What Is Beyond The Observable Universe?

[Silverbackman]

Is it just black space extending forever? Or perhaps black space for a finite distance until another universe?

I find it hard to believe our universe is just the only universe. I don't see how it wouldn't extend for eternity instead. What is so special about our universe and the space we are in?

What do you think?

[Chronos]

By logical necessity, there is literally 'nothing' beyond the observable universe. It is impossible to apply falsifiable predictions to something that is inherently unobservable.

[Silverbackman]

By logical necessity, there is literally 'nothing' beyond the observable universe. It is impossible to apply falsifiable predictions to something that is inherently unobservable.

In other words it is more in the realms of philosophy right now. But don't you think in the future we may be able to see beyond what is now considered the observable universe and find other universes? What do you think?

It just doesn't make any sense how this universe could be the only one. I always thought of the universe/multiverse/omniverse as infinite.

If there is 'nothing' outside the observable universe it would be just black space for eternity, right? Unless the universe is round (which all current evidence points to it being flat) then you can't arrive back in the universe in the other side. Plus most likelly space, like "time" is infinite.

[mathman]

According to the inflation model, the universe is much bigger than the observable universe. On the other hand, the total universe is is still finite, but there is no such thing as outside. The simplest analogy is what is outside the surface of a sphere (ingnoring the third dimension).

[Silverbackman]

But most evidence points to the universe being flat. In that case a what would happen if you reach the end of the universe? If it were a spherical universe then we would just reach the other side. But what would happen if you reach the end of the universe? Would their be like a giant hard barrier that you can hit but not explode? Sounds to mythical to me. The universe seems to complex for it to be just finite.

The universe isn't infinitely big and infinitely small?

[Chronos]

The 'edge' of our observable universe is receeding faster than the speed of light: which means you can't get there from here.

[Silverbackman]

The 'edge' of our observable universe is receeding faster than the speed of light: which means you can't get there from here.

Well yea of course we can't really see it. However is that proof there is nothing beyond there? What proof is there that 'nothing' exists at the edge of the observable universe? We just can't see it from our place in the cosmos. Perhaps if we were on another planet across the universe we may be able to observe more into what we cannot currently see, right?

[kant]

By logical necessity, there is literally 'nothing' beyond the observable universe. It is impossible to apply falsifiable predictions to something that is inherently unobservable.

What do you mean by "logical necessity"?

I think there is something that cannot be explain 'outside' space-time of own universe, but that is a different assertion of "nothing"?

[Chronos]

Let's focus on the definition of a 'universe'. It necessarily includes all things possible to observe. This allows the possibility we have not yet observed all things possible to observe. In that sense, anything that is truly external to our observable universe is literally 'nothing'. It is, and will forever be undefinable.

[Silverbackman]

Our guess the space and time in our universe is finite. However it is just hard to believe there was no time before the big bang and no content beyond our observable universe. It doesn't make sense how things can by finite. I mean what happened before the big bang and why are there boundaries at the ends of our universe?

By studying the universe and the physical world one can truly see things aren't orderly per se. They far beyond the realms of organized imagination and can only be understood with observation and empiricism. Limits on the universe would truly make things beyond confusing.

BTW, what do scientists think happened before the big bang. Since the universe is expanding according to most of the evidence today, the cyclical big crunch is unlikely. What do scientists think are the likely choices?

[kant]

Let's focus on the definition of a 'universe'. It necessarily includes all things possible to observe. This allows the possibility we have not yet observed all things possible to observe. In that sense, anything that is truly external to our observable universe is literally 'nothing'. It is, and will forever be undefinable.

You define 'everything' to be the observable universe( U ), and anything that is not U is nothing. Am i talking to a robot, or am i talking to a human being?

[Chronos]

Just dealing with the logical inconsistencies. 'U' includes the set of events possible to observe in this universe. 'Not U' includes the set of events impossible to observe. 'Not U', hence, is not causal in the chain of events that occur in this universe. 'Not U', therefore, is irrelevant [i.e., does not exist].

[kant]

Just dealing with the logical inconsistencies. 'U' includes the set of events possible to observe in this universe. 'Not U' includes the set of events impossible to observe. 'Not U' has no effect on the causal chain of events that occur in this universe. 'Not U' is therefore meaningless [i.e., does not exist].

So if an 'event' occur outside of our spacetime; its effect is incapabe of reaching us. In your opinion, it does not exist?

Why should existence need an observer?

[selfAdjoint]

So if an 'event' occur outside of our spacetime; its effect is incapabe of reaching us. In your opinion, it does not exist?

Why should existence need an observer?

Listen to yourself! Do events we can never know about exist or not? How the hell can you or I or anyone ever know? It's just a fantasy!

[kant]

Listen to yourself! Do events we can never know about exist or not? How the hell can you or I or anyone ever know? It's just a fantasy!


What is your point? Your last three sentence seems to be in agreement with me.

[SpaceTiger]

But most evidence points to the universe being flat. In that case a what would happen if you reach the end of the universe? The generic flat universe (with a trivial topology) is actually infinite in extent. Other topologies allow for a finite universe, in which one could (in theory) loop around it, given enough time.

[SpaceTiger]

...why are there boundaries at the ends of our universe?

The only boundaries are those set by the finite age of the universe (also known as "horizons"). For example, the "particle horizon" is the distance of the largest object whose light could have reached us since the beginning of time.


what do scientists think happened before the big bang. Since the universe is expanding according to most of the evidence today, the cyclical big crunch is unlikely. What do scientists think are the likely choices?

In the standard cosmological model, there is no "before" the Big Bang. Realistically, though, we can't say much of anything about the universe pre-inflation, so the best answer is that we don't know.

[heliocentricprose]

I believe that more stars, black holes, and galaxies lie beyond the observable universe. These unseen do not effect us because of the cosmic expansion. However, (I think this has been said before) I like to think of the observable as a line of sight. You can't see it over the horizon, yet you know China exists. Outside that 'sphere' of the universe, I believe, out of pure guesswork and fantasy (of course), that the other dimensions of the universe, come into play... this is the point where I start confusing myself and start watching Spongebob Square Pants. :) Good day.

[hejs]

If we travel infinitely far into the microcosmos then we will meet the astronaut who travel infinitely far out to the macrocosmos. Sound good at least :)

[Tojen]

Isn't space created by matter? If that's the case, there should be nothing past the boundaries of the Universe, at least nothing we can perceive or relate to in any way.

[kmarinas86]

Isn't space created by matter? If that's the case, there should be nothing past the boundaries of the Universe, at least nothing we can perceive or relate to in any way.

No, the majority of physicists think it is created by "dark energy", but its not really the creation of space, it's the expansion of it.

