# What is Space outside of the universe and infinity according to Physics?

KiranKai
Space: So far for me it's 3D along with Time T. say 3D+T=4D (spaceTime), from the bigbang we have considered Time (t sub I) as well, considering Time from the start of bigbang to 13.7 Billion years after the bigbang. Since our universe is accelerating due to Dark energy, expansion is speeding up.

Now we are inside the universe, what do we call out side of the universe? How can we consider time when we do not have anything to measure in empty space? can we consider time outside the universe when there is nothing to measure or progress (Since Time is a dimension, must tag along always with space, according to special and general theory of relativity).

However, What do we call empty space outside our universe say space before taken over by our universe? or what do we call gaps between multiverse ? Further more, what is outside of multiverse (if we think about going as far as we can thinking crazy far).

I have just drawn rough diagram here to make you understand what I am trying to say.

t sub I is Time at the Bigbang, T-Progress is progress of acceleration of the universe as now.
Do not know what happened to Anti matter? can I safely say SpaceTime outside the universe ?

Can I move up and down, left and right, forward and back at a point in outside of the universe if it is spaceTime ? How can I understand it ?

According to real number line in mathematics, can we consider that space is infinite outside of our universe?

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Cody Richeson
I'm a layman, so don't take anything I'm about to say seriously. Nonetheless, I'd like to share my thoughts. If the multiverse theory is correct, then space is infinite and there is nothing for it to expand into. As to the gaps between other universes, there apparently would not be a gap; you would just keep traveling until you encountered a collection of matter that was nearly identical to the collection of matter you have been traveling away from; in other words, a parallel universe. There would be no "outside" of the multiverse because, again, it is supposedly infinite in its expanse. As to the measurement of time, since there are apparently no gaps between universes, there would always be some collection of matter that changes over time, even if it's nothing other than atomic decay, not to mention your own body slowly changing as you aged while traveling.

Gold Member
There is no satisfactory answer to this question. If the big bang was infinitely large, as some believe, then the universe is, and has always been infinite. So, the question becomes what lies beyond infinity? - in other words, it's irrelevant. The observable universe is a temporally finite sphere about 93 billion light years in diameter [comoving distance] with an age of about 13.7 billion years. Obviously, we can't observe anything more ancient than the universe itself, so again, the question is moot. Only if you assume the universe is a finite entity embedded in some arbitrarily large [or infinitely large] prexisting space is the question meaningful. The obvious answer is it is embedded in a vast/infinite sea of absolute emptiness - which is not wildly popular among scientists. Another idea is the multiverse, which is speculative and admits to no known experimental test.

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Mark M
No, the problem is that the question isn't valid. There's no such thing as 'outside' the universe. The universe may be finite in size, but it certainly does not have an edge. Think of the surface of the Earth - finite, yet you won't find an edge. Take a look at this article for some clarification:

http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf

Cody Richeson
The Earth does not have an edge but it is embedded in the surrounding space. So there is the question of whether or not the universe, even if it curves back on itself, is embedded in something.

Mark M
The Earth does not have an edge but it is embedded in the surrounding space. So there is the question of whether or not the universe, even if it curves back on itself, is embedded in something.

Because the surface of the Earth is a two-dimensional surface sitting in three spatial dimensions. The surface of the Earth is an analogy used to demonstrate one aspect of the universe, similar to to the the balloon analogy. So, don't look too deep into it (i.e. what is the universe embedded in?).

Staff Emeritus
2022 Award
The Earth does not have an edge but it is embedded in the surrounding space. So there is the question of whether or not the universe, even if it curves back on itself, is embedded in something.

That is a question that is not currently answerable. To our knowledge the universe does not curve back in on itself. If we find evidence for it in the future our view will change.

marty1
There is not a definite border to the universe. However, any photon or particle or whatever that is on a tragetory which will cause it to never ever interact with the timeline of any other photon or particle or whatever is outside of the universe in my book.

Staff Emeritus
2022 Award
There is not a definite border to the universe. However, any photon or particle or whatever that is on a tragetory which will cause it to never ever interact with the timeline of any other photon or particle or whatever is outside of the universe in my book.

I believe that while it is statistically possible for a photon to never interact with anything, calling it "outside of the universe" is still incorrect. But I get your point.

Gold Member
Dearly Missed
Now we are inside the universe, what do we call out side of the universe? How can we consider time when we do not have anything to measure in empty space? can we consider time outside the universe when there is nothing to measure or progress (Since Time is a dimension, must tag along always with space, according to special and general theory of relativity).

