If a tree falls in a forest and nobody heard it, did it fall? If a person wrote obscenities on twitter and nobody saw them or can discover them, did they write

If a tree falls in a forest and nobody heard it, did it fall? If a person wrote obscenities on twitter and nobody saw them or can discover them, did they write anything? If they did, how do you know when you haven't seen it. If they didn't, how is it different from never writing it in the first place?