# Dimensions

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#### Fallingstar1971

##### Guest
I know that General Relativity and Quantum Theory both play by their own sets of rules......

Is it possible that we are observing two separate dimensions within our dimension? On the one side of our dimension is the very large dimension, on the other side of our dimension is the very small dimension. Since we exist between them, it makes it possible for us to observe them both. And now since they are separate dimensions, they are each allowed their own sets of rules as long as they are compatible with our dimension?

Its just that when you think about things like "Are their higher dimensions?" and consequently "Are their lower dimensions?" (Thinking a bit about string theory on that one), I got to thinking, if you can have higher and lower, why not bigger and smaller?

Its just a thought

Star

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#### ramparts

##### Guest
Well, I don't know what you mean by "higher" and "lower" dimensions, but that's not really a distinction. By "higher" dimensions we mean anything beyond the standard four, no one really speculates if there are "lower" dimensions

As for bigger and smaller dimensions, well, sure, that's a distinction that does exist, but your idea doesn't really make much sense. How can there be two separate dimensions within another dimension?

Think of dimensions as being directions - when we say there are three spatial dimensions, we mean up/down, left/right, and front/back. So it doesn't really make sense to think of there being two separate dimensions somehow within our own, or something.

Oh, also you can't really talk about "our dimension". Which dimension is that - up/down? Forwards/backwards in time? However many dimensions exist, four or more, we live in all of them.

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#### Fallingstar1971

##### Guest
I gave myself a headache just trying to think of a way to express this, I did the best I could........

I understand the directional thing. Its the only way to accept "higher" and "lower" dimensions. These are poor choices of words, I know. But to be politically correct, I will simply say *other* dimensions (or directions) that we are not capable of looking twords. Along with left-right, up-down, forward-backward,now we have big-little as well (Im thinking flatland minus the big-little part)

However, if my hypothesis is correct, then it would be perfectly OK for GR and QT to have different rules. They behave like they are two separate, incompatible, phenomena. To physicists, this is bad. It goes against the one theory for everything because they cant force a relationship between the two. Universally, they should both rule their own respective Universes, yet here they both exist at the same place at the same time, contained within one larger universe.

Im saying that this is acceptable because they very well could be their own "directions" so to speak. We, as people, observing this reality, have the unique perspective of seeing BOTH dimensions at the same time. Like a "pocket" separate from the universe where one set of laws can apply, and another "pocket" where the other set of laws apply. We are on the outside (for once) and can see them both pockets in the same place at the same time.

Of course, this may be totally wrong, and I can accept that. Its just an idea that I wanted to share. It doesn't change anything but perspective. All the math and theories for each "realm" remain the same. I'm just trying to express a reason why its different, and why it OK that its different.

Of course, it very well could simply be, because it is different, for no reason what so ever.

Star

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#### PJay_A

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This is a subject I've been in deep thought about for the past couple of years. Do yourself a favor and watch Elegant Universe (aired on PBS' Nova) as well as Parallel Universe (aired on BBC's Horizons and picked up in the U.S. by the Science Channel). Both programs can be found on YouTube.

Basically, there is mathematical "proof" that there exists eleven dimensions in total and that Universe we live in is part of a "multiverse". In addition, the 3D world we live in is but a "membrane", on the "skin" of dimensions invisible to us and that all objects - no matter of the perceived distance - are all somehow connected via extra-dimensional space.

I have learned how to visualize (imagine) 4D space. It took some time and mental training to do. Once you achieve it, you can start to see how things just start making sense - that the reason why things are they way they are can only be understood once you consider possible extra dimensional properties shaping its "invisible" reality!

I'm confident this will be proven in our lifetime through the LHC or other means. You will see that Quantum Mechanics and Relativity are but peices of a large "puzzle" to a much greater unseen (yes, strange) 11-dimensional reality.

