What Is Beyond The Observable Universe?

[blandrew]

To the best of our knowledge, the expansion of the universe is isotropic about the Earth's position.


This is not so. The universe could be expanding anisotropically -- faster in one direction than another. Additionally, the universe could have some exotic shape to it -- like a donut or a sphere. The notion that such a universe would need a higher dimensional space within which to exist is false -- the geometry and topology of the universe are intrinsic properties of the (3+1)-dim surface, and do not require an embedding into a higher dimension space to be realized.

I believe there is stronger consensus for a "flat" infinite universe.

 

[bapowell]

I believe there is stronger consensus for a "flat" infinite universe.

Of course, current observations show the local geometry of the universe to be flat to within a few percent. This observation is not inconsistent with a closed universe (spherical geometry), just that such a closed universe would need to be sufficiently large to look locally flat (like the Earth to us humans). Also, a torus is geometrically flat -- it is topologically nontrivial. There is no 'consensus' regarding whether the universe is infinite or finite. Current cosmological observations have nothing to say (yet) about the global properties of the universe.

 

[blandrew]

Of course, current observations show the local geometry of the universe to be flat to within a few percent. This observation is not inconsistent with a closed universe (spherical geometry), just that such a closed universe would need to be sufficiently large to look locally flat (like the Earth to us humans). Also, a torus is geometrically flat -- it is topologically nontrivial. There is no 'consensus' regarding whether the universe is infinite or finite. Current cosmological observations have nothing to say (yet) about the global properties of the universe.

"global properties"? Unfortunate use of language :)

 

[nismaratwork]

I'm afraid I don't follow either. blandrew's comments are more in line with our current understanding of cosmology than anyone else's in this thread.

Not sure if you've noticed, but this thread is otherwise full of people thinking the universe is a sphere - of which we happen to be at the centre and, flying to the "edge", we could lay down traffic cones. Then fly past that and look around to see other Big Bangs off in the distance. This is just a complete lack of understanding of cosmology.

That may be, but the universe has a definite geometry, and we are somewhere within that. We cannot be at its edge and center simultaneously. There are better ways to describe a bounded universe and our observations of old light, than with borderline poetry. That the universe may be embedded in a membrane, or conform to the holographic principle, or a number of other options doesn't support such a fanciful description.

Speculating as to the geometry of our observable region is one thing, but conjecture as to its overall topology is part of the problem with M-Theory; it is probably not falsifiable or provable. That's not science, it's fancy.

 

[blandrew]

Where ever you find yourself in the universe, you are both at its centre and at its edge.

Looking in any direction from any point in the universe is merely an observation into the history of the universe.

Einsteins equations tell us that it would take infinite energy to accelerate mass beyond c, so your kinda stuck with the first two statements.

"What is beyond the observable universe?" ...tomorrow is.

That may be, but the universe has a definite geometry, and we are somewhere within that. We cannot be at its edge and center simultaneously. There are better ways to describe a bounded universe and our observations of old light, than with borderline poetry. That the universe may be embedded in a membrane, or conform to the holographic principle, or a number of other options doesn't support such a fanciful description.

Speculating as to the geometry of our observable region is one thing, but conjecture as to its overall topology is part of the problem with M-Theory; it is probably not falsifiable or provable. That's not science, it's fancy.

Thank you for describing my comments as poetry.

In a homogeneous and isotropic universe it could be said that, where ever you find yourself within it, your at it's centre.

Perhaps there is an assumption here that the universe is infinite and that Einsteins STR holds true.

Being at its edge and finding tomorrow beyond the observable is more cheeky i'll grant. But the universe has 4 dimensions (i'm sure someone will tell us it has more) and we live in its present, observe its past and wait for its future. So in that regard, we're at the edge.

 

[Tenny]

Where ever you find yourself in the universe, you are both at its centre and at its edge.

Looking in any direction from any point in the universe is merely an observation into the history of the universe.

Einsteins equations tell us that it would take infinite energy to accelerate mass beyond c, so your kinda stuck with the first two statements.

