Center of the Universe

General physics and astronomy discussions not directly related to Celestia
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Rassilon
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Center of the Universe

Post #1by Rassilon » 06.03.2005, 03:26

I think this is more of a question than a discussion but Im deeply interested in others insight to the question where would the center of the universe lie? Of course by our standards its the planet Earth since everything we see around us up to 14 billion light years distant surrounds us and all our celestial plotting is relative to the planet Earth....And of course as Aristotle and Ptolemy did thousands of years ago, depicting the Earth at the center of the universe and our solar system...so must we until we know otherwise? Not that we really believe this but it seems most of our science is based on that...
I'm trying to teach the cavemen how to play scrabble, its uphill work. The only word they know is Uhh and they dont know how to spell it!

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Post #2by Umeboshi » 06.03.2005, 05:20

I think any place is center of universe!
I can't use English well.

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Re: Center of the Universe

Post #3by andersa » 06.03.2005, 05:31

Rassilon wrote:I think this is more of a question than a discussion but Im deeply interested in others insight to the question where would the center of the universe lie?

When the Earth was still believed to be flat, certain cultures depicted the city of Jerusalem at the center of most "world maps" of the time. Now that we are familiar with a spheroid Earth, no point on the surface can claim being the center any longer, but the geophysical center is instead located more than 6,000 km below our feet.

Likewise, the definition of the "center of the universe" depends on the actual shape of the universe. If it's curved in a fourth dimension (which is a nice theory, but not supported by actual observations), its center is probably outside our notion of space itself, and maybe even equally distant from every point in the 3-dimensional space we can observe.
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center of the universe

Post #4by Beowulf01 » 06.03.2005, 05:49

is the woman a man loves.

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Post #5by MKruer » 06.03.2005, 05:51

There are two possibilities from what I have heard of / know.

The first says that we are on a bubble. This bubble is expanding, and because its expanding all the galaxies are flying apart from each other. The problem with this example is that if this was the ?€?3d?€

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Post #6by wcomer » 06.03.2005, 17:13

Umeboshi is correct. The center of the universe is omnipotent. Although one could also say that the center of the universe is presently nowhere. It is located in the past and has no meaning today except that most points in the universe are nearly equally distant in time from the center of the universe. All points are equally distant in space (zero spatial distance.)

Using the ballon matephor. If the surface of a balloon represents the spatial dimensions of the universe and the radial dimension is equated with time. Then all points on the balloon's surface have no spatial distance from the center of the balloon, rather their respective seperations from the center is entirely temporal. However, the balloon (and the universe) need not be perfectly spherical, hence some points on the surface may be more temporally distant from the ceneter than are other points on the surface.

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Center vs origin

Post #7by andersa » 06.03.2005, 19:19

wcomer wrote:It is located in the past and has no meaning today except that most points in the universe are nearly equally distant in time from the center of the universe. All points are equally distant in space (zero spatial distance.)

If we consider time to be one of the dimensions used to measure the universe, shouldn't the "center" of this space-time continuum be found somewhere "in the middle" of it, rather than at one of its extreme ends (its origin in the past)? Kind of the same distinction as between a polar-projection map (with the center at the North Pole) and a globe (with the center within, invisible). All points on the surface of the globe aren't equally distant from the North Pole, but all points on the equator (or any single latitude) are.

If the center is the Big Bang, where is your antipode?

(Added) As for the center of the Earth, here is another definition of such an arbitrarily chosen point. It has characteristics similar to those of the North Pole.
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Post #8by Bob Hegwood » 06.03.2005, 22:07

Pardon the intrusion from the Brain-Dead...

But wouldn't the center of the Universe exist at the point where the
Big Bang originated?

If everything in the universe is expanding outward, wouldn't the logical
solution involve running time backwards to see the point in space and time
where all the galaxies and other stuff originated?

Just curious, Bob
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Point of origin

Post #9by andersa » 07.03.2005, 00:49

Bob Hegwood wrote:But wouldn't the center of the Universe exist at the point where the Big Bang originated?
That's assuming the Big Bang originated at a "point" in 3-dimensional space at all, which cosmological theory says it didn't...

Bob Hegwood wrote:If everything in the universe is expanding outward, wouldn't the logical solution involve running time backwards to see the point in space and time where all the galaxies and other stuff originated?

