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[] Personally I think that there are 12 dimensions comprising of height,length,breadth,space-time,speed,mass,force,energy,distance,direction and electric charge

in m theory the extra five dimentions as follow M-theory on circle IIA in 10 dimensionsWrap membrane on circle IIA superstringShrink membrane to zero size D0-braneUnwrapped membrane D2-braneWrap fivebrane on circle D4-braneUnwrapped fivebrane NS fivebrane

well i found on a website that the first four are definitely height width length and time 9 width is also known as breadth) and the rest is Extra dimensions in string theory Superstring theory is a possible unified theory of all fundamental forces, but superstring theory requires a 10 dimensional spacetime, or else bad quantum states called ghosts with unphysical negative probabilities become part of the spectrum. Now this creates a problem in d=10 string theory: how to get the d=4 world as we know it out of the theory. So far there are two main proposals: 1. Roll up the extra dimensions into some very tiny but nonetheless interesting space of their own. This is called Kaluza Klein compactification.2. Make the extra dimensions really big, but constrain all the matter and gravity to propagate in a three dimensional subspace called the three brane. (For an analogy, your computer screen could be said to be a two brane of three dimensional space.) These types of theories are called braneworlds.

I found this:http://www.physicsforums.com/showthread.php?t=273388 [Links inactive - To make links active and clickable, login or click here to register]Quotein m theory the extra five dimentions as follow M-theory on circle IIA in 10 dimensionsWrap membrane on circle IIA superstringShrink membrane to zero size D0-braneUnwrapped membrane D2-braneWrap fivebrane on circle D4-braneUnwrapped fivebrane NS fivebraneSo I believe the full list of M-theory dimensions are as follows, The four spacial dimensions, gravity, space-time(as one) then wrap membrane, shrink membrane, unwrap membrane, wrap fivebrane, and finally the unwrap fivebrane I saw somewhere a person depicted them like layersunwrap fivebrane $$$$$$$$$Unwrap membrane ^^^^^^^^3 dimension Spacial or gravity ectShrink membrane(At a guess I'll put it in the middle, but I think this is the string dimension it has no opposite)3 dimensions Spacial or gravity ectwrap Membrane ########### wrap Fivebrane ************In all they form a bubble, which leads to the idea of a multi-verse made of many bubble universes.I know that is off, but at the same time it's in the right vain, so hopefully someone else can clarify the errors

In a way I like string theory and branes (M theory). Probably because I expect SpaceTime to be smooth and as we're talking about one dimensional 'strings' 'loops' (loop quantuum theory) or/and 'branes'. It makes a very weird kind of sense. But I do not like the idea of dimensions as 'singular' entities. I don't think SpaceTime is defined like a 'Lego' myself. I think of it as a Jello where all goes into each other and the arrow of time creates 'particles' for us. At least I do so for the moment When it comes to charge as a 'dimension'? I'm still not sure what a dimension should be seen as? But if you take something, not measurable in its own right but only as a outcome of a interaction, and lift it up to a dimension you will have problems. Myself I'm thinking of 'Gravity' as a possible 'dimension', that and 'energy'. Both because I expect them to exist everywhere a 'SpaceTime' exists, but then we come to what we can quantize and there it seems as 'energy' only comes in 'quanta' which differs it from 'gravity', as far as I know. 'Charge' and 'energy' seems both to be quantize-able whereas 'gravity' still isn't. But I'm not sure on anything in fact ==You might want to define a wave as continuous, and so define 'energy' as continuous too, and you might be perfectly right there? But then we have 'frequency' and defining a 'wave' as 'vibrating', creating those 'peaks & throughs' defining its 'energy'? Gravity doesn't, yet ==To see what I mean you can consider 'gravity propagating', like away from those binary stars spinning around each other. There you have two points of view to choose between. Either define it as a 'gravitational radiation' propagating at some 'frequency', or do as I and see it as the 'Jello' distorting itself, the 'distortion' moving under our arrow at the speed of light, as all 'motion' obeys that constant. Then you have a 'field' of a sort, like a spiders web defining a 'space' containing a 'distance' as defined macroscopically.==You might then want to take the spiders web analogy a step further. In a spiders web the motion/vibrations in it travels at the speed of sound, alerting the spider to its prey getting caught in it. In 'SpaceTime' you instead have the speed of light in a vacuum defining that 'propagation'. So if we look at the 'web' you might want to define 'gravity' as instantaneous in a sense, that as I define it as being existent even where you can't 'measure' it. If you look at Newtons spheres we find a possible 'zero gravity' in the middle of any sphere of invariant matter. That it is unmeasurable there doesn't mean that it isn't existent as I see it, it simply mean what it states, it is unmeasurable.So the 'web' becomes a 'dimension', in 3D + time macroscopically, and as I expect, probably all the way down past, and beyond, Planck scale, eh, maybe? In that same manner we can find the idea of 'energy' existing on all scales, from 'virtual particles' to our 'SpaceTime'. So I'm of two minds there ==( Can you see why we need it in 'New theories'? It's getting real 'wild' here, ahem. )