"What is beyond the observable universe?" ...tomorrow is.





Thank you for describing my comments as poetry.

In a homogeneous and isotropic universe it could be said that, where ever you find yourself within it, your at it's centre.

Perhaps there is an assumption here that the universe is infinite and that Einsteins STR holds true.

Being at its edge and finding tomorrow beyond the observable is more cheeky i'll grant. But the universe has 4 dimensions (i'm sure someone will tell us it has more) and we live in its present, observe its past and wait for its future. So in that regard, we're at the edge.

Hi. Accepting that it has 4D's, 1 of time and 3 of space, isn't it a dodge to equate the edge with time ? What is it's spatial rather than it's temporal edge?

 

[nismaratwork]

Where ever you find yourself in the universe, you are both at its centre and at its edge.

Looking in any direction from any point in the universe is merely an observation into the history of the universe.

Einsteins equations tell us that it would take infinite energy to accelerate mass beyond c, so your kinda stuck with the first two statements.

"What is beyond the observable universe?" ...tomorrow is.





Thank you for describing my comments as poetry.

In a homogeneous and isotropic universe it could be said that, where ever you find yourself within it, your at it's centre.

Perhaps there is an assumption here that the universe is infinite and that Einsteins STR holds true.

Being at its edge and finding tomorrow beyond the observable is more cheeky i'll grant. But the universe has 4 dimensions (i'm sure someone will tell us it has more) and we live in its present, observe its past and wait for its future. So in that regard, we're at the edge.

I see your point, but doesn't that really imply that the notion of being at a center or edge is meaningless? Maybe that's your point. Consider that the universe, according to Hawking, has (from our point of view), a singularity at a Big Bang, and crunch. I'm not saying that is the case, but for the sake of using his globe model, lets. Our present exists at a definite point along time axis from BB->BC, or infinite expansion, it doesn't matter. We're not at an edge, or a center, but definite coordinates within a system we can't properly define, somewhere in the history, and future of the universe.

If you take away the future portion, then I see your point, in that for us the present is the leading edge of our experience in spacetime. If you consider spacetime as a complete structure with a past and future, we exist at a point in that structure, defined by our "when" which also defines our "where".

Being in a homogeneous and isotropic universe means that we cannot distinguish at large scales where we are in absolute terms, but in the strictest sense the time coordinate should solve that. I don't claim that this means that you could reach an "edge" to the universe and punch through that edge into something else. It might be better to say that no matter where you go in a homogeneous and isotropic universe, in spacetime, you'd eventually return to where and when you left, if you could travel in such a fashion.

I suppose my point is that you're speaking from our point of view, that of something embedded in this universe. It is entirely possible that beyond the observable universe, is nothing, or other universes, or cream cheese if we're being cheeky. As ants on the apple we can only deal with traversing this structure of (at least, as you say) spacetime in a particular way, but in an absolute sense, that doesn't remove the orchard.

Oh hell, you've gotten to me with your cheek and poetry. :p

 

[blandrew]

Hi. Accepting that it has 4D's, 1 of time and 3 of space, isn't it a dodge to equate the edge with time ? What is it's spatial rather than it's temporal edge?

Time could be said to be geometrically fundamental in regard to the universe.

I see your point, but doesn't that really imply that the notion of being at a center or edge is meaningless? Maybe that's your point. Consider that the universe, according to Hawking, has (from our point of view), a singularity at a Big Bang, and crunch. I'm not saying that is the case, but for the sake of using his globe model, lets. Our present exists at a definite point along time axis from BB->BC, or infinite expansion, it doesn't matter. We're not at an edge, or a center, but definite coordinates within a system we can't properly define, somewhere in the history, and future of the universe.

If you take away the future portion, then I see your point, in that for us the present is the leading edge of our experience in spacetime. If you consider spacetime as a complete structure with a past and future, we exist at a point in that structure, defined by our "when" which also defines our "where".