You can do precisely that, but consider where that simulation leads: We'll trace the Milky Way back to the Big Bang, seeing other galaxies converge towards us, finally realizing that the Big Bang originated exactly...
...here!

Problem is, an observer in any other galaxy will draw the very same conclusion with respect to their own location and definition of "here", maybe thinking the Big Bang took place in their galaxy. The objective conclusion however, is that the Big Bang happened everywhere, which was indeed a very small place back then.

Without an external point of reference, such as a coordinate system with a defined origin, it's impossible to tell which galaxies are moving and which ones aren't, but all we can say is that they are all moving in relation to each other. In all likelyhood, no galaxy in the universe is more "centered" than any other, much like the old notion of a flat Earth with humans living at its center and sea water falling off its edges turned out to be false. No place on Earth is more centered than any other.
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Post #10by Rassilon » 07.03.2005, 17:43

Well I think I got my answer! I always thought science considered the center of the universe to be our galaxy so I am relieved to see its not so...

Ive always believed the center of the universe to be the above mentioned infinate dimention without a 3rd dimentionial reference point or 'center' personally....In my opinion also I tend to believe in the osculating universe or possibly in a universe without beginnings or endings....The Big Bang and the Big Collapse into infinity...

I suppose when dealing with the dimention of infinities...Without resolution or preceedings...we tend to have something we cannot fully explain as we are used to having points of reference....As in computer programming there has to be a reference to everything that is computed otherwise there is no structure....But when we go beyond structure...what is there?
I'm trying to teach the cavemen how to play scrabble, its uphill work. The only word they know is Uhh and they dont know how to spell it!

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Post #11by wcomer » 07.03.2005, 18:44

Let me try this a different way.

Sticking with the balloon metaphor. Asking which point of the universe is its center is like asking which point on the surface of a balloon is its center. The answer is no point. Asking from which point on the surface of a balloon did the balloon originally expand is like asking from which point in the universe did the big bang originate. The answer is all points.

Using the Earth metaphor. What is the distance, in degrees of lattitude and longitude, from a point on the equator of the Earth to the center of the core? The answer is zero. And hence, there is no seperation between the surface and the center when measured in units of lattitude and longitude. And so it is with measuring the x-y-z distance between a point in the universe and the big bang. The x-y-z distance is zero.

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Re: Point of origin

Post #12by Bob Hegwood » 07.03.2005, 21:42

andersa wrote:
Bob Hegwood wrote:If everything in the universe is expanding outward, wouldn't the logical solution involve running time backwards to see the point in space and time where all the galaxies and other stuff originated?
You can do precisely that, but consider where that simulation leads: We'll trace the Milky Way back to the Big Bang, seeing other galaxies converge towards us, finally realizing that the Big Bang originated exactly...
...here!

Sorry, but I disagree...

The Big Bang didn't originate here, it originated at the point from which
all galaxies, stars, clouds of dust and gas have expanded away from.
Should be a simple matter to extrapolate the ever-expanding universe's
matter into a reverse mode should it not? I agree that our own galaxy
would have originated from somewhere near the center of the Big Bang,
as did all the other matter in the universe. Perhaps time, space and
matter didn't even exist before the Big Bang, but since they now do
exist, isn't it possible to track the movements of all matter back into
time to see where they all started from?

If I'm out of my depth here, I'm sorry. Just seems that a simple solution
exists to this question. If we know the relative movements of the
galaxies now, can't we run time back to see where they came from?

Thanks, Bob :?:
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Post #13by Buzz » 08.03.2005, 22:38

One should compare only the surface of the balloon with 3D space, and ignore the 3D properties of the balloon. This way you'll see that dots on the balloon (representing galaxies) do not move with respect to the balloon's surface, but that they get further apart because the balloon's surface itself expands. So the main reason for increasing distance is the expandingof space, not the movement through space...

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Post #14by Bob Hegwood » 09.03.2005, 14:38

Buzz wrote:One should compare only the surface of the balloon with 3D space, and ignore the 3D properties of the balloon. This way you'll see that dots on the balloon (representing galaxies) do not move with respect to the balloon's surface, but that they get further apart because the balloon's surface itself expands. So the main reason for increasing distance is the expandingof space, not the movement through space...

