If the Expanding Universe has no "Edge" and no center, THEN, -logically- . . .

[PJay_A]

<p>Okay, I'm having a problem understanding something. Consider our (human scientific) understanding of the Expandng Universe. We understand it basically as the Big Bang Universe, one of which is continuously pushing out in each direction, assumingly at the speed of light in every direction; therefore, it is impossible to ever "catch up" to any of its "corners". So, it's common logic that when the Hubble sees galaxies that begin to take shape over 14 billion light years away, we are actually seeing a young Universe at the "beginning" time at the "edge" of space.</p><p>Now, here is my problem. Logically, if we use the Hubble to peer 14 billion light years and we see the Universe at the "edge" of&nbsp; creation in one direction, of course this is what we would see in every directon. It is easy to see how someone ignorant of Universe dynamics and the Universal expansion might conclude that our placement in this Universe is right smack in the center. Afterall, such a person might therefore reason that the Universe' "edge horizon" is evenly 14 billion light years in each 3-dimensional direction, and simple math would offer "proof" to these people that we are indeed in the center of the Universe (since each direction adds up equally).</p><p>Rest assured, I do not see things the same way my example does. But, here's something to really think about. Let's say in another galaxy somewhere... Let's just say this galaxy is 5 billion light years from our Milky Way. And orbiting a star in this galaxy's Outer Ridge is a planet rich in a vast variety of living organisms insects, swimming type s of genomes, flying types, cute types, scary types, as well as very intelligent types. Lets say some time today, one of the intelligent types spends a moment to think about the Universe and something confuses this being enough to motivate this being to post a message on his planet's space.com discussion groups' equivillant...</p><p>Okay, this being's planet has its orbiting telescope, much like our Hubble. And they too are seeing the "edge of creation" at 14 billion light years. Since timewise, both myself and my alien counterpart are making these observations 14 billion years after the Big Bang, both our worlds would see these ambrionic galaxy formations at the 14-billion light year mark in each 3-dimensional spacial direction, regardless of the fact that my counterpart is in another galaxy 5 billion light years fro.</p><p>So far, everything I explained is in line with mainstream cosmology. Lets say such a planet 5 billion light years from us exists. When they glaze into their Hubble equivillant to see the early Universe at 14 billion light years, and we peer into our space telescope to see our 14 billion-year-old creation. And let's say by chance both of our world's space telescopes are aimed precisely at the same region of space at 14 billion light years. Logically, both would be looking at the exactly the same objects in this region of space 14 billion light years away. We would be imaging the same embriotic galaxy formations from precisely the same time period...</p><p>BUT, if this world is 5 billion light years away from us, then they should also be 5 billion light years "closer" to the spot we both are aiming our lenses at, but since they are focusing their telescope TODAY (at the same early Universe we are) and since they too live in our same Universe, they are not any immune to the same 14 billion light year marker than we are. But logic says that if they were indeed looking in that same region of space that we were, that observation could not possibly be from the same 14 billion light year marker that we are seing it. Instead, logic says that region of space would be seen to them as a fully mature cluster of galaxies, 5 billion years younger than th e embrioic galaxy clusters we see. So, to see embriotic galaxy formations, they would need to see 5 billion light years further, and no matter what they do they would not be able to see the same objects we see in its embrioic state.</p><p>So, this means when our counterpart world looks toward the Universe in its embriotic state, 14 billion light years away, they are viewing objects that we do not see, objects that to us would be 19 billion light years away. And that's impossible since these objects (to us) would be beyond our Universal "edge", before the Big Bang. But to them, these object would be well within the boundary of space-time.&nbsp;</p>

 

