Time
Time is a dimension, or property of space with which every human being is familiar. Time is measured in a magnitude of units and a variety of calendars across different cultures and geographic regions. Whether a week of time is seven days as it is in the United States, or ten days as it is in Egypt, time will never have a weight or mass because it is an intangible dimension. Because of this, time is the epitome of lightness in the form of the ultimate weightlessness. Time is not a force like gravity that captures the heaviness of objects, but rather a weightless property defined by man-made systems.