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
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.......5x10-24 (sec)......
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-16
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-3
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1010
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12
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14
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....5x1017
(sec)
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Chronon?
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Decoherence?
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:
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Direct Perception
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:
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Art
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Hominids
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Big Bang
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Micro-Time
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:
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:
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Middle-Time
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:
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Macro-Time
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Indeterminate?
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:
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De
|
ter
|
mi
|
na
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te:
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Free-will?
|
:
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Determinate
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