SUMMARY
Our planet in its orbit has 3 natural recurrences, which our calendars formalise by organising the basic unit of the day into larger groups of months and years. Conversely the 3 finer subdivisions of the day - into hours, minutes, seconds - are all purely artificial constructs: they derive from the convenience of certain easily divisible numbers, as first realised in Ancient Egypt and Sumer 5,000 years ago.
Importantly also these mere conventions of measurement, must also exert strong influence, on what one thinks about the greater question of time’s nature overall.
CALENDARS – SUBDIVIDING THE YEAR
Time measurement involves the counting up of events which recur at a regular rate. And for doing so Nature conveniently provides three very obvious natural recurring units in the form of our planetary parameters. Whence our calendars subdivide the longest such natural unit (the year) into smaller natural units of months and days.
So whereas chronology requires the counting of all years into proper sequence, the calendar involves breaking down each year into lesser and more convenient units we can better comprehend.
In addition those 3 primary terrestrial units – day. moonth, year- are reflected in various natural biorhythms (for example sleep) which play a leading role in human biology. So that while the 3 main units of terrestrial recurrence have been formalised by us into calendars, they also continue to exert strong influence on all our experience and thoughts of time.
Other planets like Jupiter or Saturn have of course very different orbital parameters: their days, moonths (of which there may be many different ones), and years are not at all like ours. So that if there were any intelligent creatures living out there, their various biorhythms (sleep, seasons etc.) would have be very different to our own. Whence their temporal experience and resultant time notions would presumably be different as well!
Here on Earth in any case the calendar is just a system for keeping better track of days. By reflecting the other 2 natural recurrences, it enables us to group the basic day unit, into larger parcels of months and years.
However the 29.57-day recurrence of the moon – originally termed a moonth - is much easier to observe and deal with, than the 365.24-day recurrence of the year. The latter is simply too big a number for most people to handle readily.
In prehistory therefore, the evidence shows that calendars based on moon records must have long preceded yearly ones. That the former were familiar at least 15,000 years ago seems proven from several prehistoric artefacts, for example 29-dot patterns inscribed below animals in the prehistoric cave paintings of Lascaux.
Clear evidence for yearly records only comes much later – perhaps the earliest such clear proof being Ireland’s Newgrange monument. This is a Stone Age construction built over 5,000 years ago, or ca. 3200 BC, to capture the rays of the rising sun on each winter solstice (December 21/22).
And since it’s still working away as intended after 5 millenia, Newgrange is also arguably the world’s oldest scientific instrument!
But In any case moon calendars were the preferred method for keeping track of the days in most early societies. Easy to count up and demarcate, they also performed a useful agricultural function by keeping track of Nature’s annual swings. And because their months are usually named after some local seasonal phenomenon like “the opening of buds or apertures” (whence our April), they are often known as “Nature calendars”.
A Nature or lunar calendar of this type was also used by early Rome from at least 800 BC, but had gradually lapsed out of synchronisation with the seasons and the natural year. So In 46 BC Julius Caesar modified it to form a new solar calendar – essentially the one that we still use today.
Based only on Earth’s annual traverse around the sun, Caesar’s calendar is subdivided into 12 months for everyday operational convenience. Traces of the old Roman lunar calendar survive in the strange way many of our months are still named. But its 12 main divisions further reflect the mathematical conventions of Ancient Egypt and Babylon: there are also 12 signs in the Zodiac because it’s an especially convenient figure easily divisible by 2,3,4,6.
THE WEEK
In contrast to those 3 planetary parameters which determine the boundaries of our calendar, its further subdivision into recurrent weeks of 7 days is a purely artificial construct. Likely there are three facts which have favoured the 7-day week as it evolved from Ancient Rome 2,000 years ago:
Firstly - the early Sumerian/Babylonian astronomers – in the country we now call Iraq - could see only 7 bodies wandering through the heavens - Sun, moon, and the 5 major planets. So 7 became an especially holy or mystical number incorporated into many other contexts – for example the Biblical story that, after creating the Universe in 6 days, God rested on the seventh one!
