Boerseun Posted June 23, 2005 Report Share Posted June 23, 2005 The debate about the shape of the Universe is quite interesting, but it raises a few issues: If we look in the Hubble Deep Field image, we see a vast array of galaxies, billions of light-years distant, and billions of years in the past. The further a galaxy is away from us, the faster its receding. At some stage, they will redshift to such a degree that they'll become invisible, and radiotelescopes is needed to observe them. If they look back at us, it will appear to them that we are receding at a breakneck speed, and they'll only be able to view us in the radio frequencies as well. But go even further: At the 'edge' of the Universe, where expansion is running at 99.9999%c, relativistic effects on these galaxies will rule - and due to time dilation, it would seem to those galaxies that the Big Bang took place only a couple of minutes ago. (I'm referring to galaxies, but whatever 'stuff' there is at the edge will obviously experience the same effects). Now - the issue I have, is that seeing as c is the limit, and the further away from another galaxy, the rate of expansion is increasing, somewhere, somehow, there must be an 'edge', seeing as they can't recede faster than c. And if there's an 'edge', there must be a central point where the Big Bang occured, with the outrunners of the Big Bang forming the 'edge'. I fully ascribe to the idea that the Big Bang took place everywhere, that space is expanding, and every point can be regarded as the 'center', but can it in all truth be said aboit a point in space that's travelling at 99.99999%c, right at the edge? Another interesting idea - if the 'Island Universe' idea holds ground, and all these 'Islands' are expanding, at one stage they will intersect. What will a observer see if he's travelling at the 'edge' of a Universe at 99%c, and the 'edge' of another Universe comes barrelling past at 99%c in the opposite direction? The relative speed at which two galaxies will pass each other will be very close to 2c, in other words, the two universes will intersect and appear to each other as only a stream of high-energy floating past, due to the high blue-shift on approach and excessive red-shift on departure. Until you can somehow catch up with this 'energy field' and it crystallises out to be a perfectly normal galaxy... Quote Link to comment Share on other sites More sharing options...
Boerseun Posted June 23, 2005 Report Share Posted June 23, 2005 As a matter of fact - seeing as we can't tell how close to the 'edge' we are, time is totally subjective. The real 'center' of our universe might be 30 billion years old, whilst we might be receding from that point at a speed which diluted time for us so that we observe the universe to be only 15 odd billion years old. I've got a headache now. Quote Link to comment Share on other sites More sharing options...
bumab Posted June 23, 2005 Report Share Posted June 23, 2005 Distant galaxies are not necessarily "flying" away at the speed of light, they are EXPANDING away at, and even faster then, the speed of light. So, there doesn't have to be an edge, as the material can exceed the speed of light due to expansion, not velocity. http://www.sciam.com/article.cfm?ch...umber=5&catID=2 Quote Link to comment Share on other sites More sharing options...
Tormod Posted June 23, 2005 Report Share Posted June 23, 2005 The real 'center' of our universe might be 30 billion years old, whilst we might be receding from that point at a speed which diluted time for us so that we observe the universe to be only 15 odd billion years old. You still have to explain the background radiation which gives us an estimate of the age of the universe: it shows a universe that has cooled off for 13,7 billion years (that was how the "13,7" figure was found). Quote Link to comment Share on other sites More sharing options...
Boerseun Posted June 23, 2005 Report Share Posted June 23, 2005 Distant galaxies are not necessarily "flying" away at the speed of light, they are EXPANDING away at, and even faster then, the speed of light. So, there doesn't have to be an edge, as the material can exceed the speed of light due to expansion, not velocity. http://www.sciam.com/article.cfm?ch...umber=5&catID=2Okay - forgot about that. But, keeping the 'Island Universe' idea in mind, will it be possible for two sets of 'expanding space' to intersect? How should this influence space itself, for either of the two 'universes'? Can two different 'spaces' overlap, whilst expanding at different rates and in different directions? Quote Link to comment Share on other sites More sharing options...
adnaan Posted June 23, 2005 Report Share Posted June 23, 2005 soo about the big bang theory.. isnt the theory stating an explosion in nothingness...? also there is something that can move at a faster speed than light???!?!? thats new to me... Quote Link to comment Share on other sites More sharing options...
Tormod Posted June 23, 2005 Report Share Posted June 23, 2005 soo about the big bang theory.. isnt the theory stating an explosion in nothingness...? No, AFAIK the theory does not say anything about what existed before the big bang. also there is something that can move at a faster speed than light???!?!? thats new to me... No, this is a misinterpretation at best. Nothing can move faster than light according to current theory. Quote Link to comment Share on other sites More sharing options...