[kant]

So, i guess the robot is giving me the silent treatment.

[Tojen]

No, the majority of physicists think it is created by "dark energy", but its not really the creation of space, it's the expansion of it.

kmarinas86,

What I meant to say was that you can't have space without matter, and vice versa. At least that's my uneducated take on it. I didn't know dark energy was considered to be the cause of space, or its expansion. I learned something already. Thanks. :smile:

[matt.o]

dark energy is not the cause of space, nor is it the cause of the expansion of space. Dark energy is thought to cause the acceleration of the expansion of space.

[roland]

Beyond the observable universe is the unobserved universe that we have yet to see. It simply goes on forever. If it is not infinite, where does it end? Think about it. It cannot possibly end.

[Chronos]

Beyond the observable universe is irrelevant. It has no consequences in our observable universe. This is a philosophical, not scientific issue.

[roland]

Hi Chronos. Yes you are right. However I do feel that this is a very negative answer to the original question.

[Chronos]

Agreed. But, I am sticking by my guns: non-observables are irrelevant.

[Silverbackman]

Chronos you do have a point. However just because this question overlaps a bit with philosophy it doesn't mean it is totally not science. We have no observable evidence that aliens exist, but nearly all scientists know even without observation that there has to be other life in the galaxy (or at least the universe).

So what would happen if you were to go theoretically in a space ship beyond the observable universe? If space is more than empty space and you do keep going in black space, then I assume there definitely is something beyond this observable universe. I assume there maybe other universes perhaps billions of "light years" away.

I mean what else can explain the ends of the universe? It wouldn't make much sense to bump into a barrier would it? We see the ends of the universe as just black space, correct? There is no proof it is nothing more than just black space.

[Silverbackman]

The only boundaries are those set by the finite age of the universe (also known as "horizons"). For example, the "particle horizon" is the distance of the largest object whose light could have reached us since the beginning of time.




In the standard cosmological model, there is no "before" the Big Bang. Realistically, though, we can't say much of anything about the universe pre-inflation, so the best answer is that we don't know.

When we say "beginning of time" we really mean when this current manifest of particles arose, correct? We refer to time as light years traveling back to the big bang but I assume time in its broadest sense has existed for infinite and while the universe(s) may manifest have a finite time span (but in reality an infinite lifespan because of the perhaps cyclical constant flux). This also gets into philosophy as well.

[SpaceTiger]

When we say "beginning of time" we really mean when this current manifest of particles arose, correct?

We technically mean the time when the density of our cosmological model diverges (the initial singularity). On a linear timescale, this would appear coincident with the creation of matter, but we usually describe the evolution of the universe on a logarithmic scale.



We refer to time as light years traveling back to the big bang but I assume time in its broadest sense has existed for infinite and while the universe(s) may manifest have a finite time span (but in reality an infinite lifespan because of the perhaps cyclical constant flux). This also gets into philosophy as well.

In the standard model, there is a finite age to the universe if one uses the standard definition of time (a ticking clock, for example) for an observer with no velocity in comoving coordinates.

[kant]

Agreed. But, I am sticking by my guns: non-observables are irrelevant.


An apple falls from a tree, and there is no one to hear or observed the occurence. That does not negate the occurence of that event(apple falling) . I think you need to use your brain more, and stop pretending to be a robot.

[heliocentricprose]

An apple falls from a tree, and there is no one to hear or observed the occurence. That does not negate the occurence of that event(apple falling) . I think you need to use your brain more, and stop pretending to be a robot.

I agree. Cosmology is the study of the universe as a whole. Since the expansion of the universe is greater than the speed of light(the speed of information in the universe), we will gradually be able to observe less and less of the universe. I don't think that means we should abandon the unobservables and work only in our 'tiny' seemingly uniform patch of space. Who knows? Maybe someday there will be a way to 'see' past the horizon.

[Burnsys]

I think this link is usefull to the thread.. it talks about inflation

http://abyss.uoregon.edu/~js/21st_century_science/lectures/lec28.html

http://abyss.uoregon.edu/~js/images/inflation.gif

Only the part of the universe that is inside the observable universe is "OUR universe".
Becouse space expanded faster that ligth we won't be able to "observe" anything beyon the age of the univers in light years (15 billons)

Anything else, exist or not, is irrelevant, becouse we will never be able to observe it.

In other universes with diferent rules, constants, dimensions etc (if they exists) the action of observe may doen't even make any sense.


http://abyss.uoregon.edu/~js/images/anthropic_bubbles.gif

[Burnsys]

I agree. Cosmology is the study of the universe as a whole. Since the expansion of the universe is greater than the speed of light(the speed of information in the universe), we will gradually be able to observe less and less of the universe. I don't think that means we should abandon the unobservables and work only in our 'tiny' seemingly uniform patch of space. Who knows? Maybe someday there will be a way to 'see' past the horizon.

How do you "Study" something you can't interact with????

[Silverbackman]

How do you "Study" something you can't interact with????

We may not be able to observe it at the moment but we need to make the assumption something is there. We have never seen life outside our planet but we assume it exists and create ways to seek out and prove it. A similar thing should be done in cosmology. We should be making insturments that can help us study the beyond.

I think this link is usefull to the thread.. it talks about inflation

http://abyss.uoregon.edu/~js/21st_century_science/lectures/lec28.html

http://abyss.uoregon.edu/~js/images/inflation.gif

Only the part of the universe that is inside the observable universe is "OUR universe".
Becouse space expanded faster that ligth we won't be able to "observe" anything beyon the age of the univers in light years (15 billons)

Anything else, exist or not, is irrelevant, becouse we will never be able to observe it.

In other universes with diferent rules, constants, dimensions etc (if they exists) the action of observe may doen't even make any sense.


http://abyss.uoregon.edu/~js/images/anthropic_bubbles.gif

Yes it maybe irrevelent and these other universes may contian different laws of Nature. However like alien life, I do think we will be able to learn about it in the future. We shouldn't give up. No one has ever seen a quark (correct me if I'm wrong) but we assume the microverse goes further.

If we had a space ship that can do this, what do you think it will run into at the ends of the universe? Will the space ship keep going or is it constricted to this universe only? What do you think?

[Burnsys]

An apple falls from a tree, and there is no one to hear or observed the occurence. That does not negate the occurence of that event(apple falling) . I think you need to use your brain more, and stop pretending to be a robot.

An apple falls from a tree and there is no one to hear or observe...
You have absolutly no way of knowing what "Reality" is... You will never know if the apple felt, or not, or if it exploded or get rotten...
With the same criteria i can say that beyond the observable horizon dragons fly and spit fire..

