space ends

[ashish27]

<blockquote><font class="small">In reply to:</font><hr /><p> And just what are all these things expanding into? <p><hr /></p></p></blockquote><br /><br />According to Stephen Hawking (and many other theorists) that question is irrelevant. Bcoz theoritical physics considers the things that is "inside" the Universe and events after the Big Bang. Theoritical physics have failed to answer what was there before the beginning of time. when t=0, all known mathematics don't work because at t=0 density, pressure, tempertaure everything becomes infinite.<br /><br />From a space travellers point of view, the question what lies outside the known Universe is yet not known. Nobody knows what happened before the BB and what the Universe is expanding into, if at all there is anything outside this Universe. So Kalstang your question is very much justified.

 

[nogard]

What if you were at the edge of the universe and on a planet looking out into space. If you were standing on one side of the planet you would see nothing a black void and on the other side of the planet you would see whatever star light and galaxy light made it to your point in the universe.<br /><br />If this was your planet what would you think. Would you even know that you were at the end of the universe? Would you say, hey over there is nothing, no space, no time. If I were to travel that way fast enough I would end up at the other side of the universe (according to some theory) Perhaps if I went to the point where no space and time exists I would cease to exist. Or perhaps if I travel that way space would expand around me.<br /><br />Fun to think like this, too bad we will never really know the answer.

 

[ashish27]

haha, yeah it is really funny. About 2 years ago from now I sent an email to StarTrek producers Paramount to have a new Trek series where a starship ends up at the edge of the Universe. Paramount was purchased by CBS and they never replied to my email.<br /><br />From a scientific point of view however there is no so called edge of the Universe. Just like the Earth has no edge so does the Universe. Many theorists beleive there is a fouth physical dimension, a person called Michio Kaku have even written a book (called Hyperspace) where he claims to have worked on 11 physical dimensions. M-theorists believe that such dimensions are curled up into microscopic proportions. I think those are all speculation.<br /><br />I personally like to beleive that our hope of knowing the unreachable lies in SETI. Perhaps a ET civilization that have evolved for billions of years may have the answer.<br />Thats why I like space science, in this subject you can always keep your fingers crossed!

 

[dragon04]

I would be very interested to be an inhabitant of a planet in the earliest formed galaxy and <b>know</b> it.<br /><br />For me, the nature (and curvature) of 4 dimensional space-time might be far less problematic.<br /><br />Would my Hubble Telescope see nothing but darkness beyond a few billion LY in a particular direction? If so, that might indicate an "open" Universe.<br /><br />Would it detect a "band of darkness" and then more galaxies? That might indicate a "closed" Universe.<br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[thesmartonewon]

where space ends. am i correct that the fartherst things from us is 16.4 billion light years away? soo in theory if nothing can travel faster then the speed of light. but the rate of expansion of the universe is speeding up. what happens if we see something 16.8 billion light years away. by the time we see it does that means that it is about to go faster then light? and from its perspective lookin at us. are we about to do the same?

 

[robnissen]

No, you are not correct. This is complicated. During the initial inflation after the Big Bang, the universe was inflated to much larger than the visible universe. How much larger, no one knows. One possibility, with currently no way to prove, is that the universe is infinite. Indeed, the singularity of the Big Bang could have been infinite. Which would lead to an infinite singularity inflating (that is a better word than exploding) into an infinite universe.<br /><br />But to get back to your original question. The furthest galaxies we can see today are approx. 13 gig light years away. Indeed, if there was no inflation, the farthest galaxy we could see would be about 7 gigs away, because it would have taken the galaxy 7 gigs to move 7 gig light years away from the big bang, and then it would take another 7 gigs for that light to get back to us. But thanks to inflation, the fartherst items we can see, were close to the location where we currently see them, after the big bang. In addition, inflation is continuing. We are seeing those galaxies where they were 13 gigs ago. Due to inflation, those galaxies are now about 45 gigs away. They are not traveling faster than C, however, instead, space is continually being created between us and them, to push them farther away. Like I said, this is very complicated.

 

[ashish27]

<blockquote><font class="small">In reply to:</font><hr /><p> During the initial inflation after the Big Bang, the universe was inflated to much larger than the visible universe. <p><hr /></p></p></blockquote><br /><br />Who told you that? Thats a totally wrong fact. I wonder from where you have picked that up.<br />and don't keep on saying complicated complicated......<br />The Universe is not complicated. It never was and never will be. Only a complicated human mind can make it look complicated. Like you have done, by stating astronomical distances as if they are empty spaces in your hard drive.

