Edge of the Universe

[nexium]

I've heard the math suggests that the Universe has no edge. Let's assume there is an edge.<br />If Earth was six billion light years from the edge there would be a circle in the sky with no stars or galaxies farther than 7 billion light years away.<br />If Earth was 0.001 light year from the edge of our universe: The edge would be receeding from our solar system at much less than the speed of light; so what would happen to photons from our sun when they reached the edge of our Universe? There is perhaps a more distant edge which no photons have reached yet? Neil

 

[alkalin]

I’m surprised a BB fan hasn’t replied yet to your question, a good one. Perhaps it’s too good a question. Warning-I am no supporter of BB.<br /><br />”I've heard the math suggests that the Universe has no edge. “<br /><br />As I understand the math of big space/time bang, there was no space before there was time, so when both came into existence, space itself expanded with all matter in it. But what you may be implying is some illogic to the math, of course. What is new about that? So let’s pretend everything came into existence at a particular moment in time; space and matter.<br /><br />What you imply is that photons might go racing out beyond space, which in the math sense is undefined. Because if there was simply more space for a photon to go, then this would imply that space does indeed exist beyond the bounds of ‘space/time’, and strongly hints at space before time. Indeed, if space was everywhere before BB, then we have a bubble of space expanding within space with the advent of time. But wait, this picture is becoming far to complicated for the math to handle—too many unknowns. So what to do? Well first just deny that there was space before there was space. So the best answer is that if a photon penetrates undefined ‘space’, the photon obviously now becomes undefined.<br /><br />Sorry Neil if my response is rather trivial, but I just have a much different view of what really is going on in the universe. And besides, I may have misunderstood what it was you were asking.<br />

 

[mooware]

<font color="yellow">it has curvature, which the photons would travel along</font><br /><br />So if it were possible for a traveler to leave Earth, eventually, said traveler would wind up back at Earth. (albeit it would take a very long time)<br /><br />

 

[nexium]

At least alkalin can think outside the box. From the main stream responces, I conclude the Universe can't have an edge, as an edge creates too many hard questions. How can you explain a curvature that can turn a photon 90 degrees in 0.001 light year = 6 billion miles = 8.76 hours travel time near a puny G2 solar system? Neil

 

[emperor_of_localgroup]

If the universe is an object, as it appears to be because it contains other objects, then it must have edges, and boundaries, doesn't matter what the present-day maths say, the maths of the future will hopefully prove otherwise.<br /><br />But what kind of edge it is? A sharp edge? Very unlikely. It is strictly my opinion, the edge may be very slowly graded into something else. The edge may also be moving, pure speculation, but the way human perceive things, the universe must have some form of endings. <div class="Discussion_UserSignature"> <font size="2" color="#ff0000"><strong>Earth is Boring</strong></font> </div>

 

[vogon13]

If I may, it seems to me you are implying in your question (reading between the lines) that if earth were .001 ly from the edge of the universe, the opposite side of earth would be 10+ billion ly from the other edge of the universe.<br /><br />It don't work that way.<br /><br />Earth would be .001 ly from the edge of the universe any direction you cared to look in. CBR at that point in universe would be (ahem) intense.<br /><br /><br /><br />{that is probably the factually largest understatement in SDC history}<br /><br /><img src="/images/icons/wink.gif" /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[pyoko]

This is my first post.<br />I was thinking, that if the Big Bang theory is correct, then things started moving outwards from the nucleus at or slower than the speed of light, supposedly forever expanding, since the Universe appears to be open.<br />Since the Universe's age is theorised to be finite, the thing that travelled the farthest from the Big Bang has to be the last thing you will meet if you travel to the 'edge'. What is beyond this? Just plain spacetime with no particles of any kind? (please don't hit me, it's my first post) <div class="Discussion_UserSignature"> <p> </p><p> </p><p><span style="color:#ff9900" class="Apple-style-span">-pyoko</span> <span style="color:#333333" class="Apple-style-span">the</span> <span style="color:#339966" class="Apple-style-span">duck </span></p><p><span style="color:#339966" class="Apple-style-span"><span style="color:#808080;font-style:italic" class="Apple-style-span">It is by will alone I set my mind in motion.</span></span></p> </div>

 

[eric2006]

I think the general consensus is that the universe is flat. Like a record. Not like a sphere. If you or a photon reached the "edge" of the universe or went "past it". You (being part of the universe) would have caused the universe to expand with you. Thus you could not travel past the edge of the universe because no matter how far out you went, you yourself would in fact "be the edge of the universe". In order to escape the universe you would have to beat yourself there (you would have to get there before you got there). Maybe if you traveled faster than light you could escape the universe. But remember you are part of the universe so you would have to escape yourself. Then where would you be? If you where outside of the universe what would your coordinates be? Because you would have to wait for the universe to catch up, you would have no space/time location. If you have no location then you aren't there.

