Astronomers have been saying recently, that the universe is expanding at such a rate that in X billion years, if you were to look at the night sky, you wouldn't see as many stars as you can see now. Therefore, to me it seems that the universe is still expanding. This also seems to me that Astronomers (rightly or wrongly) are putting Earth OR The Milky Way, which is our Galaxy, (I'm not trying to get you to suck eggs, so please bear with me) which Earth is a part of, at the center of the Universe.

Now, it strikes me that if this analogy were true, then whatever point in the sky we were to look at, whether it be north, south, east, west, up, down, whatever, then the stars and galaxies would all be going away from us at a constant rate. Surely, to prove the point that we aren't in the center of the universe, we should be able to measure the relative distances of our local galaxies. i.e. if we were at a constant distance from, say, Andromeda, this would prove that we are travelling through space at a relative speed with all the other galaxies and therefore, NOT at the center of the universe.

The only problem that I can see from this is that we are on an outer spiral arm of the Milky Way and in (lets say) 1 million years we will have spun away from Andromeda due to the axis of the Milky Way and not from the fact that Andromeda is moving away from us because we are at the center of the universe. Therefore, the way I see it, when we arrive back to where we are now (in about 5 billion years, or however long it takes to do an orbit around the Milky Way) we will be able to see what we see now at the present time.

Don't forget, it isn't all that long ago when Astronomers thought that the Earth was at the center of the universe.

Feel free to put me right if you think that my argument is wrong.

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Everything has a begining and everything has and end.

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snowflake

Having read these posts, I love the various insights but I am still confused.
God is motioned often, yet is it possible that some supreme being could have created the universe when for all we know the universe is all there is. Those who believe in God are often given to believe that their God created the universe out of nothing. So this raises the question – what could possibly exist in nothing – the complete absence of everything? Its just as unlikely the universe was created out of nothing – energy, no matter what its source, does not work that way.

To understand more fully this God thing it would do well to understand our past, where history shows it is virtually impossible to find a previous or present civilization without religion, and those many religions of our past and present were extraordinarily diverse in their beliefs and practices. I have often asked myself what they were actually practicing, and I can only conclude that it was the same thing. All these religions its seems were created on a sense of feeling that there is perhaps something extra, some indefinable quality that exists beyond what we term as the physical world, unfortunately, like ourselves, none of our ancestors were able to fully understand it and as a consequence gave it the names and practices their imaginations dreamed up. It is human nature to give names to all we understand and that which we may never fully understand. Theory is the quest to understand the unknown, and we have given the unknown many labels in our quest to understand it.

On a world where even today there are thousands of varied religions, some very ancient; it seems improbable that if such a powerful and incredible god did create the universe and wished those he created in his own image to know he created it, that there would be such diversity in all around us.

Personally, I have a tendency to believe that what the universe represents is far far greater than those explanations given in dusty tomes. Creation is far to complex to be explained away on one page. Creation, like the birth of our universe – for me, remains an unknown mystery.

It has even been motioned that our galaxy might be near the center of the known universe, because with the exception of the local cluster of galaxies, all else in the universe seems to be moving away from us. This is not likely, because we know our solar system has been moving along with the rest of the matter in space for at least four and a half billion years, and the chances are the Milky Way Galaxy has been doing it for much longer.

So this brings us back to square one. If the universe is the result of some ancient explosion, then why is it so difficult to find its center? All other explosions in the universe have left incredible evidence of the event, so why is it that no matter where we look in space, the universe appears to be uniform? Perhaps the answer to this question can be found in inner space; in the very atoms of which we are comprised, because in many respects looking into inner space is almost like seeing a smaller picture of outer space. Atoms are like tiny solar systems where electrons revolve around a nucleus, and like fractals, this design expands outward to give us solar systems, galaxies and the universe – which chances are – if viewed from the outside would probably look just like a huge galaxy.

There is only one place on this planet, where in inner space we can find something which is expanding and uniform in all directions and that is in living, growing matter. So perhaps the next time some of us feel a need to seek God, perhaps all we have to do is to is to look out into the universe – who knows, it can’t possible be any more fantastic than those incredible magical claims made by those many religions invented by our kind. In a way we are looking from the inside out.

According to BB theory there is no "center" (see http://www.astro.ucla.edu/~wright/nocenter.html, http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html - astrophysics, expandining universe -, and http://arcturus.mit.edu/ask/universe.html#q2). One could also say just as validly that everywhere is the center since all points are equivalent and non-unique.