[Mee_n_Mac]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Okay, I'm having a problem understanding something. Consider our (human scientific) understanding of the Expandng Universe. We understand it basically as the Big Bang Universe, one of which is continuously pushing out in each direction, assumingly at the speed of light in every direction; therefore, it is impossible to ever "catch up" to any of its "corners". So, it's common logic that when the Hubble sees galaxies that begin to take shape over 14 billion light years away, we are actually seeing a young Universe at the "beginning" time at the "edge" of space.Now, here is my problem. Logically, if we use the Hubble to peer 14 billion light years and we see the Universe at the "edge" of&nbsp; creation in one direction, of course this is what we would see in every directon. It is easy to see how someone ignorant of Universe dynamics and the Universal expansion might conclude that our placement in this Universe is right smack in the center. Afterall, such a person might therefore reason that the Universe' "edge horizon" is evenly 14 billion light years in each 3-dimensional direction, and simple math would offer "proof" to these people that we are indeed in the center of the Universe (since each direction adds up equally).Rest assured, I do not see things the same way my example does. But, here's something to really think about. Let's say in another galaxy somewhere... Let's just say this galaxy is 5 billion light years from our Milky Way. And orbiting a star in this galaxy's Outer Ridge is a planet rich in a vast variety of living organisms insects, swimming type s of genomes, flying types, cute types, scary types, as well as very intelligent types. Lets say some time today, one of the intelligent types spends a moment to think about the Universe and something confuses this being enough to motivate this being to post a message on his planet's space.com discussion groups' equivillant...Okay, this being's planet has its orbiting telescope, much like our Hubble. And they too are seeing the "edge of creation" at 14 billion light years. Since timewise, both myself and my alien counterpart are making these observations 14 billion years after the Big Bang, both our worlds would see these ambrionic galaxy formations at the 14-billion light year mark in each 3-dimensional spacial direction, regardless of the fact that my counterpart is in another galaxy 5 billion light years fro.So far, everything I explained is in line with mainstream cosmology. Lets say such a planet 5 billion light years from us exists. When they glaze into their Hubble equivillant to see the early Universe at 14 billion light years, and we peer into our space telescope to see our 14 billion-year-old creation. And let's say by chance both of our world's space telescopes are aimed precisely at the same region of space at 14 billion light years. Logically, both would be looking at the exactly the same objects in this region of space 14 billion light years away. We would be imaging the same embriotic galaxy formations from precisely the same time period...BUT, if this world is 5 billion light years away from us, then they should also be 5 billion light years "closer" to the spot we both are aiming our lenses at, but since they are focusing their telescope TODAY (at the same early Universe we are) and since they too live in our same Universe, they are not any immune to the same 14 billion light year marker than we are. But logic says that if they were indeed looking in that same region of space that we were, that observation could not possibly be from the same 14 billion light year marker that we are seing it. Instead, logic says that region of space would be seen to them as a fully mature cluster of galaxies, 5 billion years younger than th e embrioic galaxy clusters we see. So, to see embriotic galaxy formations, they would need to see 5 billion light years further, and no matter what they do they would not be able to see the same objects we see in its embrioic state.So, this means when our counterpart world looks toward the Universe in its embriotic state, 14 billion light years away, they are viewing objects that we do not see, objects that to us would be 19 billion light years away. <strong>And that's impossible since these objects (to us) would be beyond our Universal "edge", before the Big Bang</strong>. But to them, these object would be well within the boundary of space-time.&nbsp; <br />Posted by <strong>PJay_A</strong></DIV></p><p>Your post is well thought out except for the last part... which I've <strong>highlighted </strong>above.&nbsp; We have an observable universe but there's no law that states that there's nothing beyond that "limit".&nbsp; There's no edge perse, just a limit as to what we can "see". We may not be able to see&nbsp;this larger universe&nbsp;or prove it's there, but your aliens might well be able to (at least partly as your reasoning shows).&nbsp; We also get to see parts of this larger universe that are beyond their observable universe.&nbsp; The question (unanswerable) is how much larger is the whole universe than our observable universe.</p> <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>

 

