6 – OUR PERCEPTIONS OF CHANGE

THE FUTURE OF TIME

by Sean O'Donnell, Ph.D.

Few people doubt that our knowledge of time in the centuries to come, will be very different from what passes for temporal understanding nowadays.

To know where you may be going however, it helps to realise where you have been coming from.

In these articles I will therefore strive for systematic and simplified exploration, of all major sectors of time knowledge as currently known to science. I will not address relatively trivial matters such as more efficient time management. Instead I will seek greater comprehension, and hopefully consolidation, of time's larger mystery overall.

This project derives from “The Mystery of Time”, an AdultEd course conducted by me at the National University of Ireland Galway (NUIG) – 1988 to 2,000 AD.

6 – OUR PERCEPTIONS OF CHANGE

SUMMARY

Our notions of time are obviously influenced by those changes we can perceive. For if we never noticed change of any sort (either internal or external), then we could hardly form much notion of time.

Our perceptions of change are however very much dictated by the facts of our terrestial and further human biology. And as such they they are unlikely to have much absolute significance against the wider temporal background.

THE GOLDILOCKS REGION

Some 4.3 billion years ago when the primitive Earth turned solid as it started to circle the sun, its orbit luckily lay in the “Goldilocks region”. This means that its average distance from the sun was “neither too hot nor too cold”- in fact just right for water to exist in liquid form. Which would also prove crucial much later when life as we know it to evolve.

When primitive life then crawled out from the oceans a mere 450 million years ago, the parameters of our planetary orbit imposed other temporal regularitiesregularities which affect us still. For example the yearly cycle of cold winters followed by warm summers greatly influenced the distribution of life across Earth' surface, and so eventually how and where we humans might live. Likewise the daily cycle of light and darkness have imposed sleep patterns which affect us still.

WE THINK BY IONIC DIFFUSION

More crucially for time perception, our ascent from the oceans carried along the relics of saltwater which had closed off into nerves and veins. So the chemical composition of blood still shows a close affinity with seawater, notably in its content of sodium and potassium ions. And these same ions now form the basis for nervous conduction, diffusing in and out through their myelin sheath as they carry in observations about what is to be known of the world outside.

The important thing here is that ion diffusion is a relatively slow biochemical process. Though much depends on the varying depths of its myelin insulation, our average speed of nervous conduction can be taken as about 100 metres per second or just 220 miles an hour – not even half the speed of a jumbo jet in more everyday terms.

This means that the physical facts of nervous conduction confine our observations to a very narrow window in the spectrum of all natural changes: we can't directly observe happenings which are either very fast or very slow. In similar vein, and compared to smaller animals like birds or flies.our sense of vision isn't all that keen. So sub-millimetre objects remain invisible to us. Likewise even the lowly goldfish can sense a wider range of colours, an aspect where we are confined to a relatively tiny window of rainbow frequencies in the electromagnetic spectrum of light.

In such ways the brain is really an organ of limitation, perhaps to stop it being completely overwhelmed by the great range of changes which nature displays.

FAST CHANGES

Towards the faster end of changes for example, we can never observe the varying positions of a speeding bullet as it flashes by. Here those relatively slow ionic diffusions of impressions conducted through nerve fibres, along with the rather different facts of light diffraction and our eye's resolution power, leaves us effectively blind to such rapid change.

Over the past two 120 years however, technology has learned to harness these limitations to produce an illusion of continuous or non-quantised change. For example a cinema screen exhibits 24 slightly differing pictures every second, each further punctuated by 24 similar episodes of darkness between. But since our nervous system won't let us discriminate between changes of this order, the human 'persistence of vision' affords us the illusion of continuous changes on the screen.

Likewise a television screen employs just one single dot of light traversing on-and-off across the surface at very much faster rates. From which we build up the illusion of continuous and smoothly changing action in the picture once again.

Finally the pace of music is likewise geared to our natural limits of auditory discrimination: impressions sound far more discordant when a tape recorder runs the same tune fast or slow.

SLOW CHANGES

At the other end of the temporal spectrum, where the pace of change is very slow, our biological limitations leave us also blind. For example we can't observe that a teenager is growing by about 20 atoms per second (3 inches in one year) even as we look at him. Our eyes just can't see down to this level of discrimination once again.

