Guille, study strings as explained on this link:
http://www.pbs.org/wgbh/nova/elegant/scale.html
It's simple but you'll find that strings are resonant entities, not snippets of threads that somehow interact. Forget dimensions for the time being, be practical. We exist within a three dimensional framework where time is the sustaining concept that allows us to appreciate that. Don't bring philosophy into this thread, please.