1. Joined
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    24 Jan '11 01:361 edit
    I have been trying to get my head around Big Bang cosmological concepts. Recently I imagined three scenarias which I think help me. But I would like some comments:

    1.) You have a super fast space ship and you want to see what lies beyond the farthest possible galaxy. In the rear window of the space ship you see the last galaxy, the one farthest out in the universe. In the front window you see nothing but blackness.

    When you try to zoom your rocket to see what is way way out there beyond the farthest galaxy you cannot. The gravity of all the existing things in the unverse can only pull you back towards it. You can only fall back into the material of the Big Bang.

    This proves that the universe is actually finite. The curved spacetime does not extend beyond a certain point. And the proof of this is that you can only fall back into the universe.


    2.) You have more power in your second attempt to break away from the material of the Big Bang to trek far far out into the void to see how far from the "boundary" of the Big Bang you can go. But it would take more energy then exists in the universe to propel you forward. Time stops at your maximum thrust. You have no movement and time comes to a halt.

    This proves that the universe is finite and closed in on itself ?


    3.) You give up trying to fly beyond the furthest boundary of the Big Bang. But instead you turn your rocket to the left or the the right. Now out the side widow you see the furthestmost galaxy. Pretend you have enough time to live - billions of years. You speed your rocket in either direction. Eventually you come back to that same galaxy because space is curved in on itself. You cannot go beyond the boundary of the Big Bang. And when you traverse around through it rather than beyond it you eventually come back to the same point in it.

    Are these thought experiments consistent with the present agreed state of Cosmology and General Relativity ?

    How would you correct any of these concepts? Thankyou.
  2. Subscribersonhouse
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    24 Jan '11 03:462 edits
    Originally posted by jaywill
    I have been trying to get my head around Big Bang cosmological concepts. Recently I imagined three scenarias which I think help me. But I would like some comments:

    [b] 1.)
    You have a super fast space ship and you want to see what lies beyond the farthest possible galaxy. In the rear window of the space ship you see the last galaxy, the one farthest o mology and General Relativity ?

    How would you correct any of these concepts? Thankyou.[/b]
    #1 is not correct in that you would start to see galaxies from where you left, that were in back of you and now in front, as if you were on a giant globe and you are flying around the world, in that case if you had infinite fuel, you would just come back to the same place you started from and take the same trip over and over, but the gist of that is you would always see galaxies in front of you but going far enough, they would be the ones that were in back of you on the way out, so you just see an endless supply of galaxies but if you had a way to tag each one with an ID, you would find, OMG, I passed that sucker 14 billion light years ago. But you are always going in what seems to you to be a straight line because the universe itself is curved back on itself in a forth or fith dimensional way.

    If I understand it right, #2 is not right either, as you approach c, you flatten out (get shorter) and widen out (get fatter). I think at c you would become a pancake of some order of infinite thinness the size of the universe but still going at c.

    I think # 3 is the most correct, you can start out in any direction in a space ship and if you are extremely close to c you will eventually come back to where you started as I said in the first paragraph. All roads lead to Rome eventually.

    Assuming you go in a straight (what appears to you to be a straight line) line from Earth and keep on in that same direction eventually you will find yourself at Earth, or at least where Earth was at the time you left. You would still miss Earth by millions of light years because the whole solar system is moving about 200 miles per second, in some direction or other, not sure which direction but if you go within a hairs breath of c you may think only a few weeks goes by on your onboard clock, but billions of years go by on Earth.

    So when you get back to where you are, the movement of the stars in the heaven would put the solar system about 15 million light years away from where it was, plus the problem that the sun may go through its red giant stage and devolve to a white dwarf and the Earth and the rest of the planets would be cinders and/or gone completely.

    In any event, you would not be able to use, say, a spectrometer to analyze the sun's spectrum because the sun would be an another stage of its existence and would not be even close to the nice yellow star we see now. You would in fact be at least 14 billion years in your own future and I calculated in 14 billion years at 200 miles per second the whole solar system could be 15 million light years from where it was when you left.

