# How many dimensions are there in F-Theory?

• MathematicalPhysicist
In summary: The Oneyou didnt answer my question.The 10-dimensional IIB string theory allows two equivalent descriptions; one in which ordinary strings are very heavy while D-strings (1-dimensional D-branes) are very light, and one in which the opposite holds. This duality has a geometric interpretation in terms of two additional toroidal dimensions. But these appear not to be actual dimensions in the sense that the extra dimension in M-theory is. Although aspects of F-theory are known to originate in M-theory and have been useful tools in framing some 10-dimensional problems in terms of 12-dimensional geometries, it's ultimate meaning is unclear.Extra DimensionIn summary, the 10-
MathematicalPhysicist
Gold Member
f theory implies there are more time dimensions (if i remember correctly it is 2d).
could they have been curled up (i hope this is the correct term) like in the spatial dimension in string theory which are curled up and for that reason there are only three spatial dimensions?

p.s
how many spatial dimension are there in f theory?

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F-theory that is supposed to consist of 12 dimensions rather than M-theorys 11. Its controversial and experimentally tentative, some would say it has a strong "theoretical grounding" I think the implications of M-theory need to be fully understood before adding extra dimensions to it.

The One

The 10-dimensional IIB string theory allows two equivalent descriptions; one in which ordinary strings are very heavy while D-strings (1-dimensional D-branes) are very light, and one in which the opposite holds. This duality has a geometric interpretation in terms of two additional toroidal dimensions. But these appear not to be actual dimensions in the sense that the extra dimension in M-theory is. Although aspects of F-theory are known to originate in M-theory and have been useful tools in framing some 10-dimensional problems in terms of 12-dimensional geometries, it's ultimate meaning is unclear.

Extra Dimension

The extra time dimension, also called a dual time model and somewhat supported by QM evidence was postulated to explain some of the dual time supersymmetry issues for the most part. Its also at times called dual time supersymmetry.

And yes, form what I've read the extra time dimemtion in any model that posseses such is believed to be curled up like the extra spatial dimensions.

Yes.

Originally posted by LURCH
...I've read [that] extra time dimemtion in any model that posseses such is believed to be curled up like the extra spatial dimensions.

As I said, in the case of F-theory, the two extra dimensions aren't dimensions in the usual sense: There's no limit in which they decompactify to become normal spacetime dimensions. Although there are some applications of F-theory in which it is convenient to view one of the two extra dimensions as an additional "time" dimension, we do not view the F-torus as possessing a defacto extra time dimension. In fact, we're not sure what the ultimate significance of the F-torus or the rest of F-theory is.

Originally posted by paultrr
The extra time dimension, also called a dual time model and somewhat supported by QM evidence was postulated to explain some of the dual time supersymmetry issues for the most part. Its also at times called dual time supersymmetry.

What are you talking about and what does it have to do with F-theory?

There has been a dual time proposal within physics for some time now. Taking M-Theory as possibly the correct path, then if one is to add in this extra time as a dimension then you end up with a 12 dimensional frame. Check out http://www.aip.org/enews/physnews/1999/split/pnu462-1.htm and http://arxiv.org/abs/quant-ph/0210207 and Opposite arrows of time can reconcile relativity and nonlocality
S Goldstein and R Tumulka 2003 Class. Quantum Grav. 20 557-564 whome I cooresponded a bit back on this same subject. It may not be exactly you're F theory, but a possible 12 dimensional model exists once such is combined with regular M-Theory.

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I might also recommend checking out http://arxiv.org/PS_cache/hep-th/pdf/9606/9606176.pdf which does a good treatment of how the two theories can be related in general and I believe you will notice the treatment is such that a dimensional quality is maintained as far as the added dimension goes.

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Originally posted by paultrr
I might also recommend checking out http://arxiv.org/PS_cache/hep-th/pdf/9606/9606176.pdf which does a good treatment of how the two theories can be related in general...

In the context of this thread, what precisely do you mean by "good treatment"?