However, What do we call empty space outside our universe say space before taken over by our universe? or what do we call gaps between multiverse ?

Kiran, I like your drawings. But when I look at them I see you are always drawing x-y-z coordinates as if that was how you imagine space! I think we got that idea from a book published in 1637 by René Descartes.

If that is how you always think of space, or of spacetime, you might find quite a bit of physics after 1850 puzzling. Year 1850 was when Georg Riemann gave us a mathematical representation of space that was more versatile than xyz. Called the manifold.

For example a 3D manifold has LOCAL xyz coordinates and you can do all the usual calculations that you do with xyz---curves functions areas volumes tangents derivative...
BUT a 3D manifold can be boundaryless and yet have finite volume, and it can be AUTONOMOUS and completely described by internal relationships. It does not have to be embedded inside a higher dimension manifold in order to exist.

Furthermore doing geometry with manifolds is simple once you get used to it. Nothing mysterious about it.

For example a 2D manifold has LOCAL XY coordinate charts, like the surface of the Earth has local maps. And it can be boundaryless and still have finite "volume" ie area. And it can be completely determined by internal relationships (angle-sum in geodesic triangles, length of great circle routes, etc.) which 2D beings would experience moving around in it. And it can exist as an autonomous mathematical object of study WITHOUT being embedded in any higher dimension manifold.

Riemann taught us to imagine various possible spaces this way, as manifolds, and to work with them and calculate that way, instead of merely with xyz. So there is a kind of "watershed" or "continental divide".

Your pictures make me think you like to think concretely and physically and that you like mathematics, but they are all on the "xyz" side of the divide. All on the 1637 Descartes side. Not on the post-1850 Manifold side.
It would be easy for you to come over, I think. Learn to model space as a manifold, something I don't think you would find at all hard.

There does not have to be "space outside of space". Nor does there have to be a spatial boundary to the universe. Geometry (including curvature) can be determined by internal relationships, like how different triangles add up and how round volumes grow with radius.These are things that interest cosmologists, in fact! they try, by their observations, to measure curvature in these or similar ways, and to discover universe geometry by experiencing it from within.

After all one cannot get out

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KiranKai
I'm a layman, so don't take anything I'm about to say seriously. Nonetheless, I'd like to share my thoughts. If the multiverse theory is correct, then space is infinite and there is nothing for it to expand into. As to the gaps between other universes, there apparently would not be a gap; you would just keep traveling until you encountered a collection of matter that was nearly identical to the collection of matter you have been traveling away from; in other words, a parallel universe. There would be no "outside" of the multiverse because, again, it is supposedly infinite in its expanse. As to the measurement of time, since there are apparently no gaps between universes, there would always be some collection of matter that changes over time, even if it's nothing other than atomic decay, not to mention your own body slowly changing as you aged while traveling.

Ha I am studying physics Master's level, after looking at the universe I always feel layman no matter how far I go in understanding how far I try to know, it still feels like I am layman after all. some day even current theories might be wrong at some point.

In Fact there is outside, if there is no out side what universe is accelerating into ?
String theorists and other physicists show that we live in multiverse which are not attached to one another like membrin like a bread got sliced up. sum of the slices of breads is multiverse just an analogy.

If you say nothing outside are we living in a box or sphere or something with closed surface?

KiranKai
There is no satisfactory answer to this question. If the big bang was infinitely large, as some believe, then the universe is, and has always been infinite. So, the question becomes what lies beyond infinity? - in other words, it's irrelevant. The observable universe is a temporally finite sphere about 93 billion light years in diameter [comoving distance] with an age of about 13.7 billion years. Obviously, we can't observe anything more ancient than the universe itself, so again, the question is moot. Only if you assume the universe is a finite entity embedded in some arbitrarily large [or infinitely large] prexisting space is the question meaningful. The obvious answer is it is embedded in a vast/infinite sea of absolute emptiness - which is not wildly popular among scientists. Another idea is the multiverse, which is speculative and admits to no known experimental test.

If universe is infinite then Big Bang theory would be wrong. why wrong because it say it all started off with a bang, any bang in empty space would never reach infinity no matter how large the bang is relative to the entire empty space seemingly empty (like real number scale till the infinity). Have we discovered center of the universe yet ? where the bang started up?

even if universe is infinite and where would you start bang when you can consider any point in space as mid point in infinite space?

There should be some name given to outside or(if exist) emptyspace ... how would I calculate time out side of the space?

KiranKai
Kiran, I like your drawings. But when I look at them I see you are always drawing x-y-z coordinates as if that was how you imagine space! I think we got that idea from a book published in 1637 by René Descartes.

