"Today a young man on acid realized that all matter is merely energy condensed to a slow vibration, that we are all one consciousness experiencing itself subjectively, there is no such thing as death, life is only a dream, and we are the imagination of ourselves." -bill hicks.
Some people think time is a product of the central nervous system as a way of coping with the constant feeling of earths gravity/acceleration... maybe explains why sensory deprivation tanks work.