# Where Does Space End? It Must End Somewhere!

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csmyth3025, pantheory

If you please, could either of you clarify some of your terms?

matter, field: You seem to use matter in the conventional "particle" sense and refer to a "field" as separate entity. In GR and in QM matter has a field formulation so i am unsure as to how, or even why, you are separating matter and field. I would think we only need particle type matter to measure time and space but this technological constraint should have no bearing on the extent of space.

I think the question of "field" vs "matter" is answered by the definition given for the stress-energy tensor in the Einstein Field Equations:

The stress–energy tensor (sometimes stress–energy–momentum tensor) is a tensor quantity in physics that describes the density and flux of energy and momentum in spacetime, generalizing the stress tensor of Newtonian physics. It is an attribute of matter, radiation, and non-gravitational force fields. The stress-energy tensor is the source of the gravitational field in the Einstein field equations of general relativity, just as mass is the source of such a field in Newtonian gravity.

In Newtonian gravity, mass is the source of the gravitational field. In GR, matter, radiation, and non-gravitational force fields contribute to the stress-energy tensor - which is defined as the source of the gravitational field. The GR view of the gravitational field allows for it to exist even if there is no contributing matter component.

Chris

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Hi BJC,

If you please, could either of you clarify some of your terms?

matter, field: You seem to use matter in the conventional "particle" sense and refer to a "field" as separate entity. In GR and in QM matter has a field formulation so i am unsure as to how, or even why, you are separating matter and field. I would think we only need particle type matter to measure time and space but this technological constraint should have no bearing on the extent of space.

When I use the word field, also believing Einstein was referring to the same or similar idea/ entity. I'm referring to the Zero Point Field (ZPF) and believe Einstein in most of his writings/ references that had no other references or clarifications. In physics the Zero Point Field (ZPF) is presently known to have the following characteristics:

http://en.wikipedia....ki/Vacuum_state

The ZPF is known to contain energy (ZPE) and produce virtual particles as well as containing known particles such as neutrinos, photons of countless frequencies. Also there may be one or more presently unknown, undiscovered theoretical particles within it such as dark matter, gravitons, Higgs particles, quantum foam, etc. etc. as well as theoretical energy such as dark energy, plus almost countless other presently theorized but yet unknown physical particles as well as known energies. So bottom line is that when most physicists talk about the background field they are usually talking about a real rather than a theoretical entity which is called the ZPF. The ZPF is often referred to as the new aether including its totally known as well as theoretical contents. Whether it is the same type of aether theorized more than a hundred years ago is still a matter of debate, contrary to public opinion and the education of most of today's physicists.

As far as matter is concerned, I refer to known matter in conventional theoretical form and theory. I think it is still unknown as far as the true underlying structures of atomic particles, for instance, whether being conventional round-like structures, string-like structures, or some other form.

Hope you continue to ask questions:) I am a theorist in cosmology but this is a science forum so that anything said in this and other science forums must provide sources and also explain when mentioning/ discussing hypothesis/ theory other than mainstream. The above several paragraphs gives reference to maybe 20 or more alternative mainstream hypothesis as well as some non-mainstream hypothesis.

As to my own theory/ opinions, I believe field and matter are entirely different entities which are generally unrelated. Matter accordingly creates two kinds of waves in the ZPF, one is EM radiation and another is de Broglie waves.

Edited by pantheory
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I think the question of "field" vs "matter" is answered by the definition given for the stress-energy tensor in the Einstein Field Equations:

In Newtonian gravity, mass is the source of the gravitational field. In GR, matter, radiation, and non-gravitational force fields contribute to the stress-energy tensor - which is defined as the source of the gravitational field. The GR view of the gravitational field allows for it to exist even if there is no contributing matter component.

Chris

No, does not answer my question of why you seem to reference "matter" and "field" as separate entities. Matter has a "field formulation" but not all "fields" are related to matter.

Are you inferring there is a difference of "space in the presence of matter" versus "space in the absence of matter" ? Without matter we cannot (presently) measure space or time but that does not imply a difference. Possibly the "matter vs field" is not too relevant for this topic???

