Location of the Big Bang

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brellis

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I understand the Universe is expanding, so all galaxies are moving away from each other as if they're on the skin of a balloon. I understand the cosmological model that traces all matter back to a singularity.<br /><br />The black hole at the center of the Milky Way, Sag A*, resides in a particular location in the night sky. Does the Big Bang emanate from a particular location as well? <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
 
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SpeedFreek

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Well, first let's address the skin of the balloon analogy, to see if you understand it fully.. <img src="/images/icons/smile.gif" /><br /><br />The balloon model is a 2 dimensional example to help us understand how everything can be moving away from everything else, but have no centre of expansion.<br /><br />Only the actual surface of the balloon is used; there is no outside the balloon or inside the balloon. In this 2 dimensional balloon universe there is no up and down. You can only move in the surface of the balloon. <br /><br />As the balloon expands, all points on the surface move apart, but there is no centre of expansion on that surface. There is no also no "edge". Everything on that surface can see the other things moving away from them, but cannot feel the expansion of the space in between them. Nowhere on that surface can be considered to be the centre.<br /><br />Inhabitants of this 2 dimensional balloon universe have no concept of it's actual shape, as they would need extra dimensions that do not exist in their universe in order to visualise it (i.e. up and down).<br /><br />Now apply this concept to our own universe that has at least 3 dimensions! You may find that there is no centre of expansion and no edge...<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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brellis

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Hi speedfreek, thanks for helping me to expand my knowledge base. If only I knew where it was centered! <img src="/images/icons/tongue.gif" /><br /><br />Ok, our universe has no center and no edge, but we're identifying its structure. Our Milky Way belongs to a Local Group of Galaxies. How do we determine large-scale structure if there is no center? Is our Local Group on one side of the Universe compared to other Groups? Can our place in the Universe be defined in terms of "The Local Group is in the direction of <i>x</i> Constellation"? <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
 
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SpeedFreek

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Well, we are in the centre of our observable universe!<br /><br />As far as I am aware, the galaxies are all distributed pretty evenly across the cosmos. There are super-clusters here and there, and our galaxy is part of a small cluster.<br /><br />Our place in the universe can only really be described as <i> at the centre of our observable universe </i> because we have no knowledge of how big a portion of the whole universe we can see in our observable universe. There may be much more universe than we can see, but the light from there hasn't had time to reach us yet, due to the age of the universe.<br /><br />Also, we are at the centre of any definitions based on pointing in directions towards constellations. Of course, someone across the galaxy from us may put us in one of <i> their </i> constellations! Constellations are simply arbitrary patterns we have decided make nice shapes to use as landmarks in the sky. The component stars of constellations are often many hundreds or thousands of light-years apart, and not local to each other - they just look close to each other from here. Move to a star a few hundred light years away and the constellations would look very different.<br /><br />Our map of the large scale universe pretty much emanates in a sphere outwards from us. We know which galaxies are nearer to us than others.<br /><br />But we are pretty much just one lump amongst many lumps! <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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brellis

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<font color="yellow">We are in the center of our observable Universe! There may be much more universe than we can see, but the light from there hasn't had time to reach us yet, due to the age of the universe.</font><br /><br />Ahh! Finally I can get my brain around it! The Hubble 'scope, which during its design phase was described as being able to reach the theoretical limits of human sight, has found galaxies almost as <i>old</i> as the universe. However, that doesn't mean it has found the <i>farthest</i> galaxies. When the Hubble takes a Deep Sky long-exposure image, we have no idea if those distant, ancient galaxies are half-way across the universe, or more likely, a tiny fraction of the actual universe. A simple truth. Thank you so much for helping me to better understand the Universe. Kinda makes me feel like a grain of sand on an ever-expanding infinite beach! <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
 
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SpeedFreek

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I'm glad I could help <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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brellis

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Okay, maybe this is another case of two steps forward, one step back:<br /><br />From a site calculating how fast we're moving through the universe comes a description of our increased precision in measuring the cosmic background, giving us a 'direction'.<br /><br /><font color="yellow">For a long time scientists thought it was not possible to directly measure the direction and speed of Earth's motion<br />Then scientists discovered the Cosmic Microwave Background (CMB) radiation - electromagnetic radiation that originated from the Big Bang<br />At first, this radiation seemed to arrive at the Earth from all directions at the edge of the observable universe with a constant value<br />Recently, better instruments (on satellites) have been able to measure not only slight differences in this radiation from place to place, but also the "Doppler shift" which is caused by the Earth moving towards one part of it and away from the part "behind" us</font><br /><br />Does this potentially lead to us locating ourselves relative to the Big Bang, in some kind of extra-dimensional model?<br /><br />I am holding steadily to the concept of seeing almost all the way back to the time of the B.B. in every direction, I'm happy to report! I also understand why they described Hubble as being capable of reaching the limits of the <i>theory</i> of sight; in a balloon-type model, it's impossible for us to "see" the galaxies that would be on the "other" side of the B.B., since that light would have to be traveling faster than the speed of light for us to see it even now, so many billions of years after the fact. <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
 