[SpaceTiger]

Let's keep in mind here that the part of the universe outside our "observable universe" is not completely disconnected from us. We're causally connected to it prior to inflation, so we have some inkling that it exists. There are, however, events that may never be observable. If the universe continues accelerating indefinitely, then a supernova outside of our horizon will never be observable from earth (or what remains of it). We could, however, potentially observe a much younger version of the part of the universe where the supernova occurred. Without being able to see into the future, however, we can't say for sure whether or not the supernova itself will someday be observable.

[Burnsys]

We may not be able to observe it at the moment but we need to make the assumption something is there. We have never seen life outside our planet but we assume it exists and create ways to seek out and prove it. A similar thing should be done in cosmology. We should be making insturments that can help us study the beyond.
But you can't make an instrument to see beyond the observable universe, unless you can travel faster than the speed of light.



Yes it maybe irrevelent and these other universes may contian different laws of Nature. However like alien life, I do think we will be able to learn about it in the future. We shouldn't give up. No one has ever seen a quark (correct me if I'm wrong) but we assume the microverse goes further.

If i am not wrong, yes, we can see quarks in particle accelerators. But anyway if we can't "see" them directly we can see their trace becouse they interact with matter or energy we can observe...



If we had a space ship that can do this, what do you think it will run into at the ends of the universe? Will the space ship keep going or is it constricted to this universe only? What do you think?


i don't think there is a "Wall" at the end of the universe, i don't think it has a boundary. We live in a finite and unbounded universe. i guess if you start traveling lets say at. 0.99c for 15 billion years even if there is a boundary you will never be able to reach it. becouse the universe is expanding faster than c.

[kant]

An apple falls from a tree and there is no one to hear or observe...
You have absolutly no way of knowing what "Reality" is... You will never know if the apple felt, or not, or if it exploded or get rotten...
With the same criteria i can say that beyond the observable horizon dragons fly and spit fire..

i will play along with you, burnsys ( anyone can reply to me)

ok, we will use your analogy. Beyond the obversable universe, there is simply no way to confirm the existence of the dragon fly with a simple yes, or no answer. In otherword, the dragon fly ` s existence is uncertain. It is an unverifiable statment.The statement of the existence of the dragon fly is one that cannot be derived/answered/perdicted by the known axioms/"laws of nature". This doesn` t imply the non-existence of the dragon fly.

[Silverbackman]

But you can't make an instrument to see beyond the observable universe, unless you can travel faster than the speed of light.





If i am not wrong, yes, we can see quarks in particle accelerators. But anyway if we can't "see" them directly we can see their trace becouse they interact with matter or energy we can observe...




i don't think there is a "Wall" at the end of the universe, i don't think it has a boundary. We live in a finite and unbounded universe. i guess if you start traveling lets say at. 0.99c for 15 billion years even if there is a boundary you will never be able to reach it. becouse the universe is expanding faster than c.

Who knows, one day we may be able to make a tool that can travel more than the speed of light. Nothing is impossible. I'm sure if we were to go back in time back to when the Greeks tried to understand the universe, they probably would be quite blown away by the things we can do now and the information we have received from it. Back then it was thought that the Earth was one of the only worlds and that every other "light spheres" revolved around it. Similarly today we think that this universe maybe the only universe but I don't think we could ever know everything for sure. Science and learning is infinite and perhaps the goal of life in the end.

If the universe is unbounded I don't see how it can not be apart of a greater multiverse, don't you think? Ok perhaps our own universe is finite in terms of the extent of matter and particles, but apart of an absolute "omniverse" that may extend forever like the microverse perhaps.

So let us say you could theoretically travel beyond the speed of light, you do agree there wouldn't be a "barrier wall". Or universe will continue to expand forever and who knows, billions of years down the line it may expand into a different universe. What do you think?

[heliocentricprose]

An example of the relevance of the unobservable part of our universe is the total mass of universe. I think this and other characteristics of the universe need to be taken into account when studying cosmology. The fact remains, as already said, the observable universe IS affected by the unobservable universe. Gravity waves that have not yet reached us (because of the horizon), will affect us if inflation's acceleration ceases in the future.

Also, I have a question. The rate of expansion is accelerating, which implies that it is never constant. Is it plausible that it can slow down?

[kant]

Who knows, one day we may be able to make a tool that can travel more than the speed of light. Nothing is impossible.

In a irrational universe, everything is possible, there would be not laws of nature, and no science at all. The otherwise option is that universe is rational, and certains things is impossible.




I'm sure if we were to go back in time back to when the Greeks tried to understand the universe, they probably would be quite blown away by the things we can do now and the information we have received from it. Back then it was thought that the Earth was one of the only worlds and that every other "light spheres" revolved around it. Similarly today we think that this universe maybe the only universe but I don't think we could ever know everything for sure. Science and learning is infinite and perhaps the goal of life in the end.

Don t play drama with me. Science is very limited, because mainly sceinctist define the universe as being U. U = space+time+ energy. Physics as a science is limited by empirical observation, and to go beyond observation or U is not allowed.



If the universe is unbounded I don't see how it can not be apart of a greater multiverse, don't you think?

mutiverse is not physics.

Ok perhaps our own universe is finite in terms of the extent of matter and particles, but apart of an absolute "omniverse" that may extend forever like the microverse perhaps.

You ask your god. this cannot be answered by physic

[Chronos]

Nonsense. Your 'God' of logic appears to have feet of clay.

[kant]

^ what are you talking about now?

[Silverbackman]

In a irrational universe, everything is possible, there would be not laws of nature, and no science at all. The otherwise option is that universe is rational, and certains things is impossible.



You know there are ways around the speed of light like strings or wormholes. Science's is goal is to find the laws of nature yes. But finding ways to go around the laws of nature can be achieved. Gravity is a fundamental force that seems like we cannot overcome. However in the future anti-gravity maybe very possible. Seems like you’re dogmatic about science.

Don t play drama with me. Science is very limited, because mainly sceinctist define the universe as being U. U = space+time+ energy. Physics as a science is limited by empirical observation, and to go beyond observation or U is not allowed.


Don't know how what I said was "drama". But if you do know anything about science there are many concepts in the past that weren't observable at first but later became observable. Dark matter seems invisible, so should we give up looking for dark matter just because we don't have tools right now? Science changes from time to time and soon we will find a way to do this I'm sure.

mutiverse is not physics.

Yes "mutiverse" is not physics. Multiverse will become physics in time perhaps like black holes and perhaps even dark matter. M-theory, which is a theory in development definitely shows that their maybe other universes.


You ask your god. this cannot be answered by physic

In time it can be known. Who knows when but with negative attitudes toward it like your own will definitely delay things.