[robnissen]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>But logic says that if they were indeed looking in that same region of space that we were, that observation could not possibly be from the same 14 billion light year marker that we are seing it. Instead, logic says that region of space would be seen to them as a fully mature cluster of galaxies, 5 billion years younger than th e embrioic galaxy clusters we see. So, to see embriotic galaxy formations, they would need to see 5 billion light years further, and no matter what they do they would not be able to see the same objects we see in its embrioic state.So, this means when our counterpart world looks toward the Universe in its embriotic state, 14 billion light years away, they are viewing objects that we do not see, objects that to us would be 19 billion light years away. And that's impossible since these objects (to us) would be beyond our Universal "edge", before the Big Bang. But to them, these object would be well within the boundary of space-time.&nbsp; <br />Posted by PJay_A</DIV></p><p>You have made two errors, both related to inflation.&nbsp; 1)&nbsp; During initial inflation immediately after the big bang, the universe increased in size dramatically.&nbsp; There is no way of knowing how big the universe was at that point, because we do not know the size of the big bang singularity.&nbsp; It could have been the size of a quark, the size of a planet, the size of a galaxy, or even larger than the size of the visible universe.&nbsp; Thus, immediately after the Big Bang this universe (unknown if there are others) may have already been billions or trillions or more light years across.&nbsp; </p><p>2)&nbsp; Your second problem is that you do not include ongoing inflation.&nbsp; The light from galaxies that took 13 billion light years to get here, came from galaxies that were only about 5 billion light years away when the light we now see left them.&nbsp; During the intervening 13 billion years, inflation has pushed those galaxies much farther away (they are around 42 billion light years away now), and the light from those galaxies ended up going through an additional 8 billion light years of space.&nbsp; (Not 42 billion, because inflation that occured after the light passed a point on its way to earth, does not add time for the light to reach earth.)</p><p>Inflation is one of the spookeir concepts in science (what does it mean for space, i.e. nothing to expand?), but inflation has been experimentally confirmed.</p>

 

[DrRocket]

<p>

Okay, I'm having a problem understanding something. ..."edge" of&nbsp; creation in one direction, of course this is what we would see in every directon. It is easy to see how someone ignorant of Universe dynamics and the Universal expansion might conclude that our placement in this Universe is right smack in the center.</p><p>Edited for brevity.</p><p>You logic applies under the assumption that we live in a 3-dimensional Euclidean space, with an added parameter called "time", to make up a 4-dimensional Euclidean space-time.&nbsp; While ordinary experience suggests that such is the case, the general theory of relativity, which has proven to be capable of remarkably accurate predictions, suggests that in fact we live in a curved 4-dimensional Riemannian manifold called space-time.&nbsp; Curved manifolds require the machinery of differential geometry for understanding.&nbsp; If you would like to look at this subject in detail you might try reading "Gravitation" by Misner, Thorne and Wheeler or maybe Mike Spivak's 5- volume set "Differential Geometry."</p><p>Curved manifolds need not have a center, and can still expand uniformly.&nbsp; Consider the surface of a balloon, and forget about the little mouthpiece so that it is a sphere with no distinguished points.&nbsp; That is a curved 2-manifold.&nbsp; Now, inflate the balloon.&nbsp; The surface expands, all points move apart from one another uniformly, but there is no single central point in the recession (on the surface of the balloon).&nbsp; You are not allowed to argue that the central point is in the center of the balloon in 3-space, because as far as the 2-dimensional surface is concerned there is no 3-space.&nbsp; </p><p>According to general relativity the situation is similar for the universe.&nbsp; It is a curved 4-manifold.&nbsp; There need not be an "edge".&nbsp; Locally it looks like 3-dimensional space plus time, but globally things are stitched togetheer with curvature.&nbsp; In the case of the balloon it looks locally like an ordinary 2-dimensional surface, but little local pieces of a plane are stitched together with curvature to form a ball, and the ball has no edges.&nbsp; A circle is the 1-dimensional analog,&nbsp; It is pieces of a line sown together to form a 1-manifold that also has no edge and no central point &nbsp;(on the circle).&nbsp; Similarly, there may be and "edge" to the limits of what can see using our technology, locally in our little patch of the universe, but the universe as a whole, being curved need not have an edge at all.&nbsp; If there were an edge (what is called a boundary in differential geometry) things would be even more weird since the boundary of a 4-manifold is 3-dimensional.&nbsp; What would you give up -- time, depth, width, height ?</p><p>It is the notion of curvature that is confusing you, and in part that is because curvature in higher dimensions is a difficult subject.&nbsp; It has confused experts.</p> <div class="Discussion_UserSignature"> </div>