 

[alokmohan]

How do you know he is wrong?Thats generally believed.Can you give a link?

 

[SpeedFreek]

I think I can help here. The inflationary epoch ends with our <b>observable</b> universe being the size of a grapefruit (about 15cm across)!<br /><br />From New Scientist <br /><br /><i>" The key feature of inflation is that it stretches space-time - the three dimensions of space together with time - by a very large amount, smoothing out any irregularities that are present. Think of the difference between the wrinkled skin of a dry prune and the smooth surface of the same prune when it has absorbed its fill of water, then picture how smooth the skin of the prune would be if it were inflated to the size of the Earth, and you get some idea of how the process works.<br /><br />But cosmic inflation happened on a much smaller scale, and had ended by the time the Universe reached the size of a grapefruit."</i><br /><br />From Science News <br /><br /><i>"The most detailed portrait ever taken of the radiation left over from the Big Bang provides fresh evidence that the universe began with a tremendous growth spurt, expanding from subatomic scales to the size of a grapefruit in less than a trillionth of a second."</i><br /><br />From Scientific American: Misconceptions about the Big Bang <br /><br /><i>"Cosmologists sometimes state that the universe used to be the size of a grapefruit, but what they mean is that the part of the universe we can now see--our observable universe--used to be the size of a grapefruit.<br /><br />Observers living in the Andromeda galaxy and beyond have their own observable universes that are dif</i> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[robnissen]

<font color="yellow"><br />Now then, all the above applies only to our observable universe. As a possible scenario, the whole universe might have already been millions of light years across (and full of what was to become matter) after inflation! At that time, when our part of the universe, our observable universe, was the size of a grapefruit, the whole universe could have been millions of light years across, filled with energy just like our section, where galaxies eventually formed something over 100 million years later - galaxies that would now be trillions and trillions of light years away from us. <br /><br />People in those galaxies might work out the same thing as us, and decide that after inflation their observable universe was the size of a grapefruit too, but their grapefruit is not the same grapefruit as ours! (I know the above link says the grapefruit overlap, but that is only for for objects in our observable universe - objects outside our observable universe are looking back in time towards a totally different part of the universe that doesn't overlap ours. If an object was for instance, just under twice the radius of our observable universe away, its observable universe would just overlap ours).</font><br /><br />You are exactly right. But where it gets complicated is the size of the original singularity. While it is true that our visible universe was approximately the size of a grapefruit after inflation, there is nothing to prevent the size of the inflating universe from being two grapefruits in size, a trillion grapefruits in size, or even infinitely sized. If it was infinitely sized, then you end up with the mind-blowing scenario of any infinitly sized singularity inflating into an infinitely sized universe.

 

[weeman]

I understand what you're saying to explain how multiple observable universes don't really overlap each other. <br /><br />Even if multiple observable universes were overlapping, it would be completely undetectable to the observers in each universe. From the center of our observable universe, we see everything rocketing away from us. So, even if you travel 1 billion lightyears away from here, the center of THAT observable universe would still appear that everything is moving away. <br /><br />In addition, the fact that we even have an observable universe that seems to have an observed limit, should be solid proof that the universe is not infinite. Otherwise, our observable universe itself would be infinitely observable. Unless, of course, it is the physical limit to which our telescopes can see into space. <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[SpeedFreek]

<i><font color="yellow">"In addition, the fact that we even have an observable universe that seems to have an observed limit, should be solid proof that the universe is not infinite. Otherwise, our observable universe itself would be infinitely observable. Unless, of course, it is the physical limit to which our telescopes can see into space."</font>/i><br /><br />No, the fact that we have an observable universe with a limit due to the age of the universe coupled with the time it takes light to travel and the rate of expansion - has no bearing on whether the whole universe is infinite or not.<br /><br />The whole universe would only be infinitely observable if you had infinite time in which to observe it, <b>and</b> it wasn't expanding!<br /><br />The limit to our telescopes is time, it seems - the time light has had to travel since the big-bang. But that does not limit the size of the whole universe, as we have no idea how much of it we can see - how much of the whole universe our observable universe takes up. Our observable universe might be 90% of the whole universe, 1% of it or 0.0000000..........000000001% of the whole thing! (or less)<br /><br /></i> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[adrenalynn]

