Centre of the Universe

Robh (Rob) · #1 09-04-2009, 02:36 PM

How often have I read that the universe is expanding and that there is no centre.
Every point is expanding away from every other point.
Sorry, but I just don't get it!

Let's assume the Big Bang was the origin of the Universe.
Everything is "blowing out" from where the Big Bang occurred.
The sum total of matter and energy is expanding in a shell which is itself getting thicker.
A bit like an expanding balloon (however the balloon's skin is actually thinning). An often used analogy but the balloon does have a centre!
The major part of the matter and energy will occur in any direction roughly tangential to the shell (we are somewhere in the shell).
Radially from the expansion point, the amount of matter and energy is only the thickness of the shell.
There should be two directions, outwards and inwards where the amount of matter and energy is minimal.
Looking in any direction tangentially to the shell, matter and energy should be maximum.

So here's my first idea ...
Is the thickness of the shell still within the cosmic event horizon?
If yes, then there should be a radial direction at which matter and energy should end.
This point will be closer than where matter and energy seems to end in any tangential direction at the cosmic event horizon.
If not, then we cannot see this difference.

My second idea ...
Tangentially to the shell in any direction, gravity should be strongest.
You would expect strings of galaxies to line up in directions tangential to the shell i.e. seemingly in a plane.
Does anyone know whether the filaments of galaxies in large structures like the Great Wall and the Sloan Great Wall appear to lie in the same plane?

We may still be able to check whether our Universe has a centre.

If you've ploughed through this, you deserve a medal!
Does our Universe have a centre?
Curious, Rob.

Kal (Andrew) · #2 09-04-2009, 03:19 PM

Quote:

Is the width of the shell still within the cosmic event horizon?

Because of inflation after the big bang the observable universe which we can see is smaller than the actual size of the universe. This is why the universe appears fundamentally flat.

Robh (Rob) · #3 09-04-2009, 04:21 PM

Andrew, I agree with you on this point.
I've created some confusion using the word "width" instead of "thickness".
I've changed the words "wider" to "thicker", "width" to "thickness".
Thanks for the input,
Rob

omnivorr · #4 09-04-2009, 04:37 PM

I think the idea is that in the beginning, everywhere was the same place.... there is still nothing 'outside' it... there's just more 'inside'.

there was no space... now space is growing....

???

sjastro · #5 09-04-2009, 05:54 PM

Rob,

There is no centre, radial or tangential components as the Universe is not expanding into existing space.

Regards

Steven

rogerg (Roger) · #6 09-04-2009, 06:10 PM

I would recommend listenning to this series of podcasts from AstronomyCast:

Where is the centre of the universe:
http://www.astronomycast.com/astrono...-the-universe/

What is the shape of the universe:
http://www.astronomycast.com/astrono...-the-universe/

How big is the universe:
http://www.astronomycast.com/astrono...-the-universe/

... and... a question show:

Questions on the shape, size and centre of the universe:
http://www.astronomycast.com/astrono...-the-universe/

Roger.

NotPrinceHamlet (Graham) · #7 09-04-2009, 06:29 PM

Quote:

Originally Posted by sjastro

Rob,

There is no centre, radial or tangential components as the Universe is not expanding into existing space.

Regards

Steven

I think that that is about right. You need to step out of a euclidean mindset.

The 3K residual microwave radiation from the big bang is almost completely uniform no matter where the radio telescopes are pointed.

Robh (Rob) · #8 09-04-2009, 07:53 PM

rogerg (Roger), I looked at your links.
Found them very interesting.
The first link has a section "Where is the Centre of the Universe ?
It states ...
It is less well known that Lemaître found a more general class of solutions which describe a spherically symmetrical expanding universe. These solutions, now known as Lemaître-Tolman-Bondi (LTB) models describe possible forms for the universe which could have a centre.
... although the standard big bang models describe an expanding universe with no centre, and this is consistent with all observations, there is still a possibility that these models are not accurate on scales larger than we can observe. Our ignorance about the real answer to the question "Where is the centre of the universe?" is complete.
I think things have just got a whole lot more complicated!
Thanks, Rob

Archy (George) · #9 10-04-2009, 06:47 PM

One of the difficulties with the concept that the universe is expanding, is that one has to ask what is it expanding into?
We can avoid that problem by assuming instead that length and time are changing so as to correspond to the redshifts that have been observed. If this postulate (or model or paradigm) is correct, then there is no need for the universe to be expanding into anything and there is no need for it to have a centre.

Robh (Rob) · #10 11-04-2009, 02:48 PM

Archy (George),
You make a good point. There may in fact be other explanations for the red shift of light. Although, the "tired light" hypothesis has been somewhat discredited, I've read recently of a different approach.