Dave Mitsky

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De gustibus non est disputandum.
Never attribute to malice that which can be adequately explained by stupidity.

HI I am not sure you can use the balloon, because in theore the center should be in the center of the ball.The first thought is no one knows where the universe end so any supposition is only a guess.I believe if you start making guesses you create your own problem with no true answer,because no one knows.

So, do we have to find the center to find our location in the infinity or are we on a tangent between infinities or are we here to ask the questions to enable the continuation of the infinities? Any one?

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The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...'
Isaac Asimov

Everything that exists in 3 dimensional space has a center, this is the nature of 3 dimensional space.

The balloon analogy is brilliant if we think only in terms of viewing our universe from outside – seeing only the outside - otherwise we have to think in terms of balloons; billions of balloons, a solid ball of balloons – each one inside another, until we reach the center – all expanding outward from that center. Otherwise we end up with billions of individual and very random points of expansion.

We know nowadays that gravity can affect light and redirect it. So do galaxies, effectively being islands of concentrated gravity in space somehow affect the properties of light over vast distances? Is the red shift nothing more than the tugging effect of gravity on light as it leaves a galaxy?

Looking out billions of light years across space only gives us clues as to what was happening billions of years ago. We would have to move billions of years into the future to know what is actually happening now. So making assumptions about what is happening now is nothing more than taking what we discover of the past and accelerating it to match an acceptable theory. Problem being; is that the universe or what we discover about it, is throwing new surprises at us constantly, surprises that constantly make us rethink what we already know. Lets hope the Vast Unknown keeps doing so – we all need mysteries of some kind.

Corkft; thanks for the email but I can’t help thinking – if we already had all the answers as you suggest – what are we doing on this forum?
Answers can only be given from already discovered knowledge; otherwise we are still seeking the answers :unsure. Our kind has done this since our brains first started functioning beyond our basic instincts. It’s taken us millions of years to discover what we now know.
Technological man is still relatively new and we have much to learn and much to discover.

A nice little read about the Big Bang - (borrowed from Scientific American)
Thought it might interest some of you.

Scientific American astronomy editor George Musser explains.
This question really has two parts. First, how was matter able to get out of the big-bang singularity? After all, physicists describe a black hole singularity as a pit into which material flows but from which it cannot escape. Let us leave aside the fact that singularities are an idealization. The basic point is that the universe was born with a tendency to expand, which overcame the tendency of matter to collapse. According to relativity theory, space does not like to remain static; for all but the most special cases, it either expands or contracts. But why it initially chose the former is still a mystery.
In some ways, you can think of the universe as a black hole turned inside-out. A black hole is a singularity into which material flows. The universe is a singularity out of which material has flowed. A black hole is surrounded by an event horizon, a surface inside which we cannot see. The universe is surrounded by a cosmological horizon, a surface outside of which we cannot see. (A crucial difference, though, is that the event horizon is fixed whereas the cosmological horizon varies from observer to observer.)
The second part of the question is: Why didn’t matter in the early universe collapse into black holes? After all, physicists say that if you squeeze matter to a high enough density, it will collapse into a black hole, and the density of matter in the early universe was extremely high. The answer is that black-hole formation actually depends on the variation in density from one place to another--and there was very little variation back then. Matter was spread out almost perfectly smoothly.
In fact, cosmologists usually turn the question around. The fact that the universe did not recollapse into a swarm of black holes is evidence that sharp density variations did not exist (or were extremely rare). This lack of sharp variations, in turn, is evidence for the inflationary model that most cosmologists today accept.
Robert J. Nemiroff, assistant professor of physics at Michigan Technological University, responds.
First of all, it is not really known whether or not the universe started from a singularity. Our measurements can take us back only so far; ideas about the nature of the cosmos at the start of the big bang are mostly unproved conjecture.
Second of all, the concept of a black hole is only one type of solution to Einstein's General Theory of Relativity, our best current theory of gravity. This reading of general relativity--known as the Schwarzschild solution--is thought to give an accurate description of the gravity near an isolated, nonrotating black hole, as well as the 'normal' gravity near the earth and throughout our solar system.
But other solutions to general relativity are known to exist, including ones that apply to a whole universe. These alternative solutions typically assume that the early universe was perfectly uniform so that there were no places for black holes to form, even if the density were so great that particles were "cheek by jowl." The most popular class of general relativity solutions applying to the entire cosmos are known as Friedmann-Robertson-Walker solutions. These formulations appear to describe correctly our expanding universe; that is, they demonstrate how objects not held together by local forces (such as the electromagnetism that bonds atoms in molecules or the gravity that keeps the earth intact) stream away from one another in a predictable manner.
Still, there is room in the theories for some of the matter in the universe to be hidden in black holes that might have formed from local, unusually dense regions in the very early universe. These black holes could conceivably contribute to the large amount of dark matter that exists in the universe. Astronomers are therefore diligently searching for these objects. In one scenario discussed by Jeremiah Ostriker of Princeton University and his collaborators, black holes as massive as one million times the mass of our sun might be common throughout the universe and still be nearly invisible. Although other black holes might come out of some big bang models involving quantum mechanics, a common expectation by cosmologists is that only elementary particles survived these early epochs of our universe.