Being in a homogeneous and isotropic universe means that we cannot distinguish at large scales where we are in absolute terms, but in the strictest sense the time coordinate should solve that. I don't claim that this means that you could reach an "edge" to the universe and punch through that edge into something else. It might be better to say that no matter where you go in a homogeneous and isotropic universe, in spacetime, you'd eventually return to where and when you left, if you could travel in such a fashion.

I suppose my point is that you're speaking from our point of view, that of something embedded in this universe. It is entirely possible that beyond the observable universe, is nothing, or other universes, or cream cheese if we're being cheeky. As ants on the apple we can only deal with traversing this structure of (at least, as you say) spacetime in a particular way, but in an absolute sense, that doesn't remove the orchard.

Oh hell, you've gotten to me with your cheek and poetry. :p

Well, the faster than c expansion of the universe would presumably mean one would not return to the point of origin even if there is curvature.

"cream cheese" oh I do hope not, hate the stuff

 

[nismaratwork]

Time could be said to be geometrically fundamental in regard to the universe.

Well, the faster than c expansion of the universe would presumably mean one would not return to the point of origin even if there is curvature.

"cream cheese" oh I do hope not, hate the stuff

The +c issue is why I added the codicil, "if you could travel in such a fashion". The point about the geometry is possibly valid however. For cream cheese, how do you eat bagels? Cheesecake?! Bagels need cream cheese, they cry for it, and you would deny them this sweet offshoot of Neufchatel Cheese? No sir, I reject that premise; it's "[cream cheese] all the way down." :)

 

[Tenny]

Time could be said to be geometrically fundamental in regard to the universe.

I still don't get it. And earlier you posted ;

we live in its present, observe its past and wait for its future. So in that regard, we're at the edge

That would seem to me to be in the middle of the temporal dimension, not at the edge.

But why mix space and time ? Surely the three spatial dimensions I see around me are just that - three spatial dimensions! I don't feel I'm on the edge of the universe, though.

How can be ? I can see in all directions and there is more space. Isn't it shifting the goalpost to say I'm on the edge, but it's the edge in relation to time (which I still feel is a dodge) ?

 

[nismaratwork]

I still don't get it. And earlier you posted ;

we live in its present, observe its past and wait for its future. So in that regard, we're at the edge

That would seem to me to be in the middle of the temporal dimension, not at the edge.

But why mix space and time ? Surely the three spatial dimensions I see around me are just that - three spatial dimensions! I don't feel I'm on the edge of the universe, though.

How can be ? I can see in all directions and there is more space. Isn't it shifting the goalpost to say I'm on the edge, but it's the edge in relation to time (which I still feel is a dodge) ?

You mix space and time because that is a fundamental principle of Relativity. If you existed only in a space-like manner, you could not do anything, never mind looking around. There is a reason it's called "spacetime" and not "space and time".

 

[blandrew]

I still don't get it. And earlier you posted ;

we live in its present, observe its past and wait for its future. So in that regard, we're at the edge

That would seem to me to be in the middle of the temporal dimension, not at the edge.

But why mix space and time ? Surely the three spatial dimensions I see around me are just that - three spatial dimensions! I don't feel I'm on the edge of the universe, though.

How can be ? I can see in all directions and there is more space. Isn't it shifting the goalpost to say I'm on the edge, but it's the edge in relation to time (which I still feel is a dodge) ?

I guess this is the point of the homogeneous isotropic universe. It's only with the fourth dimension, that of time, that one can place oneself within it. In this context, I would equate "present" with "edge".

 

[blandrew]

The +c issue is why I added the codicil, "if you could travel in such a fashion". The point about the geometry is possibly valid however. For cream cheese, how do you eat bagels? Cheesecake?! Bagels need cream cheese, they cry for it, and you would deny them this sweet offshoot of Neufchatel Cheese? No sir, I reject that premise; it's "[cream cheese] all the way down." :)

Sultan-ed, sliced, toasted and buttered ...you can keep your "cream cheese" ... philistine! :)

 

[nismaratwork]

Sultan-ed, sliced, toasted and buttered ...you can keep your "cream cheese" ... philistine! :)

You sir, may be an excellent cosmologist, but when it comes to baked goods you are an unlettered barbarian. Without cream cheese, the lox cannot be properly ensconced in creamy goodness, and the scallions or red onion are too sharp. I believe this was known in the Neolithic period, when cave etchings clearly show our ancestors smoking salmon for bagels. I believe they preferred Philadelphia cream cheese too, but it's hard to translate as there was no Philadelphia at the time.

