What characterizes each dimension in M-theory?

wendten

according to M-theory, there should be 7 ekstra spatial dimensions curled up at the plank lenght, but why do they need to be curled up? if light and matter is bound to the 3rd dimension like waves of the ocean is bound to the 2D surface of the water that wouldn't that be sufficient for us not to detect them?

In addition what characterizes each dimension in M-theory?
I have come up with this answer but is that just making a mess out of it?

1-3 spacial dimensions [up-down, left-right and back,forward]
4 [time-anti time]
5 alternative configurations of our own fine tuned universe
6-11 governs the value of Martin Rees's 6 dimensionless constants [higher value-lower value]

bapowell

The extra dimensions of M-theory are ordinary spatial dimensions -- nothing more. There is no theoretical requirement for them to be compactified (curled up), but there observational reasons. For example, even if you could confine light and matter to our familiar 3D subspace, gravity would be much more difficult to contain, since it is associated with the very geometry of the space -- all 10D of it. There are models that investigate what happens to gravity in non-compact spacetimes (involving so-called "warping" of the extra-dimensional space), but these have not been extended to the full 11D of M-theory.