If that is how you always think of space, or of spacetime, you might find quite a bit of physics after 1850 puzzling. Year 1850 was when Georg Riemann gave us a mathematical representation of space that was more versatile than xyz. Called the manifold.

For example a 3D manifold has LOCAL xyz coordinates and you can do all the usual calculations that you do with xyz---curves functions areas volumes tangents derivative...
BUT a 3D manifold can be boundaryless and yet have finite volume, and it can be AUTONOMOUS and completely described by internal relationships. It does not have to be embedded inside a higher dimension manifold in order to exist.

Furthermore doing geometry with manifolds is simple once you get used to it. Nothing mysterious about it.

For example a 2D manifold has LOCAL XY coordinate charts, like the surface of the Earth has local maps. And it can be boundaryless and still have finite "volume" ie area. And it can be completely determined by internal relationships (angle-sum in geodesic triangles, length of great circle routes, etc.) which 2D beings would experience moving around in it. And it can exist as an autonomous mathematical object of study WITHOUT being embedded in any higher dimension manifold.

Riemann taught us to imagine various possible spaces this way, as manifolds, and to work with them and calculate that way, instead of merely with xyz. So there is a kind of "watershed" or "continental divide".

Your pictures make me think you like to think concretely and physically and that you like mathematics, but they are all on the "xyz" side of the divide. All on the 1637 Descartes side. Not on the post-1850 Manifold side.
It would be easy for you to come over, I think. Learn to model space as a manifold, something I don't think you would find at all hard.

There does not have to be "space outside of space". Nor does there have to be a spatial boundary to the universe. Geometry (including curvature) can be determined by internal relationships, like how different triangles add up and how round volumes grow with radius.These are things that interest cosmologists, in fact! they try, by their observations, to measure curvature in these or similar ways, and to discover universe geometry by experiencing it from within.

After all one cannot get out

Yeah thank you for your explanation, I am studying masters level course, I need to learn Manifolds, Topology and more.. I still need to improve my skills and I love mathematics and Physics too.

However, I would prefer more visual explanation since we are dealing with dimensions and shapes. We say we live in space with 4D's so I was drawing with x y z and T time. I could not draw higher D for Time so I considered universe as 2d and Time as 3ed D.

If space say again old version of René Descartes, (I can take about new one after I learn it, still need lot of work to do in math..).. if x y and z along with T , say xyz must be infinite because they are dimensions ! Don't you think? we cannot consider it as limited with respective to our universe expansion. Theoretically speaking Dimensions exceed infinity right?

We live in Dimensions say Xyz it has to be infinite because they are Dimensions.
By the way like in mathematics real number line, in the physical world can we really have infinity space? not considering our universe.

Staff Emeritus
2022 Award
In Fact there is outside, if there is no out side what universe is accelerating into ?
String theorists and other physicists show that we live in multiverse which are not attached to one another like membrin like a bread got sliced up. sum of the slices of breads is multiverse just an analogy.

If you say nothing outside are we living in a box or sphere or something with closed surface?

I assume you meant "expanding" instead of "accelerating". It turns out that the universe doesn't need to be expanding into anything at all. All expansion means is that the distance between all objects not bound together through one of the four forces increases over time. Objects have to be millions of light years away from each other for expansion to start to take hold and cause them to recede from each other.

If universe is infinite then Big Bang theory would be wrong. why wrong because it say it all started off with a bang, any bang in empty space would never reach infinity no matter how large the bang is relative to the entire empty space seemingly empty (like real number scale till the infinity). Have we discovered center of the universe yet ? where the bang started up?

The Big Bang was NOT an explosion in space. It wasn't anything at all really. It is a process of expansion. The universe waaaay back 13.7 billion years ago or so, was in an extremely dense, extremely hot state. So dense and hot that particles smashed together and annihilated with each other creating light, which was so energetic that it collided with other light and formed more particles. These particles then smashed into each other creating light and continuing the cycle. Then a curious thing happened. Everything started to recede from everything else. The density of the universe dropped and the light and matter cooled off enough to stop colliding with itself, allowing the first particles to remain behind. These particles were protons, neutrons, and electrons. After a few hundred thousand years they cooled off enough for electrons to combine with these nuclei and form stable atoms. Eventually the atoms coalesced into stars, planets, galaxies, and everything we can see.
even if universe is infinite and where would you start bang when you can consider any point in space as mid point in infinite space?

There is no single point that the expansion occurred from. It occurred everywhere and it is still occurring today. From the point of view of every object, everything else in the universe is moving away from it unless it is bound through gravity or some other force.