 

[Tenny]

I guess this is the point of the homogeneous isotropic universe. It's only with the fourth dimension, that of time, that one can place oneself within it. In this context, I would equate "present" with "edge".

I still don't get it. To equate the edge of the universe to time, seems to be just playing with language. To repeat once again, you said “we live in its present, observe its past and wait for its future. So in that regard, we're at the edge”

In what regard ? I am at the edge of the universe right now, according to earlier words here, including yours. But I certainly don’t feel like I’m at the edge of the universe. I can see the three dimensions around me, and I seem to be in the middle of them, not on some edge. And I can remember the past, and anticipate the future (to some degree). I certainly don’t feel like I’m at the edge of the universe in space, or in time, or in spacetime.

 

[Trenton]

It is highly probable our 'observable' universe is actually a black hole of radius 30, 40 or more billion light years (This is only the same as asking if it has enough mass to one day fall in on itself).

Outside this black hole will be yet more space with matter floating around and other black holes of course. (Purely my opionion, I can't prove it of course).

I don't buy this idea that outside the 'universe' is no time or space nor do I buy the multi-dimension idea

 

[DaveC426913]

It is highly probable our 'observable' universe is actually a black hole

Highly probable. Care to back that up with some references?

 

[blandrew]

I still don't get it. To equate the edge of the universe to time, seems to be just playing with language. To repeat once again, you said “we live in its present, observe its past and wait for its future. So in that regard, we're at the edge”

In what regard ? I am at the edge of the universe right now, according to earlier words here, including yours. But I certainly don’t feel like I’m at the edge of the universe. I can see the three dimensions around me, and I seem to be in the middle of them, not on some edge. And I can remember the past, and anticipate the future (to some degree). I certainly don’t feel like I’m at the edge of the universe in space, or in time, or in spacetime.

You kind of answer this yourself.

If I were to use an analogy. Let's say you've been reading a novel of indeterminate length for an indeterminate length of time. Well, you could say you were in the centre of the book and at the edge of the story.

I hardly think that's semantics.

 

[nismaratwork]

You kind of answer this yourself.

If I were to use an analogy. Let's say you've been reading a novel of indeterminate length for an indeterminate length of time. Well, you could say you were in the centre of the book and at the edge of the story.

I hardly think that's semantics.

In fact, knowing what is to come in the novel would still place you at the leading edge of whatever you know. There might be a middle, but you can also appreciate that in retrospect. Only seeing it as a complete structure with boundaries can allow you to overcome the homogeneity and isotropy, and that is definitely NOT how we live.

 

[Trenton]

Dave,

References no but only coz I don't get enough time to browse. The idea though, that we are in a black hole of perhaps 30 billion light years radius, maybe a lot more - is not that difficult to support. Much is made of so called 'missing mass' but when you look at the rudimentry approach to how mass is calculated it leaves a lot of room for inacuracy. Even without exotic theories (which I largely do not support) I suspect there is a lot more intergelactic gas, a lot more WIMPS and probably large numbers of 'failed galaxies' (which did not have enough rotational energy to avoid the entire ediface collapsing to a black hole). I could go on and on ...

 

[Trenton]

Further to the issue of the (observable) universe being a black hole; Should this turn out to be the case it is more likely that the galaxies are falling in rather than flying out. You can forget the 'current bun' model, it just would not apply. Instead the (apparent) expansion would be expalained better by progressive time dilation. Black holes are not wormholes (unless one is both an idiot and a fantasist) - but they are larger on the inside than on the out. You could fall into one and while away what would seem like years observing other infalling objects before hitting the singularity. The distance to the center would thus appear to be very large. This distance amplification would be very small in a large black hole but would be about the cosmological constant for a black hole of 30bn light years.

