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Thread: Distances between galaxies and what we see today

  1. #1 Distances between galaxies and what we see today 
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    I have a question that I hope some of you more intelligent people can answer for me in a way I would be able to understand.

    Ok I read that we can now see a galaxy nearly 13 billion light years away.
    From what I understand, it took 13 billion years for this light to get to us.
    Ok, I assume this means that 13 billion years ago the galaxy was 13 billion light years away??? What about the whole big bang thing?
    From what I have read the universe is about 14 billion years old. How is it that 13 billion years ago this galaxy was already 13 billion light years away? Within 1 or 2 billion years the universe grew to over 13 billion light years and we are just now seeing the creation of the galaxy? This is assuming we are on one totally opposite end of the universe and the other galaxy is on the other and nothing is any further on either end and we know this isn't true....
    Wouldn't that seriously break the cosmic speed limit for matter over 13x?
    From what I read it says that matter along with our current physical rules came into play a fraction of a second after the big bang. Wouldn't that mean that faster than light travel shouldn't be possible?

    only thing I can come up with is that
    1. The Big Bang is incorrect
    2. Matter can go faster than light in special cases I guess
    or
    3. The expanse of the universe at one time stretched actual space-time faster than light could catch up, then slowed

    I'm not that smart so if anyone can explain this to me I would be grateful


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  3. #2 Please help... 
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    Wow nobody? I'm really perplexed by this... I haven't been able to get this out of my head.
    Nobody has any Ideas? I mean I know Its something wrong with my thinking because
    BB is hailed as the current theory and so is Relativity...
    I must be missing something.


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  4. #3  
    Moderator Moderator Janus's Avatar
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    The speed of light limit refers to objects traveling locally through space.

    The expansion of the universe, on the other hand, involves the actual expansion of space itself. The expansion of space is not bound by the speed of light limit.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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    Catttdaddy. I do have severe doubts about the big bang but might be able to help you using big bang theory.

    Expansion needs to be through four physical dimensions, so a hypersphere. If through only three dimensions, you could trace everything back to an original point. So you have a 4D sphere, and the universe is it's 3D skin. From a 4D perspective, 3D would look flat, like 2D does to us 3D beings.

    If you have a balloon, it would help. If not you'll have to imagine it. Mark dots on it with a felt tip pen. They are galaxies. As you blow it up, the dots get further apart. If we say there is a cosmic speed limit of 1 cm per second that these dots can move,no dot can break that. But if they are moving at 2 mm per second away from each other, then one dot is moving at 2+2 mm away from another, so 4mm in one second.

    Now imagine you are on one dot and looking at another dot 9 dots away. Your dot and each of those dots are moving at 2mm per second so there is a total movement between you and the further dot of 2 + (9x2) mm per second. Or the furthest dot is moving away from you at 2 cm second.

    If you take 1 cm per second as the speed of light, though each dot is only moving at 2 mm per second, the furthest dot is moving away from you at twice light speed, though it is an accumulation of all the speeds rather than the dot moving at such a speed.

    Another way of demonstrating this is if you have a big elastic band. Put a number of dots along it's length and stretch it. Though all are moving equally, the ones at the end move the furthest.

    What is stranger is that the galaxies actually aren't moving away from each other (not allowing for local movements). It's the space between them that is expanding. More imagination needed. For the purposes of holding it together, we have a ball which for convenience we'll say has no size. From that ball, ten foot knitting needles are sticking out in all directions and where they go through another ball 3 feet away from the middle, we draw black circles around each needle puncture. Let's say the ball 6 feet across is the universe at 3 billion years old and the black circles are galaxies.

    Now 3 billion years later, the ball is 12 feet across, so 6 feet from the centre. But all the needles remain in the middle of the black circles, because the skin has just moved further away from the centre. The distance between the black circles has now increased a lot without movement.

    4 billion years later and the ball is now 20 feet across, so 10 feet from the centre. All needles still pierce the black circles as they have always done but the distance between the black circles has again grown quite a lot without them moving in any way sideways. The galaxies are ever further apart without moving as the distances between them grow.