It's also worth noting that given current BB theory, and subsequent SuperForce/SuperSymmetry, the "speed of light limit" didn't really apply until sometime post first-mover... There's a very good chance there's radiation out there apparently older than the universe (based upon observable distance) - but that it's simply from *very* early in the process. Ie. with the current speed limit, it'd take longer to reach us than the universe is old, but because it moved "away" from what eventually became us in the first "moments" where FTL was a reality, it will take longer to reach us than the universe's apparent age.<br /><br />Clear as mud? <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>

 

[weeman]

<font color="yellow"> No, the fact that we have an observable universe with a limit due to the age of the universe coupled with the time it takes light to travel and the rate of expansion - has no bearing on whether the whole universe is infinite or not. <br /><br />The whole universe would only be infinitely observable if you had infinite time in which to observe it, and it wasn't expanding! </font><br /><br />Well, you're right, you would need to have an infinite amount of time to observe every corner of the entire universe. If the universe were infinite in size, then you could argue that it must be infinite in age. Of course, just because it is infinite in size, shouldn't mean that it absolutely has to be infinite in age. Of course, this seems absurd to me, since I believe that space and time need each other to exist in the first place. <br /><br />If we looked into space with our largest telescopes, and never saw any observable end to the universe, we might conclude that it could be infinite. We could even build a telescope the size of an entire planet, and if we still didn't observe the end of the universe, then we could conclude even more that it may be infinite. <br /><br />However, this is not what we're seeing.<br /><br />We are seeing evidence that suggests that it has a finite size and age.<br /><br />I see what you're saying about the observable universe being created out of the limits of a finite timeline. I suppose my own personal opinion gets too caught up in this sort of discussion! To me, infinity creates problems. It is merely a hypothetical situation that is applied to something that is no longer explainable through finite mathematics. It is an absurdity, it is simply an idea. So, infinity should never be applied to anything that represents the constructs of the universe and everything in it. The universe simply would not exist in the way it does if it is infinite in size or age. <br /><br /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[SpeedFreek]

<font color="yellow"> We are seeing evidence that suggests that it has a finite size and age. </font><br /><br />No! You are doing it again! What we are seeing only suggests the universe has a finite age, but says nothing about the size of the <i>whole</i> universe. You are simply <i>inferring</i> that it means the universe must be finite, when we have absolutely <b>no</b> evidence to suggest that.<br /><br /><font color="yellow"> The universe simply would not exist in the way it does if it is infinite in size or age. </font><br /><br />I must again disagree here. It is true it would not match our observations if the universe were infinite in age, but if the <i>whole</i> universe was around 14 billion years old, <b>and infinite in size</b>, we would see exactly what we <b>do</b> see.<br /><br />Please, I beg you to read all 5 pages of this link:<br /><br /> Misconceptions about the Big Bang <br /><br /><i>"Baffled by the expansion of the universe? You're not alone. Even astronomers frequently get it wrong."</i><br /><br />Perhaps you might be happier if I limit myself to saying that the <i>whole</i> universe might be <i>almost</i> infinite in size... <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[weeman]

Ok. So then how is it infinite in size, yet finite in age? <img src="/images/icons/laugh.gif" /><br /><br />I understand that our observable universe limits us to actually knowing what lies beyond. My point is that if we see evidence that might suggest that it is infinite in age, then it seems absurd to think that it is infinite in size. <br /><br />I completely understand the dynamics of an observable universe, and how it limits us to ultimate knowledge of the universe. So if I sounded like I wasn't making sense, it might be because I'm having a hard time explaining my own views <img src="/images/icons/smile.gif" /> SDC (and the universe) will drive you crazy sometimes!!<br /><br />What I'm saying is that if the universe were finite in age, it must be impossible for it to be infinite in size. If it were finite in age, yet infinite in size, it almost sounds as though it popped out of existence one day and was instantly infinite. How can something that had a beginning, be infinite?<br /><br /><font color="yellow"> Perhaps you might be happier if I limit myself to saying that the whole universe might be almost infinite in size... </font><br /><br />Well now this is just silly. Even if the universe were hundreds of trillions of lightyears across, it would still be an infinitely small fraction of infinity <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[space_coops]

Yes, that has always bothered me too. As far as i am aware, if there was an event such as the Big Bang then time/space started at some point and therefore could not be infinte in age/space. Am i wrong?<br /><br />Im having trouble getting my head around the age of the universe vs the observable universe. Say we are at the centre of the observable universe (as far as light has travelled?) then can there be an observable universe outside our sphere? If so how far can the sphere's "edge" be away from ours considering the age of the entire universe?<br /><br />Anyone got any diagrams?