[kant]

You know there are ways around the speed of light like strings or wormholes. Science's is goal is to find the laws of nature yes. But finding ways to go around the laws of nature can be achieved. Gravity is a fundamental force that seems like we cannot overcome. However in the future anti-gravity maybe very possible. Seems like you’re dogmatic about science.

You cannot go around the "laws", because they form the foundation for the perdictive system in physics. The "laws" are determined empirical, generalized, and must be accepted on faith( based on those generalization). If you want an analogy, if the statement "1+1 is not to 2 " is false, math would not exist, because all other mathematics that based on it would no longer be ture.


Don't know how what I said was "drama". But if you do know anything about science there are many concepts in the past that weren't observable at first but later became observable. Dark matter seems invisible, so should we give up looking for dark matter just because we don't have tools right now? Science changes from time to time and soon we will find a way to do this I'm sure.

You miss my point: science is limited.

If science is based on the axoimatic/"laws of nature" generalization of
nature, all there is that comes with the word "science" is open to doubt, as the foundation( fundamental generalization: physical law) that supports it.

Yes "mutiverse" is not physics. Multiverse will become physics in time perhaps like black holes and perhaps even dark matter. M-theory, which is a theory in development definitely shows that their maybe other universes.

Physic is not math. Physics is limitated by its empirical, observational nature. If we can t observe/verify an assertions for things that has no effect on us, it can t be established. strings, m- thory, multiverse ...etc might have nice sounding names, but they are not rooted in empirical observation.


In time it can be known. Who knows when but with negative attitudes toward it like your own will definitely delay things.

my point: What is 'outside' the universe is not something that could be verified. It is not possible to answer such questions.

There are inherent limitations to reasoning itself in science.

[Rake]

forgive me if I am mistaken, however does the principle of entanglement not imply that there is some kind of unobservable physical system that connects particles and if so does this not also imply that causality is not the final say on what we can ultimately glean from "reality" (whatever that means)? I understand that presently this argument is more of a phylosophical rather than scientific one...

[ianthow]

What if:

1) We cannot comprehend what is beyond this universe and someONE or someTHING prevent us from seeing beyond this universe? The science and technology that we all believe in says that it is impossible to see and go beyond this universe (e.g: the universe is infinite, there is no beginning and end, etc), why are all this "rules" in place at the begining? Can we comprehend what we don't understand?

2) If we can see beyond this universe, will it do more harm than good?

3) We are all creatures on Discovery Channel and are being study or observe by someONE or THING? How do we know that we are living in a world created not by random but with a purpose? And what is that purpose?

Science is truly limited in explaining the world beyond this universe, science is based on reasoning, logic, emphirical, observation. IF you do a search on "what is beyond this universe" on Google, you will find that most answers say "more universe" or "there is no beyond as the universe is infinite" or "nothing".

To really answer the question of what's beyond this universe, we have to think beyond science but then what if we are by default unable to think beyond as the someONE or someTHING who created us prevent us from thinking beyond? The answer might lie beyond the logic, reasoning and science that we are all familiar with.

[jon_pan]

to my understanding from research:
(people who know what they're talking about, please correct me if im wrong)


Current Big Bang cosmology defines universe as "everything that exists anywhere" "Finite and Spherical."


the big-bang and the extent of our observable universe is finite and spherical, but not necesarrily everything that exists. Our universe as far as we can observe, is one of an infinite amount of finite sphere's of matter, in an infinte space where time is eternal and continuous.

so to answer your question, i would say probably the same sh.it you see around here. (around here in a cosmological sense of course)

[Tojen]

ianthow,

There's a distinct odour of New Age-ism in your post. New Age "ideas" denigrate, at the same time, science ("we have to think beyond science") and religion ("the someONE or someTHING who created us prevent us from thinking beyond") to pave the way for its own agenda ("The answer might lie beyond the logic, reasoning and science...").

[patrik75]

Could it be that it is not a relevant question to ask? I am thinking of entanglement and distance as an "illusion". Right or wrong?

[Soul Surfer]

We may not be able to see directly or measure the properties of anything outside our observable universe but we can predict potential properies based on the fact that is probably made of the same "stuff" that our observable universe is made of. Bearing in mind of course that conditions may well exist where the current physical constants we observe may be tweaked a bit.

Or actual universe may well extend a long way beyond our observable universe but there is strong evidence that it had some sort of beginning, is evolving and changing with time and will eventually have an end.

This suggests that our universe is likely to be a finite object in a "multiverse" of indefinite extent.

We also have strong evidence that there are seperate "universes" budding from our universe in the form of black holes. This tends to strengthen this feeling that multiple universes exist.

This makes me favour an overall fractal structure for the multiverse in which the laws of physics have evolved to produce maximum numbers of structures of maximum longevity following the general rules of "evolutionary metaphysics".

You can find a bit more about this on my website but the basic thinking behind "evolutionary metaphysics" is to look at the processes that would operate in any system with physical laws, to create complexity by exploiting metastable and recycling processes to extend the life of what would otherwise be only transient and random intereactions.

[SpaceTiger]

We also have strong evidence that there are seperate "universes" budding from our universe in the form of black holes. This tends to strengthen this feeling that multiple universes exist.

What evidence is that? Last I heard, that was only speculation.

[Soul Surfer]

The evidence is purely in the properties of the object. Any activities inside an independant universe can by definition never be observable from our universe. All that can be done is theoretical modelling which is not subject to such barriers.

A black hole is a construct into which mass may pass and we will not be able to observe it altough it does have still an effect in the form of a gravitational field in our universe.

It is true that once our universe has cooled down sufficiently (a long time from now) the black hole will start to evaporate very slowly and will eventually vanish but the time that even a stellar mass black hole will take to do this is very many orders of magnitude longer than the current age of our universe.

Anything inside the hole will not be able to see out and will be largely unaware of the size of the space because the gravitiational field will tend to distort things so it looks very much larger. OK there may be a certain amount of high energy inflow from outside in the form of things that look like cosmic rays. but their source will not be detectable.

If that isnt a specification for an independant universe I don't know what is!

OK I will concede that it may well be possible to measure that the space is finite and see a retreating set of echoes of one's self at greater and greater distances like looking into a set of parallel mirrors but since when has that been a bar to declaring a universe. I am aware of at least three occasions in cosmology over the last hundred years or so when there was serious consideration that we might be able to do something like this in our universe (one of them is around now)!

[SpaceTiger]

The evidence is purely in the properties of the object. Any activities inside an independant universe can by definition never be observable from our universe. All that can be done is theoretical modelling which is not subject to such barriers.

Anything for which there is no observational test falls into the realm of philosophy and using words like "evidence" here is deceptive.