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SpeedFreek

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Having read that article, I think what we are seeing is that, although the expansion of space-time seems the same everywhere, in local areas any measurements taken will be affected by the apparent motion of the things in those local areas.<br /><br />What I mean is, we know that everything in the universe is moving, and we also know that the space in between everything is expanding.<br /><br />So our sun is moving around the galactic centre, and our galaxy is moving through the universe. We see the doppler shift of the CMB differently depending if we are looking at our direction of travel or away from it.<br /><br />Gravity causes galaxies to be attracted to each other, and so galaxies move around in space - everything in the universe is swirling around! At the moment, the Milky Way and Andromeda are on a collision course.<br /><br />But this doesn't help us define where the big bang happened! We are moving towards one section of the CMB and away from another, true. But everything we can see, and everything else outside our observable universe, all of it, is INSIDE whatever was created at the beginning.<br /><br />And of course, we have to take into account the comoving distance - i.e. the furthest objects we see are 13.5 billion ly away. But that's where they were 13.5 billion years ago. Due to the expansion of space, they are now estimated to be something like 78 billion ly away! And who knows what gravitational interactions they have gone through in during the last 13.5 billion years.<br /><br />Also, it might pay to remember that the CMB is the closest thing we know to the "big bang". At the beginning of the universe, everything was supposedly compressed into a singularity - a single point in space. So that point - which might be termed a point of origin, is now spread in a sphere around the edges of our observable universe. So maybe what you think of as the location of the big bang is actually the <i> outside </i> of our observable universe in every direction! Remember, as <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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brellis

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<font color="yellow">So, maybe we can define the location of the big-bang as the outside edge of the universe (if there is such a thing)? Now I have a headache!</font><br /><br />Another reason why they say ignorance is bliss!<br /><br /><font color="yellow">what you think of as the location of the big bang is actually the outside of our observable universe in every direction! Remember, as we look into the depths of space we are looking backwards in time.<br /><br />we can see, and everything else outside our observable universe, all of it, is INSIDE whatever was created at the beginning</font><br /><br />Thanks speedy. Once again, you have explained the cosmic stuff in an understandable way. I'm trying to 'graduate' into a coherent state on the subject of cosmic theory, and you have helped immeasurably. Perhaps you should write a book! <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
 
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newtonian

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brellis - Let’s back up a bit here!<br /><br />First of all, I am not certain there is no center – certainly there is a center in 4-d including time.<br /><br />Second, I expect there are many different types of edges to our universe, for example:<br /><br />A. The edge of our light cone, aka visibility horizon.<br /><br />B. The edge of the light from our universe, which involves multiple light cones, some overlapping, some not.<br /><br />C. The edge of gravitationally bound, or loosened but influenced, matter in our universe.<br /><br />D. The edge of matter in our universe including matter that may have been expelled faster than light either at the big bang or later in some inflationary epoch. That matter may, depending on definition, be considered beyond the edge of our universe.<br /><br />E. The edge of faster than light energy or matter from our universe, perhaps including dark energy or even tachyons.<br /><br />Third: One should not assume the balloon model is correct. I prefer the following ‘flat’ model:<br /><br />(Isaiah 40:22) . . .There is One who is dwelling above the circle of the earth, the dwellers in which are as grasshoppers, the One who is stretching out the heavens just as a fine gauze, who spreads them out like a tent in which to dwell. . .<br /><br />In this model the universe is expanding like a stretching fine gauze with its threads and filaments. This is how our universe appears from actual observations, and also from computer extrapolations from these observations. We are expanding in all directions 3-d.<br /><br />Now picture a stretchable fabric, like a flexible tentcloth. Each point on such an expanding fabric of space would expand away from the other, and more distant points would expand away faster.<br /><br />Again, this is what is actually observed scientifically.<br /><br />Except for local anomalies, like the Great Attractor, etc.<br /><br />In those cases, an additional detail of Biblical astronomy/cosmology applies:<br /><br />(Job 38:31-33) . . .Can
 
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newtonian

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speedfreek - Just to simplify what might be being observed:<br /><br />There is a difference between the expansion of the fabric of space itself from movement on(in) said fabric.<br /><br />For example: movement in the 3-d fabric of space has a speed limit, c, for ordinary matter, perhaps also most dark matter.<br /><br />However, we do not know the speed limit of expansion of 3-d space, let alone 4-d space/time - though it is certainly faster than light speed (=c).
 
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SpeedFreek

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Well, if the furthest objects are estimated to be 78 billion ly away and have only taken around 13.5 billion years to get there, then yes it certainly seems like the expansion of space happens faster than the speed of light.<br /><br />The flat model does a good job of describing what we see - the things furthest from us are moving away the fastest.<br /><br />But this still doesn't give us a location for the big-bang. The geographical centre of the universe doesn't relate to it really. Whatever model you use be it big-bang or brane, you end up with the question of space-time, and whether it existed <i> before </i> the universe. Did the universe expand <i> into </i> space, or was the space <i> created </i> with the universe? If the latter, then the only significant description of the location of the point of creation is the outside, as everything is inside whatever was created. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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