Couple other points:

In GR, the gravitational field is also a source of the gravitational field. Pressure is the source component for the pure vacuum energy equation.

My "speculative point" that space exists prior to the Big Bang is also inferred in the statement that the Big Bang was not an explosion at a single point but happened simultaneously across all space.

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No, does not answer my question of why you seem to reference "matter" and "field" as separate entities. Matter has a "field formulation" but not all "fields" are related to matter.

Are you inferring there is a difference of "space in the presence of matter" versus "space in the absence of matter" ? Without matter we cannot (presently) measure space or time but that does not imply a difference...

I think we're both on the same side of the question here. My comments about "fields" and the stress-energy tensor were in response to pantheory's comments ( Posted 19 June 2011 - 12:05 PM):

I don't perceive these quotes as necessarily conflicting since it is commonly believed today that the field (the ZPF) can and does exist in the absence of matter, but that matter does not exist in the absence of field, and accordingly space does not exist in the absence of both, which relates to the question of this thread...

My comments were intended to point out to pantheory that the existence of space-time does not require the existence of matter, but does require the existence of fields - which may or may not include matter as a component of the stress-energy tensor.

Chris

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My understanding of the big bang model is that matter did not exist until some time after TBB. If the theory says that space existed before matter existed then it-(the theory) implies space can exist independant of matter.

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Is it so difficult to imagine we can only see a finite amount of an infinite Universe. When I look out of my window, over the sea, I can see the Horizon. I wonder what would happen if I could travel to the Horizon? Is there anything on the other side of it? Would I disappear from one side of the Earth and reappear on the other side? Is there any point in speculating what might be on the other side of it?

As I move the horizon moves so I can never reach it so it is nonsense to ask what will happen if I get there because I never will. But what would happen if I got in my boat and rowed out to sea, I would be able to see farther than I could when I was on land and now I can see another island that I couldn't see before. That's because the distance between my island and the new island is constant, but what if the amount of sea between us is increasing faster than I can row. I will never see this new island no matter how fast or for how long I row.

Suppose now that the was a third island half way between my island and the new one, I of course will never know about the 'new island' because I can not see it from my island nor can I travel to it fast enough to be able to see it. An observer on the third island however can see the 'new island' for he is close enough to see it, but it is moving away from him also. If I were to row to the third island (which is also moving away from me) it would take me so long to get there that the 'new island' will have dissapeared from the third island's view before I get there.

I will never be abe to see the new island, although there are things beyond my horizon I will never be able to see them. In fact (figure of speach) more and more things will dissappear beyond my horizon never to be seen again.

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My comments were intended to point out to pantheory that the existence of space-time does not require the existence of matter, but does require the existence of fields - which may or may not include matter as a component of the stress-energy tensor.

Chris

Hi BJC,

When I use the word field, also believing Einstein was referring to the same or similar idea/ entity. I'm referring to the Zero Point Field (ZPF) and believe Einstein in most of his writings/ references that had no other references or clarifications. In physics the Zero Point Field (ZPF) is presently known to have the following characteristics:

...

As to my own theory/ opinions, I believe field and matter are entirely different entities which are generally unrelated. Matter accordingly creates two kinds of waves in the ZPF, one is EM radiation and another is de Broglie waves.

Thanks to both. There does not appear to be any basic disagreement although i am intrigued by "pantheory's own theory/opinions".

I would think any answer to "where does space end?" must consider conditions prior to the Big Bang. If the inflationary model is considered then vacuum energy existed prior to the Big Bang which implies space but no time (whatever time is!!)

Vacuum energy has a constant energy density - does this imply a constant space field. Would this field be infinite? Does infinity even have a meaning when discussing a constant static energy field?

Dark Energy Wiki

Two proposed forms for dark energy are the cosmological constant, a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant is physically equivalent to vacuum energy.

Inflation (cosmology) Wiki

In physical cosmology, cosmic inflation, cosmological inflation or just inflation is the theorized extremely rapid exponential expansion of the early universe by a factor of at least 1078 in volume, driven by a negative-pressure vacuum energy density.
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My understanding of the big bang model is that matter did not exist until some time after TBB. If the theory says that space existed before matter existed then it-(the theory) implies space can exist independant of matter...

