actually i just never got round to the follow up. "But it will exist and thus isn't a concept or a theory since it will happen. What will happen 10 minutes from now? I don't know but I know something will happen in 10 minutes for sure. It is the future." actually there is no gurantee that anything will happen. the universe may collapse upon itself in 9 minutes 59 seconds and time and space will no longer exist.

as for the tree in the woods. sound is a perception.it is how we perceieve the vibration of air particles. it only exists once it is heard as sound. otherwise it is merely air vibrations and not sound.