beyond the expanding universe

Originally posted by sonhouse
It will cause a lot of rethinking about embedded dimensions and such. Just because we can show mathematically other dimensions are not needed for relativity to work does not mean there are no other dimensions.

Yes off course. Everything I said was taking into account only present day knowledge but I know that knowledge evolves.

But what I was trying to say is that we are accustomed to think to spaces embedded in higher dimensional spaces for them to be curved but with the Universe such thing isn't necessary.

Originally posted by adam warlock
Yes off course. Everything I said was taking into account only present day knowledge but I know that knowledge evolves.

But what I was trying to say is that we are accustomed to think to spaces embedded in higher dimensional spaces for them to be curved but with the Universe such thing isn't necessary.

My problem is how can that happen physically if there are no extra dimensions? How can something (the universe) wrap itself around nothingness? It would imply something there that it could have a reference to ALLOW it to curve in on itself.

Originally posted by sonhouse
My problem is how can that happen physically if there are no extra dimensions? How can something (the universe) wrap itself around nothingness? It would imply something there that it could have a reference to ALLOW it to curve in on itself.

No! The thing is that on our Universe the metric isn't constant. It changes in space and time due to matter/energy presence. On top of that we don't what the natural metric of the Universe (if the Universe is plane parabolic or hyperbolic) .

I can't really really explain this anybetter than this. Here what is fundamental is the concept of metric. On our everyday life the metric is Euclidean and constant and that's why we got this bad habits of thinking that things need to be embedded in higher dimensional spaces, but if the metric changes things don't have to be like that.

I don't think that we can visualize this (at least I know I can't) but that doesn't mean it is impossible.

Originally posted by sonhouse
My problem is how can that happen physically if there are no extra dimensions? How can something (the universe) wrap itself around nothingness? It would imply something there that it could have a reference to ALLOW it to curve in on itself.

you are trying to see a 3D deformation with an immutable 3D background where things happen. The wrapping is not around something. The wrapping is space itself.
That's a question as good as asking "what's besides universe"?

Originally posted by serigado
you are trying to see a 3D deformation with an immutable 3D background where things happen. The wrapping is not around something. The wrapping is space itself.
That's a question as good as asking "what's besides universe"?

Yes, space is what I am talking about. I seems to me if space 'bends' then what is there that is outside the bend? I don't see how space can just float in a nothingness of undefined non-space. It seems more intuitive to me there is a something that space floats in, and that something seems to me (of course I can be totally wrong) to be another form of space, maybe other dimensionality of some sort.
It just seems we are beginning to see through the beginning of the big bang and there had to be something there for our universe to form from and into. If you define space as what our universe is made of, then what was it it then what was there before there was a universe? Nothingness leads to something? I doubt that very much.

Originally posted by sonhouse
Yes, space is what I am talking about. I seems to me if space 'bends' then what is there that is outside the bend? I don't see how space can just float in a nothingness of undefined non-space. It seems more intuitive to me there is a something that space floats in, and that something seems to me (of course I can be totally wrong) to be another form of space ...[text shortened]... as there before there was a universe? Nothingness leads to something? I doubt that very much.

I don't know how to answer that for sure: no one does. And it may be beyond our capacities. But in the light of the current models you can't see that "something" space floats in. It might existl only abstractly to explain mathematics of the space.time, but it doesn't make sense physically. As for time, try to imagine it as something that doesn't go on linearly. We see it that way because we are "time-bonded". We "happen" as time goes by, so it's difficult to assume anything else then a linear time frame, but again... We are limited to our own perception of reality, and true reality is not like that.

Originally posted by serigado
I don't know how to answer that for sure: no one does. And it may be beyond our capacities. But in the light of the current models you can't see that "something" space floats in. It might existl only abstractly to explain mathematics of the space.time, but it doesn't make sense physically. As for time, try to imagine it as something that doesn't go on line ...[text shortened]... . We are limited to our own perception of reality, and true reality is not like that.

But we have on big advantage over the universe, we dream, we imagine. So we can try different ideas and see if we can punch holes in them and so far we come up with ideas that views the universe as just one of many and that does not necessarily mean there are other dimensions, space, the space outside our universe could just as well be infinite but our little bubble we call the universe just one bubble and I use the term bubble to mean whatever shape the universe really is, bell shaped, hexagon, whatever, just one of many. We are finding out more than we ever dreamed we could from the study of the CMB, the latest being we see the evidence now of the universe being filled with extremely low energy neutrino's just a smidge above absolute zero in temperature and penetrating our bodies by the millions each second, but totally undetectable by any means on earth, only through the cosmic microwave background radiation and the deep study of it going on right now. There are hints we may be seeing evidence of giant strings or some kind of spacetime break in our universe, so stick around, we are going to figure it all out in the next few decades.

Originally posted by FabianFnas
No, wrong. Not within science.
Universe [b]is everything. It has no boundary to anything else.[/b]

i would like to give my opinion: universe is everything but it does have boundaries.

after all, the bing bang singularity had finite volume(0). so it is more correct to say that although the universe has boundaries, you cannot go across them because there is nothing across those boundaries.

