Diameter of known universe in statute miles!

[holocene]

I need some help from the math guys to tell me if I have this correct. <br /><br />While there are different opinions on just how big the universe is, I am using a figure of 78-billion light years across. By my math, this equates to:<br /><br />458,532,779,108,321,580,000,000 staute miles<br /><br />And written out:<br /><br />Four hundred fifty eight sextillion, five hundred thirty two quintillion, seven hundred seventy nine quadrillion, one hundred eight trillion, three hundred twenty one billion, five hundred eighty million statute miles.<br /><br />Anyone have any opinions regarding the accuracy of this?

 

[bonzelite]

there is no way to calculate the "accuracy" of the size of the cosmos. that is beyond the scope of our sciences. to posit the idea that it can be calculated assumes the position that the origin and manner of the creation is known, the age is known, the shape is known, the means to calculate these things are correct; the embodiment of what is contained "within" it is known --none of this is known nor can be known presently.

 

[docm]

Even if you had a diameter for the universe in one direction that won't likely hold for other directions because its shape is a matter of conjecture. This makes estimating a mean diameter and volume impossible. <br /><br />Some think it's spherical, some a flattened sphere and some even think it's a dodecahedron;<br /><br />http://news.nationalgeographic.com/news/2003/10/1008_031008_finiteuniverse.html<br /><br /><img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

 

[kmarinas86]

ehhhh what's up doc?

 

[doubletruncation]

The number as written assumes far too much precision. There are only two significant digits in the first number written, 78 billion ly, that doesn't mean that the measurement is exactly 78,000,000,000.0 light years. If 78 billion ly actually is a correct measurement, then presumably it's really 78.1... billion, or 78.2.... billion or 78.3.... billion or 78.07.... billion or what have you. The point is that because they only claim to know the first two digits in that number, when you multiply it by another number (the conversion of light years to miles for example - which is known to a very high degree of precision) you shouldn't keep more than the first two digits. So the number you would quote is 4.6 * 10^23 or 460 sextillion. Keeping any of the additional digits implies a false sense of precision in the value of this number. <br /><br />The other thing to keep in mind is that the value of 78 billion is not really thought to be the size of the *observable universe*. Instead, it's the extrapolated minimum bound on the topology scale of space, assuming that the cosmology that is currently favored as a model of the universe is not only correct, but that it also continues to hold beyond our horizon. It's more of a limit on the size of the bubble that we live in given cuurent observational errors and assuming that basic cosmology not only holds here but continues to hold beyond where we can directly measure it - the actual bubble size would presumably be even larger than this. Assuming that the currently favored cosmology is correct, the observable universe has a radius of 46.5 billion light years. If you look farther away you're effectively looking at things that happened farther back in time. At some distance what you would be seeing is light from the big bang (assuming nothing intervening would block it, which is pretty much a false assumption for light until a few hundred thousand years after the big bang). That distance would currently be 46.5 billion light <div class="Discussion_UserSignature"> </div>

 

[publiusr]

Somebody keeps knocking the mile marker signs down with a baseball bat...

 

[weeman]

The material universe could very well be larger than 78 billion lightyears. Since we see distant objects expanding at high velocities, we can assume that the Universe should still be expanding today. Unless it has already begun to collapse and the light from the collapsing universe hasn't reached us yet <img src="/images/icons/smile.gif" /> . So, if light left an object say 10 billion lightyears away, it would reach us in 10 billion years only if we lived in a static universe. However, the widely accepted theory today is that the universe is expanding. So if light left an object 10 billion lightyears away, then the expansion would require it to travel for a much longer time than 10 billion years. When the light finally reached Earth, that object could very well be 100 billion lightyears away! <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>

 

[meek_and_lowly]

Post Removed

 

[mental_avenger]

Speed of light = 1.802,265,898 MegaFurlongs / MicroFortnight <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

 

[arcane_raven]

this also depends on what is past the event horizon of our know universe (an event horizon emplies the point of no return not only with black holes)

 

[keermalec]

Hm there's something I don't get. If the universe is 16 billion years old (ie 16 billion years have lapsed since the big bang) then the universe cannot be bigger than 32 billion light years across. Outside this sphere no particles can exist unless they are travelling faster than light, which is not possible in this universe.<br /><br />So 32 billion light-years is 3.03 x 10E23 km or 1.89 x 10E23 miles...<br /><br />Is anything wrong with this reasoning? <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>

 

[SpeedFreek]