Christ Ftaclas is an associate professor of physics, also at Michigan Tech. He adds the following:
The space-time singularity associated with the big bang differs in two important ways from the singularity associated with a black hole. First of all, a black hole has an "outside." That is, we assume that at large distances from the black hole space-time is essentially flat and defines a background against which we observe the black hole. This is not true in the case of the big bang, because we are all participants.
The second difference is critical to this question: one of the initial conditions of the big bang is expansion of the matter, whereas a Schwarzschild black hole is associated with a static gravitational field. One might think motion would not make a difference, because no velocity is great enough to escape from a black hole, but that is only true for a particle whose motion is measured relative to the stationary black hole. In the case of the big bang, everything is moving, with the result that the solution to the gravitational-field equations is fundamentally altered.
Edward L. ("Ned") Wright is the vice chair for astronomy at the University of California at Los Angeles; he also maintains a thorough on-line Cosmology Tutorial. Wright offers a somewhat different approach to this question:
A black hole is a local region from which light cannot escape. It has a boundary called the event horizon. Inside the event horizon, light cannot escape to infinity, whereas outside the event horizon, light can escape to infinity if it is traveling in the right direction. Even outside the event horizon, however, light that travels straight in toward the black hole will not escape.
In contrast, the universe is thought to be homogeneous and isotropic. Isotropic means that all directions appear the same; this property of the universe is well established by observations that show the effective temperature of the cosmic microwave background is identical in all directions to one part in 100,000. Homogeneous means that any place in the universe is equivalent to any other place. We can observe the universe from only one position, of course, but it does appear to be homogeneous on very large scales, after smoothing over the stars, galaxies, clusters of galaxies and superclusters.
A homogeneous space cannot have a boundary, so there can be no event horizon. And the future behavior of light rays cannot depend on their directions in an isotropic space. Thus, a homogeneous and isotropic universe is not a black hole. The universe does have one similarity to a black hole: light cannot escape from it. But this is true for any place in the universe and for light traveling in any direction, unlike the case for a black hole.
If this proof by contradiction seems unsatisfying, the advanced reader could look at the technical solution to the question. Solving the field equations will show that the space metric in a Friedmann-Robertson-Walker universe expands from infinite density without forming a black hole.

Fascinating stuff.

Consider:

The universe is four-(at least)-dimensionally bound together, what we call space-time.

When we look out in space, we look back in time - towards the Big Bang. The farthest observed galaxies are the closest to the Big Bang in space-time.

Hubble's Deep Field examinations imply that galaxies at 10+ billion years are in all directions.

The Big Bang "centre" therefore appears to be an outside sphere all around us. An analogy of us being on the inside of an inside-out black hole is perhaps appropriate, with the sought after "centre" being the outside "event horizon".

Also..

If our universe came into existence at the Big Bang, then that is when matter and space-time all began.

The Big Bang explosion, as said elsewhere in this thread, was in explosion OF space, not IN space. And the centre is back along the time axis of space-time.

Further, the actual question of what there was before the Big Bang, is nonsensical, totally meaningless. Time itself started at the Big Bang. The question only comes up because we humans have such a strong sense that time is an eternal constant. We feel we move inexorably forward at a constant rate. It may well be infinite in the future, but it is not infinite in the past. And along the way, Einstein showed that it was a variable in its progression.

What there was before the Big Bang, and any God or gods as creator are subjects that are inherently unknowable. Outside the natural world - supernatural if you will. They are perfect subjects for discussion under the heading of Philosophy, where enlightenment may well be found. Here, in this forum, Ockhams razor should be wielded deftly.

