just curious?

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majornature

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Well i was looking at a program a couple of month back and i learn that scientist can study stars as far back as 10 billion light years away. It is also assumed that most of our universe is missing?<br /><br /><br />Now the question i have is this: If the universe is estimated to be at least 15 billion light years old and can be observed as far as 10 billion light years away could it be that most of our "missing" universe has been discovered?<br /><br /><b>The Wind Tell Stories...Listen!!!!</b> <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>
 
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search

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Hello majornature<br /><br />Click highlighted words to read more and listen to the music of the universe<br /><br />I will tell one short version of the story of the Universe here. The version which corresponds with the standard model (Lambda-CDM) and therefore correspond to the scientific consensus. <br /><br />Almost all the information is from WIKIPEDIA which although it is not the most scientific correct site it gives a good search tool for your questions now and in the future. As you get deeper you will need other sources. <br /><br />It is a good starter though.<br /><br />Probably the oldest galaxy yet found, IOK-1, was discovered in September 2006 by Masanori Iye at National Astronomical Observatory of Japan using the Subaru Telescope in Hawaii. Its emission of Lyman alpha radiation has a redshift of 6.96, making it thirteen billion years old. While some scientists have claimed other objects (such as Abell 1835 IR1916) to be even older, the IOK-1's age and composition have been more reliably established.<br /><br />The age of the universe from the time of the Big Bang, according to current information provided by NASA's http://en.wikipedia.org/wiki/
 
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SpeedFreek

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EDIT: I hadn't seen the above post by SEARCH when I wrote this.<br /><br />Well it depends what you are referring to. It sounds like you are talking about the missing mass of the universe, the so called "dark matter". Is that what the program was talking about?<br /><br />If it is dark matter you are referring to, then it hasn't been "discovered" yet. It has been theorised, and some observations seem to confirm it.<br /><br />How it works is that at galactic scales, the rotational motion of galaxies seems to defy normal physics. The stars at the edges of galaxies seem to be moving far faster than we expected them to be - in fact, they seem to be moving so fast that they should just fly out of the galaxy instead of being gravitationally bound to it. The solution we are looking into is that galaxies are far more massive than previously thought, and thus exert enough gravity to hold the stars in. But this extra mass (which is something like 90% of the universe!!) hasn't been observed. Thus the name dark matter.<br /><br />Either we cannot see most of the mass in the universe, or our understanding of gravity doesnt work at large scales.<br /><br />That could be the missing universe you are referring to.<br /><br />OR....<br /><br />The current thinking is that the universe is around 15 billion years old and the furthest objects we have detected are around 13.7 billion light years away. As we look further, we look back in time and these are the "earliest" objects we can see, from around 1.3 billion years after the so called big-bang.<br /><br />The reason for this is that we are at the centre of our observable universe i.e. the light from more distant objects has not had time to reach us yet.<br /><br />So the universe could be for example 100 billion light years across, but only 15 billion years old. If that is the scenario, then we can only ever see a small fraction of the whole universe, due to the constraints of the speed of light and the age of the universe. The rest of the universe <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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search

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I was also editing my post...now is more user friendly....
 
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newtonian

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SEARCH - Excellent research, as usual.<br /><br />Well, if the universe has a finite diameter, then does it have an edge? See my thread on this theme just started if you want to post the answer there instead.<br /><br />I might add that a recent television program quoted astronomer Wendy Friedman as finding the age of the universe to be 12 billion years old by a number of methods.<br /><br />I trust you see a problem with a 12 billion year old universe with objects 13.7 billion light years away!<br /><br />Is this solved by faster than light inflationary models - hence a radius larger than age (i.e. time for light to travel radius), solved by additional light cones in our universe?
 
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newtonian

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majornature - Probably not most discovered yet.<br /><br />Hubble deep field photos are limited in number and spots studied. <br /><br />There is much yet to be observed - and more deduced by cause and effect but not yet able to be observed.<br /><br />This is an exciting time for astronomy as more data pours in!
 
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search

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Thanks<br />See post above<br />" The ambiguity in size is dependent on the detailed models of Hubble's law, especially the nonlinear nature of dark energy component of the universe which is causing the expansion of the universe to accelerate." <br /><br />
 
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majornature

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Yeah it was a program called "Most of Our Universe Is Missing?" <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>
 