But what if it is space itself that is expanding? The limit on things travelling at the speed of light only applies to things that have mass. But lets go back a bit first.<br /><br />Our observations tell us the furthest <i> oldest </i> objects we can see are around 13 billion light years away from us. But the light we see from them is around 13 billion years old.<br /><br />If the universe were static, they would have had to have been 13 billion light years away from us 13 billion years ago, for their light to take so long to reach us! So either the universe was already really huge just after it was created, or something else is the cause (or actually both could be true in way).<br /><br />So how can their light take so long to reach us, if this light left them 13 billion years ago? How far has that light had to travel since? Well, we see their light is red shifted (like doppler effect), which seems to indicate that they are moving away from us. Or should I say, they were moving away from us 13 billion years ago when the light left them. And since then, the space in between them and us has been expanding, and distances getting larger.<br /><br />Now then, we dont think these distant objects appeared right at the beginning of the universe! It is estimated that the earliest objects took maybe 750 million years to form.<br /><br />Lets take a simple example. Forget any figures you have heard, this is just to illustrate a point. Lets say the universe actually expands at the speed of light. So after 500 million years the universe would be a billion light years across if it all started at one point.<br /><br />Say objects started giving out light at that time. The furthest objects are 1 billion light years apart when their earliest light leaves them. Space is expanding at the speed of light. How long would their light take to catch up with the objects on the other side of the universe? Well, it would never catch up, of course<br /><br />But it did catch up with us, so we can assume th <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[nova_explored]

ah speedfreak, thankyou for clarifying it by muddling it even more <img src="/images/icons/wink.gif" /> <br /><br />but expansion is exactly the dilemma in ever knowing a true measurement of the size of the universe. personally i don't think it is possible, and now after reading your post i am convinced of that.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[nova_explored]

here's a thought. If space is expanding faster than the speed of light at the edges of our known universe, wouldn't the light be caught in a flux of sorts, trapped at that place, like a light barrier, since the wave function of light is infinite?<br /><br />space tells matter how to move, light the same. If it is moving faster than light, it should redshift into infinity, shouldn't it? <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

You may indeed be correct <img src="/images/icons/smile.gif" /><br /><br />My earlier post was a gross simplification in a lot of areas.<br /><br />For instance, the red shift of distant objects isn't so much because they were moving away from us when the light left them, but is more likely because space has expanded while the light was travelling towards us, thus <i> stretching </i> the lights wavelength.<br /><br />If space expands fast enough, there may come a point where the lights wavelength is stretched so much it cannot be detected anymore. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[Mee_n_Mac]

<font color="yellow"><i>"If space expands fast enough, there may come a point where the lights wavelength is stretched so much it cannot be detected anymore."</i></font><br /><br />So you're saying I wouldn't be able to run down to Radio Shack and buy a sensitive enough DVM ? How depressing. <img src="/images/icons/wink.gif" /> I've not given it much thought but what is the limit in some hypothetical "old" universe to redshift of observable photons ? Would we detect, given some super duper voltmeter, a 0.00000000...1 Hz cosmic waveform ? If so then how what might we expect for phasing given all the EM energy coming in from different directions ? Hmmm, mebbe when I get home and have a few Black Russians I'll give it some more thought. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>

 

[suttungr]

Something just clicked! I've always wondered how we could view events from 13 billion years in the past when that light should have long since passed this point in space that we're in right now? <br /><br />Does this analogy describe what you're explaining?<br /><br />Take a rubber band and cut it and laid it flat. Then draw evenly spaced lines on the band with an ink pen. Label those distances between marks as "light-years" or "miles" or any label you want. Then stretch the rubber band. An observer on the rubber band stretches with the rubber band so to him, a "mile" is still the distance from one ink mark to the next and never changes, although to us the "space" has expanded...<br /><br />Or did I totally miss your point?

 

[SpeedFreek]