Secondly- 7 days was a convenient interval between markets in Europe, a span dictated by how long food might keep reasonably fresh in pre-refrigerator days...
Thirdly - 7 divides fairly neatly into that inconvenient lunar cycle of 29.57 days
Other societies however have had different lengths of week. Notably the French Revolutionists of 1789 tried to decimalise time along with the more successful metrication of space. But their new ten-day week soon proved highly unpopular with all classes of society. Not least among them were the workers who now had only one day’s rest in 10, not of one in 7 as before.
Very sensibly therefore Napoleon soon abolished the 10-day week in his Vatican Concordat of 1801. He wanted to please The Pope by bringing back the 7-day week – which also restored Sunday as the traditional religious seventh day of rest!
CHRONOMETRY: SUBDIVIDING THE DAY
As with the week, the 3 smaller units we use for subdividing the day – hours, minutes, seconds - are also all purely artificial constructs. And their lengths or durations are all entirely based on amenable numbers, handed down from antiquity once again.
So the 24-hr. day is again an extension of Ancient Egyptian practice – which originally divided both day and night into 12 equal hours whose length could be quite different.
But 24 is further divisible by 8 and 12, and is therefore even more amenable for dividing down both day and night combined.
Thereafter the 24-hour day went through many vicissitudes – for example those unequal hours of day and night further varied with the seasons – until reaching the total uniformity we have now. Which again just shows how the temporal attitudes of other cultures have often been so very different from our own.
In any case unequal or seasonal hours became impossible when some unknown European monk perfected the mechanical clock around 1280 AD. Obviously the new clocks could only display regular hours of equal length throughout both night and day. Further they usually had only one hand pointing to each hour.
But soon these first clocks attained another hand pointing out 60 smaller or more minute divisions, as it crawled hourly round its circular dial of 360 degrees. And again both these further sexagesimal numbers (i.e. based on 60) had been developed in Babylon around 200 BC. They arose through extension of the old Egyptian use of 12 - being still more readily divisible in any number of ways.
As mechanical clocks became more reliable in the late sixteenth century, time started to impinge more forcibly on peoples’ cultural, scientific and everyday concerns. So a second regular subdivision of the hour became common with the addition of a third clock hand.
And by 1700AD the 1-metre pendulum built into long-case or ‘grandfather’ clocks could beat out an accurate second with the regular tick-tock of each swing. Time concerns thereby began to intrude into everyday life most forcefully.
Later it was realised that clock accuracy relates directly to the frequency with which its ‘pendulum’ of whatever sort will beat. So the standard second is now defined as the time it takes for 9,192,631,779 ‘beats’ of the Cesium-133 atom to recur. The second is also the basic time unit in the Standard International physics system.
Still it’s salutary to remember that the second is an entirely artificial measure of duration, one which divides the natural unit of the day by 24,60,60 because these figures were found to be so convenient in Babylon over 2,000 years ago.
But again as before these measurements by hours minutes, seconds – to say nothing of days, months and years – must also impinge on our temporal attitudes very forcefully. This is a theme further supported by those very different time notions displayed by other societies without our conventions of time measurement.
Finally you can see this more clearly by considering a total opposite. Suppose then that we lived on a non-rotating planet forever perpendicular to its orbit as it circled the sun. In that case there would be no day/night divisions, no seasonal alterations, nor anything to indicate the passing of a year. Time measurements for people there would have to be very different from our own terrestrial system, and so likely engender very different temporal attitudes.
And these are points to be kept in mind when considering the main thrust of this blog: it aims for a fresh look at time in totality - and possibly reconfiguration of the whole problem in some radical new way....
Friday, December 16, 2011
Tuesday, October 11, 2011
7 - CHRONOLOGY – THE NUMBERING OF YEARS
SUMMARY
Many chronologies exist, or have existed, for the numbering of years. But that we in the west now number the current year as 2011 is due to one Dionysius Exiguus - a Roman friar who instituted the present system in what we now term 525 AD.
