Big bang part 1 :)

[Earl]

afaik we can see 13 billion years back / distant.

I have seen thats defines the edge of the universe.

But does that not contradict that the big band happened everywhere at once?

[Doc]

There is no border as far as I know as the big expansion happened everywhere at the same time.

If you are asking is space infinite in the sense that you could travel in a straight line and end up back where you started? Then yes I think it is.

Think of it as ants on a balloon.

[Earl]

If you are asking is space infinite in the sense that you could travel in a straight line and end up back where you started? Then yes I think it is.

Err..

are we talking a 4D Mobius Strip?

I cant get my head around it looping.

[themos]

I have seen thats defines the edge of the universe.

No, it defines the edge of the observable universe.

We see more of it today than yesterday.

[Earl]

So this limit / edge is just the light which has reached us so far from the point 13 billion years ago?

[Doc]

Err..

are we talking a 4D Mobius Strip?

I cant get my head around it looping.

In my mind it makes more sense to be balloon shape then just flat. Many years ago people thought the world was flat and you would fall of the end, now we know it's not, I think the same thing applies to space.

[George]

Hmmm so if I go to the edge of the observable universe and look in that must imply there's a centre point?

[simon84]

If we were to find something that is on the very edge of our observable universe and if it dissapeared from view that would suggest that the universe is expanding faster than the speed of light.

If thats the case then surely expansion means that it started at a point and for the universe to be infinite it has to expand faster than the speed of light.

If that is the case then I dont see how it would be possible to travel in a straight line and return back to the point of origin. To do that you would have to travel in a circle.

To coin a phrase "Space... is big. Really big. You just won't believe how vastly hugely mindboggingly big it is..."

[simon84]

Hmmm so if I go to the edge of the observable universe and look in that must imply there's a centre point?

Yes, Earth is the centre point of our observable universe, as Vega would be if you were viewing from Vega.

[ncjunk]

Wrong edge George,

If you went to the edge of the observable universe instantly and looked around you would be able to see the same "distance" 13 billion light years all around you but looking from a different place.

13 billion is the distance the furthest light, we can see at the moment, has travelled.

Not a physical edge in that sense.

[Doc]

Hmmm so if I go to the edge of the observable universe and look in that must imply there's a centre point?

No because the universe is expanding in every direction so there cannot be a centre.

[George]

If I blow up a balloon (and the universe has been described as a big balloon) there is a centre point........maybe I need some beer

[Earl]

The Center point is just based upon your point of view, from where we look we are central, it is only human to viewout from ourselves.

The Universe has no center it is just Is all over.

[simon84]

If I'm not mistaken isnt almost impossible to say what the universe is beyond the observable boundary?

It could be just a nadgers bigger but due to expansion and the speed if light we'll never know unless all of sudden the universe stops expanding and the the light then catches up.

The one that gets me is the suggestion that the acutal universe is smaller than the observable universe and that distant galaxies are actually nearer galaxes but viewed from a different moment in time.

[ncjunk]

Now what a laugh that would be if we are observing the same galaxies many times..

I have wondered if light could be bent sufficiently to allow the same galaxy to appear in two positions...not just gravitational lensing but bent around in an arc so big that it appears in a whole new part of the sky.

I will come back to this thread in a couple of hours when you have all solved it and read the summary...to hot over here to do any thinking.

[George]

The one that gets me is the suggestion that the acutal universe is smaller than the observable universe and that distant galaxies are actually nearer galaxes but viewed from a different moment in time.

I'm off to the pub......this is too much

[simon84]

George, if you considered the pint glass as the edge of the.................

[themos]

If I blow up a balloon (and the universe has been described as a big balloon) there is a centre point........maybe I need some beer

Good point. But notice that this centre is not part of the balloon surface. So it's not really "the centre of the baloon". What is it then?

The baloon surface is 2-D. To visualise it we put it in a higher-dimensional space, 3-D. What you noticed is the centre of this visualising aid, the "embedding" as it's known.

Can all 2-D surfaces be embedded in 3-D? No! Some surfaces require a 4-D embedding.

[Earl]

If there was / is shrinkage that would be visually observable and redshift would not be correct?

[Earl]

I think the Balloon discription creates more problems as it is to constrained within how we view a balloon.

I view it as two objects moving away from each other with XYZ axis, but then take into acount that they might not actually be moving they are stationary and the space is the moving part, then of course you can then add movement into it as things drift also...

and then your brain implodes and the pub in reality is probably the better option.

I

[Doc]

Read this it explains it alot better then me:

Where is the centre of the universe?

[simon84]

Thats why I dont think a balloon is a great example because a balloon has a definite edge.

Our observable universe has no edge as you stated earlier we see more everyday.

So if something did dissapear from the edge of our observable universe and the universe is indeed expanding faster than the speed of light then it only needs to be viewed in three dimensions.

[simon84]

Read this it explains it alot better then me:

Where is the centre of the universe?

Thanks for that Mick, I take back what I said about the balloon not being a good example. Very good article.

[simon84]

Also as you can probably tell I dont read an awful lot about this subject and my thoughts are purely my honest opinions. Which is why when I play poker with my brothers and our friends who are both happily married and both have phd's I often get shot down in flames.

[Earl]

That article does a nice job are showing what is ment by the balloon example. very nice

Could it be said that as the universe has no center the center is actually a POV from the observer and every Observer if there locations were scatered over the universe would be in there own Center?

Making the Earth the Center of our universe...(HAHA I like the irony there)

Or would it be the Center of our Galaxy due to the Gravitational Bind?