Time Flies

The nature of time has fascinated thinkers for centuries, who speculated that hours, days, months or years began with the stars. Nowadays, physicists might prefer to take things back to the Big Bang for the beginning of time. The assumption has already been made which is that the essence of time is directionality, with a beginning, and possibly an end. This conception of time may be visualized as an arrow. This is also a common understanding of time. For most people, time marches on. The arrow of time is overwhelmingly evident when people deal with the world around them. Our senses also tell us so.

Not everybody will be entirely satisfied with this recourse. According to them the problem consists of extrapolating from the mathematics applicable to the world of subatomic particles to the macroscopic world of sense experience. At the subatomic level, explanations of the behaviour of particles apply within a time-reversible framework: It does not make any difference if one runs a film of what is happening forwards or backwards, so to say, the calculations still work. At the macroscopic level of explanation, however, where the behaviour of large numbers of atoms and molecules are being considered collectively, new laws apply. The tendency of all matter is to break down to the simple homogenous arrangement of constituent parts-that is, for entropy to increase-under the second law of thermodynamics. This is the time-irreversible process. It is being seen on all around, for example, when we leave a cup of tea to go cold. It is such observations which give conception of the uni-directionality of time.

A satisfactory fusion is yet to be achieved in the two theories of quantum mechanics and relativity. If a theory were to emerge that accounted satisfactorily for the apparent incompatibilities between quantum mechanics and relativity, there would still remain the question of emergent properties.

An obvious place to look for examples of emergent properties is in the world of life. One strikingly illustration is the simplest of organisms seem capable of purposeful behaviour concerns the slime mould, Dictyostelium discoideum. When food is short, groups of normally free-living cells join to form a multi-cellular slug with a discernible head and tail that wriggles in search of bacteria. Like the ant hive, Dictyostelium is a super-organism, a genetically homogenous being composed of autonomous individuals, organized altruistically for the collective good. It is not easy to see how such behaviour can be considered time-reversible. It is impossible to understand fully what is going on at the molecular and ultimately subatomic levels in the organisms concerned without considering the wider context.

Considering phenomena at the microscopic level only is the reductionist error. It leads to postulate such impossibilities as Wellsian time-travel. The absurdity of this idea is dealt with adequately with the paradoxes that such an activity would entail laid bare fully. Modern chaos theory is a further difficulty for time-travel. Regarding reductionism: one of the most highly developed skills in contemporary Western civilisation is dissection: the splitting-up of problems into their smallest possible components. We are good at it. So good, we often forget to put the pieces back together again.