That's as good an analogy as any! <img src="/images/icons/smile.gif" /><br /><br />2 dimensional models like you describe do indeed help us to understand, although when you say the observer stretches with the band and thus doesn't see any change locally, you seem to imply this is because we are growing in size relatively (stretching with the band) and thus distances look the same! This doesn't seem to be case in real life. Our observations imply that space is expanding very slowly at close distances, and very fast at the furthest distances. Your model is good, but needs some further discussion!<br /><br />The expansion of space and the acceleration of that expansion can be visualised using your model, but that model is not being stretched any quicker at the edges than at the middle! The stretching doesn't need to speed up. A constant stretching will show the furthest distances moving away faster than the nearest ones.<br /><br />Imagine your rubber band or sheet of rubber is marked with regular units. Each mark is 1 unit. Imagine we are in the middle of this rubber band/sheet. Now imagine stretching the sheet so that 1 unit stretches to take the space 2 units did.<br /><br />So, the mark closest to us has doubled its distance from us. 1 unit has now become what 2 units used to be. Now then, when that nearest mark reaches where the second nearest mark used to be, how far has the second mark gone? It is now <b> 4 </b> units away! And the mark that used to be 4 units away is now 8 units away. See where I am going here? <img src="/images/icons/smile.gif" /><br /><br />The mark closest to us has moved from 1 unit away to 2 units away. A mark 100 units from us has moved to 200 units away. A mark 5000 units away has moved to 10,000 units away! All in the same amount of time.<br /><br />Now imagine those marks represent a light year. And the stretching takes, for example, 100 years to double the distance to our nearest mark. So, close to us, space seems to expand relatively slowly. It <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[ianke]

I have followed a few of these online discussions about the subject of expansion and the size of the universe. Some of them are way above my level of understanding at this point, however I am learning a little more each day. I have noticed though that you (speedfreek) seem to be the person to ask to get concise and understandable answers to many questions on this field of study. I therefore have a couple of questions on this subject for you and the rest of the people on this sight. <br /><br />1. Does your "rubber band sheet" explaination of faster universal expansion account for all of the observed speeding up seen and discussed in the media (tv and magazines)? Since, as you have said, that we really do not know the actual size and shape of the universe, wouldn't it make more scientific sense to adjust our hypothesis of size, shape, and velosity for the cosmos rather than to add dark energy to the equation? It seems to me that adding unknowns to your beliefs is akin to saying magic occurs.<br /><br />2. Can we make any assumptions about the size, shape, or even acceloration of our universe from the observations we have already made? <br /><br /> a.Size seems hard to pin down. We don't appear to see past the blinders of that 13 billion light year visual limit. So what is our best guess?<br /><br /> b.Shape? I don't even know how to begin to ask this. <br /><br /> c.As for speed, it seems to me that the red shift observations could be due to gravitational effects, or WOLFE's effect on red shift, or speed, or distance, or God knows what combination of factors to explain the observed data. How do we pin this down?<br /><br />When I first started my quest for understanding these issues, I thought things were a little more well understood. Now, it seems that all I have done is confuse myself further. Someone please help me nail at least one foot down to some fact on this issue. Perhaps I could search around a little better with the other foot instead of meandering from <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

Firstly Ianke, may I welcome you to SDC (space.com)! <img src="/images/icons/smile.gif" /><br /><br />Many thanks for the compliment. I try to use simple concepts and language to explain things, and maybe my explanations are easier to understand than some, but I must admit I am <b> not </b> always correct in my posts and often misunderstand these concepts myself. There are many people on these boards that are far more knowledgable on these matters than I. I just seem to have a knack for composing understandable explanations for abstract concepts, but I hope by making them simple people will think them through for themselves and either it all makes sense or someone will correct me!<br /><br />I have only a superficial knowledge of cosmology, and I ask myself the very same questions you have asked.<br /><br />1. The rubber sheet model (originally used by Einstein) is a good model for explaining the curvature of space-time, and also lends itself to explaining how space can possibly expand faster than light over large distances.<br /><br />But it is only a model to help us visualise the concepts. When Einstein likened the universe to a rubber sheet, with objects of larger mass making deeper "dents" in the sheet, he knew, of course, that the universe is not actually a large rubber sheet! <img src="/images/icons/wink.gif" /> But his model accounted for gravity and how it deflected light around more massive objects.<br /><br />When it comes to the expansion of the universe, dark matter and dark energy, as far as I know all we really have to go on is the red-shift of observed objects and there may indeed be other expanations for that red-shift. <br /><br />As for dark matter and energy, I think the same way as you do. I questioned the idea that when we originally discovered that stars at the edges of galaxies move faster than they should relative to the stars nearer the centre (which seemed to violate our current ideas about how gravity worked at the time) it must mean there was more matte <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[Smersh]

<blockquote><font class="small">In reply to:</font><hr /><p> Four hundred fifty eight sextillion, five hundred thirty two quintillion, seven hundred seventy nine quadrillion, one hundred eight trillion, three hundred twenty one billion, five hundred eighty million statute miles. <p><hr /></p></p></blockquote><br /><br />I wonder how many times around the Earth that is. (Maybe Steve Fossett or Richard Branson would be interested in a hot-air balloon attempt or something) <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1><p><font color="#800000"><em>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea."<br />Churchill: "Nancy, if you were my wife, I'd drink it."</em></font></p><p><font color="#0000ff"><strong>Website / forums </strong></font></p> </div>

