Internally, time is frequently represented by the metaphor of a line. We envision time physically reaching out into the future, along which we plot the events of our lives. The line might be either straight or curved. It can be one-dimensional, two-dimensional, or three-dimensional. But no matter how we visualize it, time flows in only one direction: forward.
Externally, time is measured by clocks and calendars. These are based on the rhythms of nature; thus, they too are metaphorical. Clocks measure time by indicating either an exact hour or minute, while calendars chart the passage of time over several months. Both clocks and calendars are accurate to within a few minutes per day and a few days per month, respectively.
Our perception of time is also influenced by emotions. When we are scared or anxious, time seems to move more quickly; when we are happy or content, it slows down. This is why stress tends to make us feel like time is running out, and why having fun with friends helps us deal with this feeling. Time is subjective, depending on your perspective; it can seem slow or fast from one moment to the next.
Time is a very important concept in philosophy and religion. As far as humans are concerned, there is only one reality, and so there can be only one correct way to view time.
Time is the seemingly unchangeable progression of existence and events that occur from the past, through the present, and into the future. Time is operationally defined in physics as "what a clock reads." In other words, time is the order in which events occur, or the sequence in which we note them as happening.
Time can only be measured with respect to another event. For example, if I say it has been raining for a week now, you could ask me how long it has been raining. You would not want me to reply by counting down from today's date; instead, I would say "it's been raining for seven days." Here we use the word "day" as shorthand for "a period of time since sunrise yesterday."
The concept of time has many implications for humanity that reach far beyond the behavior of rain clouds and clocks. At its most basic, time allows us to organize our lives by giving each day a beginning and end. Only with this framework in place can we sleep during some parts of the day and work at others, eat regularly and exercise when we feel like it, go to school every morning and come home every evening.
Time also plays an important role in religion. All major religions have their own concepts for time, including but not limited to Judaism, Christianity, and Islam.
Temporality is a philosophical word that describes how time is perceived. Traditionally, temporality has been viewed as a linear progression of the past, now, and future. However there are other views on temporality such as: cyclical, dialectic, diachronous, dynamic, episodic, infinite, progressive, sequential, synchronous, and transient.
In physics, time is considered to be one of four dimensions of space. The other three dimensions are length, width, and depth. Like the others, time can be divided into intervals called "time slices". Each time slice has a beginning and an end. Time itself does not have any physical properties; it is only when observed from a particular time-slice that some things appear to happen sequentially. So in a sense, time is like depth in that you can't see it but you can feel its effects.
Time is a fundamental part of human existence and understanding it plays an important role in many fields of knowledge, including but not limited to science, philosophy, religion, and art.
Temporal concepts arise very early in human thought. The pre-Socratic philosophers identified two main forms of temporal order, before-after and earlier-later. They also noted that events that occur together later tend to be remembered better than those that do not.
Time has been defined in many dictionaries as follows: The indefinite continuation of life and events in the past, present, and future as a whole (Oxford Dictionary) Webster's Collegiate Dictionary defines time as "the measured or quantifiable duration during which an activity, process, or situation occurs or persists." The American Heritage Dictionary defines it as "the series of periods between one event or period to another that form[s] a whole" (American Heritage Dictionary).
Time can't be destroyed, only transformed. What was past is now history. What is happening now will soon be history. What is yet to come will eventually become history.
History is the record of what has happened over time. History is divided into two main sections: ancient history and modern history. Ancient history covers events that took place before about 1500, while modern history covers events since 1500. However, some sources include pre-ancient history events until about 400 BC when Herodotus recorded historical events.
People have always wondered about their past and their future. Mythology is full of stories about gods and men who had special powers because they were heroes in their own right or because they had dealings with deities. Orpheus sang so beautifully that he could bring animals back from death, Python swallowed people whole but later vomited them up again, and Zeus used his thunderbolts to destroy both mortals and monsters.