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#### ramparts

##### Guest
Fallingstar, we see the effects of general relativity and quantum mechanics in our standard four dimensions. In fact, that's what GR is - it describes how those four dimensions behave. So they have to co-exist somehow. And to you, then, I pose this question: in situations when both theories are important (i.e., the centers of black holes and the very early universe), what happens? Clearly something has to happen, the two theories can't be irreconcilable all the way down.

PJay, while the ideas you're talking about are certainly possibilities (and rather popular ones), they're absolutely not proven, by any stretch. Brian Greene (who narrated The Elegant Universe) actually made a point, if I recall, of the fact that this is all quite untested so far.

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#### csmyth3025

##### Guest
Ramparts,
A thought occured to me when reading these posts about extra dimensions. We live in a world of 4-dimensional space-time (as far as we know currently).

Stealing an analogy from popular explanations of General relativity, suppose our 4-dimensional space-time is the equivalent of the proverbial 2-dimensional rubber sheet and we are the equivalent of flatlanders living on that rubber sheet. If there is mass ("normal" mass) in a dimension "vertical" to our "2-dimensional rubber-sheet world" would we be able to detect it? Could this mass, which exists at right angles to the dimensions we can see, still deflect our rubber sheet world and produce a distortion which we perceive as unaccounted for gravity (aka Dark Matter)?

I'm sure I'm not the first person to ponder this question. Since you seem to keep up with this sort of thing, I'm wondering if you know of any work (probably mathematical) that follows this line of speculation.

Chris

ramparts":385p49bk said:
Fallingstar, we see the effects of general relativity and quantum mechanics in our standard four dimensions. In fact, that's what GR is - it describes how those four dimensions behave. So they have to co-exist somehow. And to you, then, I pose this question: in situations when both theories are important (i.e., the centers of black holes and the very early universe), what happens? Clearly something has to happen, the two theories can't be irreconcilable all the way down.

PJay, while the ideas you're talking about are certainly possibilities (and rather popular ones), they're absolutely not proven, by any stretch. Brian Greene (who narrated The Elegant Universe) actually made a point, if I recall, of the fact that this is all quite untested so far.

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#### ramparts

##### Guest
Hey Chris - Well, a lot of people have speculated about higher-dimensional matter (that is, matter analogous to your vertically extended matter), although the beauty of extra dimensions is that they get you to very interesting places without invoking such matter, so generally for simplicity's sake they're less often utilized. There are also certainly restrictions on it, and the flatworld analogy works great for this - imagine you're living in Flatland, and there's stuff above you. You'll find yourself pulled up to a different flatland slice, but since you have no idea what "up" is, all you see is the rest of your world completely disappear So there's restrictions there.

In fact, there is a very popular set of theories - generally called braneworld theories - in which there are other, usually compact dimensions which experience gravity, but the other major forces are restricted to our brane, or our 4D world, so from our perspective the gravity is "leaking" out into the other dimensions. This naturally explains the so-called hierarchy problem, the observation that gravity is so much weaker than the other forces, which is why these theories are especially popular.

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#### csmyth3025

##### Guest
ramparts":1ex11igp said:
Hey Chris...
...In fact, there is a very popular set of theories - generally called braneworld theories - in which there are other, usually compact dimensions which experience gravity, but the other major forces are restricted to our brane, or our 4D world, so from our perspective the gravity is "leaking" out into the other dimensions. This naturally explains the so-called hierarchy problem, the observation that gravity is so much weaker than the other forces, which is why these theories are especially popular.

There's an interesting comparison of the relative strengths of the electomagnetic force vs gravity in the Wikipedia article on fundamental forces. Summarizing the relevant portion:

"...To get an idea of just how strong the electric force is, let us make a calculation. In a 1-gallon-U.S. (approx. 4 liter) jug of water, there are approximately 4,000 grams of water or...[210000000 C]...of total electron charge. Thus, if we place two such jugs a meter apart, the electrons in one of the jugs repel those in the other jug with a force of...[4.1x(10e26) Newtons]...This is larger than what the planet Earth would weigh if weighed on another Earth! The nuclei in one jug also repel those in the other with the same force. However, these repulsive forces are cancelled by the attraction of the electrons in jug A with the nuclei in jug B and the attraction of the nuclei in jug A with the electrons in jug B, resulting in no net force..."

