Where does space end?!

[vulcan]

If he 'works', he obviously can't!

[Pug]

Lol! Thinking about it though he doesn't do a lot, mostly stands around bending ears of anyone who'll listen about his latest views on what he's read in 'the sun'.....

[vulcan]

Well, The Sun is certainly the centre of our existance, so don't knock it ... unless you know better ;?)

[vulcan]

To answer the original question, space doesn't end. Infinity is simply a concept that we can't get to grips with as all our experiences have boundaries. Infinity is impossible for the human mind to contemplate. Infinite distance, infinite time. You have to stand back to appreciate it!

[Tadakun]

i'd say that "space" ends when you stop trying to further your understanding. out of sight out of mind.

[mikeknowle]

Infinity is impossible for the human mind to contemplate. Infinite distance, infinite time. You have to stand back to appreciate it!

When I was younger I started daydreaming about how big space was. I'm not saying I glimpsed infinity or anything, but I fainted and fell over with the shock of realising how big it was.

[ollypenrice]

'Ends' is itself ambiguous. What does it mean? Where does the surface of a sphere end? It doesn't, but it is not infinite because the sphere can expand, so we say it is 'unbounded' but not infinite. As the mighty Neils Bohr said, we are '...somehow suspended in language.'

Olly

[umadog]

As I understand it, the question is related to whether the universe is open or closed.

Shape of the Universe - Wikipedia, the free encyclopedia

I believe that if it's closed you'll return to your starting position if you travel for a sufficiently long time in the same direction.

Regardless of the shape of the universe, it isn't clear how meaningful it is to ask what is "outside" it, since outside the universe there is no space and no time.

[MrsR]

To answer the original question, space doesn't end. Infinity is simply a concept that we can't get to grips with as all our experiences have boundaries. Infinity is impossible for the human mind to contemplate!

This is my belief.

[keef_uk]

It must end somewhere, because else how can it always be expanding. Begs the question then whats its expanding into?

[thesatanbug]

It doesn't end. It never started either. It was always there and always will be.

I find it easier to just accept it has no boundaries and is timeless. It's an infinite void with a finite amount of matter flying around, that in theory could expand to completely fill that void or can all be crushed down to the size of a decent semi-detached.

And all on a whim. Makes you think don't it? :hello2:

[Pakmoto]

Newer evidence suggests that the expansion of our universe is in an open state, as the speed of expansion isn't constant it's accelerating, in a closed universe the speed of expansion would be slowing or constant,

This theory lays evidence to suggest nothing is restricting the expansion of our universe,

I use the term "our universe" as it's possible they may be a lot more than just one, next time your washing the pots, imagine the bubbles floating on top of the water are all universe's, and one of them is ours.

[x6gas]

We don't really know or understand enough about the nature of the universe yet. It's why continued investment in fundamental research is so important if we do want a greater understanding of the universe.

Just adding a bit more to the analogy of the surface of a sphere:

Firstly imagine that you live in a universe with only two physical dimensions (ignore temporal dimensions of time). Things in your universe have length and width but not height. It would therefore be really, really difficult to imagine height and the concept of up and down would be very abstract... so much so that you'd probably have to have a few pints just to speculate about it. It's not that you have length and width and a very, very, infintesimally small height - you have no height at all. Incidentally, you're not 'tall' at all; nor are you 'short' at all. These things have no meaning in your physical universe.

Now in your 2 dimensional universe you live on a surface. To you, it's flat. It has to be. There is length and width, so you can move forward and back and left and right. But of course you have no concept of moving up or down. You can't. You've explored this surface and it seems to have no end.

Now a superbeing from a 3 dimensional universe comes visiting and she sees that you are actually living on the surface of a sphere. She can see you exploring and understands why the surface to you is boundless. Of course she also knows that you are really moving in 3 dimensions across the surface of a sphere but this doesn't change the fact that, as far as you are concerned, you are only moving in 2 dimensions.