 

[ianke]

Thanks again speedfreek! It is way cool to be part of this. You folks rock! I also understand the rubber sheet is a only 2D model from the big Albert E. I was looking only at the expansion aspect though. <br /><br /><br />While I am not a physicist, I do hold degrees in science. I am a retired research chemist. This does give me a full understanding of the scientific method. Where my real confusion comes in is in the dark energy issue. Dark matter is not a theory I have looked at other than through what I have seen or read in the general media. Therefore, I have no arguement with dark matter. Dark matter(matter we can not see) seems to fit its use in explaining galactic rotation. It also doesn't need the invention of unknown things to actually fit the model. all matter, particles, and even anti-matter are at least real.<br /><br /> It is another matter all together when it comes to dark energy. The only reason that I have heard argued for the existance of dark energy is that it explains a speeding up of cosmic expansion. All of the other reasons seem to me to be somewhat superfluous. "Accounting for 70% of the universe" is meaningless unless the universe can only be 1 size and one size only. <br /><br /> It appears to me that alternate explainations for the observed speed up could just as easily fit by changing our perception of the data, or by changing the size, speed,etc. of the universe in the original equations. I can conceive of many other options that would explain the observed without the invention of magic. I don't mean to say that Dark Energy is absolutely false. It may well be that we find it to be true. I just think that the theory gets way more weight than the data merits. <br /><br /> To put this argument to the test, let me give an example of an hypothesis that could fit. For this purpose I will assume that the universe is not it's accepted size but many orders of magnitude bigger, and we are not at the center. Also, let us imagine tha <div class="Discussion_UserSignature"> </div>

 

[ianke]

1.7*10^19 times I think. lol <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

You are indeed thinking the same way I do about these issues, and you have managed to put your ideas into a very concise and effective post. I totally agree that our current "best" theories could be wrong and may have to be changed once/if we manage to find out what the bigger picture is.<br /><br />I think the main problem is that humans are intrinsically curious and impatient creatures, and we want all the answers <i> now! </i> But our theories are based on a lot of guesswork in our interpretation of observed data.<br /><br />The business of <i> dark energy </i> bothers me as much as it bothers you, I think!<br /><br />It does seem plausible that although our observations seem to show that our observable universe is expanding (based on a certain way of interpreting our data, which may indeed be incorrect) a possible larger, unobservable universe could already be contracting.<br /><br />But remember, to attribute it all to gravity alone ("Gravity can do it all!) really means to attribute it all to the nature of curved space and time, as General Relativity describes it. General Relativity seems to be pretty much accepted and has stood up to any test we have given it, so far.<br /><br />And it is General Relativity that predicts the cosmological red-shift of distant galaxies (which is what we think we observe), in accordance with Hubbles Law. Which brings us back to the expansion of spacetime.<br /><br />With General Relativity, the idea is that it is not the matter in the universe that is expanding, but the very fabric of space itself. Gravity is not due to a force but rather is a manifestation of curved space and time, with this curvature being produced by the mass-energy and momentum content of spacetime itself. In a way, gravity is merely a side-effect of spacetime! <img src="/images/icons/wink.gif" /><br /><br />This brings us no closer to knowing if dark energy exists and accounts for something like 75% of the universe, but recent WMAP data seems to concur with the dark energy <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[MeteorWayne]

Both of you sum up things very well.<br />Dark matter is an explanation for some anomolies.<br />Dark energy is an explanation for another.<br /><br />It is possible/likely they are correct, but there is no way to be SURE at this point in our data acquisition and analysis.<br /><br />Maybe we're just getting it wrong. Not accounting for some othet unknown effect.<br /><br />We are living in an exciting time where these ideas are developing, and maturing. New data comes in every day. That was not true a dozen years ago. Then it was once a week or less. Now EVERY DAY piles of data come in.<br /><br />I suspect we will resolve some of these issues in the next decade or two.<br />I'd imagine the data will come from a direction we would not anticipate as of now, and the solution might be the mainstream one, or could be from one of the "fringe" ideas. As a historian of the advancements of science over the last 4 decades or so, I love the process of discovery. It's a fun and educational process to watch.<br />{/philosophy nerd depowered} <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>