Originally posted by serigado
You need the metric of your space (how far from each other are two different points in your surface or hyper-surface). In a sphere it is easy, but in real world, general relativity says we need to include the dynamical variable time to describe that same metric. And that it is dependent on things like mass, that can be assigned positions in that 4 dimension verse is not really expanding into something. It's simple the metric that is being changed.

"When you see expansion of the Universe, the universe is not really expanding into something. It's simple the metric that is being changed"


interesting. so distance between two points stays the same but time changes. this might be correct but to me it seems a much more complicated way of describing the same result. since time is related to space (time-space), you can say that one is constant and the other is expanding. (or both are expanding at the same time one faster than the other). but it is easier to say that the size of the universe is getting bigger

in regards to the extra dimensions that we cannot perceive:

they are contained within our own universe. you cannot say that the n-th dimension(n>3) exists outside this universe because outside the universe there is not time, nor space. so how can a dimension exist in nospace?

they are simply invisible to our senses. like an ant walking on a piece of paper not being able to go anywhere but on that plane

Originally posted by Zahlanzi
"When you see expansion of the Universe, the universe is not really expanding into something. It's simple the metric that is being changed"


interesting. so distance between two points stays the same but time changes. this might be correct but to me it seems a much more complicated way of describing the same result. since time is related to space (time- ...[text shortened]... ster than the other). but it is easier to say that the size of the universe is getting bigger

It's a lot more complex then that. You're trying to understand difficult concepts without knowing their definition.
I see people doing their interpretations of "space-time", big-bang, dimensions, without having studied what they are, many times doing transpositions to religious viewpoints or trying to fit their personal viewpoints of the Universe.
There's a good reason why these concepts are only taught in the last years of advanced physics courses. They're difficult, and even good physics students commonly misinterpret them.

There are somethings we are better off not trying to understand, this is one, because if the universe is expanding, into something that isn't there, how can it expand, because if it can expand, it means that there has to be something there or else it couldn't expand.

This just makes you wonder to much and now has me looking out the window trying to figure out something that no one at all understands.

Often I see in textbooks and in popular books in astronomy and cosmology an illustration depicting the BigBang - as an explosion in yellow and white colours in a black surrounding and background. It is not. It is not possible to imagine an explosion like this.

An explosion is something that explodes into something, the universe during the BigBang is not. Try to skip the image of the explosion into something black and empty. Don't have this image in your head, because it is heavily false.

In the moment (or right after) it was an massive expansion everywhere in the universe. Not somewhere in particular, but the entire universe at the same time. This expansion happens even today, everywhere. At this time the universe was hot, so hot that matter and light interacted. It was hot because it contained as much energy as we have to day but in a very smaller volume. Eventually it became colder. At a particular stage the temperature dropped below the point where matter and light didn't interact any longer, and the universe became transparant. From this stage the background radiation emanates, now very red shifted into maicrowave radiation.

You cannot ever see the universe from the outside. There is no outside. Therefore you can only observe the unvierse from within. Every attempt to do otherwise is futile, because univers isn't like this.

So if you will try to imagine universe, how it looks, during the BigBang, then you will see nothing but bright light, nothing more. No background, nothing else, only bright light.

Originally posted by FabianFnas
Often I see in textbooks and in popular books in astronomy and cosmology an illustration depicting the BigBang - as an explosion in yellow and white colours in a black surrounding and background. It is not. It is not possible to imagine an explosion like this.

An explosion is something that explodes into something, the universe during the BigBang is no ...[text shortened]... l see nothing but bright light, nothing more. No background, nothing else, only bright light.

This is according to our present knowledge. I have a funny feeling this scenerio will change in the coming decades as we figure out more and more about this closed universe we find ourselves in. For instance, as I have said before, if one of the conjectures is true, that our universe is the inside of a black hole and thats what happens to most or all black holes then there is in fact something the universe expanded into, or at least from. It seems to me if you could take a typical black hole and measure the size you would find internal metrics making it appear to be very large indeed, but we can 'see' the outside of the black hole and know it has X,Y,and Z such and such dimensions and mass so there would be an obvious differance between the outside from our perspective and the inside from their perspective. So it might be we would see infinity inside a teacup but from the outside a teacup is just a teacup. If that were to be the case, then you would seemingly have to invoke other dimensions to account for this. How else would you describe it? If we see the up and down and left and right and in and out as such and such outside the black hole and inside the box the dimensions are obviously multiple light years across, that would seem to me to be sticking into another dimension by definition.

Originally posted by serigado
It's a lot more complex then that. You're trying to understand difficult concepts without knowing their definition.
I see people doing their interpretations of "space-time", big-bang, dimensions, without having studied what they are, many times doing transpositions to religious viewpoints or trying to fit their personal viewpoints of the Universe.
There' ...[text shortened]... ics courses. They're difficult, and even good physics students commonly misinterpret them.

this post didn't explained anything, just told me i am to ignorant to comprehend those notions. try and explain. and tell me why is more logical(not more mathematical convenient) to add a spatial dimension instead of a temporal one.