I think it highly likely that a being from a universe with 4 physical dimensions visiting our 3 dimensional universe would be able to make a similar observation and it would be just as plainly obvious to them what our universe is like as it is to the 3 dimensional being viewing the 2 dimensional universe.

Incidenally, if you want to try to envisage a 4 dimesional cube, think on this: It would be a cube whose six faces are also cubes (instead of the squares in a 3-d cube) but the edges of the cubes would be common with its neighbours even though all of the angles are still 90 degrees. Difficult to explain in words, harder to even imagine!

[x6gas]

If your brain is now aching, here's a (2 dimesnional!) representation of a 4 dimensional cube (hypercube). What makes it challenging is that each of the frusta (truncated pyramid) on each face is actually a cube with equal length sides and 90 degree angles.

Fun, isn't it.

[ollypenrice]

It must end somewhere, because else how can it always be expanding. Begs the question then whats its expanding into?

It isn't expanding into anything. All of space is expanding.

You are imposing on cosmological space a set of notions formed from your experience of local space, which is not surprising because that is where our brians and language evolved. Local brains for local problems! So if you think of a ballon expanding you think of it as expanding in a room, say. Eventually it will fill the room. You have to persuade your brain to get rid of the room!

One of our expert members said recently that the expansion of the universe is like monetary inflation. It happens everywhere at the same rate and does not propagate from any one place. Very nice analogy.

Cosmological understanding involves accepting that what applies locally is not the whole story. It also involves accepting that the universe doesn't care a hoot for what we might think is reasonable!

That's the fun of it.

Olly

[thesatanbug]

^^ That box doesn't help me I'm afraid. My universe would swallow that up an infinite number of times. and has no edges or limits. It just goes on for ever. If you kept going in a straight line that's all you'd ever do.

[ollypenrice]

It doesn't end. It never started either. It was always there and always will be.

I find it easier to just accept it has no boundaries and is timeless. It's an infinite void with a finite amount of matter flying around, that in theory could expand to completely fill that void or can all be crushed down to the size of a decent semi-detached.

And all on a whim. Makes you think don't it? :hello2:

There is very good evidence (but not proof) suggesting that it did start about 13.7 billion years ago. You don't like the idea? Neither do I in a sense, but does the universe care?

I think the idea is a lot easier to accept if, as many cosmologists do, you take the view that the 'time' that we recognise is local to the big bang universe, which is not necessarily all that there is.

Time as we know it may just be a dimension embedded in a wider matrix of other dimensions.

Olly

[x6gas]

Now read Olly's post in conjunction with mine...

Our 2 dimensional being's 'universe' is the surface of a sphere. But really it's a spherical balloon that is expanding. Points on the surface of the sphere are getting further away from each other as the balloon (universe) expands. But to explain the expansion (which for our 2-d being just looks like a linear expansion of something getting further away) you need more dimensions than the 2-d being can understand. Bear in mind also, that if the 2-d being has developed maths it will probably have been constructed from its 2-d physical experience, geometry etc...

[thesatanbug]

^ Don't upset or contradict my theories on the universe please. It took me 50 years to arrive at that perfect solution on how it all fits together. I'm too old to start all over again.

[vulcan]

It is impossible to qualify or quantify things that we don't know about. Ignorance is bliss. If some super being were to give us a glimpse of these things, our heads would explode. Even discussing them makes my head itchy - on the inside where I can't scratch!

[x6gas]

Ignorance is bliss.

Absolutely not!

Knowledge is power...

[vulcan]

Absolutely not!

Knowledge is power...

Only up to a point. They also say that 'a little knowledge is dangerous'

[StarryEyes]

Oh wow what have I started?!

Thanks to you all for your thoughts and responses. Very interesting reading even if I don't understand all of it! Seems it's not just me who's head hurts when thinking about this topic.

[vulcan]

Now you can see how religion came about. It is much easier to 'believe' than it is to 'think'.

[Defender]

infinant IMO, the space was there long before the big bang (IMO), the big bang provided the matter/electrons/ect ect, space is nothing, it's what nothing looks like.

Unless we live in bubble universes like some believe.