假如一棵树在森林里倒下

if a tree falls in a forest and no one is around to hear it, does it make a sound?

philosophical thought experiment

“假如一棵树在森林里倒下而没有人在附近听见，它有没有发出声音？” 是一个哲学思考实验，提出关于观察和现实知识的问题。