THERE ARE 7 UNITS OF TIME MEASUREMENT
“To measure” is to “determine extent by counting out standard units”. Hence metres or miles for distance, litres or gallons for liquid volumes, and so on.
Likewise nature has provided us with 3 standard units – day, moonth and year -for the measurement of time. These were all largely fixed when the Earth solidified and assumed its orbital parameters around the sun some 4.3 billion years ago, though hey have altered slightly over the intervening aeons.
Much later came humanity’s 3 subdivisions of the day into hours, minutes, seconds. But this finer set of time units is entirely artificial, originating around ancient Babylon about 2,000 BC.
To these 6 basic units of time measurement we must also add the week – a parcel of days originating in ancient astronom,y but which also serves our human habits well.
In any case, and whether we realise it or not, our 7 main methods for time measurement must also strongly influence our temporal ideas overall. And so they merit further consideration at this early stage....
Time measurement as practiced by us also falls neatly under 3 headings – chronology, calendars and chronometry. Chronology means the numbering of years arranged in proper past-to-future sequence. Calendars involve rather untidy procedures for subdividing each year into moonths, weeks, days. And chronometry is a much more exact branch of science – dividing each day into finer units by wholly artificial means.
Each of these 3 main systems of time measurement I will then consider briefly in their turn....
CHRONOLOGY – THE COUNTING OF YEARS
Most primitive societies have no real system for keeping count of the years: they depend on personal memories or oral tradition hardly stretching back more than a few centuries at most. Beyond that the tribal memory is of certain “peak moments” - like ancient battles or heroes - all gradually merging into a legendary and quite undated “once upon a time”.
For example when Homer or his contemporaries sang of The Siege of Troy, they were likely dealing with real events from perhaps 300 years before. This event likely took place around 1150 BC, but its exact date remained unknown then as now.
Likewise the Ancient Egyptians - who formed the first organised civilisation that we know of from 3,000 BC onwards - were to our eyes remarkably casual with the dates of history. What passed for chronology then was largely regnal , or based on the reigns of individual monarchs.
Each new Egyptian ruler therefore regarded his own arrival on the throne as that all-important First Event of history. This chronological egotism was also recorded on all monuments. So modern Egyptologists now have some difficulty with ordering the reigns of the early Pharaohs into proper historical sequence.
Regnal dating was also common in other major ancient societies like the Chinese and the Roman, and seems to have been a common early chrono-cultural constraint.
In contrast the Jewish story of Creation in the Bible emphasised that time clearly had a beginning – a tenet which may have influenced modern Big Bang cosmologists more than they might care to realise. And because the Bible also recorded the ages of all the patriarchs from Adam and Eve onwards, it seemed to offer a firm chronology from the start.
So, logically enough, the ultimate First Event in the Jewish AM (Anno Mundi) chronology was the Creation of the world. This they dated to what we now term 3761 BC , meaning also that it is now AM 5772 in such terms (Add 2011 to 3761...).
Around 700 BC however the Greeks began to emphasise rationality without recourse to religion, so further requiring a new sequencing of years. They based their novel chronology on the relatively new Olympic Games, a regular recurrence which conveniently took place triennially. So for them that crucial First Event became the year of the First Olympics, which took place in what we now term 772 BC.
But early Olympic records seem to have been not wholly accurate, so causing problems for Herodotus and Thucydides when they assembled the first true histories in the 5th century BC.
The Romans succeeded the Greeks, and copied them closely in many ways. Naturally however they regarded their own history as more important than one dated by mere games. So for them the greatest First Event was obviously the foundation of their capital at Rome. Hence came their AUC chronology (Ab Urbe Condita: from the foundation of the city) ,commencing in what we now term 753 BC.
Surprisingly however the AUC system was never much used throughout the height of Empire, being largely applied by later scholars who wrote up its history. Instead, as in Egypt, regnal dating was still very much the norm. Each year in Roman history was therefore usually identified by the names of those two consuls who happened to be in power then.