Ah, but they do move with respect to the center of the balloon. Still
seems to me that we could calculate where the center of the ballon is
located, based on the current postions of the ballon's walls. No?

Or, is it that we don't have enough information concerning the entirety of
the ballon's walls?

Thanks, Bob
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Re: Point of origin

Post #15by Evil Dr Ganymede » 09.03.2005, 19:42

Bob Hegwood wrote:The Big Bang didn't originate here, it originated at the point from which all galaxies, stars, clouds of dust and gas have expanded away from.


Yes. And if you rewind things back, you'll find that "here" is the same for every point in the universe. Going back in time, everything retracts to a single point - the big bang.

Using the balloon analogy again, the big bang is the infinitely small, uninflated balloon. "Now" is a large inflated balloon, and we're on a point on the surface of that balloon, and spacetime is the balloon's surface. From that perspective, the "centre of the universe" lies at the centre of the balloon, which is "down" from the surface and therefore in a dimension we can't perceive. Furthermore, there is no single point in our present universe (ie on the surface of the balloon) that you can say the big bang happened at, because really it happened EVERYWHERE because we're on the greatly expanded surface of what was once an infinitely small balloon.

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Re: Point of origin

Post #16by t00fri » 09.03.2005, 20:47

Evil Dr Ganymede wrote:
.. and spacetime is the balloon's surface.


Could you please mark the 'time'-coordinate on the balloon's surface ;-) or go back to read once more Walton's carefully phrased balloon analogy.

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Re: Point of origin

Post #17by Evil Dr Ganymede » 09.03.2005, 21:11

t00fri wrote:
Evil Dr Ganymede wrote:
.. and spacetime is the balloon's surface.

Could you please mark the 'time'-coordinate on the balloon's surface ;-) or go back to read once more Walton's carefully phrased balloon analogy.


OK, space then. Whatever. Though I was rather under the impression that space and time couldn't really be separated.

Either way, it doesn't really detract much from the point I was making.

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Post #18by Drake » 15.03.2005, 07:23

Evil Dr. G is right. Everywhere is the center of the universe. (Ask anyone who is truthful and they give you the answer that THEY are the center of the universe, and they are right!)

A common misconception is that the Big Bang was an explosion of energy into space and that you could track all the motion of matter back to an "origin." It was an explosion of space. The balloon analogy is just that - an analogy. The surface of the ballon has to be imagined as three-dimensional somehow. There is no "center" or "down" or hollow part of the balloon since the universe is the surface.

How about this analogy (but still bogus since this implies a boundary)... imagine a solid piece of infinitely stretchable rubber smaller than any dimension. The rubber represents the extent of everything - the universe - all volume. There is nothing outside the rubber. "Outside" the rubber has no meaning. It starts off with no dimensions and unbelivably rapidly expands to a really big volume. The expansion is caused by each point in the rubber making more rubber around it, and so on, forever. Since everything - all space and all energy - started off from the same point, it is all the center. Imagine somehow using dye to mark the "center" of the point as it emerges into measureable dimensions. After expansion, the dye is present everywhere. It all happened right here. And waaaaaay over there too. Just a lot of rubber (space) has been made in between in the meantime. That is how, on average, everything in the universe is moving away from everything else. More rubber is being created all the time. It might even be accelerating... And, oddly enough, this is what it looks like at the "edge" of the universe too. There is no boundary between "universe" and "not-universe." We are located as far away from some other point as is possible given the current size of the universe, so we are on the edge, as are they. But of course we are also at the center, as are they. Now if that doesn't warrant going out and imbibing, I don't know what does!

The "shape of the universe" phrase has to do with something else entirely. It does not refer to what the universe would look like "outside," whatever that would mean. It has to do with density, or alternatively will gravity win, lose, or tie with the expansion of space. Our universe is, as far as we can tell, "flat," which means it will continue expanding forever and that parallel light paths will, on average, stay parallel. See http://map.gsfc.nasa.gov/m_mm/mr_content.html for a fun picture and more info.

Hope this helps.
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Post #19by trenner » 04.04.2005, 02:42

I just read this, and I couldn't resist....

Have you checked this out?
http://www.hia-iha.nrc-cnrc.gc.ca/cu/main_e.html

Regards
Terry


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