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newtonian

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SEARCH - Decided to research the Scientific American article about the Big Bang from which you got your estimate. Here is the paragraph:<br /><br />Sciam, 3/05, p. 43 article on Big Bang<br /><br />“What does mark the edge of observable space? Here again<br />there has been confusion. If space were not expanding, the<br />most distant object we could see would now be about 14 billion<br />light-years away from us, the distance light could have<br />traveled in the 14 billion years since the big bang. But because<br />the universe is expanding, the space traversed by a photon<br />expands behind it during the voyage. Consequently, the current<br />distance to the most distant object we can see is about<br />three times farther, or 46 billion light-years.”<br /><br />You had compared this with the WMAP estimated radius of the universe as at least 78 billion light years.<br /><br />There is actually no discrepancy here.<br /><br />The Sciam figure is the current distance of the furthest observed objects near our visibility horizon. That would be less than the radius of the total universe, as some of our universe is beyond our visibility horizon.<br /><br />In other words, the furthest object we see is about 13 billion light years away as we see it, but the space has expanded further during those many years so that now said object is actually 46 billion light years away now.<br /><br />I.e., we are seeing in the past.<br /><br />Hence, if both figures are correct, then we see 46/78ths of the universe now (or then).<br /><br />Am I understanding this correctly?
 
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SpeedFreek

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To majornature,<br /><br />Most of our Universe is Missing? is indeed a program about dark matter , so I will refer you to the relevent portion of my above post where I address dark matter. <img src="/images/icons/smile.gif" /><br /><br />So the part of your original post that asks about the visible universe has nothing to do with the search for dark matter and whether we have discovered it yet.<br /><br />These are 2 different (but both very interesting!) cosmological questions. The difference between the visible universe (what we see) and the comoving universe (where what we see actually is by now) has nothing to do with the missing mass of the universe - your question is about the dark matter (and dark energy) problem.<br /><br />Unfortunately (or fortunately if you are interested in it!) due to your mention of the size of the observable universe versus its age, this thread has been mostly about the comoving distance of the universe, which doesn't help us find the missing mass of the universe. <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>
 
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SpeedFreek

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A few notes for Newtonian <img src="/images/icons/wink.gif" /><br /><br /><font color="yellow"> Well, if the universe has a finite diameter, then does it have an edge? </font><br /><br />The post by SEARCH refers to the radius of the <i> observable </i> universe only, and how the universe we can see is now further away than it looks. It does not address how large the whole universe is, except to imply it could be much larger than the part we can ever see.<br /><br />According to Einstein, the universe is "finite but unbounded". Note that <i> space </i> is part of the universe, so this doesn't mean space goes on after all the stars stop! As I'm sure you know, there are various theories as to whether the universe is infinite or not, and seeing as we can only ever see a small portion of the universe it is doubtful whether we will ever be able to prove it one way or the other. That doesn't stop people trying though!<br /><br /><font color="yellow"> In other words, the furthest object we see is about 13 billion light years away as we see it, but the space has expanded further during those many years so that now said object is actually 46 billion light years away now. <br /><br />I.e., we are seeing in the past. <br /><br />Hence, if both figures are correct, then we see 46/78ths of the universe now (or then).<br /><br />Am I understanding this correctly? </font><br /><br />Not really. We always see ALL of our observable universe and we have no idea how much more universe there is. Granted, what we see has moved further away by now, and other stuff may have formed in between us and the edge of the observable universe by now.<br /><br />The WMAP figure was for the comoving distance, and was estimated at 78 billion light years. This means the objects we see at 13 billion ly are actually 78 billion ly away by now. I don't know where the Scientific American article got the figure of 46 billion ly from.<br /><br />Note that all these estimates are simply for the comoving dista <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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search

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Newtonian<br />I have seen 42, 46, 78 and so on but as it was stated "dependent on the detailed models of Hubble's law, especially the nonlinear nature of dark energy component of the universe which is causing the expansion of the universe to accelerate." you will get different values.<br /><br />Check this (this was a simple approach using Wikipedia but more scientific then one needs to go further) and you will see what the meaning is.
 
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newtonian

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speedfreek - I stand, or - er - sit, corrected.<br /><br />I hadn't caught that the WMAP estimate was for co-moving distance.<br /><br />So SEARCH was correct and I misunderstood.<br /><br />You may be correct that we cannot know if there is an edge.<br /><br />As I stated (perhaps on my locked edge thread) - there is a finite number of light cones in our universe - therefore light can only have reached a finite distance.<br /><br />Matter could have outdistanced the light edge.<br /><br />And space could have outdistanced both, but perhaps not beyond the limits (edge) of dark energy influence.<br /><br />We need to know the exact expansion speed of space, and the upper limit of actual motion on the fabric of space by matter, and if gravity speed is constant as the speed of light, and the speed of dark energy.<br /><br />If you find any links on this tangent, please post them.
 
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newtonian

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SEARCH- Your last link will take time to analyze.<br /><br />Those are a large number of different models for our universe!<br /><br />Do you have any links to any models whereby our universe has an edge?<br /><br />See my above post for different types of edges. (light, mass, space, dark energy, etc.)
 
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