Depending on how you choose to define matter, the hadron epoch was probably the earliest appearence of what we usually think of as matter (Baryons such as protons, neutrons, and their anti-particles; and mesons of various types - which are generally considered force carriers).

The Lambda-CDM standard cosmological model is the most widely accepted model of how our universe evolved. It doesn't say anything about conditions earlier than about 10-36 seconds (the inflationary epoch) except that all parts of our observable universe were in causal contact prior to inflation. Because this is a model of our universe, it necessarily includes matter (because we observe matter in our universe).

On the other hand, there are solutions to the Einstein Field Equations of General Relativity that permit universes that contain no matter (a de Sitter universe is one such example). These solutions are strictly theoretical since they obviously don't depict the universe we live in today. If the universe continues to expand (which it is expected to do) and the matter in it becomes more spread out, that matter will become more and more insignificant:

According to the models of inflation and current observations of the accelerating universe, the concordance models of physical cosmology are converging on a consistent model where our universe was best described as a de Sitter universe at about a time t = 10 − 33 seconds after the fiducial Big Bang singularity, and far into the future.

Chris

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between3and26characterslon,

My understanding of the big bang model is that matter did not exist until some time after TBB. If the theory says that space existed before matter existed then it-(the theory) implies space can exist independent of matter
.

The general consensus of the BB model is what you have stated: matter did not exist before the BB. I think the general BB consensus is that space and energy preceded the creation of matter. I agree that the consensus of theorists believe that space can exist separate from matter.

I think the question now being discussed is whether space can exist separate from the Zero Point Field. In this question I don't think there is a consensus among theorists but according to the Einstein quotes presented here and my own postings and logic presented, is that space has no meaning in the absence of everything else within its boundaries. Accordingly whether space is considered to be finite or infinite or whether space is bounded (the OP question) might be solely based upon the definition of space that is being used. The definition which I adhere to is this: Space is a distance, area, or volume bounded by two or more points within the Zero Point Field (ZPF). Einstein said that space does not exist in the absence of field.

There may be no consensus concerning a generally accepted definition of "space" by theorists but the most common definition that I find considers space to be a boundless, unending continuum defined something like this one: Space is conceived in three dimensions although in modern physics time is usually added to space as part of a boundless four-dimensional continuum known as spacetime.

Edited by pantheory
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BJC,

.....I would think any answer to "where does space end?" must consider conditions prior to the Big Bang. If the inflationary model is considered then vacuum energy existed prior to the Big Bang which implies space but no time (whatever time is!!)

Vacuum energy has a constant energy density - does this imply a constant space field. Would this field be infinite? Does infinity even have a meaning when discussing a constant static energy field? ....

There is no consensus concerning the standard BB model whether space existed before the BB. I like your wording by stating that the Inflation model "implies" that it did. Many do believe that space existed first. Also many believe that the field (ZPF) existed before a BB. I think the point in question involves the definition of space, which brings up philosophical questions. Such a question would be: what would be the meaning of space and time in the absence of all other facets of reality. Einstein, I think, explained his answer to this question based upon two quotes of his which can be joined together concerning his response to the general question:

"..... if all the matter (and field) in the universe were removed....(what would happen)? (His response): "..... my theory proves that space and time would disappear along with matter" (and field)

Einstein said "... there exists no space empty of field."

Edited by pantheory
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between3and26characterslon,

.

The general consensus of the BB model is what you have stated: matter did not exist before the BB. I think the general BB consensus is that space and energy preceded the creation of matter. I agree that the consensus of theorists believe that space can exist separate from matter.

I think the question now being discussed is whether space can exist separate from the Zero Point Field. In this question I don't think there is a consensus among theorists but according to the Einstein quotes presented here and my own postings and logic presented, is that space has no meaning in the absence of everything else within its boundaries. Accordingly whether space is considered to be finite or infinite or whether space is bounded (the OP question) might be solely based upon the definition of space that is being used. The definition which I adhere to is this: Space is a distance, area, or volume bounded by two or more points within the Zero Point Field (ZPF). Einstein said that space does not exist in the absence of field.

