. The balloon model is a way to grasp the notion that a surface can be limited, yet without boundaries. It can help you visualize why you never will fall off the Earth. It can help you with understanding that this might be apllicable to higher dimensions too. It doesn't tell us anything about the actual form of the universe. The article contradicts most of your above assertions. Of course, the main ideas of the article are an alternative to inflation and a way for the Big Bang to be initiated, which naturally contradicts those theories in many ways. It tries to solve some serious problems in the current theories. It builds on them. There are very few scientists who claim to have the ultimate theory. -- CeeBee Uxbridge: "By God, sir, I've lost my leg!" Wellington: "By God, sir, so you have!" Google CeeBee @ www.geocities.com/ceebee_2 |
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