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Thread: Universe size questions

  1. #11
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    Default Re: Universe size questions



    thank you nFA.
    all very fascinating for sure!!

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    Default Re: Universe size questions

    nFA,
    thank you for all you have posted.
    I just saw your post #10.
    and when I read that and what you said before,
    comparing the comoving coordinates expansion factor of 3.5,
    to the redshift wavelength of the CMB,
    I am not clear.
    if you could elaborate on that at all,
    or there's anything you can say to make it clearer to me, I would appreciate it very much.
    I think I understand that comoving reference frame factors out the expansion of the universe.
    and then I'm lost.
    Last edited by chas53; 04-14-2019 at 07:38 PM.

  3. #13
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    Default Re: Universe size questions

    Does this help? The link includes animations of how differently comoving distance and proper distance behave. Note that there is coordinate distance too!

    https://en.wikipedia.org/wiki/Comovi...es#Definitions
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  5. #14
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    Default Re: Universe size questions

    thank you very much nFA.
    I read it a bit.
    is the redshift CMB measurement, expanded by a factor of ~1000, the Proper Distance?

    and the expanded by a factor of ~3.5 value, the Comoving Distance?
    but if the answer is yes, how can that be?
    if it expanded by a factor of ~3.5, thats an expansion.
    its not getting factored out!
    Last edited by chas53; 04-14-2019 at 08:41 PM.

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    Default Re: Universe size questions

    Hi. New here. I agree with your thinking that the universe is infinite. I too have many thoughts about this. I think it is inescapable that we as a species are blind to perceiving at least one other dimension, and probably many more. I concur with the analogy of what a two dimensional being would see when a three dimensional object interacts. That being would not be able to see anything more than the shadow created. Fascinating concept demonstrated with shadows of a three plane object on a two dimensional surface. I believe that what we perceive as the universe is that same case - we are seeing a four dimensional universe's shadow. Some heady stuff.

    The enigma that we all struggle with is how the universe was simply born spontaneously out of nothing. The "Big Bang". Well wrap this around your head: We have the same problem with exactly the opposite happening with a "Black Hole". It defies logic the same way but in reverse. Matter and energy simply evaporate out of existence. That is not supposed to happen either. So obviously there is something else going on behind the scenes, and that is probably an artifact of another dimension.

    What I pick up on is that as matter is absorbed into a black hole, there is a dimensional collapse of everything, including time into a singularity, eg length, width, depth and time reduce to a single point, and the disappears. It is the exact opposite of how we theorize how the big bang created the universe. So look at that evolution: A huge explosion unfurls and dimensions unfold from a singularity exponentially in every direction. Looking at it this way we can start to appreciate why the quantum world of the infinitesimally tiny began as swirls of energy strings that organized into atomic particles with incredibly fast time cycles and as this evolved reality blew up in scale - itself a dimension - with proportional time/space frameworks. I think it is inescapable. The Time/Space analogy of gravity is a very good one, and it is fascinating to me that it is illustrated on a rippled flat plane. It fascinates me that planetary systems seem to have a disk shaped swirling plane, as do galaxies. I suspect that may just be a matter of our dimensional perspective. I realize that as the dimensions unfolded, the all were built on a common axis between them, centered around the original singularity of that big bang. I think it is as simple as that - our perspective though is obscured.

    I have been wrestling with whether the universe has confining boundaries. I wonder what happens if you fill up a water balloon with seltzer and give it a shake. What does it do? Probably nothing. Its an experiment I'd like to try, with a pair of scissors, an empty glass and a jigger of good scotch for a follow up experiment!

    The concept, to answer your question is relevant only to scale. I suspect though that the shape of the universe is something more like a Klein Bottle. Four dimensional - leaving us with the paradox of The Big Bang and the Black Hole. We can't see where it all suddenly came from into existence and back out of existence. From where? To where? We are in a dimensional blind. D'ya think???

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    Default Re: Universe size questions

    Still need to be careful. We are looking at two different measures of distance between two different points. The two points are given by the location of the present observer of the CMB and the surface where the CMB photons were emitted. So with that caution....

    Quote Originally Posted by chas53 View Post
    thank you very much nFA.
    I read it a bit.
    is the redshift CMB measurement, expanded by a factor of ~1000, the Proper Distance?
    Yes, the formula 1 + z = a(now)/a(then) is the proper distance measure of the expansion of the universe. It is the factor in the FLRW metric that models the expansion.

    and the expanded by a factor of ~3.5 value, the Comoving Distance?
    but if the answer is yes, how can that be?
    if it expanded by a factor of ~3.5, thats an expansion.
    its not getting factored out!
    But it shouldn't be factored out completely. The 3.5 factor represents, in Comoving Coordinates, the difference in length from where the CMB was when it was emitted and where it is now. Those are two different points. What happens is that one has this comoving coordinate for the CMB emission then and when one plugs that into the metric you get the 13 Bly distance. Then you get another distance now to the same comoving coordinate which is 46 Bly. So it's a little tricky. The comoving coordinate is the same but the distance to that coordinate has changed over the last 13 B yr.
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    Default Re: Universe size questions

    Hi and welcome.