There should be some name given to outside or(if exist) emptyspace ... how would I calculate time out side of the space?

There is no such thing. It is a meaningless concept. It's like asking what does the color red taste like. Red isn't a flavor and there is nothing outside of the universe, as the universe IS everything.

jackmell
What do we call empty space outside our universe say space before taken over by our universe? or what do we call gaps between multiverse ? Further more, what is outside of multiverse (if we think about going as far as we can thinking crazy far).

It all makes perfect sense to me if we acknowledge our imperfect understanding of existence and accept the possibility of catastrophe points or "critical points" in that existence: your question is ill-posed because you're failing to acknowledge this and hence, you're encountering a paradox. That paradox is eliminated once you acknowledge the existence of such critical points, a dividing line which separates qualitatively different phenomena. We see critical points in natural phenomena throughout the Universe where a certain point is reached and the dynamics changes, abruptly and qualitatively (like water freezing) and there may exist a critical point at the Big Bang which separated some pre-existence from our own. If so, then using phenomena in our Universe such as "space", or "boundary", or "inside" or "outside" or distance, time, other metrics, may simply not be applicapable in describing phenomena (such as a boundary) outside of our Universein in the same way that the concept of swimming looses meaning on the other side of the critical point of freezing.

Gold Member
Dearly Missed
Yeah thank you for your explanation, I am studying masters level course, I need to learn Manifolds, Topology and more.. I still need to improve my skills and I love mathematics and Physics too.

If space say again old version of René Descartes, (I can take about new one after I learn it, still need lot of work to do in math..).. if x y and z along with T , say xyz must be infinite because they are dimensions ! Don't you think? ...

We live in Dimensions say Xyz it has to be infinite because they are Dimensions...

If you are fortunate and have a good teacher it will not be difficult for you. I guessed earlier from your writing that you like mathematics and I am happy to hear this from you directly.

When you come here and ask questions about physics and cosmology you will also be practicing using English, which is a good idea too, or so I think anyway.
=================

I cannot explain why I am curious about this---for some reason I am curious: I would like to know, if you would not mind telling me, what is the word for DIMENSIONS in your first language?

I am trying to understand why you imagine that dimensions must be infinite.

When you study the modern geometry of manifolds you will understand (I think) that frame of xyz dimensions is only used to APPROXIMATE nature's geometry in some specified NEIGHBORHOOD. The xyz frame only works well in some limited LOCAL region.

So to cover the whole manifold we need SEVERAL local maps. One map cannot say it all.
It does not work well enough when one gets too far from the home base. So we need several maps.

And the other thing that is new about manifolds is that where they OVERLAP the maps must be consistent with each other, perhaps allowing for a little distortion. One should be able to understand how to make them match up.

The manifold idea gives us a new conception of space, and of spacetime. So now it is possible for space to have Dimension (LOCALLY) and for space to be without boundary and yet be finite. And for space to be independent and free of any surrounding space. This is what I meant by "autonomous". It does not need to be embedded in any larger space. It can exist on its own and all its geometry can be described by the experience from within the space.

With manifolds we do not need "space outside of space", and space can have finite volume and finite circumference---or it can be infinite. Either one works, with manifolds.

Mark M
If universe is infinite then Big Bang theory would be wrong. why wrong because it say it all started off with a bang, any bang in empty space would never reach infinity no matter how large the bang is relative to the entire empty space seemingly empty (like real number scale till the infinity). Have we discovered center of the universe yet ? where the bang started up?

This is incorrect. There is no center to the universe, and the big bang wasn't an explosion. Is the collective name of the expansion of the early universe and the synthesis of the elements in the early universe.

I think the problem is that when you hear 'expansion' you think of an expanding balloon. However, when we talk about cosmological expansion, we refer to the growth of distances. If two bound systems (i.e. galaxies) are separated by some distance now (called the proper distance), then the proper distance at some later time will be larger. The galaxies themselves didn't move, just that there is now more distance in between them. And since this occurs in between every bound system, it follows that there is no center of the universe.

There should be some name given to outside or(if exist) emptyspace ... how would I calculate time out side of the space?

You can't, because no such place exists.

To add to marcus's excellent explanation, the reason we must treat the universe as a manifold is because we describe it with our most successful theory of gravity, general relativity. GR treats spacetime as a manifold, and that the curvature of this manifold creates the fictitious force of gravity. Along with being a theory of gravitation, we can apply to cosmology. It will place the requirement that, as marcus has been explaining, we can't think of the universe as having an edge or boundary. Instead, expansion is metric, as I explained above.

mpv_plate
...any bang in empty space would never reach infinity...