THE AD SYSTEM
1300 years after the city was founded however, the new Christian religion had grown largely dominant in the fading Roman Empire. So Friar Dominus Exiguus (470-540AD) proposed that the birth of Christ be regarded as that all-important First Event. He was a mathematically skilled computus whose main function was to determine the date of Easter, member of a respected profession from which the modern term computer comes!
Exiguus was chosen by the pope to determine the date of Christ’s birth in Roman terms. This he reckoned to be 753 AUC - which he also renamed as Year 1 in the new Christian AD chronology (AD = Anno Domino, Year of the Lord).
Exiguus may have been four years out in his calculations, since most people now think that Christ was born in 4 BC. Still his system was adopted by the Venerable Bede, a monk at Jarrow whose great History of the English People was finished in 731 AD. Thereafter AD chronology spread during the ninth century through Mediaeval Europe, and so was long prevalent when western science and commerce started to flourish there after about 1500 AD.
Bede also occasionally used BC (before Christ) chronology, which counted backwards – though with no Year Zero - from 1 AD. But this usage then largely lapsed until the 16th century, when again it became important for Biblical calculations of the ultimate Creation date.
AD and BC abbreviations naturally emphasise the part played by Christianity in our current chronology, an historical role which some people don’t like to recognise. So around the mid-19th century Jewish scholars began to adopt CE {Common Era) instead of AD when numbering the years. Likewise BCE (Before Common Era) can be used in preference to the BC term.
OTHER CHRONOLOGIES
Although AD (or CE) counting of years is now the preferred practice in science and commerce, many other systems are still in use. For example Muslim chronology dates the First Event to the flight of Muhammad from Mecca in 622 AD. Uniquely however the Muslin year is reckoned as the sum of 12 lunar months, and so approximately 11 days shorter than our own.
This also means that Muslim chronology is slowly gaining on the AD system in terms of yearly totals: the western year 2011 is now reckoned as 1432 in most Islamic lands.
Tuesday, August 23, 2011
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.
.
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.
Friday, June 24, 2011
5. The Full Time Spectrum
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.
5/ The
Full Time Spectrum
SUMMARY
The
Spectrum of Time, which might be more accurately termed a spectrum of
durations, ranges from the very briefest to the very longest intervals that
science knows. Its current boundaries are between 5x10-24 and 5x1017
in terms of seconds. But the second is really a wholly artificial unit derived
from the limitations of human experience.
So it
might be better to expression the spectrum in terms of the more basic chronon
as currently understood. In which case the totality of temporal duration
amounts to 10 41 chronons (i.e. 5x10 17 seconds divided
by 5x10-24 seconds) in all.
Strangely
too this number is close to the square root of the accepted figure for all
atoms in the Universe. This may be just a statistical coincidence – or else an
expression of matters quite totally beyond our comprehension at this stage.
When
tackling some new scientific problem, it's wise at first to try and grasp it as
a whole. One way of doing so is to form a spectrum - which is an array of
similar entities, arranged in order of their magnitude. A spectrum is only
possible if all its entities can all be measured in terms of a single basic
unit. And for time the second provides this unit conveniently.
A useful
model here is the complete spectrum of light, of which the rainbow provides a
visible manifestation, though just a tiny part of the whole. With the metre as
its basic unit of wavelength, the spectrum of light only started to clarify in
the late nineteenth century. Then J.C. Maxwell discovered that all kinds of
light are basically a form of electro-magnetism.
Thereafter
the study of light could at last become a mature science, i.e. one with the
natural facts organised into optimum order. And into its spectrum could soon be
slotted many new forms of light, which were previously unimagined because they
were invisible to human eyes: gamma rays, X-rays, microwaves, radio waves,
etc..
This
useful example also suggests, that to clarify a similar Spectrum of Time might
be likewise profitable. As I first outlined in my book Future, Memory and
Time (1997)1 , this would consist of a range of
durations or intervals all laid out in proper sequence, ranged from the
briefest to the largest that we know. Further these intervals are best
expressed in terms of the second, already accepted as the basic time
unit in physics and also familiar to people in their everyday affairs.