    Quote Originally Posted by HBH View Post
    The enigma that we all struggle with is how the universe was simply born spontaneously out of nothing. The "Big Bang". Well wrap this around your head: We have the same problem with exactly the opposite happening with a "Black Hole". It defies logic the same way but in reverse. Matter and energy simply evaporate out of existence. That is not supposed to happen either. So obviously there is something else going on behind the scenes, and that is probably an artifact of another dimension.
    I'm going to try to be precise about language here which often leads us astray.

    The enigma of the universe being created out of nothing no longer trouble me. The measurements of the Planck team indicate that the average density of the universe is zero. So there is no energy cost to making a universe.

    With a black hole the reverse is note true. Matter and energy that fall into a BH's event horizon
    1) add to the total mass of the BH
    2) takes an infinite time to make the passage across the event horizon to a distant observer. Thus to the distant observer I never disappear as I fall into a BH even though my gravitationally red shifted clock and biological processes say it's accomplished in a finite time. The distant observer never sees me disappear.

    What I pick up on is that as matter is absorbed into a black hole, there is a dimensional collapse of everything, including time into a singularity, eg length, width, depth and time reduce to a single point, and the disappears. It is the exact opposite of how we theorize how the big bang created the universe. So look at that evolution: A huge explosion unfurls and dimensions unfold from a singularity exponentially in every direction. Looking at it this way we can start to appreciate why the quantum world of the infinitesimally tiny began as swirls of energy strings that organized into atomic particles with incredibly fast time cycles and as this evolved reality blew up in scale - itself a dimension - with proportional time/space frameworks. I think it is inescapable. The Time/Space analogy of gravity is a very good one, and it is fascinating to me that it is illustrated on a rippled flat plane. It fascinates me that planetary systems seem to have a disk shaped swirling plane, as do galaxies. I suspect that may just be a matter of our dimensional perspective. I realize that as the dimensions unfolded, the all were built on a common axis between them, centered around the original singularity of that big bang. I think it is as simple as that - our perspective though is obscured.
    I find reasoning involving a supposed singularity a bit suspect. The existence of a singularity at the center of a BH or at the "origin"(?) of the universe is a mathematical artifact of the equations of GR that tells us that the GR theory has broken down and can't make predictions there. It is not physically real. Most workers suspect that a successful quantum theory of gravity will abolish singularities. Singularities are not physically real. They are mathematical indications that your theory is incomplete.

    I have been wrestling with whether the universe has confining boundaries. I wonder what happens if you fill up a water balloon with seltzer and give it a shake. What does it do? Probably nothing. Its an experiment I'd like to try, with a pair of scissors, an empty glass and a jigger of good scotch for a follow up experiment!
    I'd be willing to watch as long as Glenmorangie Quinta Ruban was on offer.

    The concept, to answer your question is relevant only to scale. I suspect though that the shape of the universe is something more like a Klein Bottle. Four dimensional - leaving us with the paradox of The Big Bang and the Black Hole. We can't see where it all suddenly came from into existence and back out of existence. From where? To where? We are in a dimensional blind. D'ya think???
    But Klein Bottles are curved and the Planck measurements indicate no significant curvature to the universe. More than a dimensional bind I think we are in a conceptual bind. None of us is thinking clearly enough to successfully produce a quantum gravity theory yet. Until that is done, we are confused and in the dark.


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    Default Re: Universe size questions

    nFA,
    just want to say thank you so much for your reply.
    I will read it later and reply again.

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    Default Re: Universe size questions

    Just my two cents, I believe in infinity, there is always something on the other side of the mountain. Humans will probably never find the definitive answer but we love to seek knowledge! Bless the thinkers! Bill
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    Default Re: Universe size questions

    Big Bang. Where did everything emerge from? Black hole. Where did everything in it go to? Paradox.
    Birth of life. Where did that "Life" come from? Death, where did that "Life" go? Paradox. Maybe we are like that chameleon that has been placed on a plaid surface. Madness can only ensue. It is obvious that we are blind to other dimensions. Time/Space is a theoretical. Time can be infinitely large or small, as can space. They common axis is Scale. We keep tripping over our perception of GOD and build religions around it. What if Spirituality is yet another dimension just as valid as the rest of them. Upon the Big Bang a Singularity came into being and with it all of the dimensions extended from that point in infinite directions, accelerating exponentially in scale and all around that common axis of the singularity where it began. Think about that. First nothin, then everything multiplied in scales.

    Have you ever tried to swat a fruit fly? Nearly impossible. The magically dodge. They are just too fast. That is an example of time/space in proportion to size. Their time cycle - or frequency - is much shorter. We lumber at them. We are no match. They perceive our movements like we perceive the growth of trees. It's a scalar thing. A "giffy" measures relative speed of an electron. If objects moved around at out scale that fast it would be catastrophic. So the quantum physics of the sub atomic are really just a scalar thing. As the singularity mystically comes into existence creating what we think is a unique Big Band, dimensions of a singularity, a logical reference point, becomes a dot. That dot then expands in all dimensions and accelerates into a universe. We are born from the joining of cells that are nothing more than chemical reactions between atoms when you get right down to it. Life probably started in water under pressure with just so much stardust particles squeezed together until there was a spark. It is all just another element of the dimensional matrix. Dot. Length, height, depth, space, time, scale, spirit... all centered on that original point of singularity. Black hole. Exactly the opposite. What we struggle with religion is all about is that we are blindsighted dimensionally and can only feel the artifacts of that "spiritual plane". We get a little carried away and upset with that. Such is the universe. Such is life. Just my humble opinion.

 

 
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