Perhaps pervect can give more detail, but to the best of my knowledge, the standard model of the universe and the standard model of a black hole are not compatible with one another unless one invokes a wormhole connection, which is in itself a matter of pure speculation.


A black hole is a construct into which mass may pass and we will not be able to observe it altough it does have still an effect in the form of a gravitational field in our universe.

The standard definition of a black hole gives it only three properties: charge, mass, and spin. The only property we think we've been able to measure so far (for some black holes) is mass. These measurements don't tell us anything about whether or not the black hole has spawned a new universe.



It is true that once our universe has cooled down sufficiently (a long time from now) it will start to evaporate very slowly and will eventually vanish

Based on what? An extrapolation of \Lambda CDM? There's no reason to think that the current model of the universe will be good for all time.



If that isnt a specification for an independant universe I don't know what is!

You've granted black holes and our universe several rather arbitrary properties in the process of getting there.

Is it possible that the formation of a black hole spawns a new universe? Sure! Is there any evidence for it? No. At this point, it's pure speculation -- it doesn't come naturally from standard theory and it hasn't made any predictions that have been confirmed by experiment.

[Soul Surfer]

How then do YOU define the properites of an independant universe?

Of course this is pure speculation the original question posed here was one that could only be answered with pure speculation because it dealt only with unobservables.

Mathematical modelling is a perfectly acceptable approach to coping with unobservables our current cosmological understanding is strongly dependant on using the matematival modelling of galaxy strucures and clustering to "prove" that our theories about the composition of the universe fit what we observe

[Soul Surfer]

Note I tend to use the term our universe to mean everything that we can observe and strongly infer (like areas hidden by inflation) and the multiverse to mean everything there is.

I personally favour a multiverse that obeys the perfect cosmological principle it that on a large enough scale it is generally similar for all time and space and has evolved to be so. it contains very many evolving universes (like our own) at all stages of development and is probably fractally structured.

I would strongly prefer to end up with an aspect of scale invariance in which the space and time were a property of the universe and the inside of a budding univese was of indefinite size to those who were inside it.

[SpaceTiger]

How then do YOU define the properites of an independant universe?

I'm not bickering with your definition of "independent universe", I'm bickering with what seemed to be a claim that there is observational evidence for them. If you acknowledge it as speculation then I have no quarrel.

[Silverbackman]

How could a black hole "spawn" another universe? I would think it would lead to another universe perhaps? And who is to say black holes in other universes are like our own. Yes it is speculation at the moment.

[Arian]

You guys, here are a few points
1. Space is not Infinite.
2.There is a high, high high probabiltiy of life
THe point is, if we can't see it, somebody else probaby can.
The universe is also looped, this means that if you go infinitly in one direction you will come back to one place again and again.BUt this can never happen because the universe expands way faster then the speed of light, but you can't go faster then the speed of light.
Its like the Earth exapnding really fast to a point that you can't actually ever go around it.

[matt.o]

You guys, here are a few points
1. Space is not Infinite.


How do you know? Which measurements prove this?

2.There is a high, high high probabiltiy of life


Obviously, we are here. But what is the probability of life in other solar systems? Have you worked this out?

The universe is also looped, this means that if you go infinitly in one direction you will come back to one place again and again.BUt this can never happen because the universe expands way faster then the speed of light, but you can't go faster then the speed of light.
Its like the Earth exapnding really fast to a point that you can't actually ever go around it.

Again, how do you know the universe is "looped"?

You have stated things as fact that are far from fact.

[kmarinas86]

You guys, here are a few points
1. Space is not Infinite.
2.There is a high, high high probabiltiy of life
THe point is, if we can't see it, somebody else probaby can.
The universe is also looped, this means that if you go infinitly in one direction you will come back to one place again and again.BUt this can never happen because the universe expands way faster then the speed of light, but you can't go faster then the speed of light.
Its like the Earth exapnding really fast to a point that you can't actually ever go around it.

When you think like you finally know the truth, your research suffers.

[Garth]

Hi Arian and welcome to these Forums!

You may think your post has been replied to rather brusquely. If you had put your points of view as a series of questions then you would have received some thoughtful and helpful answers. They may have led to an interesting discusssion, however there are others here who do know the subject in depth and rash or false assertions are countered quickly.

Keep asking questions and you will learn. :smile:

Garth

[Silverbackman]

Regarding the shape of the universe, most evidence shows that it is flat (at least the curvature).

[CosmologyHobbyist]

Is there any chance that the big bang was a quantum event? If so, wouldn't that require quantum field to pre-exist the universe? If that is the case, doesn't quantum field provide possibility for pre-BB space and time? Is quantum-event BB still a valid theory, or is it gone for some reason?

[Garth]

Is there any chance that the big bang was a quantum event? If so, wouldn't that require quantum field to pre-exist the universe? If that is the case, doesn't quantum field provide possibility for pre-BB space and time? Is quantum-event BB still a valid theory, or is it gone for some reason?Yes! :smile:

[But we have to wait for a tested quantum gravity theory to be sure.]

Garth

[Flatland]

String Theory actually claims to explain what happened before the BB.

[Chronos]

String Theory actually claims to explain what happened before the BB.Re-review what matt.o had to say. I think you are hopelessly deluded. String theory predicts . . . not a damn thing. Feel free to to contradict that assertion with . . . a testable prediction. I love those things.

[wolram]

I think some one has just put a paper in about the (bouncing) universe,so
if he is correct there never was a begining, and it may be possible to see
beyond the BB, the paper may be in arxives by now.

[Balence]

Its impossible to know exactly. We can speculate their are more stars and galaxies out there, and other things we would expect to find in the known universe. Its possible that if you went so far into the universe that you may find a place that is a duplicate, seeing as odds make no difference when looking at infinity.

[callistoite]

I have a simple answer.

We dont know "yet"

[Tapeworm69]

Okay. There is obviously no answer to this question... YET!
I think philosophically we have to assume both that there is both, something "beyond" our universe and that there also is nothing. You must assume both, seeing as you know neither to be true or false. Get it?

[Sorry!]

Ok I have been trying to bend my mind around the whole there is nothing outside our universe (as in we can not know ever) But on the first page I read an analogy of a Sphere whats outside a sphere.. can anyone explain this to me?>

[squidsoft]

Suppose we lived in sum world:

\sum_{n=1}^{\infty} \frac{1}{n^s}

and we asked, "what is outside of sum world?". We know if we go far enough, sum world reaches a singularity (it diverges). But is there anything beyond that singularity? Is there something larger that encompasses sum world and reduces down to it when certain conditions are met? Of course the answer is yes: zeta world. How is zeta world different than sum world? We certainly can't use the same "methods" (convergent sums) of sum world to describe zeta world. The two worlds are qualitatively different but zeta world contains sum world and can completely describe sum world using zeta methods (a contour integral). How did we get to zeta methods? How can we get to those methods which can describe our Universe as well as the larger world for which ours is only a particular instantiation?

