what "plucks" the string in string theory?

i guess its a form of energy ? or i havent read enough about string theory yet?

or have the strings been vibrating for infinity?.. and if thats the case do the strings ever change their vibration and if so how does that change occur?

Hum,
Well I guess that they oscillate in at least 10 dimensions and that they can change frequency:
But if they change frequency then that would mean that all particles could change into any other particle/empty space/force.
And i suppose that there is no such `thing` as energy at all just vibrations. The strings are the energy.

Best to do a quick google on it

Well, since nobody even really knows what the "strings" in string theory really are, there isn't really an idea of what's making them oscillate.

what "plucks" the string in string theory?

i guess its a form of energy ? or i havent read enough about string theory yet?

or have the strings been vibrating for infinity?.. and if thats the case do the strings ever change their vibration and if so how does that change occur?
what do you mean, "what plucks the strings"? why do you think something plucks the strings? That's like asking, "where do electrons get their kinetic energy?"

particles get their energy from collisions with other particles. Smash two electrons together with enough energy (on the string scale), and you can make them jump to excited oscillating stringy states.