Definition of Time

What is Time?

When we say the word, time, we usually know exactly what we are trying to communicate. For example: When a boy asks his mother, “What time is dinner?” and she responds with, “At 5 o’clock and we are having your favorite desert,” there is no confusion. He will make every effort to be at the table when dinner is served.

From this perspective we all know exactly what time is. Therefore, it is remarkable that there has been so much confusion in establishing a meaningful definition. The following statements provide a few examples of how it has been done.

1. "Absolute, true, and mathematical time, of itself, and from its own nature flows equably and without regard to anything external, and by another name is called duration." (From Newton's statement in the first pages of The Principia)
2. The measured or measurable period during which an action, process, or condition exists or continues. (Webster's New Encyclopedic Dictionary). Note: If you look up period in the dictionary you will see that it is defined in terms of time creating a circular definition).
3. "Time is the essence of existence" (Loren R. Anderson)

These statements, while attempting to give meaning to the word, time, do not define it with a characteristic that we can use in the laboratory. Therefore, we need to gain a better understanding of what we mean when we use the word, time.

Our Use of the Word TIME

We use the word "time" to express at least two primary ideas. Therefore, to avoid confusion we will use the following notation.

We will use all capital letters for concepts similar to the question of: ”What TIME is it?"

We will use lower case type or capitalize only the first letter for concepts similar to the question of : ”How much Time will it take?"

The Meaning We Apply to the Word “TIME”

As we ponder the basic meaning of TIME, we realize that we can think of it as:

• Our position with respect to the orientation of the hands on a clock. Example: We can plan to be at work when the hands on the clock indicate 8:00am.
• Our position with respect to the Sun, planets, and stars. Example: We can plan to meet on the top floor of the Empire State Building when the position of the Earth, Sun, and stars indicate that it is Tuesday, February 14, 2012, at 5:00pm.

On further examination, we find that we use TIME as a method to predict and confirm our position with respect to other things. We simplify this concept through recognizing that TIME is where you are.

The Definition of Time

We use Time to predict and confirm our position with respect to other things. We can simplify this concept by recognizing that TIME is where you are. This concept, known as the "Position Definition of TIME,” leads to the following definitions of our relationship with the past, present, and future.

TIME is equal to position, which corresponds to where something is.

TIME Past is where you have been and where, or the way, things were.

TIME Present is where you are and where, or the way, things are.

TIME Future is where you will be and where, or the way, things will be.

A separation in TIME (commonly referred to as length) is equal to or corresponds to a separation in position.

A change in TIME (commonly referred to as time) is equal to or corresponds to a change in position.

These simple definitions make it possible to define standard units of Time, Length, and Matter in terms of light as outlined in section 2.5 of the book Time, Matter, and Gravity

This simple definition also plugs “A Hole at the Heart of Physics” (see the article by George Musser on page 48 of the September 2002 issue of the Scientific American Magazine). For in the words of George Musser “The laws of physics contain a time variable, but it fails to capture key aspects of time as we live it-notably, the distinction between past and future. And as researchers try to formulate more fundamental laws, the little t evaporates altogether.” We can eliminate this problem by using the Position Definition of Time as outlined above and in the book Time, Matter, and Gravity.

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