    Though the universe is said to be 13.7 billion years old, through this method it is believed by big bangers that the universe is maybe 100 billion light years across.

    It is said in the earliest moments of the big bang, that faster than light expansion did happen.It is called the inflationary period and explains why there is a uniformity to the universe. It stopped when the whole universe was the size of a cricket ball and then changed to the slower than light expansion.

    It is said that several billion years ago, expansion sped up a bit due to dark energy.
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  6. #5  
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    The speed of light limit refers to objects traveling locally through space.

    The expansion of the universe, on the other hand, involves the actual expansion of space itself. The expansion of space is not bound by the speed of light limit.
    Basically, now correct me if i am wrong but that would mean that using a standard measuring device within space, 1 ft would be 1ft now or 13 billion years ago. Only if you were using a measurement from outside of space would this change.

    Ok, well the question still stands. How did a galaxy get 13 billion light years away, only 2 billion years after the big bang?

    Basically what are you saying?

    Is it that light is a measuring instrument from outside of space and using the "light year" as a measurement of distance within space is subject to constant change as the universe expands?
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  7. #6  
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    Thanks for the reply Cyberia, I appreciate it and enjoy your posts.

    I think I get the analogy of the balloon but I must be missing something.

    In all your examples it still seems like from the beginning things were physically (using a standard measuring device within space) closer together then grew apart but always moving relative to the other galaxies. If the universe expanded faster than the speed of light how would the light ever reach us? wouldn't we be constantly outrunning the light?

    Ok I understand that light moves at the speed of light for all parties independent of motion. Why was it so far to begin with where the light we see is 13bil years old?
    Unless you are pointing to what Janus said....
    So is it that space itself is longer?
    For instance, on the very small scale that 1tf today is 1.5ft in the next 5 billion years if you measure with a measuring device from outside of space but if you measure it with a device from inside space it will still be 1ft?

    Is this what you guys are saying?
    13 billion years ago, just 2 billion years after the big bang,
    If you were in the universe It would seem 100bil LY across the same as it does now. Its only if you went back in time and used a measuring stick from today that you would find that the 100bil LYs would only be 2ly with a measuring device from our time?
    Thank you for helping!
    I wonder what makes you have reservations about the bb?
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    Quote Originally Posted by Catttdaddy
    Ok, well the question still stands. How did a galaxy get 13 billion light years away, only 2 billion years after the big bang?

    Basically what are you saying?

    Is it that light is a measuring instrument from outside of space and using the "light year" as a measurement of distance within space is subject to constant change as the universe expands?
    The idea as I said with the balloon is that the space between each galaxy expands. Though light is a cosmic speed limit (as far as we know), when you add up all the distances between the galaxies in the universe, they far outstrip light speed (once the universe has got big enough). As you blow up the balloon, the bigger it gets, so the wider the distance between the dots with each puff.

    Even though a very distant galaxy is given a redshift equal to moving away from us at say 100,000 miles per second, it is moving away from us no faster than a nearby galaxy which only has a redshift equal to moving away at 100 miles per second. It is all the expanding gaps (say a thousand 100 mps gaps) which seem to give it such a speed of recession.

    Light is a constant speed of 186,282 miles per second. A light year is the distance light travels in one year. In a universe 13.7 billion years old, it is impossible to see more than 13.7 billion light years in any direction, though the universe may be much, much bigger.
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  9. #8  
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    Quote Originally Posted by Catttdaddy
    If the universe expanded faster than the speed of light how would the light ever reach us? wouldn't we be constantly outrunning the light?
    Much of the universe has a CUMULATIVE speed of faster than light away from us so we will never see it.

    Why was it so far to begin with where the light we see is 13bil years old?
    Since light moves so slow on a cosmic scale, we can look back in time nearly 13.7 billion years to near the beginning of the universe.

