ABSTRACT
Dictionaries have pages to say about the meaning of the word time. Time is nonspatial. Time is a duration. Time is a number. The number represents years, days, or minutes or a point in the continuum of time. Stephen King suggested that time is a melting snowman. Alan Lightman wrote a delightful treatment of time in his book Einstein's Dreams. Each tiny chapter deals with a different view of time, time running backward, stopped, a view of the future. Biologists generally recognize five senses—hearing, smell, taste, touch, and vision. Keeton explained that the phrase, the "sixth sense", has been used to denote various kinds of extrasensory perception. Coleman defined a biological clock as "an innate physiological system capable of measuring the passage of time in a living organism". The phrase biological clock can include clocks that measure days or years, but the concept was mainly developed for rhythms of about a day, which have been named circadian rhythms.
