tk is based on the movement of human energy/electricity through the air.
some believe in it, some don't as it can't be scientifically measured. i tend to believe it's possible even though the record for it is sketchy; i don't believe anyone has even come close to tapping the energy inherent in tk. geller, castaneda, and the like are only the tip of the iceberg. qigong and tai chi chuan are more in line with tk but again are only the tip of the iceberg. and the shamans, palm readers, and people like miss cleo make a mockery of tk. there's more to it than that.
for those who want to know how to harness it, i would say use it properly. it's not an energy that should be used for silly parlor tricks.
sometimes you're better off not knowing how to do certain things until you're ready to use them responsibly.