There may be no consensus concerning a generally accepted definition of "space" by theorists but the most common definition that I find considers space to be a boundless, unending continuum defined something like this one: Space is conceived in three dimensions although in modern physics time is usually added to space as part of a boundless four-dimensional continuum known as spacetime.

Is it not the case that in TBB theory the early stages of the universe were too hot for matter to form. You would then have space but no mass. If so my qustion would be did gravity exist before mass and was this the inflationary period.

Anyway the point I was really getting at is that space without matter seems to be an accepted part of another theory. Space without field is somewhat different.

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between3and26characterslon,

Is it not the case that in TBB model the early stages of the universe were too hot for matter to form (?) You would then have space but no mass. If so my question would be did gravity exist before mass and was this the inflationary period (?)

This is a very good question. Again I don't think there is a mainstream consensus concerning an answer. One faction might say that the outward forces of pure energy did not allow matter to condense out from the highly concentrated energy of TBB. There is no agreement whether matter existed at all during the BB inflation era. The proposed equations seem to imply that there was not. There is still argument as to when the proposed inflation period ended. Some believe that it never ended and continues today as dark energy. Others believe in Einstein's cosmological constant concerning an explanation for the hypothetical dark energy. Concerning gravity, some theorists might say that gravity does not exist at all in the absence of matter. Most believe that gravity existed from the beginning.

.

Anyway the point I was really getting at is that space without matter seems to be an accepted part of another theory.

There are cosmological models like the De Sitter model where an entire universe of space exists without any matter. But since this would not be our universe, theorists would probably find it difficult to use such a matter-free universe model except within maybe a multiverse model. Some believe, however, that the Zero Point Field is an infinite continuum and that it preceded a BB beginning and was the source/ cause of that beginning. This is an infinite universe, infinite space, but finite mass model. Others like Hawking have proposed multiverses/ other worlds, proposing our BB universe is only one universe of many or infinite quantities. This is another "infinity" model of reality.

.

Space without field is somewhat different.

Calling some hypothetical volume(s) "space" when there would be no matter or field within or surrounding it, makes no sense at all to me. This is my problem with a definition of space which includes the idea of a continuum if matter and field are finite in quantity as in the standard version of the BB model. Based upon a flat universe model and Einstein's concept of space (also mine), there is no such thing as space beyond the boundaries of matter and field, since accordingly matter and field must be used to define space. Einstein also seemed to believe that the concept of totally vacant space was inconsistent with his cosmological equations based upon GR, when he said "...space does not exist in the absence of field."

Edited by pantheory
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• 4 months later...

I have to ask some before further explanation

Why should something begin and has no end?

Does existence has a starting point?

Why should extinction govern the nature of existence?

I think that there exist only single mind,as such of the example of said so dreaming man he create his new universe containing things and events while dreaming.

And the man believe that he is in real universe while he is dreaming.

HOW CAN SOMEONE PROVE THAT THIS said so UNIVERSE is not the result of DREAMING ACTIVITY of a SINGLE INTELLIGENT MIND

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HOW CAN SOMEONE PROVE THAT THIS said so UNIVERSE is not the result of DREAMING ACTIVITY of a SINGLE INTELLIGENT MIND

In a dream, if you spin a top it just keeps spinning. To tell if it's a simulation (different from a dream) try and bend a spoon with your mind -- but remember, there is no spoon!

Edited by Iggy
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I have to ask some before further explanation

Why should something begin and has no end?

Does existence has a starting point?

Why should extinction govern the nature of existence?

I think that there exist only single mind,as such of the example of said so dreaming man he create his new universe containing things and events while dreaming.

And the man believe that he is in real universe while he is dreaming.

