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Thread: Size of the known Universe

  1. #1
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    Does anyone have any idea what the current thought is on the size of the universe?

    sgrantstein@galichia.com

  2. #2
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    Infinite

  3. #3
    Janus320 Guest
    Originally posted by Littlemews@Jan 7 2004, 06:19 PM
    Infinite
    Yes it is infinite and the reason why is at <removed>

  4. #4
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    I&#39;ve removed your link again. Please don&#39;t use the Universe Today forum as a marketing channel to advertise your site. I&#39;m happy to have you participate in discussions, though.

  5. #5
    JoAnn & Bob Henstra Guest
    If you consider the universe as anything other than infinate, if it has an end&#33; What might the end be made of, and what would possible be on the outside of that?

  6. #6
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    I think it depends upon the definition of the "Universe." If the Universe was created by the "Big Bang" it would have to be finite. It could be expanding at the speed of light into "nothingness" where nothing, not even light or time exist. This nothingness could extend into infinity. If you could somehow see through this nothingness, you might discover that universes like ours are scattered throughout the nothingness like raisins in raisen bread.

  7. #7
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    Intereting, if there are many universe&#39;s, what binds them? What are they held in? It&#39;s hard to concieve of there being no end, yet, it&#39;s harder to concieve of a place with nothing. Even if nothing is there, doesn&#39;t there have to be a space for it to occupy? If there is empty space, what is it? Now I have a headache.

  8. #8
    The current theory is that the universe is 13.7 billion light years in radius.

  9. #9
    YZ Guest
    Say the Universe is a globe shape. Maybe when you get to the "side" of the universe, you&#39;ll emerge on the opposite "side" a full diameter away. Might be where all those theories about curved space might be useful. <_<

  10. #10
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    The Universe being created by the big bang does not nessicarily mean that the Universe has to be finite. If it started out as one centrealized object that exploded it would have to be surrounded by empty space or their would be nothing for it to expand into. Empty space is still something since you can still travel through it.

  11. #11
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    The big bang was not an explosion of space ... the big bang didn&#39;t explode [iinto[/i] something. It was an explosion of space&#33; The universe may be 13.7 light years in diameter .. but it at one "wall" all you get to on the other side is the other side of the universe. Like in the old video game &#39;Asteroids&#39;, the asteroids and your little space ship goes out one side of the screen and in the otherside. That is what the universe is like. There is no outside of the universe.

  12. #12
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    very nice analogy Josh, so what you are saying, assuming that I understand, is that there is no wall, no boundary, no centre even though it is expanding at c (?) from its 13.7 billion ly radius. Can i assume that i am not the only one who has difficulty visualising it except as the asteroids game mentioned by josh?

  13. #13
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    Originally posted by Josh@Jan 12 2004, 09:09 AM
    The big bang was not an explosion of space ... the big bang didn&#39;t explode [iinto[/i] something. It was an explosion of space&#33; The universe may be 13.7 light years in diameter .. but it at one "wall" all you get to on the other side is the other side of the universe. Like in the old video game &#39;Asteroids&#39;, the asteroids and your little space ship goes out one side of the screen and in the otherside. That is what the universe is like. There is no outside of the universe.
    Then why does the universe expanding itself if there is nothing in the middle of the universe repelling things?

  14. #14
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    There is a sort of centre to the universe .. but that centre is everywhere. Regardless of where you go in the universe (according to current theory anyway) you can look out at the rest of the universe and see it expanding from that point. That is the nature of the big bang. While it wasn&#39;t an explosion from a point source (becuase there was no point before the big bang) it was still an explosion and a pretty damn powerful one at that.

  15. #15
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    Some lines of speculation based on there having been a big bang and an inflantionary period from 10^-43 to 10^-35 seconds after start assert that more of the universe is not observable from each point in space than is observable. This is due to space having expanded during the inflationary period such that each spatial dimension was extended at a speed greater than that of light. In another thread in this forum someone stated that it is believed by some to be at least 75 billion light years in radius (or maybe diameter, I forget). Note that regions outside your observational domain do not (actually cannot) impact you with either energy (photons) or gravity. Nor does your domain affect those regions. In a very practical sense that&#39;s as good as the non-observable region being non-existent. Speculating about its size and properties comprises a set of fool&#39;s errands.