 

[newtonian]

pyoko - Hi! And Welcome!<br /><br />There are probably other universes beyond the edge of our universe, though "edge" needs to be defined to understand this.<br /><br />You are correct that our universe is "open" in the sense that it will expand eternally - at least if current popular interpretations of the increasing scientific data are correct.<br /><br />[Note - our universe may or may not be closed thermodynamically - i.e. acted on by outside forces - at this time; most assume it is a closed system in this sense - however I do not assume anything - compare the origin of dark energy]<br /><br />You are correct that there would be an edge of the extent of light of our universe. <br /><br />The Bible indicates (an illustration) that some stars, apparently black holes, have escaped the light and gravity of our universe and therefore have no set course and will be in darkness eternally:<br /><br />(Jude 13) . . .stars with no set course, for which the blackness of darkness stands reserved forever. <br /><br />Would these distant black holes, beyond the gravity and light of our universe, be beyond the edge of our universe, having achieved escape velocity from our universe?<br /><br />You see the need to define "edge!"<br /><br />Btw, inflation theories imply FTL (faster than light) is possible and has happenned.

 

[eric2006]

I heard before that the hubble is looking towards the edge of the universe to see it's own start. The theory being that the farthest matter/light/energy in the expanding universe is the oldest. I find it aslo interesting to note that we have found stars that appear to be older than the age of the universe.

 

[newtonian]

Eric2006 - Yes, very interesting indeed - it may be evidence of FTL (faster than light) expansion of the universe at some point in the past.<br /><br />The age is actually distance - i.e. say a quasar is 14 billion light years away but our universe began 12 billion years ago (estimate by astronomer Wendy Friedman). Did it get there (or we get here) due to FTL exoansion (as in one of the inflation theory models)?<br /><br />Or are we measuring wrong - misinterpreting red shift to some extent for example?<br /><br />I suspect FTL expansion, but I have an open mind on the matter.

 

[j_rankin]

Simply....a photon will never reach the edge of the universe because the universe is expanding, perhaps at the rate the photon is travelling, but of course in every direction. What i don't agree with is the hypothesis that the universe's expansion itself is making space expand. I don't see the logic in that because that would surely mean that everything in the universe is also expanding, and then we wouldn't ever even notice the universe is expanding.

 

[j_rankin]

"The age is actually distance - i.e. say a quasar is 14 billion light years away but our universe began 12 billion years ago (estimate by astronomer Wendy Friedman). Did it get there (or we get here) due to FTL exoansion (as in one of the inflation theory models)? "<br /><br />What I hypothesize is that at the time of the big-bang, there was already space......as in leftover black holes that weren't included in the big-bang (or immensely dense galaxies that were not part of the big bang itself, and later exploded into quasars). Perhaps these leftovers were responsible for triggering the big-bang itself, causing instability. I hypothesize that there are at least 10 of these so called leftover mniniature galaxies.<br /><br />Why must there be only one point the universe contracts into? Maybe several points became extremely tiny and dense, due to immensely supermassive black holes, and they hadn't yet been gobbled up by the ultimate central black hole before the big-bang.<br /><br />Just a touch of speculation.

 

[j_rankin]

Why does spacetime have to be relative to the big-bang? Perhaps there is no beginning or end because there is always distance.

 

[eric2006]

"What i don't agree with is the hypothesis that the universe's expansion itself is making space expand. I don't see the logic in that because that would surely mean that everything in the universe is also expanding, and then we wouldn't ever even notice the universe is expanding."<br /><br />It is not that matter is expanding. It may well be though. But it would be very slow. Space/time is expanding. Like rubber. Without movement/expansion of space/time we would (in my opinion) not have any time at all. What I am curious about is this. If we did find the missing dark matter and could guess that the universe will contract one day. During the contraction of space/time would time itself flow backwards all the way back to the singularity? If so then could the big bang start over again? Maybe we are stuck in an infinite cycle of bangs and crunches. Maybe each of them is exactly the same and produces the same universe everytime. We could have had this conversation an infinite amount of times.<br />

 

[eric2006]

"Why does spacetime have to be relative to the big-bang? Perhaps there is no beginning or end because there is always distance. "<br /><br />A static universe was the view of scientist for many years. We know that the universe is expanding because of the Doppler effect. Take a balloon and draw little dots all over it. Then blow it up. Each dot is a galaxy moving away from the center.

