> why does ruby not leave the thread lone to do its thing,
> and do other things ?
it does ... usually, but since you're explicitly joining it, it'll wait 
in start method untill thread finishes

> 
> instead, it seems to get stuck in the while loop, as if i didn't put it
> in a separate thread.
You did, and then you turned multi threaded application into single 
threaded one

> 
> any help much appreciated, thanks.
remove join. read documentation (as java user you should be used to it)