    Neither center nor edge are meaningful when applied to the universe. Although we can pose questions like "what is the color of genius?" or "how soft is the temperature of the sun?" or "what is the odor of beauty?", the meaning of such verbalizations is overloaded in ambiguity if at all extant; their contemplation, outside carefully context coupled definitions is not a very wise use of brain power.
    One might ask what is the color of one hand clapping....but to little avail.

  16. #16
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    Well the forumula of the volume a sphere is

    V=4*3.14159*r^3/3

    If you take r as 14 billion ly you then get:

    V=4*3.14159*14000000000^3/3
    V=12.56636*14000000000^3/3
    V=12.56636*2744000000000000000000000000000/3
    V=34482091840000000000000000000000/3
    V=11494030613333333333333333333333 cubic ly

    So the volume of the Universe is &#39;11494030613333333333333333333333 cubic ly&#39;, if the universe has a radius of 14 billion ly. The calculations of this are not completely accurate.

  17. #17
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    That&#39;s a lot of nuts.

    I want to go back to the "if you flew out one side of the universe you&#39;d fly back in the other." My speculation would be that if you could reach the boundary and zipped across it wouldn&#39;t you be taking you&#39;re time and space with you, thereby extending or stretching the universe rather than popping up (just a phrase) on the other side?

    Evil Steve

  18. #18
    Francisco J. de Anda Guest
    [FONT=Times][SIZE=1][COLOR=blue] If we think that the Big Bang happened 15 billion years ago and the fastest you can travel is Light speed the limit of the radius of the Universe is 150 000 000 000 light years, but as we know that we canīt travel at light speed adn we also know that we have never got near to the speed and we are far slower now this number should dramatically fall.

    panchjosedea@hotmail.com

  19. #19
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    Originally posted by lazserus@Jan 9 2004, 05:34 PM
    The current theory is that the universe is 13.7 billion light years in radius.
    I am curious how this is figured? If our current capability is seeing about 13-15 billion light years away, what is out there further than that? I think that there are billions of universes and these congregate, like galaxies to superclusters, to form many superclusters of universes. My point is how can we establish age of something when we can&#39;t see the entire thing? Maybe the age of our universe is 13.7 billion years old, but the other billions of universes are very diverse ...

  20. #20
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    jce1975, why do you suggest that there are ...
    "... other billions of universes ..."?

  21. #21
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    Originally posted by Chook@Feb 9 2004, 01:57 AM
    jce1975, why do you suggest that there are ...
    "... other billions of universes ..."?
    I just through that comment out there because honestly, no one knows what lies beyond what our technology allows us to see (visibly and otherwise). Until we can, many possibilities exist ...

  22. #22
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    Josh, I just read your explanation, and I have to say that it is the best answer I have yet seen. Absolutely elegant in it&#39;s simplicity.

    I hope you are ok with my using it in conversations without acknowledging the source

  23. #23
    Faulkner Guest
    While it wasn&#39;t an explosion from a point source (becuase there was no point before the big bang) it was still an explosion and a pretty damn powerful one at that.
    So it DID come from a point source? It didn&#39;t? A singularity? No? Is the Universe infinite? Did it "expand" from "finity" to infinity? Is the expansion curved, so that it meets up with itself? How can the Universe erupt out of a dimensionless point? A quantum fluctuation? Did a "virtual particle" become the Universe???????????

    etc etc...

    PLEASE ANSWER NOW&#33;&#33;&#33;

  24. #24
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    No it didn&#39;t come from a point source. To quote Josh in an earlier post:

    the big bang didn&#39;t explode [iinto[/i] something. It was an explosion of space&#33;
    In other words, there was nothing, then there was everything. The word "explosion" conjures up images of an expansion of something into something, which is not the case of the universe. Everything that is came into being at the same moment, then expanded from there.

    How am I doing josh?

    That is why, when you are at any point within the universe, there is no way to reference "start". It is all "start"--the centre is everywhere all at the same time.

  25. #25
    Faulkner Guest
    Is that the best these highly-paid cosmologists can come up with? There was nothing. Suddenly: the Universe&#33;

    But this Universe (by implication) must have started tiny (because of the expansion that we detect). It COULD have been a point-source singularity&#33;

    But the real question is...Was it NAKED???

