What Is Time?

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, Confessions, XI, 14

Podcast of the Day

Melvyn Bragg and guests discuss the history of mankind’s attempt to understand the nature of time. At the end of the 19th century, H.G.Wells imagined travelling through time in The Time Machine; “The palpitation of night and day merged into one continuous greyness; the sky took on a wonderful deepness of blue, a splendid luminous colour like that of early twilight; the jerking sun became a streak of fire, a brilliant arch in space”. When he was writing we thought time was unbending and universal and counted out by Newton’s clock. A hundred years later we have had Einstein and relativity, quantum theory, and atomic clocks, but in the third millennium, is mankind any closer to understanding what time really is? What, in short, do we know about time itself? A Greek philosopher thought that time was a figment of the imagination and there are contemporary physicists who go a long way to agreeing with him. Newton’s views on time were bent by Einstein. The ancient skills of astronomy once ruled the known world and skill in time usage could be said to be enthroned as a master craft in our day. “But at my back I always hear time’s winged chariot hurrying near and yonder all before us lie deserts of vast eternity” - Marvel wrote that of love, but it could be our epigraph for time.

Listen to the In Our Time episode on Time

Video of the Day

Short Article of the Day

...Our perception of the world is of a world of change, of motion and transience. Parmenides was convinced that the reality is quite different. He argued as follows. The ordinary notion of change indicates some thing or state of a thing going from being future to being present to being past. Yet we also ordinarily contrast the what is — i.e., the present state of things — with the what is not — i.e., the merely possible or long gone. The future doesn’t actually exist; if it did, then it would exist now! But then nothing can go from actually being future to being present: if the future is not real, then the present state of things cannot come to be from a future state of things. Hence, change is impossible and illusory. Parmenides concluded that the world is really a timeless, static unity. The terms ‘past,’ ‘present,’ ‘future’ do not designate intrinsic properties of things or events...

Continue reading Adrian Bardon's article: Does Time Pass?

Further Reading

Time is what we use a clock to measure. Information about time tells us the durations of events, and when they occur, and which events happen before which others. Nevertheless, despite 2,500 years of investigation into the nature of time, there are many unresolved issues... •What time actually is; •Whether time exists when nothing is changing; •What kinds of time travel are possible; •Why time has an arrow; •How to correctly analyze the metaphor of time’s flow; •Which features of our ordinary sense of the word "time" should be captured by the concept of time in physics; •Whether contingent sentences about the future have truth values now; •When time will end; •Whether there was time before the beginning of our big bang...

Continue reading the Internet Encyclopedia of Philosophy article on Time by Bradley Dowden

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