When this
is done as below, the Spectrum of Time is then seen to divide into three major
sectors. Micro-time, Middle-time (or what we may also term Personal-time) and
Macro-time ascend in order from the very briefest to the very largest interval.
The boundaries between them are of course dependent on the not-too-certain
state of our knowledge in this year 2011; further there are certain sectors
remaining to be filled in.
To view
the Spectrum of Time all laid out in this way – no matter how tentatively as
I've depicted below - can then bring our visual intelligence into play. For
this depiction also highlights one great problem: current science assigns very
different properties or implications to the temporal in Micro-, Middle-, and
Macro-Time.
So that
in unification or reconciliation, of these seemingly very different sectors,
may lie the start of solution to time's problem overall.
MICRO-TIME: THE BRIEFEST INTERVALS
Micro-time
describes the temporal realm of quantum physics, which concerns the very
smallest manifestations of matter, space and time. This is a region where
current understanding is generally agreed to be unsatisfactory, primarily
because it all seems so weakly grounded in the reality of experience.
In quantum
theory the very briefest possible interval is known as Planck Time – about 10-43
seconds in extent. If true, Planck Time must be the briefest possible
expression of temporal duration – and so constitute the boundary of our Time
Spectrum at the lesser end. But whether it is a true reflection of reality, and
not just a mathematical construct produced by theory, seems best judged still
unclear. Wherefore it seems wise to leave our Time Spectrum open at this lesser
end – ready for expansion out to Planck Time if this is ever proven to be real.
Of more
practical or less theoretical consequence here may be the chronon - a
still hypothetical atom or indivisible unit of time. Its duration is easily
calculated from common or everyday procedures, extending these out to the very
limits of what is operationally possible.
Starting
with everyday practice therefore, time can be defined as distance divided by
velocity. For example if you drive your car over a distance of 80 miles at an
average speed of 40 miles per hour, then the time for your journey is 2 hours.
Next we
can extend this simple practice out to well proven physics limits of speed and
distance. Here the fastest speed is that of light at 3x 108 metres
per second (or 11 million miles per minute if you like). At the other end of
nature the shortest distance we can consider operationally may be taken as the
diameter of an electron at 3 x 10-15 metres, (or about one million
billionth of a yard across.)
So the
time for the fastest to cross the shortest, may therefore be the briefest
interval possible.
Simple
division then gives the duration of this chronon – the proposed atom or
indivisible unit of time – at 10-23 seconds in extent. (Though when
other special effects are taken into consideration, this value must be slightly
modified.) Whence 10-23 seconds may currently form the practical
boundary for our Time Spectrum at its briefer or lower end.
At this
level also reality is thought to be indeterminate according to current Quantum
Theory. This holds that there can be no possible way of predicting what an
individual small particle like an electron will do next. For example the
electron when moving may choose to veer left or right in direction; there seems
no possible law of physics – even in principle – to decide which.
Such quantum
indeterminism is in total contrast to classical determism at the
other end of the Time Spectrum. The latter is the region where reliable and
well proven laws of physics can always predict what large objects (say a
speeding snooker ball) will do next.
So at
what stage does quantum indeterminism for particles change over to classical
determinism? Precisely when this fundamental process of change (which
physicists call decoherence) may happen is still undecided, though
values between 10-15 and 10-19 seconds are commonly
suggested. But until this matter has been better clarified, it seems sensible
to adopt 10-17 seconds as a likely average. So that durations of
this order may constitute the longer boundary of micro-time.
PERSONAL OR MIDDLE-TIME
Much
longer time intervals are of course involved with direct personal
experience. Here we are limited to intervals of 10-2 (or perhaps 10-3)
seconds at the briefer end: how fast we can perceive changes is governed by the
rates at which our nerve cells can activate and communicate. And so the
illusion of flowing movement in the cinema is produced by 24 slightly differing
frames exhibited between 24 transmission breaks each second: we simply can't
register or discriminate between changes at such brief intervals.
