A philosophical brain teaser

You know how the rest of this brain teaser goes … does it make a noise? This is a question from the Conscious Universe, and eminent thinkers in the past have argued that there’s no actual substance to the physical world – objects like computers, cars, trees and houses. That is, it’s a world accessible only to the mind – for all that we can be truly aware of is our ideas or perceptions of these things.

Its traditional name is philosophical idealism, whose greatest exponent was Irish thinker Bishop George Berkeley (1685-1753). He denied, essentially, that there’s anything such thing as matter. He didn’t exactly say material objects don’t exist; rather, that the world is basically mind-like, an issue for our perceptions. If we analyse the ‘substance’ of a material sensation (something felt or seen, say) such things have no reality other than in the mind. With sight, what we really perceive is light, colour and shape – we don’t see their causes. We live in a world of abstracts. But the idea that the world isn’t in fact solid is hardly without scientific support.

And there is one fascinating thought experiment Berkeley would have loved. It’s the old metaphysical teaser which asks: ‘if a tree falls down in a wood, and there is no one there to hear it, does it make a noise?’ Berkeley would have said ‘yes’ straightaway. (God hears it.) But give yourself a few minutes to think it over.

A few people on whom I have sprung this vexing riddle are in no doubt that the tree makes a noise. The sheer weight of the tree guarantees it will come down with an audible crash, right? (Try it out on your friends – it can lead to all sorts of good-natured argument.) Naturally, it has been discussed on the Internet, and there are answers ranging from an emphatic ‘yes’ to musings about ‘what do we mean by sound?’ (Elsewhere, there’s a range of smart- ass answers supplied by the usual shining wits.) When I asked a friend, he fixed me with a frown that said ‘why are you wasting my time with this?’, and more or less replied: ‘it stands to sense that it makes a noise – you idiot.’

But please do remember, there is no one there to hear it. Got it now? If your answer was yes, read on. If your answer was no – you may be on to something! Our data about the world outside comes through any of the five senses. However, none of them are very reliable – so what processes are at work in auditory perception? Well, when we hear, airwaves cause our eardrum to vibrate, and an electrical signal is carried to the brain which (allegedly) interprets it as ‘noise’. But before this, the sound doesn’t exist – the impulse itself doesn’t ‘contain’ sound, as such. (Any more than digital information in an MP3 file is music before we play it in a device.) The encoded data needs to be interpreted, so the brain ‘decodes’ it into what we finally experience as sound.

Now go back to the part of the question which says no one can hear the tree fall. No squirrels, stray dogs or craftily placed microphones linked to a recording device. Mere airwaves do not a noise make, as Yoda might have said. You can, of course, imagine this tree falling, and there it is – you hear it. But that’s because you’ve just created the sound yourself. Remember, there’s nothing capable of registering a noise, here. You’re not even allowed to imagine it falling – because as soon as you do, it makes a noise! If you simply don’t think about it, there is silence.

Sound only exists within the observer’s mind. You, by dint of your senses/mind-construct, invent the world in which you live. Our habit of thinking that reality is always ‘out there’ is wrong. It’s really a trick of language to say the sun is bright because it is emitting light. It seems self evident, but it’s just as correct to say that sunlight exists because of our eyes, or our mind. We create the world, our reality, just by being there, and though it’s a well worn cliché it is, in one sense, quite true.

The eminent physicist Erwin Schrödinger wrote:  “We cannot make any factual statement about a given natural object (or physical system) without ‘getting in touch’ with it. This ‘touch’ is a real physical interaction. Even if it consists only in ‘looking at the object.’”1 He even says that “matter is an image in our mind.”2 At any rate, “In perception and observation subject and object” are “inextricably interwoven,” and their connectivity is an “inter-action.” This is the crux of the matter – both subject and object are intervoven:

“The world is given to me only once, not one existing and one perceived. Subject and object are only one. The barrier between them cannot be said to have broken down as a result of recent experience in the physical sciences, for this barrier does not exist.”3

In other words, our world is naught but our perception of it and we must beware – for our senses are always playing tricks on us. This is why the Buddhists advise us to ‘look upon the world as a mirage.’ This turns out to be excellent advice, and even modern science suggests the bit about the ‘mirage’ is perfectly true! The answer to the Quantum Brain Teaser – therefore – is ‘no’. Even Scientific American agrees: ‘”Sound is vibration, transmitted to our senses through the mechanism of the ear, and recognized as sound only at our nerve centers. The falling of the tree or any other disturbance will produce vibration of the air. if there be no ears to hear, there will be no sound.’

1. Schrödinger, Science and Humanism, p. 49.

2. Ibid., p. 11.

3. Wilber, Quantum Questions, p. 81.