 

[George Jones]

The idea though, that we are in a black hole of perhaps 30 billion light years radius, maybe a lot more - is not that difficult to support.

Then support this with peer-reviewed mainstream references. Physics Forums Rules,

https://www.physicsforums.com/showthread.php?t=5374

in part, say

Overly Speculative Posts: One of the main goals of PF is to help students learn the current status of physics as practiced by the scientific community; accordingly, Physicsforums.com strives to maintain high standards of academic integrity. There are many open questions in physics, and we welcome discussion on those subjects provided the discussion remains intellectually sound. It is against our Posting Guidelines to discuss, in most of the PF forums or in blogs, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion.

Personal theories are not allowed here.

 

[eha]

Some people still believes there is nothing beyond universe, and they don't even accept empty space or anything else. But they can't answer the question when you ask "How are you going to fill up the rest of the infite volume?" They can't realize the truth of "Black space extend forever". I wonder how many intelligent people are there can't see this fact? Isn't that hard to understand, am I wrong?

 

[DaveC426913]

...am I wrong*

Well, yes.

 

[nismaratwork]

Well, yes.

I believe you meant to say, "really really wrong."

eha: What exactly do you mean, because I find your wording vague, and you don't seem to offer obvious alternatives.

 

[Tenny]

You kind of answer this yourself.

If I were to use an analogy. Let's say you've been reading a novel of indeterminate length for an indeterminate length of time. Well, you could say you were in the centre of the book and at the edge of the story.

I hardly think that's semantics.

Definitely sounds like semantics or more.

How did you deterimine the centre of the book if it's length was INdeterminate ?

Edge of the story ? What does that analogise ?

 

[nismaratwork]

Definitely sounds like semantics or more.

How did you deterimine the centre of the book if it's length was INdeterminate ?

Edge of the story ? What does that analogise ?

I don't think you understand what it means that the universe is homogeneous and isotropic. I recommend a googling of the terms, and what they mean. The book analogy is really quite apt in 3+1 dimensions.

 

[eha]

Okay! What I say is; We are within a space which extends forever in 3D. Our universe occupies a certain volume within this infinite black space. We can't find even a one single atom outside our universe. I don't think there are another universe or universes around or in deep distant space. Our universe itself is a biggest miracle within endless space. The chance for another miracle is so slim, so slim nearly zero. I strongly believe these facts due to my knowledge in astronomy for 50 years and my logic.
I prefer to receive very short and very plain answers.
Thanks, love you all!

 

[Trenton]

George,

Less of the rules of overly speculative posts. The question of if there is sufficient mass to eventually arrest the expansion and lead to a crunch is an old one and all I am doing is re-phrasing it. It is mathematically the same as asking if the observable universe has a swartzchild radius large enough to contain it - ie is a black hole.

The story on this has to date been one of astronomers discovering more and more mass so it is quite probable more will be discovered.

Beyond that it is just a question of applying the relevant relativistic equations - which I either have got right or wrong.

It is not my fault people don't like the consequences of these equations.

 

[nismaratwork]

George,

Less of the rules of overly speculative posts. The question of if there is sufficient mass to eventually arrest the expansion and lead to a crunch is an old one and all I am doing is re-phrasing it. It is mathematically the same as asking if the observable universe has a swartzchild radius large enough to contain it - ie is a black hole.

The story on this has to date been one of astronomers discovering more and more mass so it is quite probable more will be discovered.

Beyond that it is just a question of applying the relevant relativistic equations - which I either have got right or wrong.

It is not my fault people don't like the consequences of these equations.

You agreed to rules when you joined, it's that simple.