Jay-qu Posted June 24, 2005 Author Report Share Posted June 24, 2005 But, keeping the 'Island Universe' idea in mind, will it be possible for two sets of 'expanding space' to intersect? How should this influence space itself, for either of the two 'universes'? Can two different 'spaces' overlap, whilst expanding at different rates and in different directions? I have heard of it described as to soap bubbles floating in the air and then colliding - so depending on size and composition one could absorb the other of both could pop - but who really knows... Keep in mind that as the universe expands its the space that expands, so things are getting bigger - can someone clear up if matter actually also expands and hence mantains density or if it will eventually disperse out so there is lightyears between atoms... Quote Link to comment Share on other sites More sharing options...
Boerseun Posted June 24, 2005 Report Share Posted June 24, 2005 I have heard of it described as to soap bubbles floating in the air and then colliding - so depending on size and composition one could absorb the other of both could pop - but who really knows... Keep in mind that as the universe expands its the space that expands, so things are getting bigger - can someone clear up if matter actually also expands and hence mantains density or if it will eventually disperse out so there is lightyears between atoms...It's space itself thats expanding. Galaxies are getting further and further away from each other, but the galaxies themselves keep their dimensions. In other words, visible stars in the Milky Way are all rotating around the galactic core, and their relative distances from each other stays approximately the same - and even small satellite galaxies in orbit around larger galaxies will keep their relative distance. It's on a larger scale that the expansion takes place. But atoms keep their size and shape. Unless you are into McCutcheon's 'expansion' theory which tries to explain gravity through the expansion of individual atoms - which I think is highly unlikely. Quote Link to comment Share on other sites More sharing options...
lindagarrette Posted June 24, 2005 Report Share Posted June 24, 2005 But atoms keep their size and shape. Unless you are into McCutcheon's 'expansion' theory which tries to explain gravity through the expansion of individual atoms - which I think is highly unlikely.What about the Big Rip theory? Ultimately entropy will be maximized and there will be nothing left. No stars, no atoms, no radiation. Quote Link to comment Share on other sites More sharing options...
Harzburgite Posted June 25, 2005 Report Share Posted June 25, 2005 No, this is a misinterpretation at best. Nothing can move faster than light according to current theory.Nothing can travel faster than light, but space can expand faster than light. And that is current inflation theory. Please see bumab's excellent link..ah, it seems to be dead. Unfortunate. It addressed many common misconceptions about the Big Bang. Quote Link to comment Share on other sites More sharing options...
bumab Posted June 25, 2005 Report Share Posted June 25, 2005 Thanks, Harz! They must have moved the page- here's the link again for those who are interested: http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=0009F0CA-C523-1213-852383414B7F0147 Quote Link to comment Share on other sites More sharing options...
Tormod Posted June 25, 2005 Report Share Posted June 25, 2005 Nothing can travel faster than light, but space can expand faster than light. And that is current inflation theory. Please see bumab's excellent link..ah, it seems to be dead. Unfortunate. It addressed many common misconceptions about the Big Bang. I have said as much in a different thread - we discussed this a while back when someone talked about the Hubble limit. My point was that it is an illusion that something is travelling faster than the speed of light, whereas expansion can make objects separate faster than the speed of light. Quote Link to comment Share on other sites More sharing options...
lindagarrette Posted June 25, 2005 Report Share Posted June 25, 2005 Thanks, Harz! They must have moved the page- here's the link again for those who are interested: http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=0009F0CA-C523-1213-852383414B7F0147 Here's a fabulous page about string theory's history and status. I didn't know where else to put it but it came from the article cited above. http://www.edge.org/3rd_culture/susskind03/susskind_index.html Quote Link to comment Share on other sites More sharing options...
bumab Posted June 25, 2005 Report Share Posted June 25, 2005 Excellent post Linda! Back to the topic, hypothetically could the speed of light be used as an absolute reference frame? If one assumed light to be motionless, and the everything else to be moving at c... still wouldn't give a Newtonian universe, however, since relatavistic effects would still apply- increase in mass as one slowed down (drag in the Higgs field)? Ahh... I've been up to long. Nap time. Quote Link to comment Share on other sites More sharing options...
Little Bang Posted June 26, 2005 Report Share Posted June 26, 2005 Linda, that is an excellant link, but do you expect the guy that writes a book on government UFO cover up to point out the flaws in his logic? I would not expect Dr. Susskind to point out any flaws. Quote Link to comment Share on other sites More sharing options...
Tormod Posted June 26, 2005 Report Share Posted June 26, 2005 Linda, that is an excellant link, but do you expect the guy that writes a book on government UFO cover up to point out the flaws in his logic? I would not expect Dr. Susskind to point out any flaws. Huh? Which flaws? Why would he point out flaws in his *own* logic? That's why there are articles to read so we can point them out ourselves. Which ones did you find? Quote Link to comment Share on other sites More sharing options...
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