[callistoite]

Well.. c'mon guys. lets take it easy..
Forget about we being the tiny little human beings on this small planet that we call "earth".
Suppose we are BIG in size. about 10s of billions of times Bigger than the observable universe, that we even have to use microscopic equipments to actually see a galaxy floating in the empty space, it will take billions of light years for an earthling to travel from your toe to head. an earthling will be much much smaller than an "atom" - if we call it that way - on your body.

In that size, if you look around, what can you see?
Okay, just for a change, shall we not talk about philosophy and add a little bit of creative, sci-fiction like thought?

[DaveC426913]

If, instead of being here in the Milky Way, we are actually 11 billion light years away in a different galaxy, we're still going to see a universe that is homogenous in every direction. We're not going to look one way and see a giant black void. If we did, it would be because the universe is not homogenous at large scales, that there is and edge and there is a centre.

So, what's beyond our observable universe is more, similar universe.

We can't ever see it, but we can deduce it.

[_____A-L-E-X_____]

I wonder how the recent "discovery" of dark flow plays into all this-- what if whats just beyond the visible universe can gravitationally affect that which is just within?

[ray b]

there be dragons

at least thats what the old maps said
about the areas as yet unexplored

[Hal King]

That's the wonderful thing about cosmology -- fantastic possibilities and predictions -- most of which can never be proved wrong!

Just for the fun of it, I calculated -- using the current model I'm playing with -- how much the observable universe makes of the total amount that 'must' exist NOW due to the Cosmological Principle.

Answer was: 39.349307% meaning the other 60.650693% we can't see -- but by the Cosmological Principle should be more of the same. By this model it turns out that this percentage doesn't change -- but the universe just keeps getting bigger.

In order to get a limit I had to ASSUME that the photons did NOT travel backward in time on their way to us -- regrettable.

There were several other assumptions -- like ONLY considering matter as 'something to see' and a value for the expansion velocity for matter (0.8660254 of the speed of light). Nothing important.

Now I'm sure everyone feels much better knowing this.

[Chronos]

An interesting proposition, and unsupported. Do you have any papers in mind? Your calculations appear to be a naive solution to the Friedmann equation.

[keepitmoving]

more of the same.

[Onslaught]

I know that this is a physics forum but just because physics can't explain the proposed question in totality doesn't mean you can't have some insight into a possible solution.

I doubt that the questioner wanted an exact answer. You should let your imagination explore these ideas sometime. Who knows what someone with your knowledge in physics might come up with. I bet you could come up with better answers than were given in this thread.

Just because you don't have an answer doesn't mean you shouldn't try to answer.

[Cryptonic]

I know that this is a physics forum but just because physics can't explain the proposed question in totality doesn't mean you can't have some insight into a possible solution.

I doubt that the questioner wanted an exact answer. You should let your imagination explore these ideas sometime. Who knows what someone with your knowledge in physics might come up with. I bet you could come up with better answers than were given in this thread.

Just because you don't have an answer doesn't mean you shouldn't try to answer.

Nah they don't like that here, I have learned. Just another bastion of closed-minded reactionism, like the horrible bautforum.

[Onslaught]

I was also wondering what people thought about poincare dodecahedral space. I haven't found any papers refuting this theory about the shape of space. Especially with the recent WMAP data.

[Chronos]

The dodecahedral proposition is weak. See, for example:
Dodecahedral topology fails to explain quadrupole-octupole alignment
http://arxiv.org/abs/astro-ph/0611640

[Onslaught]

Thanks for the link, thought it sounded to good to be true.

I find it impossible to comprehend a universe that is infinite, because no matter how you try to explain it, it HAS to end somewhere. Even if you use the balloon analogy that's like saying walking on a straight path on earth will bring you back to where you started. However if you take a rocket at escape velocity you can go beyond this.

Should there be a way, no matter how inconceivable, to escape from this so called Universe. i.e. an escape velocity for our Universe?

[Chronos]

By most models, the speed of light is the escape velocity of this universe. That is obviously impossible to achieve. It is unclear if the universe is finite. I tend to think it is from a strictly observational standpoint - e.g.. Olber's paradox. There may be 'stuff' outside our universe but I see no possible way to confirm this by observation,

[danda22]

hmm. a very hard question to consider with no definite answers.

i tend to belive that there is nothing outside our universe. just... nothing

btw. even if youu were travelling at lightspeed you could never escape"" or even reach anywhere near the edge of our universe. (the furtherst particle away from the "middle")
simply because it is also expanding at the speed of light.

[DaveC426913]

hmm. a very hard question to consider with no definite answers.

i tend to belive that there is nothing outside our universe. just... nothing

btw. even if youu were travelling at lightspeed you could never escape"" or even reach anywhere near the edge of our universe. (the furtherst particle away from the "middle")
simply because it is also expanding at the speed of light.

The universe has no middle. The universe has no edge.

The best model that shows how this can be so is that the universe is curved and closed. A 4-spatial-dimensional sphere.

Travel in any direction long enough and you will arrive back at your starting point.

[cfung]

This is what I know about the structure of the universe.

In our universe there are 2 parts. The observable part, like many have said, is +/-13.7 billions light years long. Then outside the observable you've got the unobservable part of the universe.

It's unobservable simply because light isn't catching up with the speed at which the universe expands. The distance between the edge of the universe and the light that's trying to reach the edge of the universe is what we meant by unobservable universe.

In other words, the universe is being expanded and light is trying to fill in and cover the created space-time, but the space-time being created is faster than what light can cover, so there is always an unobservable part of the universe where light hasn't reach.

But even without light, this unilluminated space-time obeys the laws of physics, it's nothing more than space without light. With that said, the unobservable universe is existing and so it's relevant that we understand what it is.

However, what's outside the edge of our expanding universe? There could be something like a higher dimension or a turtleback, though as much as there is a possibility of something outside, there's an equal chance that there is non-existence (if existence involves space-time). But if you want a correct answer to the question, what's outside the edge of the universe, the answer would be: there is the edge of our universe.

Many who understands often label the question pointless to ask, since one is asked to describe an object that is non-existing in the world.
Likewise if there's a non-existing object called Mr.X, how would you describe Mr.X to me? Seriously, try answering that until you get a sense of impossibility.

To see how it's unanswerable, Steven Hawkings once rephrase such questions along the following: What is north of North Pole? North Pole, probably.

