If a tree falls...

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

This philosophical question of unknown origin is quite popular, and has been mused upon by so many. But the real point of this question, in my opinion, is not about the physics of sound transmission, but about questioning people's acknowledgment of knowledge that has not come to their awareness. It seeks to probe into our willingness to believe in things that we are unable to, or are yet to perceive.

For example, we know that the earth is round, but people in the pre-scientific ages believed it to be flat. Could we then pose a similar philosophical question by saying that: If the earth is round and no one travels around it, does it still have a complete loop? Well it is obviously still round regardless, but all human decisions would be made as if it were flat.

To some extent, the assumption of the flat earth was not a real problem for most endeavors (except travel), and that assumption is still necessarily being made today. We still use terms like 'level ground' and 'flat surface' in our construction industry; even the use of an accurate laser level would approximate the ground as being 'flat.' Further, the mathematical definition of a straight line also makes the flat earth assumption seem inconsequential.

A straight line is defined as a circle with a radius of infinity. This means that the level of curvature gets smaller as the radius gets larger, until the curvature becomes negligible with very great radii, such as the radius of the earth (approx. 6400km). So for the average Joes and Johns who build and farm, there would be no real consequences (besides appearing ignorant) to believing that the earth was completely flat, seeing that whatever slight curvature it has does not factor into their endeavors in any way. However, fields like meteorology, astronomy, and geology require the precisely accurate model of the earth with every single bulge and dent for their calculations.

To return to the main point, it is clear that although so many things are true, we are only required to work with those that affect the subjects we are dealing with, and consider the rest to be inconsequential. For example, while writing this paper, I'm sure that there were several loggers at work felling numerous trees in forests around the globe, but none of the forests were close to me, so whatever sound they made was of no consequence to me, because they made no noise to distract me from typing. However, to the loggers at work, that sound was all-important, seeing how they listen to that important crackling to know when the tree is about to begin its dangerous fall.

In conclusion (stating the obvious), people observe their environment using all their senses, and assess the conditions they are in, but are completely unaffected by anything that is outside their sphere of perception. So the sound made by the tree that falls when no one is around to hear it is inconsequential, but the fact that there is one less tree to populate the forest is important.