If the universe is infinite, it was infinite already at the moment of the big bang. It did not have to reach infinity.

The only difference between infinite universe today and at the moment of the big bang is, that at that time everwhere (in the whole infinite space) there was incredibly hot plasma... while today there are galaxies and intergalactic space. The infinite universe did not grow since the big bang: it is always just infinite. It may sound very strange, but it is possible: infinity allows such weird behavior.

So the big bang was not in one location. It was everywhere. Every single point of today's space experienced the hot inferno of the big bang. No matter if the point is on Eart, Neptune or in another galaxy.

In the case of finite universe it is a bit different, but even in this case it is still true that the big bang happened in every point of the space. The space itself is finite, but it has no boundary, because it is a closed manifold.

marty1
I believe that while it is statistically possible for a photon to never interact with anything, calling it "outside of the universe" is still incorrect. But I get your point.

Would you at least consider the first photons to exit the big bang to be at the edge of the universe?

pi = sqrt 10
In respect of vacuum, there are two theories:
First theory states that the vacuum is just newly created Born with the Big Bang united with time. According to that theory, the vacuum is mobile relative (Einstein)
The second theory states that the vacuum is eternal and independent of things , events and time, according to this second theory, the vacuum is an absolute constant static (Newton)
Nothing outside the Expanding Universe according to the first.
Independent and eternal vacuum is what exists outside the universe according to the second .

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Staff Emeritus
2022 Award
Would you at least consider the first photons to exit the big bang to be at the edge of the universe?

This is not how the big bang worked. Photons were created everywhere in the universe when it was hot and dense. There was nothing to exit from as the big bang was not an event within space. It was the initial expansion process. The name is a misnomer given by someone who was against the initial theory.

Where is T?...I would prefer more visual explanation.

I'm a layman. I have spent a few weeks working through the FAQs and the two substantial sticky threads (most helpful, highly recommended).

With all due deference and respect, someone must answer the OP in a way that satisfies the multitude of others (like myself) who have (or will have) the same question.

Though there may be reasons to dispute the "reality" of it, it seems undeniable that, with respect to the balloon analogy (BA), time is radial. There is no other reasonable place for it in the model, we are not disavowing time, so the OP is completely within reason to ask, “Where is T?”

When we speak of “the universe”, it is important to acknowledge that we refer to all space (and its contents) at a given instant. More specifically, we refer to all space for a set of comoving particles. But the universe “now” applies to just one layer of space within spacetime.

The whole purpose of the BA is to illustrate the expansion of that space. In admitting this, we must concede that the balloon will be bigger at all future times and smaller at all past times. Space, collected for these times, forms concentric layers like an onion. The next layer out is always larger than the one before it, demonstrating expansion with no obvious limit. Going the other way however, there is an obvious limit, at the center of the onion, which I think we must also admit is the region of the Big Bang event. The universe (now) does not contain the Big Bang event (a.k.a. singularity) but spacetime must.

Here’s the best diagram I could find on the net (admittedly, not at a scientific site). The balloon surface is a 3-sphere, a flat representation of all three spatial dimensions. One might imagine a school globe but, instead of an ordinary map on its surface imagine a hologram. Even though its flat it shows all three dimensions (latitude, longitude and altitude in this case).

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KiranKai
If you are fortunate and have a good teacher it will not be difficult for you. I guessed earlier from your writing that you like mathematics and I am happy to hear this from you directly.
Yeah, Good teacher? it's internet. I do not have any teacher yet. I have been learning things by my self. I am using online lectures so far I haven't found Topology or Manifolds lectures. I have to learn all these things. I am here because I am loner and I do not have anyone to talk about universe or science or physics etc.

When you come here and ask questions about physics and cosmology you will also be practicing using English, which is a good idea too, or so I think anyway.

I think you are exaggerating a little bit here. I may not be expert in english but I am using it everyday regardless tying to come to forum and improve in here. You can't anticipate things related to people or fathom their ability cos just they type something here. I have been to UK studied at Kings college london, No one ever had any problems with my english. Do you?

You just have a talk to person, just a practical talk then you can get the proper picture of any kind of person (In intellectual level). I know that I still need to improve but I am not that bad, like coming here to practice. I come here cos I am loner, I never had a friend and I have something to share.

Physics and Mathematics are my girl friends and I am Dyslexic so I am not that expert in learning things or What I mean is I learn things slowly.