    I wonder what makes you have reservations about the bb?
    The BB uses a lot of unknowns and there are problems. Some of them:

    A multiverse as the origin of the singularity. Unproven.
    The singularity. Unproven.
    Inflation. Unproven.
    Other dimensions as in a hypersphere. Unproven.
    The universe was at one time trillions of times as dense as a black hole but expanded? An unproven idea.
    In just 13.7 billion years, we have voids upto a billion light years across, walls of galaxies (15x300x500 million light years) and an 18 billion solar mass black hole.
    The Dark Flow from early in the universe where galaxies are seen rushing towards each other across a billion light year void when they should be moving apart under expansion.
    3/4 of distant galaxies failed the afterglow test so the CMB seemed to be in front of them instead of behind them.
    Quasars 6-10 billion light years away do not show time dilation.
    Quasars with hugely different redshifts linked together.
    HE 1523-0901 is one of the oldest stars in the universe at 13.2 billion years old. It is in our galaxy, a mere 7,500 light years away.
    The CMB should be about 3,000.C, the temperature it was formed at but is just 2.7K, the temperature of space away from any star.
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  10. #9  
    Moderator Moderator Dishmaster's Avatar
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    I know, this reply is not the topic of this thread. So, if you want to start (another) discussion on the evidence for the Big Bang hypothesis, we could start another thread. Until then:
    Quote Originally Posted by Cyberia
    A multiverse as the origin of the singularity. Unproven.
    This is not a key ingredient to the Big Bang paradigm. It is also not scientific, because it is both unprovable and unfalsifiable.
    Quote Originally Posted by Cyberia
    The singularity. Unproven.
    True, but I am not sure that it is strictly needed to support the Big Bang hypothesis.
    Quote Originally Posted by Cyberia
    Inflation. Unproven.
    True to a large extent. At least it is consistent with observation. See also here.
    Quote Originally Posted by Cyberia
    Other dimensions as in a hypersphere. Unproven.
    As before: This is not a key ingredient to the Big Bang paradigm.
    Quote Originally Posted by Cyberia
    The universe was at one time trillions of times as dense as a black hole but expanded? An unproven idea.
    Well, this is a tautology to your opposition. If something expanded and is still expanding, it must have started with a very dense configuration. So, I don't consider this an argument.
    Quote Originally Posted by Cyberia
    In just 13.7 billion years, we have voids up to a billion light years across, walls of galaxies (15x300x500 million light years) and an 18 billion solar mass black hole.
    I don't understand this argument. Are you saying, you can't imagine, how this could have happened?
    Quote Originally Posted by Cyberia
    The Dark Flow from early in the universe where galaxies are seen rushing towards each other across a billion light year void when they should be moving apart under expansion.
    Gravitational interaction. This clearly shows that there is an evolution in the universe, because the situation was different then. So, I consider this a direct argument against a steady state universe instead.
    Quote Originally Posted by Cyberia
    3/4 of distant galaxies failed the afterglow test so the CMB seemed to be in front of them instead of behind them.
    Are you referring to the Sunyaev-Zeldovich effect?
    Quote Originally Posted by Cyberia
    Quasars 6-10 billion light years away do not show time dilation.
    References please. How do you measure time dilation in these distant objects? A big is the effect?
    Quote Originally Posted by Cyberia
    Quasars with hugely different redshifts linked together.
    This was refuted many times, and yet the Arp disciples cling to this statement.
    Quote Originally Posted by Cyberia
    HE 1523-0901 is one of the oldest stars in the universe at 13.2 billion years old. It is in our galaxy, a mere 7,500 light years away.
    Where is the problem?
    Quote Originally Posted by Cyberia
    The CMB should be about 3,000.C, the temperature it was formed at but is just 2.7K, the temperature of space away from any star.
    Gross misunderstanding of the nature of the CMB. The photons were emitted, when the universe had a BB temperature of around 3000K, but their wavelengths are now redshifted to this value. When they interact with matter, they can be transformed into heat. Yet, the general mean temperature of the interstellar medium is much higher, which is largely due to the interstellar radiation field of stars.
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