 

[eric2006]

"What I hypothesize is that at the time of the big-bang, there was already space......as in leftover black holes that weren't included in the big-bang (or immensely dense galaxies that were not part of the big bang itself, and later exploded into quasars). Perhaps these leftovers were responsible for triggering the big-bang itself, causing instability. I hypothesize that there are at least 10 of these so called leftover mniniature galaxies." <br /><br />What would these left over black holes be left over from? Where did all this matter you suggest come from? You stated that maybe it existed outside of our universe independant of our big bang then please explain what you mean. Where did you get the number 10 from?<br /><br />"Why must there be only one point the universe contracts into? Maybe several points became extremely tiny and dense, due to immensely supermassive black holes, and they hadn't yet been gobbled up by the ultimate central black hole before the big-bang.<br /><br />I don't think the big crunch would form a massive black whole. Because a black whole warps space time. In a big crunch all the space/time would collapse back into the singularity. So there would be no space/time left to warp.<br /><br />I have often wondered if our big bang was in fact a white hole. Perhaps our universe got it's start as a black whole inside of another unvierse ejecting matter into this one as a white hole. That idea doesn't appear to hold much weight when considered against other things.

 

[j_rankin]

"I have often wondered if our big bang was in fact a white hole. Perhaps our universe got it's start as a black whole inside of another unvierse ejecting matter into this one as a white hole. That idea doesn't appear to hold much weight when considered against other things. "<br /><br />How could the universe have been a white hole? Surely it was intensely dense and had enormous gravity and must therefore have been a black hole.<br /><br />And that's another point that confuses me. The universe just before the big-bang must have had an enormous gravitational force. And if gravitons exist.....then they must have reached out far beyond the universe. Hrmmm.

 

[j_rankin]

I cannot see how it is possible that the universe was as small as big-bang theorists believe. And this goes against the whole theory of spacetime and much of general relativity.<br /><br />If the whole universe is the result of probability, as many theorists believe (especially quantum theorists), then i feel there must be a limit to the possible.<br /><br />There are absolute extremes, and i believe that time is simply the exploration of every possibility between those two extremes.

 

[eric2006]

"How could the universe have been a white hole? Surely it was intensely dense and had enormous gravity and must therefore have been a black hole. "<br /><br />It could be neither. The problem is that white holes and big bang cosmology are two very different solutions to Einstein's general relativistic equation for gravity. White hole 'solutions' require a background space-time in which their particular curvature manifests itself, and within which the world lines of particles emerging from this type of singularity can be defined. Big bang solutions require no 'embedding space' a priori because unlike the 'local solutions' of white holes and black holes, the cosmological solutions are global solutions for the geometry of spacetime. There is nothing outside of them to serve as a background for world lines to be defined. You cannot convert the big bang singularity into a white hole singularity for the same reason that you cannot change a cat into dog. If the big bang was caused from a black hole then the universe would be contracting and not expanding. The standard big bang models are the Friedmann-Robertson-Walker (FRW) solutions of the gravitational field equations of general relativity. These can describe open or closed universes. All these FRW universes have a singularity at the origin of time which represents the big bang. Black holes also have singularities. Furthermore, in the case of a closed universe no light can escape which is just the common definition of a black hole. So what is the difference?<br /><br />The first clear difference is that the big bang singularity of the FRW models lies in the past of all events in the universe, whereas the singularity of a black hole lies in the future. The big bang is therefore more like a white hole which is the time reversal of a black hole. According to classical general relativity white holes should not exist since they cannot be created for the same (time-reversed) reasons that black holes cannot be destroyed. Thi

 

[j_rankin]

u just confused the hell outta me lol.

 

[j_rankin]

yeah i'd like that alot. This whole concept is confusing to me. Partly not because i don't understand what it means, but because i don't accept it. Perhaps if i had it explained better then i would begin to accept it or at least be able to better judge it.

 

[eric2006]

It is interesting that you chose the word "information". I have heard Stephen Hawking speak of "information" being possible to leak from a black hole. Do you speak of the same thing he does and if so can you describe what he means?

 

[soterious]

i have a question. If our universe started from another universe that crashed into ours and started the big bang(etc.) would it be possible that eventually our universe would expand outward opening others but couldnt there be a chance that our universe and another are heading straight at each other? and what would be the impact to us and to our universe to have our edge crash into another?

 

[siarad]

<blockquote><font class="small">In reply to:</font><hr /><p>The universe just before the big-bang must have had an enormous gravitational force. And if gravitons exist.....then they must have reached out far beyond the universe. Hrmmm.<p><hr /></p></p></blockquote><br />Gravity is limited to the speed of light, which can't escape black holes, so how does gravity manage to draw anything in or your gravitons reach out. <br />Likewise for the BB to happen it must have exceeded light-speed to escape or it is just an expansion of a BH in which we live