=================

I cannot explain why I am curious about this---for some reason I am curious: I would like to know, if you would not mind telling me, what is the word for DIMENSIONS in your first language?

my name is kiran, the meaning of my name is Beam of light (with 3x10^8mts/sec). you can google it. DIMENSIONS<===> विस्तार pr. \\vistar\\ (magnitude and direction). But I do not use my first language to explain physics or science I explain in english with good satisfaction. Perhaps in time you will acknowledge it.

I am trying to understand why you imagine that dimensions must be infinite.
I will explain all the things that I had in my mind in next reply since it is little big.

When you study the modern geometry of manifolds you will understand (I think) that frame of xyz dimensions is only used to APPROXIMATE nature's geometry in some specified NEIGHBORHOOD. The xyz frame only works well in some limited LOCAL region.

yes ,I am limited to the xyz frame 3d+T with time, I would like to liaise with xyzt because it is more familiar with real world problems then Manifold geometry (I still need to learn it).
Experience as an astronaut in space when you deal with the same xyzt. I want to go with much real life situation then accurate geometry of manifolds.

So to cover the whole manifold we need SEVERAL local maps. One map cannot say it all.
It does not work well enough when one gets too far from the home base. So we need several maps.

And the other thing that is new about manifolds is that where they OVERLAP the maps must be consistent with each other, perhaps allowing for a little distortion. One should be able to understand how to make them match up.

The manifold idea gives us a new conception of space, and of spacetime. So now it is possible for space to have Dimension (LOCALLY) and for space to be without boundary and yet be finite. And for space to be independent and free of any surrounding space. This is what I meant by "autonomous". It does not need to be embedded in any larger space. It can exist on its own and all its geometry can be described by the experience from within the space.

With manifolds we do not need "space outside of space", and space can have finite volume and finite circumference---or it can be infinite. Either one works, with manifolds.

I will have fun with it when I learn something about manifolds. yeah but if a manifold is closed manifold, say closed universe which satisfies with Ricci curvature. Does it mean that all the dimensions end at closed universe or manifold ? so no outside grid of space time.

In GR, Einstein's field equation with ricci tensor says it universe is closed manifold then there is no dimensions considered out of it or out side of it.

well I will tell ,Why dimensions need to be considered infinite, please tell me if my understanding is correct or wrong in next reply.

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KiranKai
Why am I talking about outside universe ?

Time Line of the Universe
Credit: NASA/WMAP Science Team

There must be some external causes for

1.Quantum fluctuation (changes in amount of energy at a point in space)
2.Vacuum energy (73% vacuum energy in the background, 23% dark matter, 4% atoms and matter we see.) (negative pressure by vacuum energy resulted in rapid expansion of universe resulted in inflation)
3.after Inflation back to present day 13.7 billion years after big bang, accelerating universe also with the help of dark energy.

Quantum fluctuation
vaccum energy
Negative pressure due to inflation and many more reasons.

before formation of big bang and it's expansion. I imagined a grid relative to our own universe as background. therefore I considered it as space time infinity (Please correct me if I am wrong) so I called it outside the universe with relative to our universe.
it's my imaginary grid. I thought other external activities must have happened to cause this event.

Say if you are at most extreme outer edge of progressive expansion of universe. How light from your sun would travel in nothing with no spaceTime outside the universe (the background grid) or nothing?

If I use spaceship traveling close to wormholes connecting universe U1 u2 u3 u4 with wormholes w1 w2 w3 w4 in mutliverse system what is external space called ? which I considered as infinity xyz coordinate. so what do we call empty before big bang this nothing in space ? common background grid for rest of the multiverse in that way I considered dimensions to be infinite.

considering external system and external activity (which I considered) represented in 3d only space dimensions grid on our universe.

this is the way I understood it for myself, it's just the way I thought, please help me understanding this... like how light would travel away from our universe.

Note:Please correct me if I got it wrong at any point in understanding this way

Flatland
If universe is infinite then Big Bang theory would be wrong. why wrong because it say it all started off with a bang, any bang in empty space would never reach infinity no matter how large the bang is relative to the entire empty space seemingly empty (like real number scale till the infinity). Have we discovered center of the universe yet ? where the bang started up?

The Big Bang did not occur in empty space. How did you reach a master's level physics without knowing this?

To avoid being a distraction (sorry), I have copied my post to a new thread.

KiranKai
The Big Bang did not occur in empty space. How did you reach a master's level physics without knowing this?

Ha ha that is simple I reached masters level because I never had "The Universe" in my syllabus, I always read lots of books and watch online lectures even if I never had. I am not exactly saying it as space I am calling it outside process external and posted question what do we call outside among multivarse, You all are not understanding me at all.. I am unable to express my self more.

you see I am considering more here in terms of Dimensions using another reference frame.

you call yourself flatland if you would consider higher dimensions you would understand what I am referring to.

you live in flatland how come you reach 3d world ? you would see things differently once you advance to higher dimension.

