Using salt as a medium for visualizing sound waves
This video does a great job of creating the visual patterns associated with sound waves. Its a simple science experiment done with lots of salt. Second video after the jump.
natural hallucinogen with circles
Relax your eyes and stare at the center. Look around at the end. Works better for some than the original rectangular version. There’s no hidden images or anything in the video, just the rolling circles. Your brain is making the effect.