[Chronos]

Our universe could be embedded in an infinitely large 'void', but, I fail to see how that helps us understand the universe. It would also raise issues like why matter occupies just an infinitesimal volume in all that can be characterized as 'spacetime'. Creepy. Cosmology is hard enough as is. All we can say with any certainty at present is the universe is observationally finite. That may not be all there is to it, but, it is all we can hope to describe for now. Better theories may give us new perspectives, but, better observations would raise my comfort level more quickly.

[ray b]

The universe has no middle. The universe has no edge.

The best model that shows how this can be so is that the universe is curved and closed. A 4-spatial-dimensional sphere.

Travel in any direction long enough and you will arrive back at your starting point.

do you have any proof of that last statement ???????????

[DaveC426913]

do you have any proof of that last statement ???????????

No, I'm not stating it is so, I'm stating there exists a model of the universe with this geometry.

[diogenesNY]

The universe has no middle. ...[edit]...


But Dave, isn't it _all_ middle? :)

diogenesNY

[DaveC426913]

But Dave, isn't it _all_ middle? :)

diogenesNY
Sure, that too.

But of course, 'middle' is only meaningful inasmuch as it is distinguishable from every other point; it is unique.

If it is all middle, then it is not unique.


To modify your statement: it all was middle.

[diogenesNY]

Sure, that too.

[edit]

To modify your statement: it all was middle.

A point lucidly made, well taken, and appreciated.

diogenesNY

[Onslaught]

By most models, the speed of light is the escape velocity of this universe. That is obviously impossible to achieve. It is unclear if the universe is finite. I tend to think it is from a strictly observational standpoint - e.g.. Olber's paradox. There may be 'stuff' outside our universe but I see no possible way to confirm this by observation,


I would be careful in saying that it is impossible to achieve faster than light travel, it may be highly improbable but not impossible. These are theories for a reason. If scientists have learned anything in our short time in this universe it is that "universal truth is not measured in mass appeal."

I agree that the universe will most likely turn out to be finite, but what if the speed of light can be reached or even surpassed, imagine the implications. Now I am admittedly slightly ignorant when it comes to these matters but my understanding of Einstein's famous equation E=mc^2 is that the amount of energy it takes to move an object is that objects mass multiplied by the speed of light squared. Hypothetically if we were able to control this much or MORE energy and focus it we should be able to travel light speed.

One problem I can't explain is that the faster you go or more energy you use your mass seems to increase a lot, which would require more energy to move but maybe when your mass reaches a certain amount you tear through the fabric of space-time.

Just a thought I had, feel free to mathematically, logically, or theoretically tear my argument to shreds. :-)

[map19]

E = mc^2 is nothing to do with moving mass. It is the energy equivalence of mass.
To move mass the simple F = ma is all that is needed.
As you go faster your mass does NOT increase. It's the problem posed by Special Relativity that a "Stationary" observer appears to see your mass increase. Or putting it another way, if you are moving compared with another frame of reference, observers on that frame see your mass as increased, while you see their masses as increased.
In your own frame, and their own frame, there is no increase.

[Onslaught]

Thanks for the clarification, I guess that idea is DOA.

Is there any reason to believe that F=ma doesn't work or works differently towards the 'edge' of the Universe or do we assume that since it works here it must work everywhere?

[map19]

No. From astronomical observations it seems that the same rules of physics apply all over. And the same chemistry.
However, you can never say never.

[Anticitizen]

I think that to make a statement like "conceptualizing the nature of the universe's 'edge' is irrelevant because it's unobservable" and refusing to even consider the possibilities is rather unproductive, if not downright unscientific. Through simulation and modeling we can construct hypotheticals, and quite accidentally run across something useful or testable. Just because we can't fly a probe to the edge of the cosmos doesn't mean we won't construct a model that just so happens to explain, say, lambda/the cosmological constant/whatever as an added bonus. Many times, a theory been made to explain one thing - and then, quite accidentally, someone steps back and says 'hey! this also explains THIS wacky phenomenon!' They may never experimentally verify the thing they originally set out to explain, but those happy accidentals that end up getting explained as a result certainly can go a ways in supporting the theory.

I get sensitive about those sorts of statements because they half-seem to be actively trying to stifle progress. String theory, for instance, predicts nothing, and instead of simply being content to simply not believe it, some people go out of there way to call it useless, a waste of time, etc. Those people will be in for a surprise if ever some testable prediction does pop up at some point as a result of the work that's been put into it (Note, I'm not trying to turn this into a string theory discussion, I just used it as an example).

In any case, it's a fun question whether verifiable or not. Now, to get more on topic:

When I was 15, I was puzzing over this same question (or one similar enough). Assuming the universe is a finite bubble of spacetime, what happens to the traveller that sneaks up to the 'edge' and tries to push beyond? Is there a beyond?

I followed a few assumptions (and note they're only assumptions):

The universe is
- finite
- spherical
- spacetime is the 'medium' in which matter, energy, and measureable dimensions exist
- anything 'outside' of the bubble of spacetime must have zero measurable distance. There is no 'there' there

Okay. The universe obviously has a measurable diameter, and a volume. Here's where I ran into a puzzler: How can a universe have an edge, a perimeter, and outside surface area as it were, and be 'surrounded' by an area of zero distance? I figured that was impossible - that a traveller moving toward the outside edge would be getting closer and closer to an area of zero distance. There can be no such thing as a 'perimeter' or surface area to the bubble if it's rubbing elbows, or expanding into, with an 'area' of zero distance.

But the universe does have pockets of measurable area that 'rub up' against areas of (theoretically) zero distance: singularities.

Therefore, as one would travel to the 'edge' of the universe, he'd find that he's moving through space that curves into a singularity. That's the only way the universe can be 'surrounded' by an area of zero distance - no matter what direction you travel in, go far enough and you'll fall into a black hole, basically. This means the universe has a diameter and an area, but no perimeter.

It would also mean that the 'edge' of the universe is a massive gravity well. :)

I invented a word for this all-encompassing singularity; 'pangularity', from the latin pan meaning 'all'. (It was easier to pronounce than 'omnigularity'.)

This tied in to something else I was pontificating about at the same time: relativity in a spinning disc. If you take a disc and spin it so the outer edge accelerates near the speed of light, the measured perimeter would shrink, but the diameter and area remains the same. If it was a magical disc whose edge could spin at the speed of light, you'd have a perimeter of zero distance. Given the equivalence of acceleration and gravity, the relativistic spinning disc could serve (at least mathematically) as a two-dimensional model for the pangularity idea. This was good news for me, because I was failing Algebra at the time. :)

I ran into a problem. At the time, it was 'common knowledge' that the universe's expansion was slowing. According to my hypothesis, the further you travelled away from the center of the universe, you should start falling into the 4D curvature of space into the pangularity, and therefore start speeding up instead of slowing down. So I said 'well, so much for that', congratulated myself for having a neat idea and forgot all about it, until I read an article about a year later about the surprising new measurements that demonstrated the universe was accelerating in its expansion. I did a happy jig and congratulated myself for being the smartest human being on the planet.

