I have had following thought regarding the nature of matter (strings). I would very much like to hear the opinion of others as to its worth.
There is the possibility that our universe is a 4D (3D - 1T) membrane existing within a 11D (10D - 1T) space. The boundaries of holes in this membrane are 2D - 1T membranes. If we assume that this 2-D sheet can be curled round the 10th space dimension (see article by Dr. Michael Duff in Scientific American - The Theory Formally Known as Strings) then a closed tube with very small radius is formed. From a distance the tube becomes a closed string in 9D space.
The physical universe then becomes analogous to bubbles in a liquid. The vibration of the boundaries of the 'bubble' in the various space dimensions gives rise to the different particles we see.
'Something in nothing (our usual view of matter) is equivalent to nothing in something (a new view of the material)