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F-theory is highly weighted on algebraic principles and determines more mathematical than physical phenomena (at least physical phenomena we currently know of). F-tori may actually be complexified using resonance theory to that of an M+2-torus where we keep the M-torus as as Rn manifold but merely add the 2 extra dimensions as complex numbers of the order C6 upon CY-manifold compactification. This method requires resonance between number fields and dimensions. Another resonance idea is that the number of dimensions for entropic astrophysical domains can be rendered in holographic "H-theory". H-theory requires that the astrophysical perturbations be 18-dimensional and that these are compactified into 2-dimensional Kb-surfaces called Klein Bottle universes for the internal space of a black hole. Hypersymmetry breaks the surface of the black hole and early cosmological supersymmetry as 18-dimensional world-sheets are intersected. Here 18 is the only known non-arbitrary number to have hypersymmetry ie. 8X8 has 16-dimensional representation so 9X9 has 18-dimensional representation. CY compactification having 6X6 in the form of F-theory and C6 being the root of 9-&asymp;1/2 relating asymptotically. Adding the 1-dimensional heterotic string intersect as a particle of spin 1/2 we then have 1X8 in the form of

9+9=18 and 18/2=9+9

A 2-dimensional surface compact for 18 is the hologram ie. the 2-dimensional non-orientable "emulsion plate" for the Poisson distribution of matter in the universe. Every distributed point in cosmological space-time is the superprojection S proj---> S/C6<--->Rn of hyperdimensional hypersymmetry. Hypersurfaces of dimension 2 resonate to supersymmetric gravity in the T2XK3 manifold symmetry by means of fibers S(T1) proj--->S(K3)/R2<--->Rn+2. It is these fibers upon the intersection of M+2-tori, via perturbations, that are angularly commensurate. Our 16-dimensional model also resonates across universes to the 18-dimensional as if they were two intersecting planar world-sheets with a string of variables. For this we have a superholographic point of projection π such that 16=µ3 : 18=∑2 and µ+∑=π1. Rep16 and Rep18 are maintained curviliearly by a margin of 2 dimensions and π1 as the superholographic projection of the intersecting particle domain.

Originally posted by loop quantum gravity
f theory implies there are more time dimensions (if i remember correctly it is 2d).
could they have been curled up (i hope this is the correct term) like in the spatial dimension in string theory which are curled up and for that reason there are only three spatial dimensions?

p.s
how many spatial dimension are there in f theory?

1) There are 10 spatial dimensions in F-Theory (just like in M-Theory, since the real difference between the two (AFAIK) is that F-Theory adds an extra time dimension).

2) I don't see why the other dimension should be curled up, but it is possible. An interesting point to consider is that, whether it is curled up or not, it would be a medium for time travel without time regress.

## What is F theory?

F theory is a theoretical framework in physics that attempts to unify the forces of nature, including gravity, electromagnetism, and the strong and weak nuclear forces. It is based on the concept of higher-dimensional spacetime, with 11 dimensions instead of the usual 4 dimensions (3 spatial dimensions and 1 time dimension) in our observable universe.

## What are curled dimensions?

Curled dimensions, also known as compactified dimensions, refer to the additional dimensions beyond the four that are "curled up" or compacted into tiny, unobservable sizes. These dimensions are theorized to exist in order to account for the fundamental forces of nature and explain the properties of particles.

## How does F theory explain the existence of curled dimensions?

F theory suggests that curled dimensions exist because of the shape and size of these dimensions determine the properties of particles and the forces that govern them. The curled dimensions are believed to be too small to be observed directly, but their effects can be seen in the behavior of particles and the laws of physics.

## What is the significance of F theory and curled dimensions in understanding the universe?

F theory and curled dimensions offer a potential explanation for the fundamental forces of nature and the properties of particles. It also provides a possible solution to the long-standing problem of unifying gravity with the other three forces. If proven to be true, F theory and curled dimensions could greatly advance our understanding of the universe and lead to new discoveries in physics.

## What evidence supports F theory and curled dimensions?

Currently, there is no direct evidence for F theory and curled dimensions. However, some aspects of these theories, such as the existence of extra dimensions, are supported by other areas of physics, such as string theory, which is another attempt to unify the forces of nature. Further research and experimentation are needed to provide more evidence and potentially confirm or disprove F theory and curled dimensions.

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