String Theory predicts the existence of gravitons (see Wikipedia: Gravitons). Scientific experiments are currently underway in an attempt to detect gravitational waves which "carry" gravitons (analagous to light waves and photons). The experiments cannot detect individual gravitons. However, if gravitons have any mass, then fields of gravitons might cause light to lose energy over large distances i.e cause a red shift.

OneOfOne (Trevor) · #11 12-04-2009, 11:45 AM

I always think of the balloon analogy in terms of a two dimensional representation of 3 dimensional space. The whole of the current universe is represented by just the surface of the balloon itself. Think of the "thickness" of space as being squashed into the balloon surface, so no matter which direction we are looking, we are always looking along the surface of the balloon. Therefore there IS no central point of expansion. Looking "into the balloon" would be like looking back to how the universe was at some previous time, but not in the way we usually think of looking back in time when looking billions of light years away, in this case we are still looking along the surface of the balloon, but just at something a long way away...if you get what I mean.

Robh (Rob) · #12 12-04-2009, 12:51 PM

Trevor, I get what you mean with this model. Your explanation is well put.
But I wonder, does it actually reflect reality?
Consider this proposition.
Suppose the Universe we see is actually a very large bubble or void (Giant Cosmic Bubble), which is part of the larger Universe beyond.
Suppose, the mass density within our bubble is much lower than the average mass density of the Universe at large.
The gravitational effect of this would be to mimic an expansion towards the areas of higher mass outside.
There is of course a centre to this bubble.
http://www.newscientist.com/article/...id.html?page=1

Regards, Rob.

OneOfOne (Trevor) · #13 14-04-2009, 08:09 AM

I must admit, I have often thought that even though our universe may exist in our "space and time" and there may be parallel universes as well in a different "space and time" that we can never see, but, equally, maybe there could be a multitude of other universes that are not part of ours, but given enough time we may actually "see" or come under the influence of. Perhaps the gravity from these universes is causing some effect on ours which we are interpreting as something else? And struggling to find a theoretical solution to because we can't think outside the "sphere"?

bloodhound31 · #14 15-04-2009, 11:53 AM

Who was it that has that wonderful signature?...."In the beginning there was nothing....and then it exploded."

Get your head around that.

I love this type of thinking an expanding universe provokes. It really stretches the mind. If your imagination is expanding, where is the centre of your imagination, and what is it expanding into?

Will imagination continue indefinately, speed up and end in an imagination rip, or slow down and stop, only to collapse and explode again?

xelasnave · #15 15-04-2009, 01:14 PM

This is a most wonderful thread and it is great to read the views.

Firstly as hard as it may be to realise the Big Bang Theory is exactly what it says of itself...a theory...and as close to being an established reality, with a limitless supply of supporting observation, it can only remain an idea presented by a human in an effort to explain "everything"... be it fact well really who knows..other than those of such arrogance that thery believe they actually know everything.

Having determined the Universe was expanding... (and such a proposition is presented as a reality and no alternative offerred such that there can be no reason to exclude expansion as an established fact).... an extrapolation backwards reasonably establishes that the Universe started at a point and expanded from that point..,

firstly I say that such an extrapolation is unreasonable ...why should we jump at the conclusion drawn here... is the human brain not capable of any other reasoning other than to fit any observation into a similar human experience...I hint at our experince that all things growing come from a seed and that creation of something from nothing is indeed most reasonable (Well it is not reasonable but comes from a hang over from the fisrt book of the bible that God created all we see)...

The big bang requires a God to place the seed as there is no reasonable science that can give us everything from nothing...

The big bang requires the theory of inflation to support it in its current form..without inflation we have a major worry as to how to get everything the same...so rather than bite the bulet and wonder how to answer such a question with reason and facts gained from observation Mr Guth put forward "the theory of inflation".. a theory with out scientific support,,no experiment or observation..but it sounds good and as it saves our favorite theory ..the big bang..it was accepted wirth no reasoning as to why it sounds incredibly lame...

The theory lets the Universe grow from a basket ball to over 100, maybe 150 billion light year diameter in some 30 seconds...

if one can accept such one should find the Bible very easy to accept for one must have extrodinary powers of acceptance of unsupported fact...

So could it be that the expansion is simply nonsence??? could it be that the Universe is not expanding, could it be that for what ever reason although we think it is in fact it is not... be it tired light or some part of science that is hidden from us that leads us down this riddiculous reasoning that the Universe is like an animal..born of a seed and grows till it is big..and presumably will then die.

This is Science on human experience seeking a result that soothes human desires to have a purpose.

Why should the Universe be anything other than infinite?.

All the talk of geometry does not get past this little point... if it is expanding it must expand into something... technical manoverings will not let that aspect settle in a spot where it seems reasonable or a provable reality.

The big bang has run away with, and excludes opportunity to consider data other than its usefulness to support the big bang theory...and that is not doing anyone any good at all...

