April 30th, 2012

David Eagleman writes:

Each organism presumably assumes its umwelt to be the entirety of objective reality. Until a child learns that honeybees enjoy ultraviolet signals and rattlesnakes see infrared, it is not obvious that plenty of information is riding on channels to which we have no natural access. In fact, the part of the electromagnetic spectrum visible to us is less than a ten-trillionth of it. Our sensorium is enough to get by in our ecosystem, but no better.

The head is a paraphrase of a bit that Philip K. Dick used in a 1978 speech titled How To Build A Universe That Doesn’t Fall Apart Two Days Later where he said: Reality is that which, when you stop believing in it, doesn’t go away.

One of my students and I had a disucssion last week about whether or not blind people saw darkness. He could not wrap his head around the idea that while he could neither see in the ultraviolet nor the infrared, he did not percieve any blackness in those parts of the electromagnetic spectrum. We can only trust our senses as far as they go, and no fUrther. Just because we don’t perceive a threat — think typhus in the water — does not mean evil spirits are at work.

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