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Bob Berman

Bob Berman’s Strange Universe

Does a Falling Free Make a Sound?

Astronomer and author Bob BermanPosted March 10, 2009 – The Sound of a Falling Tree

Who hasn’t heard the old question, “If a tree falls in the forest, and nobody is there, does it make a sound?” If we conduct a quick survey of friends and family, we shall find that the vast majority answer in the affirmative. By taking this stance, people are actually averring a belief in an independent universe that exists just as well without us as with us. This fits in tidily with the Western view held at least since Biblical times, that “little me” is of small consequence in the cosmos.

But look closer. Sound is a disturbance in some medium, usually air, and a tumbling tree produces air-pressure variations. Tiny, rapid, puffs of wind. There is no sound attached to them. If a person is nearby, the puffs physically cause her ear’s tympanic membrane to vibrate, which then stimulates nerves only if the air is pulsing between 20 and 20,000 times a second – with an upper limit more like 10,000 for people over 40, and even less for those of us whose misspent youth included earsplitting rock concerts.

Nerves stimulated by the moving eardrum send electrical signals to a section of the brain, resulting in the cognition of a noise. This experience, then, is symbiotic. The pulses of air by themselves do not constitute any sort of sound. The ear’s neural architecture and a brain conjure the noise experience, and are every bit as necessary for sound as are the air pulses. In other words, the external world and human consciousness are correlative.

When someone dismissively answers, “Of course a tree makes a sound if no one’s nearby” they are merely demonstrating their inability to ponder an event nobody attended. They’re finding it too difficult to take themselves out of the equation. They somehow continue to imagine themselves present when they are absent.

Now consider a lit candle. The flame is a hot gas that emits photons — tiny packets of electromagnetic energy waves. Each consists of electrical and magnetic pulses. Neither electricity nor magnetism have visual properties. So there is nothing inherently visual, nothing bright or colored about a candle flame. But if these same invisible electromagnetic waves strike a human retina, and if the waves happen to each measure between 400 and 700 nanometers from crest to crest, then their energy is just right to deliver a stimulus to the eight million cone-shaped cells in the retina. Each in turn sends an electrical pulse to a neighbor neuron at 250 mph until it reaches the warm, wet, occipital lobe of the brain, in the back of the head. There, a cascading complex of neurons fire from the incoming stimuli, and we subjectively perceive this experience as a yellow brightness occurring in a place we have been conditioned to call “the external world.”

So there isn’t a “bright yellow” light “out there” at all. At most, there are invisible electrical and magnetic pulses. WE are totally necessary for the experience of a yellow flame. Again it’s correlative.

Consider rainbows. This one’s easy, since it’s obvious that we are absolutely necessary for a rainbow’s existence. When nobody’s there, there simply is no rainbow. (Rainbows have such a low intrinsic reality, they don’t even cast reflections). Three components are necessary for a rainbow. There must be sun, there must be raindrops, and there must be a conscious eye (or its surrogate film) at the correct geometric location.

A person next to you will complete their own 42° geometry from the sun’s anti-solar point, and will be at the apex of a cone for an entirely different set of rain drops, and will therefore see a separate rainbow which needn’t even look like yours. If the sunlit droplets are nearby, as from a lawn sprinkler, your companion may not see a rainbow at all. Your rainbow is yours alone. But now we get to our point: what if no one’s there? Answer: No rainbow. An eye-brain system must be present to complete the geometry. A rainbow requires your presence just as much as it requires sun and rain.

Few would dispute the subjective nature of rainbows, which figure so prominently in fairytales that they seem only marginally to belong to our world in the first place. It is when we fully grasp that the sight of a skyscraper is just as dependent on the observer, that we have made the first required leap to understanding the nature of things.

The above is taken from a chapter in my new book, co-authored with Robert Lanza, MD, Biocentrism, published next month.

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