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radius of the universe

Discussion in 'Electronic Design' started by RichD, Dec 23, 2008.

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  1. RichD

    RichD Guest

    The usual analogy to describe the geometry of spacetime
    is an expanding balloon. The surface is 2-D, closed, warped
    in a 3rd dimension, inaccessible to the balloonists. However,
    the ballon has a center - in the 3rd dimension.

    Now, extend this picture to our expanding 3-D universe;
    can we compute the 'radius', the distance to the center,
    in the 4th space dimension? Analogous to the balloon
    model, it should be the same for all observers.

    And that would educe a circumference, would it not?
  2. Sam Wormley

    Sam Wormley Guest

    No Center

    Also see Ned Wright's Cosmology Tutorial

    WMAP: Foundations of the Big Bang theory

    WMAP: Tests of Big Bang Cosmology
  3. Yep, and the answer is 42 astronomical cubits.

  4. Guest

    Now, extend this picture to our expanding 3-D universe;
    Considering the universe as a sphere it certainly should have a center.
    However considering gravity, expansion and other things we don't know about
    yet things might not be as we thought they were ;)
    Maybe we can't exist outside the visable universe. Or it's just as any
    ordinary space. But VERY empty :)

    Now if it would be possible to travel outside the visable universe. There's
    something interesting to discover.
  5. Guest

    Correction; the internal and external volumes (and the center of
    course) are inaccessible, the surface is all that's accessible.
    Sure, why not? The yardstick will be the path of a photon from the
    Big Bang to your eye (in the 5-dimensional space in which our
    expanding 4D universe is expanding) and that path will resemble an
    Archimedean spiral. However it will be slightly altered by such things
    as Cosmic Inflation early on, when the expansion rate increased
    greatly for a while.
    Yeah, but we can never see but a small bit of it.

    Mark L. Fergerson
  6. Dear RichD:

    Representing space.
    .... Time.
    The "Big Bang".
    the "raisin bread" model..
    I believe the "distance" has been calculated to be 14.5 Gy (may
    have moved again).
    .... at any given *now*, with the usual synchronization problems.
    Not a unique circumference, since there is no guarantee this
    Universe is hyperspherical. Might be a dang torus.

    David A. Smith
  7. Guest

    I think that the point is that the universe looks as if it is between
    13.6 and 13.8 billion year old

    so you can't get anyplace that further from us than 13.8 billion ight
    years, and no place further away that that can get to us, so that we
    can say anything useful about more remote areas, and they can't affect

    In that sense, we do live in a gold-fish bowl (albeit it a rather
    large one).

  8. Guest

    People have looked for evidence that we can see the same bit of space
    from two different directions, and not found any, which doesn't prove
    anything much.

    My understanding was that the smart money was on the 4-D equivalent of
    the saddle-shaped geometry, but I can't remember why.
  9. MooseFET

    MooseFET Guest

    It appears that the universe is finite but doesn't have a boundary in
    all 4 dimensions. You need to consider the 5th dimension to be able
    to say that there is something we could call a center.

    I would argue that the universe must be finite for the following
    reason: Consider the location and speed of just one electron. This
    information must be stored somehow. From quantum mechanics we know
    that there is a limit on the resolution. From Einstein we know that
    the speed has an upper limit. The only remaining number that could be
    infinite is the position in an infinite universe. If this was the
    case, the number of bits would be infinite. From Shannon, we know
    that it takes energy for each bit that you store. From Einstein, we
    know that this energy would have mass. From this, I claim that an
    electron in an infinite universe would have infinite mass.

    Nice crack pot theory. Huh?
  10. krw

    krw Guest

    How does that work? 6 x 9 x 1 Astronomical Cubits? 6 x 3 x 3 AC?
  11. Guest

    The radius of the universe is infinite, the diameter is finite.
  12. Sam Wormley

    Sam Wormley Guest

    No Center

    Also see Ned Wright's Cosmology Tutorial

    WMAP: Foundations of the Big Bang theory

    WMAP: Tests of Big Bang Cosmology
  13. Uncle Al

    Uncle Al Guest

    No. The outside of a black hole's event horizon has a finite diameter
    implied pole to pole. The inside diameter is infinite, passing
    through the center singularity. Think "tardis" but with a roomier

    Tell us how to locate paired interior poles of an event horizon.
  14. Kandor.

  15. Since the 4th dimension is time, by your reasoning the distance to the
    centre is 13.7 billion years, give or take.

    Dirk - Transcendence UK - A UK political party - Our podcasts on weird stuff
  16. krw

    krw Guest

    Now *YOU* sound like the creationist. ;-) Who cares if there was
    one, or more than one "big bang"? Such things are unknowable thus
    unimportant. Who says there is only one universe? Who cares?
    Can't reach us, or it isn't a "big bang". Again, you're setting
    yourself up as the creationist because *you* can't see the other
    universes, yet believe they exist (or don't).
    That simply means the bang wasn't perfectly
  17. The further we look in any direction, the older the objects are, and if
    they are as old as the universe, they were part of the big bang, where
    space-time was in its most contracted state. Thus, although we appear to be
    in the center of a spherical universe, we actually are looking at the
    center when we look in any direction. So, in a sense, we (or any observer)
    are located on the inside surface of an expanding sphere, and we cannot
    look outside of this sphere (as it is undefined future space-time into
    which the universe is expanding).

    All light from the time of the big bang and thereafter is contained within
    this sphere and is gravitationally bent so that other elements of the
    universe located on other points of the sphere appear to be located at
    specific points in space-time which we can quantify by three-dimensional
    spatial vectors as well as the time vector. This contributes to the
    distortion, so that the oldest objects appear to be furthest apart (in
    spatial sense), while they are at their closest proximity to each other in

    Otherwise, there is the paradox that two objects in deepest space, but
    spatially opposite each other, would appear to be separated by twice the
    light-years of the age of the universe, so they would have had to exceed
    the speed of light to be located where they appear. But they are actually
    in close proximity to each other and are simply seen where they were at the
    beginning of space-time, but gravitational lensing creates the distortion
    that makes them appear to be impossibly far apart.

    At least that's my philosophical view of things...

  18. Sam Wormley

    Sam Wormley Guest

    The further we look out... the further back in time we peer to
    younger and younger objects.

    Thus, although we appear to be
    Every point is just as much the center as any other point.

    No Center
  19. hanson

    hanson Guest

    ......... ahahaha... AHAHAHAHAHA.....
    hanson wrote:
    ahahahaha... AHAHAHAHA... Thanks for the laughs, guys!
    ahahaha... ahahahanson
  20. krw

    krw Guest

    So you mock "creationists" by making up silly stories with even less
    internal consistency, history, or teaching?
    Of which you made up out of whole cloth.
    Perhaps it doesn't hurt, but it certainly help no one either.
    ....and that would be useful how?
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