Technology
however can now afford us indirect or secondary experience of much
briefer events. For example slow-motion presentation from ultra-fast cameras
can let us observe indirectly what happens as a bullet smashes through a window
pane. And the fastest such cameras can now operate down to 10-12
seconds – which suggests we may soon be able to reach down to that curious
quantum boundary of decoherence from the upper end.
Extending
personal time capabilities in the other direction also clarifies that our
maximum duration of direct experience must be limited to 100 years, or
3x 109 seconds at most. A a newborn baby may therefore live through
just 3 billion seconds, and only if he or she lasts long enough to become a
centenarian.
Further,
if you combine this longest figure for total life with the briefest personal
limit of 10-2 seconds, it must be that the maximum number of
thoughts or obervations you can ever experience will be about one hundred
billion (1011) at most. Though in practice of course this maximum
number is likely to be far less.
Indirect personal experience can however
stretch out far longer than the individual's lifetime. So that if for example
we walk through the ruins of Pompeii, we can easily experience something of
life 2,000 years ago
It
therefore seems reasonable to delineate two further useful boundaries for the
upper end of personal or Middle-time. One is the duration of recorded history –
i.e. from the time when people first consciously began to deliberately leave
records on their surrounding world. Currently this goes back to the first known
forms of cave art in Southern France – animal paintings now dated to 30,000
years ago, or 1012 seconds in our terms.
But
personal may even stretch back still further – to the emergence of the first
proto-humans perhaps 3 million years ago. So that at 1014 seconds
this must mark as the final upper boundary of personal or middle time.
Crucially
too we humans are supposed to differ from animals in that we can exercise free
will. If so we can always influence the otherwise immutable course of physical
determinism in time. For example the physics of wind pressure may well predict
that a forthcoming storm will blow down some ancient tree in your garden. But
you are always free to negate this most likely temporal outcome and
generate a less likely one. Simply by choosing a stout plank to prop up
your tottering old tree!
In so
much as we think that temporal outcomes are subject to intervention by free
will, the personal region of Middle-time seems therefore crucially different,
to those other two sectors on either side. But whether or not free will is
really valid has long been a topic of debate among philosophers, aquestion
which remains unsettled to this day...
MACRO-TIME: BACK TO THE BIG BANG
In any
case humanity, with its two main boundaries for personal time experience, only
arrived on the scene during the last 0.1% of time's totality: we only evolved
during the last 4 kilometres of that 14,000 km journey as expressed on the
Millimetre Scale (Blog 4). Long before us there extended vast aeons of what
geologist John Hutton first termed 'deep time', but which seems more accurately
termed Macro-time in spectrum terms. This stretches right back to the Big Bang
birth of our Universe, some 14 billion years, or 5x 1017 seconds
ago.
Such
therefore must constitute the practical upper limit of our Time Spectrum,
insofar as we are really only knowledgeable to some degree about time-past.
Still we can leave the boundary at this end open, for expansion into larger
regions of time-future eventually. But such can be only permissible whenever
our knowledge of this unhappened sector becomes more firm or less speculative
than it is now..
Macro-time
too is thought to be totally determinate insofar as the laws of physics govern
it totally. As such it contrasts with personal or Middle-time which seems to
involve free will, and further with Micro-time as governed by quantum
indeterminacy.
Again therefore to resolve or reconcile these
differences is probably one of the main problems confronting any proposed new
Science of Time..
THE SPECTRUM OF TIME
|
.......5x10-24 (sec)......
|
-16
|
-3
|
1010
|
12
|
14
|
....5x1017
(sec)
|
|||||||||||||||||
|
Chronon?
|
Decoherence?
|
:
|
Direct Perception
|
:
|
Art
|
Hominids
|
Big Bang
|
||||||||||||||||
|
Micro-Time
|
:
|
:
|
Middle-Time
|
:
|
Macro-Time
|
||||||||||||||||||
|
Indeterminate?
|
:
|
De
|
ter
|
mi
|
na
|
te:
|
Free-will?
|
:
|
Determinate
|
||||||||||||||
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