  26. #26
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    Let&#39;s take 13.7 billion light years as the size of the currently (speed of light limited) observable universe from best guessing at the value of the Hubble constant. This is larely speculation not a measurement. An observer on an object that far away, by looking in the direction opposite from the direction to us should be able to see an object 13.7 billion lightyears in that direction as will an observer on that object be able to see an object 13.7 billion lightyears still further on in the established direction of looking, etc.,. I&#39;m not sure how this ever ends which means that the volume of the universe increases without limit unless something about the inflation and normal expansion introduces a limiting process; even if so how do we bring this sizing algorithm to a close? :unsure:

    Note that "observable" begins to take on ambiguity. If there are observers all along the way, this universe without size limit is "observable" (the abscence of an observer doesn&#39;t trump observable anyway) which is not what we normally mean by this term. We can&#39;t use "observed" which is technology limited and suggests an entirely different context. The term "locally observable" comes to mind for what we have been meaning up to now. h34r:

  27. #27
    Phillips Guest
    I&#39;d like to weigh in on this issue. First, no discussion concerning this topic would be valid without refering to the `Theory of Inflation&#39; . While eluded to before, it expanded the `universe&#39; a million, trillion, trillion, trillion (10x23rd) times volume/size wise.
    `We&#39; as enities exist in a `visible universe&#39; of 13.5 billion or so `years&#39; in size (each light year being 6 trillion miles). However, in addition to `inflation&#39; (which I haven&#39;t even accounted for yet) the universe has been `expanding quicker&#39; because of `dark matter/energy&#39; pushing everything `apart&#39; (literally the creation of `space&#39; within space/time fabric). Hence, rather than an `envelope&#39; 13.5 biilion years in size - `our&#39; universe (without inflation) would have pushed our `envelope&#39; out 35-40 billion or so light years.
    Most of the universe is not our `visible&#39; universe - and lies `outside of it&#39; - `it&#39; being the visible portion. But, this doesn&#39;t even begin to tell the SIZE. Because if the `theory of inflation&#39; is right - then forget the 40 billion light yr figure. Because what it would mean is that the `size&#39; of the `universe&#39; of which we are living enities would be a million, trillion, trillion, trillion - times larger than the `visible&#39; universe - and that would be just OUR bubble of time/space.
    But, even that `size&#39; would not be the `end&#39; of the sizing. Because all of that - all that size that I just described with inflation would be just our universe of space/time - other theories would allow either other dimensions `sharing&#39; our `same&#39; space/time structure - or, would allow for `other universes of space&#39; other than our own.
    We are less than a speck.

  28. #28
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    We are less than a speck
    Very true, although the way you describe the effect of inflation (as being outside anything we could ever measure) makes my skin crawl, because it means we can&#39;t ever be sure if that is what actually happened; it is untestable. And my idea of the Universe is that it can be traversed and measured, the rest of it is just a story, let&#39;s call it the Imaginary Universe.
    Cheers.

  29. #29
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    As a new user I will pay my dues to the scientific and educated posters by saying I know very little regards 'facts' of the universe. I just thougt this an interesting thread I found on google and thought maybe I would comment.
    My views are, the universe is big, yes...we all more or less agree on that...bigger than we can imagine. Actually...bigger than most scientists can imagine aswell...so only the knowledge of fact and evidence is going to answer this question as best as we can.
    If the universe was created by a big bang....then there must have been a space for it to expolde into...as everyone knows...fire needs oxygen , and oxygen means that there is another space that this is existent in...am I right ?...after all....There is no matter in a vaccum...and a vacuum wouldn't allow an explosion to happen without a bigger one happening within it... If that is the case...then the big bang isn't as big as the bang that it has created...if you follow me...yes or no ?
    This is an infinate conversation as far as I am concerned as we have no to very little knowldge as to what is really out there and so only speculate and calculate to what could happen as far as our earthly knowledge permits.
    I suppose thats why I tend to focus on earthly knowledge or 'local' knowledge to be safe in my understanding.

  30. #30
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    Quote Originally Posted by zacraines View Post

    If the universe was created by a big bang....then there must have been a space for it to expolde into...as everyone knows...fire needs oxygen , and oxygen means that there is another space that this is existent in...am I right ?...after all....There is no matter in a vaccum...and a vacuum wouldn't allow an explosion to happen without a bigger one happening within it... If that is the case...then the big bang isn't as big as the bang that it has created...if you follow me...yes or no ?
    No.

    First off, not all explosions require oxygen. Take nuclear explosions for example. No oxygen needed. Supernovae are a better example.

    However, as stated, the Big Bang wasn't an explosion IN space. It was an explosion OF space.

    It involves complicated physics. IIRC, something called "branes" are involved. It seems to be analogous to having higher dimensions. I may be wrong about that.

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