Short Thoughts: If a tree falls in the forest...

...does it make a sound. This seems to be a deep philosophical question, but is it really? It just depends on what your definition of sound is. If you define sound as pressure waves in air then the answer is clearly YES. The pressure waves are there, and might influence other objects in the forest.

If, on the other hand, you define sound as through the experience of a human being, then you are linking it to the perception of an individual. In this sense the answer is NO. The tree does not make a sound because there is no one whose brain activity is changed in such a way that she would call it a sound.

I find this definition problematic. What if you had a sound recording device? You could record the sound and play it back later. If no one was present when the device made its recording then where did the sound come from. Did the recording device create the sound from scratch? Or did the tree suddenly make a sound the moment you observe the sound through the recording device? In this way the question resembles the observer problem in quantum mechanics.

But if you go down this route then you have to be consistent and follow this argument through to its end. You should not allow anything to exist unless you are observing it. So the final answer to the question must be:

If a tree falls in the forest and no one is there to hear it then the tree didn't exist in the first place.