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If a tree falls in a forest and no-one hears it, does it make any sound?

This great mystery of the unheard falling tree in the deserted forest has puzzled philosophers for thousands of years. For most of that time it was regarded as a classic unsolvable conundrum, as statements of belief in either direction were irrefutable.

Note: "Irrefutable" doesn't mean "correct", it just means that it can't be disproved. For example, "God lives in my teapot" is an irrefutable statement provided you don't allow non-believers to desecrate the sanctity of the internal space in the teapot.

Meanwhile, on the allegedly silent falling trees in unaudienced forests, the puzzle went on being puzzling for an immensely long time but things started to change with the invention of the phonograph, and then the tape recorder, and then the digital audio ambiance capture module with dynamic paraphragm microphone for capturing audio holograms.

Well let's put this to the test. Suppose there's an old tree in a deserted forest, and we know it's going to fall next week, so we go along there and set up some sort of tape recording machine and see what happens. We leave the scene with the sound recorder running and come back in a couple of weeks. For sure, the tree is now fallen, and the recording machine is still running, and we know that no-one has visited and heard the tree fall because we put tamper-evident dust on all the tracks anywhere near the tree.

Taking the tape (or other sound recording media) back to the lab, what happens now?

One option is to PLAY it. That would have two consequences: Either there's be a sound of a falling tree on it, or mysterious silence. This would be very revealing, and would settle the whole thing once and for all, but perhaps there's more to it.

The other option gives rise to some even more interesting concepts. Suppose we DO NOT play the recording, but instead delete it. Now, that would raise some very curious points. Do we delete it or not? We have freedom of choice to delete the tape, or to play it, so this reveals two intriguing possibilities:

1. If all trees falling in forests make a noise regardless of whether anyone hears them, then the deleting option would do nothing more than to delete a perfectly ordinary sound of a falling tree.

2. (the more interesting option). If trees falling unheard in deserted forests make no noise unless they are later heard on a tape recorder, then our choice of whether to delete the tape would retrospectively cause the tree to have made a noise or not! This would be time travel as it would have an effect whose cause was in the future.

I think this is all very interesting as it sets new insight on a very old problem, and could potentially be a source of a research project.

However, I take a scientific view which is that all trees falling in forests (regardless of audience turnout for the event), all make a noise. If they didn't, there would be something wrong with the scientific way of thinking, and besides, I think that the philosophical notion to suggest that unsupervised falling trees are silent is a devil's advocate type of philosophical comment designed to cause debate rather than progress.

Then again, if I can listen to a few silent tapes witnessing falling trees, I may be convinced there is something more to be investigated, and it may be worth putting some CCTV cameras up to see if the falling trees are invisible too.

Plus, if my scientific belief that falling trees always make sound turns out to be proven false, there may be industrial applications. For example, when using a chainsaw to cut down trees (in renewable forestry, of course!), much energy could be saved if automatic unsupervised chainsaws could be set up to cut the trees down (before planting some new trees), as there would be no energy wasted by the chainsaw having to make that awful sound and scare the wildlife.

Also see ecology , concepts , furniture made of wood , science , belief , and audio-related stuff.

Also, What Sound does a Falling Bomb make?