One of the great dumb philosphy questions is, "If a tree falls in a forest and there's no one there to hear it, does it make a sound?" The obvious answer is: "Of course there is. What a stupid question. Next you're going to ask about that clapping thing." But philosophy isn't about the obvious; philosophy is about the devious. The answer, arrived after much debate (and much drinking) seems to be "no": Sound is only sound if a person hears it, claim the tipsy pundits.

Well, okay.

Science fiction is about, among other things, speculation and asking 'if this goes on'. Theodore Sturgeon's definition of science fiction is, "Science fiction is the only form of literature where people can change their environment." Samuel R. Delany's description is that science fiction is where all words are defined from within, and from context. So let us apply these principles and change the environent of the woods and define the context.

If a tree falls in the forest, and there's no one there to hear it, but there's a tape player recording the event, is there sound? A human hasn't heard it... yet. Is it sound when the tape is played? What if the tape is never played? What if it's played backward? What if the person or persons listening are too drunk to pay attention? Does the mere presence of a human at the time of compression and rarefaction denote sound, or do the audio images have to impinge themselves on a human consciousness?

Scenario: A sound activated tape recorder is placed in a forest near a grove of trees where it has been determined to a high probablility that one or more will fall. A tree then falls onto the tape recorder, exposing the tape to the elements. A few weeks later, Rumplestilskin (or whoever hangs out in the forest these days), checks up on the recorder. He notes that the tape is unsalvageable, but that the tape counter has advanced. A human being has determined that an aural event has occurred. Is there sound? Was there sound? When? Why or why not? If not, what if Rumplestilskin brings back his wrecked tape player where it languishes in his cave (or laboratory) for thousands of years, where it is dug up by archeologists with advanced recovery techniques and, with a sufficient budget, manage to recreate the magnetic impression on the tape? Is there sound then? What if, just as they are about to play their imaging, their budget runs out and they don't listen?

Let's riff off some of the words we take for granted, but are altered by context.

If a tree containing a dryad falls over and she's the only one around, is there sound? What if the tree is an ent, and trips looking for the entwives? What counts as human? What if the tree falls over because an alien ship has landed nearby, and they monitor the audio track? Is it sound if an intelligence hears it? What if the aliens don't have 'ears' in the same evolutionary track as humans, but can 'sense' vibrations?

If a tree falls in a forest and there's no one around the immediate vicinity but the grove is being monitored from Alpha Centaury, is there sound? The creatures (perhaps humans nostalgically looking homeward) can recreate sound patterns from the light waves. But the light waves won't arrive until four years later. Is there 'sound'? When? What count's as 'there'? If the forest has, in the meantime, been destroyed?

What if the forest is on Alpha Centauri and the creatures on Earth (perhaps Alpha Centaurians nostalgically looking homeward) watch the celluloid plant crash down in the heavier gravity and recreated the sound patterns from the doppler shifts? What counts as a forest? What counts as a tree?

Now that we've changed the parameters of the problems, let's go father afield. Scenario: the tree is in airless space; perhaps lost out a cargo door or deliberately released due to space considerations or a religious ceremony. It then crashes into -- falls -- on an asteroid. Is there sound? What if there's a human on the asteroid who feels the crash, and the sound is transmitted through the rock and into her spacesuit? Is that sound? Has she heard the tree? If her mike is open, and the vibrations are transmitted to her children on another asteroid, did they hear the tree fall?

What if the tree's vibrations have been optically recorded by beings from another time who read their instruments telepathically...

Science Fiction is a superb medium for the discussion of ethics because it challenges all assumptions. How can we even think about ethics if we can't define concepts like 'sound' or 'human' or 'intelligence'? Not all sf is concerned with these questions, but those that are have the advantage of working in a medium where such questions are important and crop up as a consequence of the story.

David E Romm produces