With the teenager therefore we don't perceive so much that he is growing – but rather that he has grown since our last encounter perhaps a year ago. In effect we are comparing what we see of him now before us, with our memory of when we last saw him a year ago. In turn this raises the central role of memory in our time impressions – a very important matter to which I will return.

Likewise we don't so much perceive that a rose is opening in the morning as become aware that it has opened since last we looked an hour ago. In which case of course we are using memory to compare its present state with an earlier state once more.

With still slower changes the total extent of our duration – 3 billion seconds if you're lucky enough to live for 100 years – must leave us even more blind than before. So that very gradual changes - as in a granite surface which erodes perhaps 1 centimetre in 1,000 years – are again quite beyond our direct or unaided observation powers.

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OTHER ANIMALS

Other animals however likely appreciate changes at rates very different from our own. Consider the lowly snail which is said to react to just 4 stimuli per second at most. We rate the snail's crawling progress – typically a few metres per hour - as extremely slow. But a sighted snail would probably view the approach of a strolling human much as we would observe an incoming jet fighter – i.e. going far too fast for the observer to move out of harm's way!

Supposing too that a sighted snail were to visit the cinema, it could probably only see a swiftly passing blur which changes too fast to make any sense at all. Likewise its appreciation of our music would probably resemble what we would hear from a tape recorder in very much accelerated or 'fast-forward' mode.

Conversely other animals can experience changes at much faster rates than we can comprehend. Swallows and flies seem likely examples: they can easily dodge our relatively slow-moving efforts to capture them. To such life-forms we probably seem as tardy and clumsy as an elephant appears to us.

Likewise a swallow at the cinema would probably see a slow and boring succession of very similar slides with dark spaces between. And even our liveliest music would be experienced as a dreary dirge – something like we would hear from a tape recording run slow.

Finally our perception of regular changes is linked to our homeothermy – the fact that our bodies largely maintain a constant temperature around 37 deg C. Here experiments show that our perception of external changes are inversely linked to our physiology. So with fevered patients the outside clock hands seem to be running slower; with hypothermia the same clock hands seem to speed up as the body slows down.

Non-homeothermic animal like lizards might therefore see the second hand of a nearby watch whizz round as they wake up into a slow state with the cold light of dawn. In the warmer condition of noon however the dial would appear to change at a slower rate. But then confusingly it would seem to speed up again as the cold of night sets in!

From which it must follow that if our bodies could not maintain a fairly regular temperature, our perceptions of change, and the temporal notions we derive from them, would probably be even more confusing than they are presently....

THE SENTIENT COMPUTER

Finally such speculations about other animals are far from an idle or impractical exercise: they become increasingly relevant as we enter the advanced computer age. For computers aren't limited by the slow ionic diffusion process: they communicate internally by electrons moving at much faster rates.

Imagine therefore a thinking computer which can observe at even a lowly ten thousand times faster than ourselves. For this machine a visit to the cinema could well be a very boring experience indeed. Or in human terms it would mean staring at just one picture for some 208 seconds (10,000 divided by 24 and then by 2), then a similar period of darkness, and so on.

Further for television that travelling flash of light, which we see as a changing picture, might present a far bigger problem for the sentient machine. For the computer to construct a coherent narrative from it, would probably resemble our problem if we could only view the Mona Lisa down through a travelling and very narrow tube.

To a sentient computer also we humans would likely appear as very slow-moving entities, quite possibly far slower than snails now appear to us. Presumably too such a temporal imbalance must leave the human race at severe disadvantage, if it ever came to all-out Terminator-style war between computerised robots and ourselves.

Indeed the seeds of this dilemna are already apparent in some recent Stock Exchange crises – where too rashly automated programs have bought and sold stocks in a mad millisecond rush before their foolish owners could realise what they had done!

WE NEED MORE ABSOLUTE STANDARDS

What all this amounts to is that the external world exhibits a near-infinite variety of changes all happening at different rates. But through our biology we are limited to a very narrow and trivial selection of the same. Whence further our derived impressions of time may be likewise limited in scope.

The Jigsaw of Time may therefore require a more absolute basis, or framework more attuned to nature than the mere accident of human biology,, if we are ever to fit its pieces together properly and so better understand it all.