by Wenbin Nah

Created on: April 15, 2008

"What then is time? If no one asks me, I know what it is. If I wish to explain it to him who asks, I do not know." -Saint Augustine

So, how do we answer the age old question, "what is time?" Is time a period of duration or the human conception of past, present and future as a sequence?

When a tree falls in the forest, and nobody is around, does it make a sound? This riddle can similarly be applied to time. Would time even exist if no human beings were around to experience its passage? Clearly, there are many greatly despairing views regarding its nature; hence it is difficult to clearly define what time actually is.

We can look up the dictionary, which gives the definition as "the indefinite continued progress of existence and events in the past, present, and future, regarded as a whole". However, such a definition given at face value is unsatisfying, as it does not fully grasp the unfathomable essence of time.

Looking back at history, time has long been a concern for philosophers and scientists. In Principia, Newton says that it is unnecessary to define time as it is "well known to all".

"I do not define time, space, place and motion as being well known to all. Only I observe that the common people conceive these quantities under no other notions but from the relation they bear to sensible objects. And thence arise certain prejudices, for the removing of which it will be convenient to distinguish them into absolute and relative, true and apparent, mathematical and common."

However, he proceeds to do just that and defines time as

"Absolute, true and mathematical time, of itself, and from its own nature, flows equably without relation to anything external, and by another name is called duration: relative, apparent, and common time, is some sensible and external (whether accurate or unequable) measure of duration by means of motion, which is commonly used instead of true time; such as an hour, a day, a month, or a year."

What Newton is trying to express, is that time is something that proceeds on uniformly regardless of whatever is happening in the world. He referred to this as absolute time, so as to distinguish this from the various ways by which we measure time which he referred to as relative time.

The concept of absolute time is well entrenched in our minds and this is evident from the fact that the field of astronomy uses an "equation of time" to derive the real time from the apparent time due to Earth's orbit round our sun. However, revolutions in twentieth-century physics with the introduction of the Theory of Special Relativity have brought about a new way by which we view time now.

The human understanding of time is still constantly changing and evolving. If you know nothing else, know that your time on this earth is your most precious resource that you possess. Use it wisely, and use it well. Till next time.

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