HOW CAN SOMEONE PROVE THAT THIS said so UNIVERSE is not the result of DREAMING ACTIVITY of a SINGLE INTELLIGENT MIND

Statistically speaking, that's probably the most likely scenario:

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Our understanding of the universe and that it has no edge is, I believe, based on general relativity and observations of the visible universe -- the part that is close enough so its light has had time to reach us. I am reading The Goldilocks Enigma by Paul Davies. It's really good and he says something I think sheds light on the subject:

" . . . raises the obvious question of whether, in the real universe, the reason that no center or edge is apparent is simply that our telescopes are not powerful enough to probe that far. And that may be so. It may be that the observable universe is buried deep in an assemblage of galaxies that, viewed on a grander scale, does have an edge . . .

"On the otherhand, the universe . . . may be infinite in all directions . . . "

I have also read that it is possible the universe to be finite but still not have a center or edge, due to space warp.

So it seems the jury is still out on whether the universe has an edge.

(I have not read the 34 pages of this thread, so I apologize if I repeat something that has already been said.)

Edited by IM Egdall
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Edge to edge,

Outside, an instant to instant expanding force of compounding and infinite posabilities. And the inside edge of 4D space are the galactic black holes themselves, and the outside edge Arts what and where it pleases amoung the vast realms of what is, and what is possible.

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Our understanding of the universe and that it has no edge is, I believe, based on general relativity and observations of the visible universe...

...I have also read that it is possible the universe to be finite but still not have a center or edge, due to space warp.

Not only is it based on general relativity -- it's based on the simple assumption that geometry can describe space.

If space is a non-Euclidean dimension then curvature opens up the real possibility that finite space can have no boundary. If someone assumes (like the OP seems to assume) that finite space has to have an edge at its end then they are implicitly assuming that space is Euclidean. I don't know from where, or on what evidence, that assumption comes.

Buttressing that thinking comes general relativity. It not only says that space need not be Euclidean, it shows that the laws of physics work quite well when it is not and shows in what circumstances it is expected not to be.

Edited by Iggy
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Not only is it based on general relativity -- it's based on the simple assumption that geometry can describe space.

If space is a non-Euclidean dimension then curvature opens up the real possibility that finite space can have no boundary. If someone assumes (like the OP seems to assume) that finite space has to have an edge at its end then they are implicitly assuming that space is Euclidean. I don't know from where, or on what evidence, that assumption comes.

Buttressing that thinking comes general relativity. It not only says that space need not be Euclidean, it shows that the laws of physics work quite well when it is not and shows in what circumstances it is expected not to be.

Well said, Iggy

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• 2 weeks later...

hi guys this is my favourite topic,my own beliefs are this.....im sure im on the right path...the universe was created....they was no big bang....how can something explode into nothingness...are you with me...no space no soundwaves,no oxygen to burn....are you still understanding this...ok if you are when all matter ceases to take up space at its fringe....(without matter time cannot exist)then what is left over is a void...now dont think the void is just one continuous white light...its not its blacknesslike death end of chat..

..everything is circular in our universe...our universe is like the inside of a balloon...the void is the skin but unlike the balloon skin it has no thickness....because there is no matter their to calculate yes....therefore it solves the paradox of whats outside the box...now who created this universe well thats easy God....

now whats really gonna freak you is matrixy "there is no universe.".....

So we are all in a matrix that God created? For some odd reason that's as logical as anything else.

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• 2 months later...

Ever since I was a young boy, I have wrestled with trying to understand space. In particular, I have never really understood how space is supposed to never end. I really don't see how that's possible. Everything ends somewhere. Where one thing ends the next begins.

Can people please provide thoughts on this?

Suppose you were imprisoned on Penitentiary Earth. You slipped out of the fortified walls somehow and you began to walk due West. When you encountered water, you found a boat or ship and continued on your journey being careful to compensate for seasonal changes in the position of the sun. Eventually you would wind up back at the 'Ol Pen, having traced a latitudinal great circle around the pole. The surface of a sphere has no end. To get out of, or off of, this surface, one needs to move in directions that are not properly "in" the surface. Try reading Flatland by Edwin A. Abbott.