You see you can't say to people like this, I am limited to express my self here in forums one on one face to face talking would be better.

you can't have universe without causing it to go bang, do you even know what caused it?
so you are saying no space what do you call this condition with no space.dimensions always exist

In string theory or Mathematical dimension rules when you zoom into something small you end up infinity like fractal geometry. you keep on getting dimensions within dimensions with in dimensions.. and so on... I considered it in large scale.

I just applied to master course I am not in masters course yet. How can you say I reached masters.

How did you reach a master's level physics without knowing this?
I never reached it yet, nor in my B.sc degree I never had universe syllabus, I am learning it so I am asking here whether I am correct in understanding it or not.

I never had anyone to discuss, it is obvious that I will not improve in understanding in anything. you say as if you are one perfect being in the universe and rest of us all useless before you.
How did you reach a master's level physics without knowing this?
saying something like this is too far long, you see we humans make mistakes, it doesnot mean that you would end up making fun of people's education degree. I clearly stated just correct me if I am wrong can't you just do it ?

say whatever you like (even without considering my feelings) yes I might be looser now but I will always try to correct my self and improve my self that's why I am here. I am not perfect being like you, you know. universe it's self big chaos. imperfection and complexity is it's true beauty.

May be 100s or 1000s of you might say things like this but I am here to correct my self so I am asking questions here.

Kiran,
Your English seems fine to me, I wouldn’t worry about it. I am not an expert but I have had questions similar to yours.

The NASA illustration is very nice but there are a few points to remember, since no illustration can get everything right. (You probably know many of these already.)

1) I think the time line at the bottom should be an arrow pointing right ($\rightarrow$), not a double arrow ($\leftrightarrow$). The Big Bang event (called "quantum fluctuations" in this illustration) at the left, is the beginning of time.

2) The illustration stops at time = now on the right side. Nothing comes out the right side. instead the right side continues to grow as time goes on into the future. A good guess is that it grows as fast as light can get there. Some would say it already goes on forever and contains all future events. (This is called a “deterministic” view). But the illustration, for convenience, stops at what we consider to be the present time.

3) If you consider any cross-section of the spacetime, at a particular moment in time. The cross-section from this illustration would be a flat disk but it represents all three spatial dimensions. The cross-section could be called a “3-disk”.

4) Inside the 3-disk is space and all its contents. Because the objects are flattened dimensionally, they would not be recognizable.

5) Your main question seems to be, “What is on the outside of these disks?” The answer can be simple.

Suppose I tell you that there are two points A and B, with no space between them. What could you say about the points?
You could say that A and B are “in contact” or “adjacent” or “touching” or “continuous”, etc.

Now consider a cross-section from the NASA drawing, with A and B on opposite sides of the 3-disk. Across the inside (like a diameter), there is space between A and B. But from the outside, there is nothing, not even space. A and B can be said to be “in contact” or “continuous”, etc.

The NASA illustration makes it look like the spacetime is embedded in some kind of space or dimension, but we have no evidence of this. This is the simple way to illustrate their spacetime.

In your first post, you drew a 3-disk with arrows all around pointing out (above). It is the same as the 3-disk at the right end of the NASA illustration, our present time. If you stretch the 3-disk so that it curves into a sphere, the bases of all the arrows will touch. That would make the 3-disk into a 3-sphere. The 3-sphere grows bigger, like a balloon as time passes. This is how the “balloon analogy” (BA) models the expansion of space.

I consider the Big Bang event at the center of the balloon with time as the radius, pointing out in all directions. Some people would see it differently. There are FAQs and many threads here on the balloon analogy.

Brainiac2
So the big bang was not in one location. It was everywhere.
.

And you believe that "everywhere" was created by the BB-correct?

KiranKai
How come anything would happen without spaceTime ?
All these quantum fluctuations, zero point energy in the background and inflation, bigbang to present universe all these process right from the start it always requires dimensions to happen.
Even before the process of Quantum Fluctuations.

Why all believe that space came to existence because of Bigbang? Space always existed even before it but I am not sure about the time.

for quantum fluctuations to exist we need Hilbert space to begin with, Space always existed even with or without bang or universe.

if I am wrong then prove me! what does it mean no spaceTime ? does it even exist?
Without atoms, matter, zero point enegry and dark matter without everything including energy in it (how energy would not exist ? energy always existed even without mass itself.. it need space to exist even without bang or no universe.) does it mean that there is no dimensions no space? (How can anyone call it nothing?) energy always existed!

say taking hypothetical time machine where I can travel before bigbang before quantum fluctuations where would I stand ? In time, consider I am from different universe allowing me to come before big bang. In this no spacetime Can I even move left-right, forward and back or up and down ? since no universe formed yet ?