 

[DaveC426913]

Okay! What I say is; We are within a space which extends forever in 3D. Our universe occupies a certain volume within this infinite black space. We can't find even a one single atom outside our universe. I don't think there are another universe or universes around or in deep distant space. Our universe itself is a biggest miracle within endless space. The chance for another miracle is so slim, so slim nearly zero. I strongly believe these facts due to my knowledge in astronomy for 50 years and my logic.
I prefer to receive very short and very plain answers.
Thanks, love you all!

eha, we do not entertain personal theories here; this forum is first and foremost a homework help forum and is conscientious about discussing established and accepted theories.

If you wish to submit a paper with your theories, there is a specific section for that with its own rules.

All this you agreed to when you signed up.

There are other fora where you can put up your personal ideas about the universe. This is not one of them.

 

[nismaratwork]

Okay! What I say is; We are within a space which extends forever in 3D. Our universe occupies a certain volume within this infinite black space. We can't find even a one single atom outside our universe. I don't think there are another universe or universes around or in deep distant space. Our universe itself is a biggest miracle within endless space. The chance for another miracle is so slim, so slim nearly zero. I strongly believe these facts due to my knowledge in astronomy for 50 years and my logic.
I prefer to receive very short and very plain answers.
Thanks, love you all!

Your basis is not scientific, but anecdotal. In short, this is your faith, and has no place here unless you can in some way support this with more than your espoused expertise. Words such as "miracle" are fanciful, not meaningful in this context. The argument that the universe is commonplace has been made as well, and nothing you've said refutes that. Care to rise to the challenge?

 

[Ich]

Beyond that it is just a question of applying the relevant relativistic equations - which I either have got right or wrong.

...which you have not done at all. So please provide references or the relevant equations.
Btw., swartzchild is not relevant, you might want to look up the vreedman equations instead.

 

[Tenny]

I don't think you understand what it means that the universe is homogeneous and isotropic. I recommend a googling of the terms, and what they mean.

I have a reasonable idea of what they mean. There was a statement made earlier by blandview (?) that we live at the edge of the universe. I queried this and was given some analogy, which I need to understand .. equally vague, in order to understand the former .. kind of circular, that!

Either that, or I'm just plain stupid and your intellect far surpasses mine - a possibility I'm ready to admit if readily shown. But all I've seen so far is circular argument and semantics - and the subtle changing of the meaning of words to suit.

The book analogy is really quite apt in 3+1 dimensions.

I am at the edge of the universe, (according to others previous posts) right ?

But I don't feel like I'm at the edge of the universe. I can see for miles in each direction - millions.

"Ah, the simpleton" I hear you say"

.. but anyway, you (and blandview more to the point) haven't 'splained it proply so far. And to say that the edge is the 4th dimension, time, kind of shifts the goalpost merely.

The present, is the futures past !

 

[blandrew]

I have a reasonable idea of what they mean. There was a statement made earlier by blandview (?) that we live at the edge of the universe. I queried this and was given some analogy, which I need to understand .. equally vague, in order to understand the former .. kind of circular, that!

Either that, or I'm just plain stupid and your intellect far surpasses mine - a possibility I'm ready to admit if readily shown. But all I've seen so far is circular argument and semantics - and the subtle changing of the meaning of words to suit.



I am at the edge of the universe, (according to others previous posts) right ?

But I don't feel like I'm at the edge of the universe. I can see for miles in each direction - millions.

"Ah, the simpleton" I hear you say"

.. but anyway, you (and blandview more to the point) haven't 'splained it proply so far. And to say that the edge is the 4th dimension, time, kind of shifts the goalpost merely.

The present, is the futures past !

"Blandview" i see what you done there.

Ok, this is what I originally posted:

"Where ever you find yourself in the universe, you are both at its centre and at its edge.

Looking in any direction from any point in the universe is merely an observation into the history of the universe.

Einsteins equations tell us that it would take infinite energy to accelerate mass beyond c, so your kinda stuck with the first two statements.

"What is beyond the observable universe?" ...tomorrow is."

-------------------

I think I've answered to, and explained this to the best of my ability in subsequent posts, so I'll not hijack this thread any longer.

I'm glad that I've aroused debate to some degree. Perhaps the issue here is the counter intuitive nature of the universe and/or the inadequacy of the English language.