 

[vandivx]

<blockquote><font class="small">In reply to:</font><hr /><p>Size is a physical dimension. The universe expands faster than we can travel within the boundaries of physics. Therefore the universe is infinite in size with respect to all possible physical measures and known methods of travel. (even if we could travel at Light speed) <p><hr /></p></p></blockquote><br /><br />"Therefore the universe is infinite in size with respect to all possible physical measures" <br />---<br /><br />that is false conclusion, I mean my old grandma who can barely walk half a mile can't ever walk all the way to nearest town, should she then conclude that it is infinitely far away? if she did it would be only as a figure of speach<br /><br />but one can never say that as scientist that because the universe might be expanding faster than we can go (look, measure etc) that it is then "infinite in size with respect to all possible physical measures"<br /><br />a number series is infinite because it is abstract, that is non-physical construct of our mind, anything in actual world cannot be infinite because nothing physical (actually existing) can be, we as humans have gotten the idea of infinite only from our own abstract constructs of our minds, we could never glean something like that from actual reality which is finite in all respects wherever we look and when we talk about infinite universe or whatever we are only confusing our mind's processes with reality (but that is nothing new, primitive people have been doing just that in many regards throughout their existence - projecting their abstract ideas into existence, most notably the notion of God for example)<br /><br />like at this very moment (and any moment) the universe has some certain size, right? and so much matter is in existence, right? and so and so many stars exists, right? <br />now why wouldn't that be valid for every moment, that is in every moment the universe contains some definite amount of matter, definite number of stars, definite amount of bo <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

<font color="yellow">If it were finite in age, yet infinite in size, it almost sounds as though it popped out of existence one day and was instantly infinite. How can something that had a beginning, be infinite?</font><br /><br />Well I am sorry I mentioned the term <i>infinite</i> now!<br /><br />How about "finite but unbounded", the possibility that the volume is finite but a straight line through space may actually end up back where it started? <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[SpeedFreek]

Well to be precise we consider that space is within 2% of being flat, according to Neil Cornish et al. The straight line may still indeed be a curve, but the radius of that curve would be larger than our observable universe. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[vandivx]

"-Infinite can also mean “beyond or outside†our physical known set of references. "<br />----------<br />that's as fine an argument for God's existence as any<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[space_coops]

<blockquote><font class="small">In reply to:</font><hr /><p>I agree that finite but unbound is a better expression.<p><hr /></p></p></blockquote><br /><br />Do you mean like a fractal? Maybe i need to read more about Chaos theory then to understand fractal geometry.

 

[weeman]

<font color="yellow"> Well I am sorry I mentioned the term infinite now! <br /><br />How about "finite but unbounded", the possibility that the volume is finite but a straight line through space may actually end up back where it started? <br /> </font><br /><br />Yes, I like the "unbounded" theory much better <img src="/images/icons/smile.gif" /> <br /><br />Don't be sorry, this is what SDC is all about, arguing over theories that are completely unanswerable! <br /><br />Thanks for your insight, Speedfreek <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[vandivx]

"-Where to place the cosmologist if the universe should be measured?"<br /><br />in the center<br /><br />Aristotle believed in the center of universe (with everything ultimately moving towards there as natural condition of things) and while he was certainly wrong on some other accounts I actually think he unwittingly hit the nail on the head here<br /><br />one should listen and think about what ancients said even if it seems extremely oddball at times because sometimes they hit paydirt<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[vandivx]

'problems' are opportunities and challenge<br /><br />center of universe goes well with absolute space of Newton <br /><br />that old cranky dog also knew more than he thought he knew <img src="/images/icons/wink.gif" /><br /><br />vanDivX <div class="Discussion_UserSignature"> </div>