Where does the universe end?

We do not know put simple.
It could be infinite and that our being here is a chance of 1 in an inconcievable number.
It could end at some point, perhaps it's spherical or something but at the current time, our technology isn't nearly powerful enough to comprehend finding out.
 
rghjones said:
I don't understand why people can't grasp nothingness/vacuums.

Surely it should be harder to comprehend that between your face and your monitor there are a billion particles of oxygen that are completely invisible. Nothing is easy in comparison.
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Outside of universe = {}
Inside universe we have some planets, comets and some space = { (.) (.) } :D

Seriously though - the universe could have expanded in a multi-dimensional sense, the expansion actually reached a peak size before pinging back and forwards until an equilibrium was found against the other universes. All this happened in the instant of the 'pop'.
In the mean time the inside of the universe is still catching up this could be seen as a big bang but could merely be time-space expanding ad infinitum within the fixed size of the universe. Hence for an observer here on earth sees an expansion. The reality is that the size of us in relation to the universe could be shrinking constantly.
There could be a big crunch without the shrinking of the universe but when the space-time has expanded enough but can't expand any more starts to become compressed so we effectively disappear eventually by being squeezed into nothingness.. meanwhile the universe continues to go about it's now stable relationship with other universes as if nothing ever happened.. the multi-verse stable once more..

Ok that may or may not be true.. but just imagine how much fun you could have trying to work out the physics in that!

What lies outside the universe. I like the Zen answer:
First there is a mountain,
Then there is no mountain,
Then there is.
First there is a mountain.
Then there is no mountain,
Then there is.
 
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It doesn't end, there just is nothing other then the universe. There is no edge you could ever reach as the universe is expanding faster then anything inside it could ever travel.

There is no empty space over the edge of the universe. There isn't even nothing. If theoretically you could go faster then the universe is expanding then my theory is it would expand around you*.

Or else it's all just an expanding sphere, that was another theory of mine. That the universe is shaped like the shell of a sphere and only occupies the space of the shell. Because the sphere itself is expanding so is the shell.

[size=-2]please note this theory is based on A level knowledge of physics, ie nothing[/size]
 
jak731 said:
this essentially means the 3d spatial universe we see is wrapped around a 4d sphere, if you go far enough you end up where you started.
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However this, a concept of a sphere, all relies on expansion from a point as an assumption that is true.

What may appear as a point based starting point (big bang) may not be when considered in more dimensions.

What is fun is that geometric shapes have been shown to break rules that are true for 2 or 3 dimensions as the number of dimension are increased to 4,5, or more.

I can see the idea of wrapping 3d over a 4d 'sphere' as there may not be a geometry that maintains a single point in higher dimensions. For example you may exist in one point and also in a couple of others at the same time due to the geometry and there is no solution that means you only exist once.
Maybe I'm just blabbering but I don't think it's quite that simple..
 
NickK said:
Seriously though - the universe could have expanded in a multi-dimensional sense, the expansion actually reached a peak size before pinging back and forwards until an equilibrium was found against the other universes. All this happened in the instant of the 'pop'.
In the mean time the inside of the universe is still catching up this could be seen as a big bang but could merely be time-space expanding ad infinitum within the fixed size of the universe. Hence for an observer here on earth sees an expansion. The reality is that the size of us in relation to the universe could be shrinking constantly.
There could be a big crunch without the shrinking of the universe but when the space-time has expanded enough but can't expand any more starts to become compressed so we effectively disappear eventually by being squeezed into nothingness.. meanwhile the universe continues to go about it's now stable relationship with other universes as if nothing ever happened.. the multi-verse stable once more..
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That still doesn't answer what the universe expanded into at the time of the "pop"; you're just temporally shifting the question.
 
Isn't latest theory that the universe is saddle shaped.
Also can we really say the universe has a true ending as its a 3 dimensional object, It really does not just end mearly changes vector?
 
