What exactly is Big Data? This video defines and explains Big Data as well as Hadoop and MapReduce in simple language.
Rating Newest Oldest. Best Answer: Time is an illusion in that it's not a real, *natural* feature of the universe. Time is not absolute, meaning there's no Cosmic Master Clock that ticks off the correct time for the entire universe.
The shadow of the sun reveals the time on an ancient sundial on the castle walls of Saint Michael's Mount, Cornwall, England. Sundials are the oldest known devices that are used to measure time. It depends on the rotation and movement of the sun.