Quote from: yor_on on 17/04/2011 15:31:05In a way I like string theory and branes (M theory). Probably because I expect SpaceTime to be smooth and as we're talking about one dimensional 'strings' 'loops' (loop quantuum theory) or/and 'branes'. It makes a very weird kind of sense. But I do not like the idea of dimensions as 'singular' entities. I don't think SpaceTime is defined like a 'Lego' myself. I think of it as a Jello where all goes into each other and the arrow of time creates 'particles' for us. At least I do so for the moment When it comes to charge as a 'dimension'? I'm still not sure what a dimension should be seen as? But if you take something, not measurable in its own right but only as a outcome of a interaction, and lift it up to a dimension you will have problems. Myself I'm thinking of 'Gravity' as a possible 'dimension', that and 'energy'. Both because I expect them to exist everywhere a 'SpaceTime' exists, but then we come to what we can quantize and there it seems as 'energy' only comes in 'quanta' which differs it from 'gravity', as far as I know. 'Charge' and 'energy' seems both to be quantize-able whereas 'gravity' still isn't. But I'm not sure on anything in fact ==You might want to define a wave as continuous, and so define 'energy' as continuous too, and you might be perfectly right there? But then we have 'frequency' and defining a 'wave' as 'vibrating', creating those 'peaks & throughs' defining its 'energy'? Gravity doesn't, yet ==To see what I mean you can consider 'gravity propagating', like away from those binary stars spinning around each other. There you have two points of view to choose between. Either define it as a 'gravitational radiation' propagating at some 'frequency', or do as I and see it as the 'Jello' distorting itself, the 'distortion' moving under our arrow at the speed of light, as all 'motion' obeys that constant. Then you have a 'field' of a sort, like a spiders web defining a 'space' containing a 'distance' as defined macroscopically.==You might then want to take the spiders web analogy a step further. In a spiders web the motion/vibrations in it travels at the speed of sound, alerting the spider to its prey getting caught in it. In 'SpaceTime' you instead have the speed of light in a vacuum defining that 'propagation'. So if we look at the 'web' you might want to define 'gravity' as instantaneous in a sense, that as I define it as being existent even where you can't 'measure' it. If you look at Newtons spheres we find a possible 'zero gravity' in the middle of any sphere of invariant matter. That it is unmeasurable there doesn't mean that it isn't existent as I see it, it simply mean what it states, it is unmeasurable.So the 'web' becomes a 'dimension', in 3D + time macroscopically, and as I expect, probably all the way down past, and beyond, Planck scale, eh, maybe? In that same manner we can find the idea of 'energy' existing on all scales, from 'virtual particles' to our 'SpaceTime'. So I'm of two minds there ==( Can you see why we need it in 'New theories'? It's getting real 'wild' here, ahem. )Looking at Einstien Energy is equal to mass X light speed, I'm sure gravtiy is considered a dimension in M-thoery. I suggested mass as the other, but actaully maybe it is energy.3 spacial dimensions 5 string dimensionsleave three more diemensions to get to 11, Space-time or just time, gravity, energy or mass, electrical charge being the only one I think Spook1456 adds really.Energy as the missing dimension- I suppose would include mass and light speed with it. So what do you think Yor_on?3 spacial, 1 time, 5 string and then- energy and gravity as the missing two dimensions?Would be helpful if someone that studied String could answer what are the six dimensions the five strings are added to was tho.

This was on today, a discussion on Psyics and String theory Conversation with great minds, Big picture//www.youtube.com/watch?v=FOq7FVwvR5A [Links inactive - To make links active and clickable, login or click here to register]

If you really wanna learn about string theory then the only real source of video on the internet is leonard susskind's "the theoretical minimum" I will warn you that there is around 200 hours of lectures before enough is known to introduce strings and a good working knowledge of linear algebra (try Mit OCW 1806 - about 30 hours lecture time) and integral calculus (try MIT OCW Single Variable Calculus to start with - again about 30 hours lecture time) is a prerequisite to understanding anything in depth. Additionally this is seen by most academics as ludicrously short!With respect; videos by Michio Kaku do more harm than good - whilst he is a great physicist he seems to have lost the plot when it comes to his public engagement of science.

Here is a fine article about some classical Unified field theories (and dimensions):http://relativity.livingreviews.org/open?pubNo=lrr-2004-2 [Links inactive - To make links active and clickable, login or click here to register]

Quote from: imatfaal on 19/04/2011 18:31:25If you really wanna learn about string theory then the only real source of video on the internet is leonard susskind's "the theoretical minimum" I will warn you that there is around 200 hours of lectures before enough is known to introduce strings and a good working knowledge of linear algebra (try Mit OCW 1806 - about 30 hours lecture time) and integral calculus (try MIT OCW Single Variable Calculus to start with - again about 30 hours lecture time) is a prerequisite to understanding anything in depth. Additionally this is seen by most academics as ludicrously short!With respect; videos by Michio Kaku do more harm than good - whilst he is a great physicist he seems to have lost the plot when it comes to his public engagement of science. I cannot really comment about Michio Kaku, I do disagree with his proposed solution for fukushima tho.As a quick question do you by chance actually know what all the 11 different dimensions are, that they use for M-theory?