The saddle shape is a representation of hyperbolic geometry (wiki link, second image shows the saddle shape). The problem in cosmology at the moment is that the only large scale force we know of and understand (and not even fully) is mavity, if this was the only force affecting the expansion rate, ie causing it to decelerate things would be much simpler than they are. As the case is their seems to be a large scale repulsive force that works at massive distances and is accelerating the rate of expansion, infact it is now thought to be pushing everything apart faster than mavity is pulling it together. Their is no mechanism physics today can use to explain this phenomenon, it is a complete unknown. It is called dark energy today, mainly because we don't understand it. Their are theories, all of which remain unproved, they range from a possible misunderstanding of mavity, that perhaps it works differently on very large scales, to possibly a fifth force that we don't know about.
 
the universe just exists to put a downer on things by making us all feel so small and insignificant.

on a serious note, im pretty sure we know how fast its expanding, which it is, and don't we have a random idea when it started? so then tat would give you a very, very rough idea of when it ends atm.
 
sid said:
Outside the horizon, space is expanding faster than light speed. The distance to that horizon is 90billion light years (larger than age of universe btw)
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http://www.nasa.gov/audience/foreducators/5-8/features/F_How_Big_is_Our_Universe.html

The image below is both the oldest and youngest picture ever taken. It is the oldest because it has taken the light nearly 14 billion years to reach us. And it is the youngest because it is a snapshot of our newborn universe, long before the first stars and galaxies formed. The bright patterns show clumps of simple matter that will eventually form stars and galaxies. This is as far as we can see into the universe. It is time, not space, which limits our view. Beyond a certain distance, light hasn't had time to reach us yet.
62139main_wmap.jpg
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So are these two different things, or is the 90billion thing just made up? because it says they can't see beyond 14billion light years? or am I hopelessly mixed up?
 
Nitefly said:
Because in the eyes of some, it just isn't logical.

It's not overly unreasonable - I find it difficult to comprehend that something goes on forever and ever, just like existence not having a starting point.
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wooooaaahhhhh - my minds caving in now with that new thought - existence not having a starting point. :eek:
 
Imagine a 5 dimension cube projected onto a 4 dimensional cube. You can't, but mathematically it is trivial - the same procedure as drawing a 3D cube on a 2D plane.

Just because your feeble human minds are not capable, does not make things impossible.
 
Doosht said:
wooooaaahhhhh - my minds caving in now with that new thought - existence not having a starting point. :eek:
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Sarcasm? :p

I find that if you don't ask how everything within our reality came into being, then you have to accept that everything just 'is' and 'has always been'. I'm not sure what's more ridiculous, everything we know has been around forever with no starting point, or that someone put on their wizard robes and created everything in 7 days.

Either way, it isn't worth driving yourself mad trying to understand the unexplainable - that is, why does anything exist at all?
 
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I worked for the international cosmollogy ( or how ever you spell it ) conferance and spoke to some american bigwig on this subject and he told me the universe is looped ie if you were to fly a space ship in a strait line away from earth eventually you will come back to earth again. Or think of an inverted earth...
 
Stovies said:
what is space expanding into?
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Don't forget when you say space you mean spare-time.. so outside out space time bubble there is no space and no time.. there is truely nothing - I think that if you were able to get to the edge it would simply become harder and harder to travel forward as the space-time becomes more sparce, until a point where there was no space time to travel into and you could only ride the wave of the expanding universe..

hmmm, ok this gets me thinking... I thought I had some understanding of this..

arent the physical laws of our universe a unique part of our space-time bubble..? if we are expanding into a void can we collide with another space-time bubble with different laws?

or am I stuck thinking in 3 /4 dimentions?

gees this is a head f@?> I'll go read more I dont understand it at all..
 
I personally believe in the multiverse/string theories. There are endless universes out there probably sort of bubble shaped floating along side each other in a sea in hyperspace. Big bang events occur when these bubble universes collide with one another. All the universes have different laws of physics so a large proportion of them probably wouldn't support life. This could possibly explain why mavity is such a weak force in comparison to electromagnetism, strong/weak nuclear force. Gravitons aren't bound to the bubble's membrane and mavity essentially leaks from the universe next to us into ours.
 
The thing that makes my head hurt, even more than the ale induced hangover I am so delicately nursing as I type is the big bang.
 
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