RE: ??1?? Question Everything?
That is something most humans usually learn or are able to comprehend at some point when they are children. :P hahaha It's called the ability to understand object permanence and therefore, I fall on the philosophical side that the tree does exist both before and after it falls. Observation is only needed subjectively by people with ultra literal minds that can't determine if something exists or not unless they see it with their own eyes. Granted, since your question is hypothetical, the speculative tree, forest and all the rest of the ideas in the question don't actually exist anywhere or at anytime but in the conceptual land of human brain's imaginations. Love the question! hahaha I hope my answer clears it up or makes it more muddy, either way I'm fine with that. :P hehe
I must say I get what the question is posing, I really do .. BUT to play another side of the fence - isn't it interesting that we only view the question from a human point of view? We don't stop to consider the multitude of other creatures in said forest? ;)
I appreciate your answer, and glad you enjoyed the question. :)
I agree that we could question more what the perspectives that other living creatures have but the question then becomes how we go about doing that? Science and technology are getting pretty close to being able to "read" what goes on in the brains of humans including individual thoughts, etc. and it would be cool to also apply that (somewhat still future) tech to other animals and plants to better understand how they experience their subjective/individual lives and to what degrees they are sentient and thinking about life. Fun stuff to think about. :)
I just wish I could download my memories and show my kids what their grandparents & great grandparents were like. What the 70s were like (hahaha perhaps no, I'll fast forward through those!).
Haven't scientists recently discovered that trees 'talk' to each other? Slowly but surely we'll uncover more mysteries Mother Nature has for us. :)