I started getting silly and conjecturing completely baseless speculations, such as the existence of a white hole, a convex singularity, at the center of the universe serving as the 'other side' of the pangularity, and the universe constantly recycling its matter and energy... etc.

Of course, that was almost 15 years ago, and I've gotten a little wiser, if not smarter. I don't think it can be adapted to explain why everything is moving apart from everything else at an accelerating rate. As two objects get closer to the outer edge of the universe, they should actually come closer together as they fall into the pangularity. And if the gravity well's effects were to extend into our local observable area of the universe, movement of objects should seem biased in one direction, assuming we're not parked in the exact center of the universe, etc. Of course, the volume and diameter of the universe could still be expanding due to inflation in this model, but the perimeter is always zero.

I still suspect that if spacetime is expanding 'into nothing', then the perimeter must have zero distance.

But it was fun speculation, and speculation can lead to some very interesting ideas. I think that the culture of strict positivism ('the question is irrelevant!', etc) seems counterproductive.

[DaveC426913]

I think that to make a statement like "conceptualizing the nature of the universe's 'edge' is irrelevant because it's unobservable" and refusing to even consider the possibilities is rather unproductive, if not downright unscientific. Through simulation and modeling we can construct hypotheticals, and quite accidentally run across something useful or testable. Just because we can't fly a probe to the edge of the cosmos doesn't mean we won't construct a model that just so happens to explain, say, lambda/the cosmological constant/whatever as an added bonus. Many times, a theory been made to explain one thing - and then, quite accidentally, someone steps back and says 'hey! this also explains THIS wacky phenomenon!' They may never experimentally verify the thing they originally set out to explain, but those happy accidentals that end up getting explained as a result certainly can go a ways in supporting the theory.

I get sensitive about those sorts of statements because they half-seem to be actively trying to stifle progress. String theory, for instance, predicts nothing, and instead of simply being content to simply not believe it, some people go out of there way to call it useless, a waste of time, etc. Those people will be in for a surprise if ever some testable prediction does pop up at some point as a result of the work that's been put into it (Note, I'm not trying to turn this into a string theory discussion, I just used it as an example).

In any case, it's a fun question whether verifiable or not. Now, to get more on topic:

When I was 15, I was puzzing over this same question (or one similar enough). Assuming the universe is a finite bubble of spacetime, what happens to the traveller that sneaks up to the 'edge' and tries to push beyond? Is there a beyond?

I followed a few assumptions (and note they're only assumptions):

The universe is
- finite
- spherical
- spacetime is the 'medium' in which matter, energy, and measureable dimensions exist
- anything 'outside' of the bubble of spacetime must have zero measurable distance. There is no 'there' there

Okay. The universe obviously has a measurable diameter, and a volume. Here's where I ran into a puzzler: How can a universe have an edge, a perimeter, and outside surface area as it were, and be 'surrounded' by an area of zero distance? I figured that was impossible - that a traveller moving toward the outside edge would be getting closer and closer to an area of zero distance. There can be no such thing as a 'perimeter' or surface area to the bubble if it's rubbing elbows, or expanding into, with an 'area' of zero distance.

But the universe does have pockets of measurable area that 'rub up' against areas of (theoretically) zero distance: singularities.

Therefore, as one would travel to the 'edge' of the universe, he'd find that he's moving through space that curves into a singularity. That's the only way the universe can be 'surrounded' by an area of zero distance - no matter what direction you travel in, go far enough and you'll fall into a black hole, basically. This means the universe has a diameter and an area, but no perimeter.

It would also mean that the 'edge' of the universe is a massive gravity well. :)

I invented a word for this all-encompassing singularity; 'pangularity', from the latin pan meaning 'all'. (It was easier to pronounce than 'omnigularity'.)

This tied in to something else I was pontificating about at the same time: relativity in a spinning disc. If you take a disc and spin it so the outer edge accelerates near the speed of light, the measured perimeter would shrink, but the diameter and area remains the same. If it was a magical disc whose edge could spin at the speed of light, you'd have a perimeter of zero distance. Given the equivalence of acceleration and gravity, the relativistic spinning disc could serve (at least mathematically) as a two-dimensional model for the pangularity idea. This was good news for me, because I was failing Algebra at the time. :)

I ran into a problem. At the time, it was 'common knowledge' that the universe's expansion was slowing. According to my hypothesis, the further you travelled away from the center of the universe, you should start falling into the 4D curvature of space into the pangularity, and therefore start speeding up instead of slowing down. So I said 'well, so much for that', congratulated myself for having a neat idea and forgot all about it, until I read an article about a year later about the surprising new measurements that demonstrated the universe was accelerating in its expansion. I did a happy jig and congratulated myself for being the smartest human being on the planet.

I started getting silly and conjecturing completely baseless speculations, such as the existence of a white hole, a convex singularity, at the center of the universe serving as the 'other side' of the pangularity, and the universe constantly recycling its matter and energy... etc.

Of course, that was almost 15 years ago, and I've gotten a little wiser, if not smarter. I don't think it can be adapted to explain why everything is moving apart from everything else at an accelerating rate. As two objects get closer to the outer edge of the universe, they should actually come closer together as they fall into the pangularity. And if the gravity well's effects were to extend into our local observable area of the universe, movement of objects should seem biased in one direction, assuming we're not parked in the exact center of the universe, etc. Of course, the volume and diameter of the universe could still be expanding due to inflation in this model, but the perimeter is always zero.

I still suspect that if spacetime is expanding 'into nothing', then the perimeter must have zero distance.

But it was fun speculation, and speculation can lead to some very interesting ideas. I think that the culture of strict positivism ('the question is irrelevant!', etc) seems counterproductive.While speculation can be fun, it is a fine line you walk here. Overly-speculative discussion and personal theories are expressly forbidden. (Remember that PF is first and foremost a homework help forum, and thus concentrates on currently-accepted physics.)

[Anticitizen]

I understand and apologize - I went a little too deep into it. The purpose of the post wasn't really about the idea itself, though - the moral of the story was the point I made in the first two paragraphs about keeping an open mind. In this case, a wacky, arguably untestable idea I had made one prediction one I didn't intend to make - that the universe's expansion would accelerate. Turns out it is. I'm 99.9% sure it's for a completely different reason, of course, but I think my point stands that 'irrelevant' concepts may lead to real conclusions. I suppose I should've used a real-world example (that is, something established in physics).