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KiranKai
Kiran,
Your English seems fine to me, I wouldn’t worry about it. I am not an expert but I have had questions similar to yours.

The NASA illustration is very nice but there are a few points to remember, since no illustration can get everything right. (You probably know many of these already.)

1) I think the time line at the bottom should be an arrow pointing right ($\rightarrow$), not a double arrow ($\leftrightarrow$). The Big Bang event (called "quantum fluctuations" in this illustration) at the left, is the beginning of time.

2) The illustration stops at time = now on the right side. Nothing comes out the right side. instead the right side continues to grow as time goes on into the future. A good guess is that it grows as fast as light can get there. Some would say it already goes on forever and contains all future events. (This is called a “deterministic” view). But the illustration, for convenience, stops at what we consider to be the present time.

3) If you consider any cross-section of the spacetime, at a particular moment in time. The cross-section from this illustration would be a flat disk but it represents all three spatial dimensions. The cross-section could be called a “3-disk”.

4) Inside the 3-disk is space and all its contents. Because the objects are flattened dimensionally, they would not be recognizable.

5) Your main question seems to be, “What is on the outside of these disks?” The answer can be simple.

Suppose I tell you that there are two points A and B, with no space between them. What could you say about the points?
You could say that A and B are “in contact” or “adjacent” or “touching” or “continuous”, etc.

Now consider a cross-section from the NASA drawing, with A and B on opposite sides of the 3-disk. Across the inside (like a diameter), there is space between A and B. But from the outside, there is nothing, not even space. A and B can be said to be “in contact” or “continuous”, etc.

The NASA illustration makes it look like the spacetime is embedded in some kind of space or dimension, but we have no evidence of this. This is the simple way to illustrate their spacetime.

In your first post, you drew a 3-disk with arrows all around pointing out (above). It is the same as the 3-disk at the right end of the NASA illustration, our present time. If you stretch the 3-disk so that it curves into a sphere, the bases of all the arrows will touch. That would make the 3-disk into a 3-sphere. The 3-sphere grows bigger, like a balloon as time passes. This is how the “balloon analogy” (BA) models the expansion of space.

I consider the Big Bang event at the center of the balloon with time as the radius, pointing out in all directions. Some people would see it differently. There are FAQs and many threads here on the balloon analogy.

In my new diagrams I have considered space Time and space itself is flat. which starts from Quantum fluctuation like Nasa version.

Say Point A at the time of Quantum fluctuation, say point B, started to exist at 13.7 billion years 2011 Jan 20 time 20:12.

You can ask me what is the distance according to the diagram, The distance can only measured in time since space flattened in 2d like flatland. Time as third dimension.

Distance is time itself. 13.7 years difference. my problem is that I say space (Dimensions) always existed and it is infinite not universe as space (flattened 2d world in Nasa's and mine)
the Nasa's Image shows time line of our universe. but when there is nothing before bigbang no quantum particles no mass (enegry can't be created so always existed ). How come energy existed in nothing ? if Bigbang created spacetime. Energy should exist always even with or without bang or our universe. we should have dimensions only space even without bigbang.

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KiranKai
The Big Bang did not occur in empty space. How did you reach a master's level physics without knowing this?
energy neither can created nor destroyed, it always transforms from one form to another Where would energy exist if there is no space?

I learned to question textbooks, I learned to question things based on what people discovered so far. there are some people who stick to what textbooks or degree education says.

say that you live in world where textbooks say Earth as center of universe. you would obviously live and tell people that Earth is in center. I would like to rise question why? how? any proof ? Education is nothing but basic foundation rest is up to us to check it and change it if necessary there are some physicist in history who do not even have masters degree and yet they are honored for their achievements.

there are many correction being made in Master Degree level textbooks it self so where would I stand in correcting my self? why would you not think independently other than education by your own self. You are fixated to education knowledge, always question that education why?

tell me where would energy go without space before bang ?

Dmitry67
Discovery channel should be banned from making "educational" videos about Big Bang and the other stuff. Clearly, it does more harm than good.

KiranKai
Discovery channel should be banned from making "educational" videos about Big Bang and the other stuff. Clearly, it does more harm than good.

why? Histroy channel, BBC, pBS nova are making it too the universe series ?
Why saying so?