I've read about theories that postulate the "leakage" of gravity to other dimensions, but I can't fathom why gravity, but no other forces, would be subject to such leakage.

Chris

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#### ramparts

##### Guest
Well, it comes down, as I said, to gravity propagating through all dimensions and the other forces (like electromagnetism) only propagating through our four dimensions, or through our "brane". The question then, is why gravity behaves one way and the other forces behave in another. The simple answer for gravity is that if it's an effect of spacetime, then by definition it should exist in all dimensions. Why the other forces would be constrained to our brane I don't know - that is, I don't know what the current speculations are. I see no reason for them to necessarily propagate in all dimensions, though, if (unlike gravity) they're not effects of spacetime curvature.

There are also unified theories, such as the Kaluza-Klein theories, which describe E&M as a 4-D effect of higher dimensional gravity, which is pretty cool. Projections from higher dimensions, if you want to look at it that way. That's one possible explanation.

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#### darkmatter4brains

##### Guest
I think all these misc theories just show how we hardly know what the heck is going on :lol: I like how we're spending enormous efforts to develop String Theory, which will expand the Standard Model and gravity into one unified theory, but we don'e even know if the Standard Model is right? What if we don't find a Higg's Boson at the LHC. We may have to rethink everything!

The Higg's Boson is pretty funny too. The Standard Model, which most people consider mathematically unattractive, has a major shortcoming - it says nothing should have mass. (I won't even mention the dozen+ free parameters that are needed to even make the theory work). Well, that sounds like a major problem to me. So what do we do - come up with the Higgs Field to repair what already seems to be a theory which leaves much to be desired. I'm not saying it's wrong either - it's just that we have a lot of work to do I think.

Also, all the current efforts, whether it's the Standard Model, String Theory, some brane theory, etc., all seem to share two things in common. One, they are mathematically disgusting and extremely complex. This seems to moving away from the original goal of simplicty and beauty, which was desired in any physical theory. Granted they are conceptually elegant, but the details are disgusting.

The other thing that many seem to share in common is that they utilize higher dimensions, which brings me back to the main point I wanted to make. I personally feel that somehow higher dimensions are going to play a strong role in whatever we do eventually find to be the correct theories of phyics in the future.

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#### undidly

##### Guest
ramparts":3g08gfp8 said:
Well, it comes down, as I said, to gravity propagating through all dimensions and the other forces (like electromagnetism) only propagating through our four dimensions, or through our "brane". The question then, is why gravity behaves one way and the other forces behave in another. The simple answer for gravity is that if it's an effect of spacetime, then by definition it should exist in all dimensions. Why the other forces would be constrained to our brane I don't know - that is, I don't know what the current speculations are. I see no reason for them to necessarily propagate in all dimensions, though, if (unlike gravity) they're not effects of spacetime curvature.

There are also unified theories, such as the Kaluza-Klein theories, which describe E&M as a 4-D effect of higher dimensional gravity, which is pretty cool. Projections from higher dimensions, if you want to look at it that way. That's one possible explanation.

""Why the other forces would be constrained to our brane I don't know .""

Are they?.
Magnetism,yes.
Magnetic lines of force (I know they are not real) travel FROM and TO the magnet in our brane that is why there are no magnetic monopoles.
Electrically charged particles are monopoles so where do the lines of force return,or do they extend to infinity?.
I suggest they return through an extra spacial dimension.
If we could observe the electric monopole from the other side it would be of the reverse polarity.

Magnets have both poles in our brane.
Electric charges have one pole that we can see and the other at right angles to our brane (where we cannot see,measure or observe it).

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