The most exciting thing to come out of the sky is the fact that galaxies line up like buttons on a string..and yet as this has no bearing on support for the big bang we ignore this most amazing piece of info to be presented to us... why is it so...why do the galaxies line up so..the only comment I ever heard was... well one could expect this structure as a result of the big bang.... well sadly this is where though is focused.

Is this discovery not hinting of things we know nothing of??? well lets not even look at it...it is irrelevant to big bang notions...

But other than the big bang why do they lie up this way..what is going on... to answer this question is important but to sideline it as mere support for the "big bang structure" is simply not science.

And for all those folk who say the background radiation proves the big bang I say yes sure it does ...but if one did not have the "theory" to support could we not have alternatives to explain the observation... COULD WE NOT SEE DATA AS AVAILABLE TO SUPPORT OTHER STUFF NOT JUST bb...sorry caPS MISTAKE..NOT SHOUTING..

So my view (and no one needs to know it I well recognise) as to the UNiverse having a center is ...it can not have a center as infinity knows of no center... as to the observable Universe its center is and always will be ones self... yes the word observable makes the Universe a personal thing and as observer you have the privelledge of always being at the center..of everything really.. and that is the way each human will see themselves and indeed the total Universe..they are and will always be at the center....and be right and correct about everything they observe from thier priveleged place.

If you sdupporet the big bang idea that is ok but save it and replace Mr Guth's wild fancy re inflation... I mean how can that idea still fly.. no logic mixed with no science to support a belief....

alex

Robh (Rob) · #16 15-04-2009, 02:56 PM

Xelasnave (alex),
Fascinating read. You've covered a heap ... from God, to the theory of inflation, an infinite universe, galaxies "on a string", the CMBR, no physical centre, a subjective centre. Ideas, don't you just love it!
I was a great fan of the Big Bang until the concept of Dark Energy was mooted to explain the accelerated expansion. Got to be something wrong somewhere.

Rob.

Shnoz (Sophie) · #17 15-04-2009, 04:12 PM

Very interesting thread!

With the centre of the universe; the other day my computing teacher was explaining wormholes to me.
He said that they are theoretically formed because spacetime is curved like a ball, and black holes create infinitely deep pits in the surface of the ball. Each of these pits leads to the centre and can connect to other black holes somewhere else on the surface of the ball. Would the place where the black holes connect be the gravitational centre of the universe?

And if this ball was expanding, every point on the surface of the ball would be moving away from every other point. Could we then replace the 2D surface of the ball with our 3D space?

I think I may have raised more questions than I solved.

Robh (Rob) · #18 15-04-2009, 04:50 PM

Quote:

Originally Posted by Shnoz

With the centre of the universe; the other day my computing teacher was explaining wormholes to me.
He said that they are theoretically formed because spacetime is curved like a ball, and black holes create infinitely deep pits in the surface of the ball. Each of these pits leads to the centre and can connect to other black holes somewhere else on the surface of the ball. Would the place where the black holes connect be the gravitational centre of the universe?

I think I may have raised more questions than I solved.

I think you have opened up a can of worms here!!!
Seriously though, Sophie, I don't know whether we know enough (or I should say I know enough) to promote or discount this idea. It sounds entirely feasible and an attractive idea (that was unintentional)- blackholes connecting via a gravitational centre. Maybe someone else here on IIS can comment on this possibility.
Thanks for the input.

You have got us all thinking here on IIS!

Regards, Rob.

Barrykgerdes · #19 15-04-2009, 04:52 PM

This is a lovely thread and most of the posts are based on the theories put forward by thinkers to explain something that the human mind cannot comprehend. Remember they are only theories.

There is no centre of the universe. The universe is infinite. Infinity is what it says no beginning no end so therefore no centre. Try putting that into the theories. What we call the universe is only what we have so far been able to see. A Big bang may have started our universe. It may not have. If there was one big bang, then in infinity there has been an infinite number of big bangs.

I can say no more. I know what infinity means but my mind cannot comprehend that in a finite environment, can anyone's.

Barry

xelasnave · #20 16-04-2009, 01:05 AM

Infinite is a most interestring proposition.
We can not arrive at infinite by doubling a finite ..so if we electect for a infinite universe it can not be made from a seed that is doubled and doubled etc etc.. such a process will never arrive at infinite ...so if we elect for big bang our universe will always be finite..and if finite there must always be something else out there..think about that it is so simple one can miss the enormous implication of such on our current cosmological philosophy.
Still no one seeks an answer or a speculation in respect to the galaxy line up, observed, and as I present above ..forget looking for a center and ask why do they line up like buttons on a string..for what purpose... is there no one who will engage the opportunity of cosmological speculation, the correct answer to which may well provide most of all we need to know about our universe? Why do galaxies line up like buttons on a string????

alex