# The Fouth Dimension

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Well this is my first post and I'm kinda getting the hang of physics and one of my favorite topics is the different "realms" or dimension. One question I have is, is there proof that there is a fourth dimension. And if there is how can we get there?

time.

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Most modern theories have more then 4 dimensions.

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No, I think time is the first dimension because time controls the second and the third dimension.

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The assignment of numbers to dimensions is arbitrary.

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In fact, one usually lables time as dimension number '0' (or at least , I do).

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To the best of my understanding, none of the major considerations of higher dimensions imply that the other (spatial) dimensions are the same as the normal three we experience. Time is its own thing, of course, and yes it behaves like space in many ways, but as far as the other ones go, I don't think it's possible to "get there," really. Some of them are even said to be finite in some sense; that is, once you go so far in the nth dimension, you're back where you started, so you get a looping sort of effect.

The closest sort of thing to the scifi you probably want, I would think, would be the concept of "imaginary time" as relates to alternate histories/futures. If you could traverse a distance of imaginary time, you might end up in a world where English muffins were called French muffins, or where Hitler won WWII, or where the sun exploded, etc. But I think Hawking says it's absolutely impossible to travel between these parallel universes, and consideration of their "existence" is not a whole lot more than a mathematical model for our observations of this universe.

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Well I found this website that explains the fourth dimension or also known as "tetrapace". http://tetraspace.alkaline.org/

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Well I found this website that explains the fourth dimension or also known as "tetrapace". [url']http://tetraspace.alkaline.org/[/url]

That site's a load of crap.

Spacetime has four dimensions (as Sverian indicated these days the convention is take time as the 'zeroth dimension', but it is only just a convetion and it doesn't really matter, infact rather than assigning numbers we could assign the names 'John', 'Paul', 'George' and 'Ringo' if we wanted), for any given obsrever 3 of them will be the three dimenisions of spaceas experinced by him (i.e. 'space' for some observer is a hypersurface of spacetime) and one will be his time dimensions.

I personally like to think of thing in terms of vector spaces, so a dimension to me is just the cardinality of the largest set of linearly indpendent vectors.

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Supersymmetry introduces new 'fermionic' directions to space-time (our normal directions are 'bosonic') so if that turns out to be true then I suppose you could say there are more than 4 dimensions.

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In fact, one usually lables time as dimension number '0' (or at least , I do).

Depends. That convention follows in relativistic quantum field theories. In classical relativity, on the other hand, time is usually in the fourth component of a 4-vector.

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Spacetime has four dimensions
Not necessarily. GR has 6. Most people are taught classical relativity in high school and college unless one is perusing a degree in physics. The ideas of the standard model of relativity is largely because of the work done by Friedman. Einstein didnt like the idea until 2 years after the publication, then decided it served as a better mathematical model because it incorporate the electroweak forces. Later attempts at adding more dimension to the theory (to incorporate the strong force) have ben unsuccessful, though there are some models that may get some attention if a 5th force is discovered (hense the God Particle that will be looked for in Switzerland).

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1veedo, how sure are you about that? I've never heard about relativity having more than 4. What are the other two?

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Not necessarily. GR has 6.

GR is a theory in four dimensions, not six. That much is obvious from the mere name given to GR's principal subject of study, space-time.

Most people are taught classical relativity in high school and college unless one is perusing a degree in physics.

Most people are taught classical relativity?

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Not necessarily. GR has 6. Most people are taught classical relativity in high school and college unless one is perusing a degree in physics. The ideas of the standard model of relativity is largely because of the work done by Friedman. Einstein didnt like the idea until 2 years after the publication, then decided it served as a better mathematical model because it incorporate the electroweak forces. Later attempts at adding more dimension to the theory (to incorporate the strong force) have ben unsuccessful, though there are some models that may get some attention if a 5th force is discovered (hense the God Particle that will be looked for in Switzerland).

No offence, but did you just make all of that up!

1) spacetime in both the special and general theory of relativty has four dimensions

2) Friedmann's main contribution was his equations, howvere he died when relativty was still very young consquently he did not have a major influence on how relativty is viewed today.

3)The theory of the electroweak force orginated in the 1970's, Einstein died in 1955.

I think you may be slightly confused with Kaluza-Klein theory which was an early failed attempt at uniting general relativty and electromagnetism by introducing a fifth spatial dimensions, later some of the ideas from this theory were used in braneworld and stringy theories.

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Tetraspace, you sound like you'd be interested in string theory. Click here for a great website on the string theories. In this theory, there are thought to be at least 10 dimensions.

Quarks and Gluons (sub-sub-atomic particles if you will ) are thought to exist in 10-14 dimensions

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Not necessarily. GR has 6. Most people are taught classical relativity in high school and college unless one is perusing a degree in physics. The ideas of the standard model of relativity is largely because of the work done by Friedman. Einstein didnt like the idea until 2 years after the publication, then decided it served as a better mathematical model because it incorporate the electroweak forces. Later attempts at adding more dimension to the theory (to incorporate the strong force) have ben unsuccessful, though there are some models that may get some attention if a 5th force is discovered (hense the God Particle that will be looked for in Switzerland).

I don't think there is a single correct statement in that entire post!

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I think you may be slightly confused with Kaluza-Klein theory which was an early failed attempt at uniting general relativty and electromagnetism by introducing a fifth spatial dimensions, later some of the ideas from this theory were used in braneworld and stringy theories.

There has been a resurgence of interest in KK theories lately as an alternative to the Higgs mechanism. People have realized that our experiments have not really ruled out KK theories with rather small compactification scales (ie. not curled up very tightly), so they would be a possible method for breaking electroweak symmetry. IIRC they have to have at least 2 extra dimensions to keep the compactification scale low enough to work though

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I got lots of response on this.

No offence, but did you just make all of that up!

1) spacetime in both the special and general theory of relativty has four dimensions

2) Friedmann's main contribution was his equations, howvere he died when relativty was still very young consquently he did not have a major influence on how relativty is viewed today.

3)The theory of the electroweak force orginated in the 1970's, Einstein died in 1955.

I think you may be slightly confused with Kaluza-Klein theory which was an early failed attempt at uniting general relativty and electromagnetism by introducing a fifth spatial dimensions, later some of the ideas from this theory were used in braneworld and stringy theories.

Maybe it was Feyman, but I didnt think he had much to do with relativity; sum-over-paths... I know, from Greene’s The Elegant Universe that after Eienstein presented his theory of general relativity, another scientist suggested a new model that incorporated electromagnetism and the weak nuclear force (by using 6 dimensions). Eienstein didn’t like his ideas at first but later, like his cosmological constant, admitted to the validicity of the model.

One of our physics teachers at my high school, whom I took computer science from, talked about how he “didnt like the new physics book” one day because it only taught “the classic model” and “left out the 6D theory”.

(PS. I just shortened the two forces for electroweak so I didnt type both of them; I was not refering to cosmology)

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