The limits of the universe

[Drosera]

almost moderate level question :cup:

 

Hubs and I were debating what (if any) physical limits there would be to the universe. My main points were that when the big bang first happened, it must certainly have had an expanding radial limit to itself. But wherever we look through a telescope, all we see is visions to the past, ultimately leading back to the big bang.

 

I'm curious about what (if any) ideas about the physical limits of the universe might be now? In essence, what is furthest away from the big bag "center"?

 

I'm of two minds on this. Either there is some as yet unseen actual boundary to the universe. Either that, or perhaps we (and all matter/energy, from its own perpectives) lie at that boundary, and always will.

 

Thanks for any input. :)

[Jay-qu]

Since the expansion is of the space itself and not just the matter within it, each point in space has equal claim to calling themselves at the 'center' of the universes. So there is no point from which to measure to an edge, if we could even find an edge that is..

[Zythryn]

Since the expansion is of the space itself and not just the matter within it, each point in space has equal claim to calling themselves at the 'center' of the universes.

 

I can't wait to tell my wife that I really AM the center of the universe:eek_big: ;)

[Little Bang]

The universe can have only two possibilities, steady state or not. If it is steady state then the universe is infinite and therefore has no boundries. If it is not then that implies a beginning, be it the big bang or some other mode of creation. Space time and matter are inextricably locked together, you can't have one without the other two. The word boundry is were one thing ends and something else begins. In the case of an expanding universe there can be no boundries because space, time and matter make up the universe and nothing exists outside the universe. Opinion # 1244560

[EWright]

The universe can have only two possibilities, steady state or not. If it is steady state then the universe is infinite and therefore has no boundries. If it is not then that implies a beginning, be it the big bang or some other mode of creation. Space time and matter are inextricably locked together, you can't have one without the other two. The word boundry is were one thing ends and something else begins. In the case of an expanding universe there can be no boundries because space, time and matter make up the universe and nothing exists outside the universe. Opinion # 1244560

 

Respectfully, Little Bang, I would argue that while u can not have matter without spacetime, you can have spacetime without matter. There was no matter in the universe at the time of the big bang, in any leading theory. Also, if the accelerated inflation of the universe continues as it is, there will one day be no matter again, as all atoms and subcomponents will be stretched infinitely thin.

 

Also, do not dismiss the idea of a bounded universe. We can only account for the observable universe: that which we can see. While I agree, that there can not be anything outside of the universe (by definition of its name), I am not opposed to the idea of a bounded universe. I had a theory on this many years ago, that I have set aside and do not adhere to, but that I do still find interesting. Perhaps I'll share that here sometime. But for now, I still have to get to submitting part two of my Theory of Temporal Relativity. Click my signature below to read it.

[BrainForce]

:wave:I also think Jay qu is right as expansion is for space itself.

[InfiniteNow]

Either that, or perhaps we (and all matter/energy, from its own perpectives) lie at that boundary, and always will.

I fall into this camp if I'm interpreting correctly. Much like my username and my search understand the concept of now, I like how your words subtley resonate a similar point... All there is, is boundary, and that's where/when everything "is."

 

 

 

Respectfully, Turtle,...

Turtle hasn't posted here. You quoted Little Bang. :phones:

[lindagarrette]

, I still have to get to submitting part two of my Theory of Temporal Relativity. Click my signature below to read it.

 

I enjoyed reading about your Theory. The main inconsistency I noticed is something you yourself pointed out and that is: time is a measurement, not an object. Time is how we measure the sequence of events -- how long they last or the sequence between them. Either they go faster or slower, or stay the same, relative to something else. But time itself does not travel so it cannot have a speed. Linda

[sebbysteiny]

Also, do not dismiss the idea of a bounded universe.

 

I'm not sure what this means but a number of people have mentioned it.

 

So if my answer is the same as those above, then we have at worst a bit of repetition.

 

I personally don't understand the trouble. It's true that the centre of the Universe expansion could be considered to be at all points in the Universe (as it is all moving away from everything else), but even so, there would be a diameter that is agreed for all observers.

 

Instead I think the answer is that there is no physical limit, or rather there is one, depending on how you view it.

 

Spacetime is curved. If you go in a straight line for long enough, you end up where you start from.

 

In 3d, it's like being on the Earth. Is there a physical boundary on the Earth's surface beyond which you can't go? Well you could say, since you can't leave the Earth's surface, then the Earth's surface is the boundary. Or you could say that since you can keep on going for ever, there is no boundary.

 

Either way, you can't get out of the Earth.

 

The universe is the same but in 4 dimensions. So you can go on for ever but can never leave. A bit like that scene at the beginning of Matrix 2.

[Jay-qu]

You have no way of proving that the universe is hyper-spherical.. but I will ask anyway, what is it that brought you to this conclusion?

[TheFaithfulStone]

WRONG At the edge of the universe is a very large dog. I predict his name is Maximillian. Next issue! With one being as unlikey as anyone understanding this reference, and ten being absolute metaphysical certitude, what is the likelihood of this thread descending into a flame war.

 

Jay-jiggity-jaw-cue-ball. GO!

 

TFS

[i do have a point, see if you can find it.]

[sebbysteiny]

It may not be hyper spherical. That's almost certainly an approximation. It could be hyper eliptical or hyper any shape. But space time is expanding and we can't escape spacetime we'll just keep on going round the universe.

 

It's general relativity.

[Jay-qu]

I was unaware general relativity predicted finite but unbounded universes..

 

It is possible to have hypershaped universes that dont curl back on themselves, what makes you think that it does?

[sebbysteiny]

True. I'm not aware that general relativity PREDICTS it, in that were it not to be true, general relativity would not work.

 

However, many models of curviture do result in such a finite but unbounded Universe. I have also seen that prediction in a number of sources I felt were reliable but I can't remember them :cocktail:.

 

Anyway, that's my piece.