I've been asked to discuss a particularly interesting question.
If a tree falls in a forest, but nobody is around to hear it, does it make a sound.
I suppose I'll start by saying that there are many ways to look at this question, and it leads on to many others. The question, in it's simplest form, seems easy to answer, yes you may think, if a tree falls it makes a sound, regardless of whether there is anyone there or not.
But there are complications, what do we mean by sound, and how can we prove that the tree makes a sound. We can define sound in many ways, the oxford english dictionary defines sound as:
• noun 1 vibrations which travel through the air or another medium and are sensed by the ear. 2 a thing that can be heard. 3 music, speech, and sound effects accompanying a film or broadcast. 4 an idea or impression conveyed by words. All of a sudden we see that the tree, by this definition does not make any sound, as there are no ears to sense it. The tree, we assume, does make vibrations in the air, but these are not sensed.
So the question brings complications based on our use of common words like "sound", and the more you think about it, the weirder it gets, imagine the tree falling now, and making that loud cracking sound, but that sound is made by the vibration of your eardrums and your brains interpretation of that vibration, and here there are no eardrums to vibrate, no ears to hear it, and because there are no ears, the tree falls in complete silence, hitting the ground without making a sound. It is only once we introduce a pair of ears that there is sound, but before, just silent soundless vibrations in the air!
However there is an even more thought provoking side to the question.
How can we be certain that an event occurs, if we do not observe it.This question was summed up by a physicist called Schroedinger who put forward the idea for a rather interesting experiment.
Put a cat in a box, with a vial of poison, and a radioactive isotope... the isotope has an exactly 50% chance of giving of a certain particle which will be detected inside the box, and the poison will be released. The box is soundproof and there is no way to see the cat, so you have no idea if the cat is alive or dead, until you open the box. Schroedinger postulated that the cat was neither alive or dead... but that it remained in a bizzare state called quantum uncertainty, and it wasn't until you opened the box that you brought a resolution to this state and the cat became alive or dead...
It sounds pretty far fetched, and I'm not going to go into the details (google: Schroedingers cat) but what's even more bizzare is that this so-called "quantum uncertainty" and the "collapsing of quantum waveforms" has actually, on much smaller scales than that of a cat (try individual particles) been proved correct!!!
experiments have shown that particles, in certain situations hang in a sort of limbo untill observed, and once observed snap into their observed state.
This doesn't happen on larger scales like cats and trees, but it's worth remembering that while the cat in the box does either die or live, and the tree in the forest does make vibrations in the air... things are not always what they seem, and our observing them can have implications and, on a quantum level, we cant say that something happens, even if it should theoretically have done so, unless we observe it.
To finish then, the question challenges us on many levels, it challenges our perception of reality, it's very hard to imagine that tree falling in colmplete silence, yet it does, because noone is there to hear it, and it's harder still to imagine that the very act of observing something can change it. that by us looking at the world, we alter it.
The ultimate extension of the question is this.
If there were no observers in the universe, noone to see anything happening, would the universe exist.
hehe...