 

[origin]

<p>Good Post.</p><p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>We understand it basically as the Big Bang Universe, one of which is continuously pushing out in each direction, assumingly at the speed of light in every direction; therefore, it is impossible to ever "catch up" to any of its "corners". </DIV></p><p>The universe is not expanding at the speed of light.&nbsp; It is difficult to determine the rate of the expansion, but here is one&nbsp;estimate just as an example; 80 kilometers per second per megaparsec.&nbsp; So a galaxy that is 3 million light years away from us will be receding at 80 kilometers/sec.&nbsp;&nbsp;&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>But, here's something to really think about. Let's say in another galaxy somewhere... Let's just say this galaxy is 5 billion light years from our Milky Way. Okay, this being's planet has its orbiting telescope, much like our Hubble. And they too are seeing the "edge of creation" at 14 billion light years. Since timewise, both myself and my alien counterpart are making these observations 14 billion years after the Big Bang, both our worlds would see these ambrionic galaxy formations at the 14-billion light year mark in each 3-dimensional spacial direction, regardless of the fact that my counterpart is in another galaxy 5 billion light years fro.So far, everything I explained is in line with mainstream cosmology. Lets say such a planet 5 billion light years from us exists. When they glaze into their Hubble equivillant to see the early Universe at 14 billion light years, and we peer into our space telescope to see our 14 billion-year-old creation. And let's say by chance both of our world's space telescopes are aimed precisely at the same region of space at 14 billion light years. Logically, both would be looking at the exactly the same objects in this region of space 14 billion light years away. We would be imaging the same embriotic galaxy formations from precisely the same time period...BUT, if this world is 5 billion light years away from us, then they should also be 5 billion light years "closer" to the spot we both are aiming our lenses at, but since they are focusing their telescope TODAY (at the same early Universe we are) and since they too live in our same Universe, they are not any immune to the same 14 billion light year marker than we are. But logic says that if they were indeed looking in that same region of space that we were, that observation could not possibly be from the same 14 billion light year marker that we are seing it. Instead, logic says that region of space would be seen to them as a fully mature cluster of galaxies, 5 billion years younger than th e embrioic galaxy clusters we see. So, to see embriotic galaxy formations, they would need to see 5 billion light years further, and no matter what they do they would not be able to see the same objects we see in its embrioic state.So, this means when our counterpart world looks toward the Universe in its embriotic state, 14 billion light years away, they are viewing objects that we do not see, objects that to us would be 19 billion light years away. And that's impossible since these objects (to us) would be beyond our Universal "edge", before the Big Bang. But to them, these object would be well within the boundary of space-time.&nbsp; <br />Posted by PJay_A</DIV></p><p>I think the problem is that you think of the edge of the universe as some actual end that if you were in a space ship you would bump into it.&nbsp; That is not how the universe appears to be.&nbsp; Take your argument to the extreme.&nbsp; Imagine that you are in a galaxy that we see as a quasar 14 billion miles away.&nbsp; The distribution of galaxies would have the same general appearance to them as it does to us.&nbsp; It is not like they would see a sky filled with galaxies in one directions and emptiness in the other direction.</p><p>If the universe is unbounded it is like saying&nbsp;of the 'edge' of the universe - you can't get there from here.&nbsp; Imagine a being that exists on a higher dimension and lives outside of&nbsp;the universe, he might notice that you are '1 foot' away from the 'edge' of the universe.&nbsp; To you however because the universe is unbounded it would look just like it has always looked - <em>relatively</em> uniform in every direction.<br /></p> <div class="Discussion_UserSignature"> </div>