    So you would not come back home, you would come back to a cinder world at best around a star that used to be the sun but now is a white dwarf or whatever it would evolve to in 14 billion years. They think the sun will begin going into its red giant phase in only 4 billion years or less so it would be around 10 billion years after that event you would come back to what you thought should be home.
  3. Germany
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    24 Jan '11 14:15
    The universe is not Euclidian.
  4. Subscribersonhouse
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    24 Jan '11 18:041 edit
    Originally posted by KazetNagorra
    The universe is not Euclidian.
    Not even close! More like just plain fripping weird🙂
  5. Standard memberkaroly aczel
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    05 Feb '11 00:57
    Originally posted by sonhouse
    #1 is not correct in that you would start to see galaxies from where you left, that were in back of you and now in front, as if you were on a giant globe and you are flying around the world, in that case if you had infinite fuel, you would just come back to the same place you started from and take the same trip over and over, but the gist of that is you wou ...[text shortened]... round 10 billion years after that event you would come back to what you thought should be home.
    "All roads lead to Rome eventually", bloody funny that.
    All roads lead to Arcturia.
    (Ooops sorry, I thought this was spirituality...eek)
  6. Subscribersonhouse
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    05 Feb '11 17:03
    Originally posted by karoly aczel
    "All roads lead to Rome eventually", bloody funny that.
    All roads lead to Arcturia.
    (Ooops sorry, I thought this was spirituality...eek)
    My last point is interesting, eh. You go out in a near c speed craft, visit the edge of the universe, come back home by going in a (what for you is) straight line, I did make one mistake, you go out to the edge, 14 billion ly and come back, your clock will go up at least 28 billion years. The universe would age before your very eyes and the original humans you would have taken the trip for would be tens of billions of years in the past and our star, maybe even our galaxy would be unrecognizable if it still exists at all. You would be forever lost and would then spend the rest of your life looking for a habitable planet, which might not even exist in 30 billion years or whatever. Your trip would have been in vain.
  7. Cape Town
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    05 Feb '11 17:52
    Originally posted by sonhouse
    .... you go out to the edge,.....
    I think you should be careful with such language. The theory you are suggesting earlier in the thread implies that the universe does not have an edge.
    In fact, I am not aware of any theory that suggests a universe with an edge. Some propose an infinite space, others propose that space is large enough that we could never visit it all, but none propose an edge.
  8. Subscribersonhouse
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    06 Feb '11 04:411 edit
    Originally posted by twhitehead
    I think you should be careful with such language. The theory you are suggesting earlier in the thread implies that the universe does not have an edge.
    In fact, I am not aware of any theory that suggests a universe with an edge. Some propose an infinite space, others propose that space is large enough that we could never visit it all, but none propose an edge.
    When I say that I mean the edge of the visible universe. The actual size of the universe is thought to be more like 50 billion light years 'across'. So the furthest you can be from anything is half that or 25 billion light years away since it would be like us traveling around the Earth on the equator, the farthest you can be away from any place on Earth is about 12,000 miles or 20,000 kilometers so with the universe in which what we would perceive as a straight line is in fact a gentle curve no matter how you go. It's funny, if you look at it like you could take that curve and try to counter it, say you bend your travel in some direction to counter that universal curve, you would in fact shorten your return trip and not have taken the longest path!

    Thinking about that curvature of space, you would do the same thing inside a black hole, it has to be just another universe with its own set of rules, probably related to the universe that spawned it with maybe some small differences. Speed of light 240,000 kilometers per second or 340,000 kilometers per second, something like that. Maybe in each spawning universe the laws work out to be the same, like if we could somehow drill ourselves into such a universe and measure the speed of light there, the metrics would all expand or contract to make it look like exactly what we see c as here in our universe.
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