Analysis of the variations in intensities and their frequency distributions in the cosmic microwave background radiation (CMB) shows that the pattern matches a roughly random pattern that is originally "flat" before it is projected upon the sky by various kinds of digitally equipped radio-telescopes. The statistical pattern virtually matches that expected for inflationary Hubble expansion of the universe. Deep space telescopic probes find that "SNe 1a" supernovae are more distant than their Hubble redshifts would indicate, so the Hubble constant, Ho, must be increasing for these and other kinds of very distant bright objects. But, motion is relative, so what it really means is that Ho must be increasing here and now, for US. Maybe you could say that the universe is open ended only on our end.

This is "acceleration" of Hubble expansion and it is ascribed to some form of potential energy that is pouring spacetime juice into our universe from some source or else it is due to "quintessence" which is supposed to be a fundamental force that is built into the fabric of the cosmos.

Now, somehow Alan Guth got transported to a completely new and different universe where he was able to view our little world in "block time". That is, he was able to see us and all that we have done and all that we will ever do from his perch in his meta-universe, outside our own. His clocks followed "meta-time" while our clocks were seen to trace a complex static path according to frozen orbital motions of the earth, the sun, our galaxy and the expansion of the entire universe (our universe, that is). Our clocks appear to him like multiple mad computer screen cursors stopped in a panoramic all-seeing time exposure photograph. We cannot join him in his world because we are frozen in "block time", so we do not even want to.

Guth sees our universe from beginning to end. All the objects that move or that have ever moved in it show like the contrails of fighter jets in a crazy dog-fight. The contrails seem like they are frozen in a big block of Jell-O. He sees how our universe began, how it suddenly jumped from a mere speck to cosmic dimensions in a short distance in "block time". All the objects that move in our universe leave contrails that seem frozen in ice. Guth observes our universe with a laser pointer that acts like a cursor as he moves the beam along a contrail to see what it is and where it leads. He can examine all the contrails in our whole universe from beginning to end. He is like God.

He gets bored with our puny universe and moves on to examine another one that seems to be much more interesting. When he turns off his laser pointer, nothing happens ever again in our block of frozen continuum. We are like statues in the museum of the multiverse. Let us hope that there shall never be an all consuming fire or that no clumsy janitor will ever knock us off our pedestal!

You finally return home to the Penitentiary where you finally come to live in peace with yourself. You have discovered that freedom is just walking around in bigger circles, anyway.

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^ G Anthony sums up my thoughts on this.

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HOW CAN SOMEONE PROVE THAT THIS said so UNIVERSE is not the result of DREAMING ACTIVITY of a SINGLE INTELLIGENT MIND

First, you would have to clearly identify an intelligent mind.

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Ever since I was a young boy, I have wrestled with trying to understand space. In particular, I have never really understood how space is supposed to never end. I really don't see how that's possible. Everything ends somewhere. Where one thing ends the next begins.

It's the difference between unlimited and infinite. As Anthony said, the Earth surface isn't circumscribed, you can walk toward a direction as long as you want in a 2-D surface, which is unlimited but not infinite. It's a bit the same with space but in 3-D, you are not likely to break your nose against the universe limit or whatever because the universe is unlimited, without borders.

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I have to ask some before further explanation

Why should something begin and has no end?

When considering how the universe began many will comment on how something cannot be created from nothing. So, an important question would be, What is nothing? Could there ever have been a "State of Absolute Nothing"? I don't think so.

http://4everuniverse.yolasite.com/

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When considering how the universe began many will comment on how something cannot be created from nothing. So, an important question would be, What is nothing? Could there ever have been a "State of Absolute Nothing"? I don't think so.

http://4everuniverse.yolasite.com/

It seems to me that "Nothing" must be considered as something that hasn't any quality. We must make the distinction between the word and the idea. Now, i think something cannot be created from nothing, because the definition of changing involves that qualities are modified. When you change, you are not someone else, you are the one you were before, but differently, it is your qualities that have changed. Therefore, assuming nothing has no quality, how could he changes to become someting ? He does not possess qualities and therefore he's not affected by changing, our universe can't have been created from nothing (according to our definition of "nothing").

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