Hi Hilmar,
I took a look a M Theory and found it interesting, but I don't really have the physics background to understand it. I have read some article that have a problem with string theory which involve 7, 10 or 11 dimension.
It seem that there are so many variable in such a foundation that about any theory can be reconciled and made to work, sometimes in hundred of thousands ways, depending on the substitution of the variable to be used. Also, after 20 year of string theory, there is not one practical experiment to verify it. It seem there is no way to experimentally test string theory.
I did a google on superconducting and came up with this interesting link, that demos how magnetic field behave in cold temperatures. Cold temperature physics is one of the newest field of psychic study and may eventually give us a fundamentally sound theory of gravity.
http://www.fys.uio.no/super/levitation/Regards,
LelandJ