Time in philosophy and science, introduction

Everybody feels time, and most people do not question it because they experi-ence every day and it is so familiar (Fraser 1987: 17–22). But if we want to understand the nature of time we have to answer many basic questions such as:

• What really is time?

• Can we stop it?

• Can we reverse it?

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• When was the beginning of time, and does it have an end?

• Does time exist objectively, or is it only a construct of our imagination?

• What is the relationship between time and space?

• What is the structure of time?

• Is time continuous or discrete?

• What does the word ‘now’ or ‘moment’ mean?

• Why does time move into the past?

• What is the reality of the future?

These and many other similar questions have been the subject of philosophy, SK\VLFV DQG FRVPRORJ\ IRU PDQ\ FHQWXULHV ZLWK OLWWOH SURJUHVV LQ ¿QGLQJ FRQ-vincing answers. The question: ‘What is time?’ is more like the question: ‘What is love?’, because it is something that everybody can feel it, but no one can give

16 Cosmology and time

DQH[DFWGH¿QLWLRQRILW,I\RXDVNWKLVTXHVWLRQWRPDQ\SHRSOH\RXZLOOFHU-tainly get as many answers. St Augustine, in his Confessions, asks, ‘What is time?’ When no one asks him, he knows; when someone asks him, however, he doesn’t know (EP, ‘Time’, VIII, 126).

The understanding of time was very important for early people both from the SUDFWLFDOYLHZZKHUHWKH\QHHGHGWRDQWLFLSDWHPDMRUHYHQWVVXFKDVÀRRGVDQG

harvest time, and from the philosophical view, which is based on sheer curiosity and love of knowledge. Many religions and ancient philosophies, therefore, have tried to answer some questions about time. Some of these religions and philoso-phies consider time as circular with no beginning or end, some consider it as OLQHDUZLWKLQ¿QLWHH[WHQVLRQLQWKHSDVWDQGLQWKHIXWXUHDQGRWKHUVFRQVLGHULW

as imaginary, while real existence is for motion or moving bodies only.

The concept of time is necessary when we ask about the chronological order of things and the duration of events. And because our life is full of events of all types, so time has its signature in all aspects of life. Some examples are: the ageing process in biology, timekeeping in mechanics, the arrow of time and entropy in thermodynamics, and the radically varying psychical time that one feels when waiting for something or in other circumstances. Therefore, in order WRXQGHUVWDQGWKHUHDOLW\RIWLPHRQHQHHGVWRH[SORUHPDQ\FORVHO\UHODWHG¿HOGV

like physics, biology, psychology and cosmology.

In recent centuries, with the revolutionary new concepts in physics and cosmol-ogy in addition to modern technolcosmol-ogy, increasing accuracy of timekeeping became very important because it is the reference for the extremely complicated motions – of the different parts of a machine for example – that have to work together in coherence. The critical importance of timing events both on Earth and in space was enhanced by precise timekeeping machines like electronic clocks, atomic clocks, and pulsars which are fast-rotating stars that emit short radio pulses at regular intervals with extremely high precision. But despite the new abstract con-cepts about time like ‘time travel’ and the ‘curvature of time’ brought about by the theory of Relativity, our modern concept of time has usually remained quite practi-cal because everything has to be done according to the clock. In fact, the modern theories of physics and cosmology have added more questions and paradoxes about time than they answered (Grünbaum 1971: 195–230).

In general we can detect two major opposing views in the philosophy of time:

1 the rational (realistic) view based on the physical understanding of the world

2 the idealistic (perhaps apparently ‘irrational’) view based on metaphysics.

Rationalists believe that the mind is the most powerful force of humankind and is able to understand everything in the world, while the irrationalists consider the world, including time, as something beyond the capabilities of our minds. For the idealist, nothing, including time, exists independently of the mind. Therefore the idealist believes that time is a construct of our mind and does not have a separate existence.

Cosmology and time 17 1.6 Time in Greek philosophy

Since the age of Homer, the Greek word chronos has been used to refer to time.

Chronos was a Greek god who feared that his sons would take over his kingdom, so he ate them one after the other – just like time, which brings things into exist-ence and then overtakes them.

We can already detect two clearly opposing views about time in the contrast between Plato’s and Aristotle’s schools of thought. Plato considers time to be created with the world, while Aristotle believes that the world was created in WLPH ZKLFK LV DQ LQ¿QLWH DQG FRQWLQXRXV H[WHQVLRQ 3ODWR VD\V µ%H WKDW DV LW

may, Time came into being together with the Heaven, in order that, as they were brought into being together, so they may be dissolved together, if ever their dis-solution should come to pass’ (Cornford 1997: 99).

Aristotle, however, believes that Plato’s proposition requires a point in time that is the beginning of time and has no time before it. This notion is inconceiv-able for Aristotle, who adopts Democritus’ notion of uncreated time and says: ‘If time is eternal motion must also be eternal, because time is a number of motion.

Everyone except Plato has asserted the eternity of time. Time cannot have a limit (beginning or end) for such a limit is a moment, and any moment is the begin-ning of a future time and the end of past time’ (Lettinck 1994: 562).

Thus time for Aristotle is a continuum, and it is always associated with motion; as such, it can not have a beginning (Lettinck 1994: 241–259, 361).

Plato, on the other hand, considers time as the circular motion of the heavens (Cornford 2004: 103), while Aristotle said that it is not motion, but rather the measure of motion (Lettinck 1994: 351, 382, 390). Aristotle clearly relates rational time and motion, but the problem that arises here is that time is uniform, while some motions are fast and some slow. So we measure motion by time because it is uniform – otherwise it cannot be used as a measure. To overcome this objection, Aristotle takes the motion of the heavenly spheres as a reference, and all other motions, as well as time, are measured according to this motion (Badawî 1965: 90). On the other hand, Aristotle considers time as imaginary because it is either past or future, and both do not exist, while the present is not part of time because it has no extension (Lettinck 1994: 348).

We shall see in Chapter 2 that Ibn ‘Arabî shares with Aristotle the idea of a circular endless time and that it is a measure of motion, but he does not consider it as continuum. On the other hand, Ibn ‘Arabî agrees with Plato that time is created with the world. In fact Plato was right when he considered time to be created, but Aristotle refused this because he could not conceive of a starting point to the world nor to time. Only after the theory of General Relativity in

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curved time that has a beginning. By this we could combine Plato’s and Aristo-tle’s opposing views. However, Ibn ‘Arabî did that seven centuries before, and he also explicitly spoke about curved time a long time before Einstein.

18 Cosmology and time