When we look out in space, we look back in time - towards the Big Bang. The farthest observed galaxies are the closest to the Big Bang in space-time.
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Can’t say I agree with this Les, because when it is possible to point telescopes in ANY direction in space, only to find it is all essentially uniform – the same – surely we would first have to define the universes center (be it full of matter or still throwing matter out) before we can state which parts of the universe are most distant from that point and therefore nearest to its beginnings. That space appears to be expanding in all directions from our viewpoint only suggests that it is doing exactly the same from all and any given observable viewpoint in the universe - this is exceedingly strange for something that is still expanding from the moment it went POP. Puzzling?

Good point Hadrian.

While I realise that you initiated this interesting thread, maybe it doesn't make sense to even ask the question about the centre of the universe? :huh:

In A Brief History of Time, Hawkins talks about the "no boundary condition" of an expanding universe. If that is true, then can there be a centre? Dave Minsky referenced this a few posts back. The universe is homogeneous.

It seems to come down to us grappling with dimensions. Our brains evolved for a 3D world with time along for the ride. We think of the Big Bang as an explosion out into space. Therefore, it must have a centre. Before Einstein and Dirac (et al), we believed that the universe was a place just this simple. After they extended our language and understanding of mathematics, we know the universe is a much stranger place than most of us can get our heads around. I know I have trouble imagining 4D space - can't draw the damn thing on a graph - yet I can work with multi-(>4)-dimensional databases in executive information system applications.

I also referenced space-time, rather than just space.

Looking back to 10+ billion year old galaxies, we see them as they were back then, and at that point they must be closer to the Big Bang in space-time. Where they are in space, right now, at this instant in reality, we have no way of knowing, but, er, they should be even further away. My brain is starting to hurt.

I think I will go study Dave Minsky's links...

To get a feel for where the "center" of the universe is, it is useful to resort to analogy. Although our perceived space is three dimensional, we can visualize a two-dimensional analog of that space -- the surface of a sphere. We must imagine our entire universe as lying on the surface of that sphere, with us at a single point on that surface. When we look out into space, it is analogous to looking along the surface of that sphere.

Our universe reached its present size by expanding from a single point. In the surface-of-the-sphere analogy, the RADIUS of the sphere was smaller and smaller the further we look back in time, eventually reaching the point where the sphere suddenly appeared as a single point at the instant of the Big Bang.

So the only point that makes any sense as being the "center" of the universe is the point at the center of the sphere. IT IS NOT A POINT IN OUR UNIVERSE. There is no point at which you can point and say, "That is the center of the universe."

Our space is three-dimensional, but it still has a curvature similar to that of an ordinary sphere.

But that curvature is in a direction in which we cannot point just as a creature on the surface of the analogous two-dimensional sphere could not point toward the center of the sphere. The only directions that he could sense would be those along the surface of the sphere. Similarly, the only directions that we can sense are those in which we can point -- up, down, left, right, ahead, and behind.

We cannot point in any direction in space and say the center of the universe is in THAT direction.

The radius of our universe is so large that we have not yet been able to detect the curvature of its surface. We do now know how far we would need to travel in any given direction to find ourselves back at our starting point. However, that does not mean that the radius of the universe is infinite but only that we can see such a small sample of the surface that we cannot yet detect its curvature. The universe is vastly larger than the tiny portion of it that we can see with our telescopes. It's like trying to determine the circumference of the earth by measuring the curvature of the ground in your back yard.

DCL,

You say that our telecsopes can anly see a tiny fraction of the Universe, then why are astronomers talking about high-redshift objects (quasars) that we can see and were formed only 200.000 years after the Big Bang?
By the way I, agree that we can only see our local part of the Universe, but that's because I think the Universe is "infinite".

There was no stable matter as such 200,000 years after the Big Bang. The period of star and galaxy formation began some 300 million years after that point. See http://www.pbs.org/deepspace/timeline/ for further information.

Dave Mitsky

__________________
Chance favors the prepared mind.
De gustibus non est disputandum.
Never attribute to malice that which can be adequately explained by stupidity.

Ok Dave,

Sorry, but at redshift z = 6.4 the current recordholder quasar (I think even higher redshifts will be found) has formed only 650 million years after the Big Bang. That still means we can almost see the "edge" of the Universe. And it means the time for objects to evolve is getting shoter and shorter.