THE ESSENCE OF TIME
by David E. Powell
Note: This document is a work in progress. Comments,
corrections, arguments, and questions may be
submitted to me on-line.
Time. Everybody has some, but most people don't have
as much as they want. But what, exactly, is time? We all may think that we
know what time is, but who among us has taken the opportunity to stop and
seriously think about it?
Time is Not Natural
Time, in and of itself, is not a natural phenomenon. By "not natural", I mean
that time is a wholly man-made entity. Time doesn't exist outside of the human
brain. Animals, plants,
indeed no other known life form understands the concept of time, any more
than they understand the concept of, say, fashion.
This is not to say that animals do not understand changes yet to occur. Squirrels
will hoard nuts, for example, in anticipation of the coming winter. That, however,
is not time as described in this paper.
In order to explain the somewhat disturbing statement that time is a product of man
and not of nature, we must first examine and refine the definition of the word time.
Time Defined
My American Heritage dictionary
contains the following definition of time:
time (tēm) n. 1. Abbr. t., T. a. A nonspatial continuum in
which events occur in apparently irreversible succession
from the past through the present to the future.
But this definition is somewhat nebulous. It uses the terms "nonspatial
continuum" and "events" as the base of the definition, which themselves
are quite abstract.
I propose a simpler, more direct definition:
time (tēm) n. 1. Abbr. t., T. a. A means of measuring the change of
objects within a specific area of space at a specific level of detail.
My choice of words for this definition will, hopefully, become clear in a
moment.
The Frame of Reference
Albert Einstein (March 14 1879 - April 18 1955) popularized the concept of
"frame of reference" when he discussed his Theory of Relativity. This
concept applies equally well (indeed, is essential) to our discussion of time.
One cannot correctly speak of "time" without specifying its spatial limits,
any more than they can speak of "food" without discussing its specific
properties (Fried chicken? Dog food? Salt?). The frame of reference for
an object can consist of many things, such as distance, level of detail,
measurement units, etc.
Bounded by Space
In our definition of time above, we qualify the measurement of change to
limit it
within certain spatial boundaries, which should come as no surprise.
After all, we use those same limits for other measurements, such as
distance, color, and taste, to name a few. Humans normally have
"default values" for these limits; we don't always specify them
explicitly because many times they are understood without having
been spoken.
To illustrate, let's imagine for a moment (as it were), that we are trying
to describe a cardboard box to someone that cannot see it. We could
accurately describe its width, height, and depth, because we can measure those
attributes and convey those values to the distant person. We can describe,
somewhat less accurately, the box's color and taste (we will offer no guess
about why these attributes are important) by observing the box with appropriate
body senses and then vocalizing the observations. The point here is
not that these measurements can be made, but that the measurements are
all confined within the boundaries defined by the edges of the box.
In other words, all measurements were made within the space occupied by the box,
its spatial frame of reference. It was not necessary to mention
this while describing the box, because it was understood that, for example,
the distance measurements began at one edge of the box and ended at another.
Level of Detail
Another point that must be made here is that of level of detail,
or precision.
Depending on the reason for describing the box, one may make assumptions
about the accuracy of the measurements that were made. For example, if
the box were being measured for the purpose of determining if it would
fit within a closet, measurements made within a precision tolerance of
a few centimeters may be appropriate, and the color and taste would be
superfluous information.
If, on the other hand, this box were being duplicated from these
measurements, they would have to have greater precision, perhaps within a
millimeter or so. Other applications might require even more precision.
The precision of the measurements can be considered an attribute of the
frame of reference, and may or may not require vocalization, depending
on the intended use of the measurements.
Since time (by our definition) is a form of measurement, then
one must specify the frame of reference relating to
the time of which we speak in order to properly describe it. This
frame of reference not
only entails the physical space associated
with the time being discussed, but also the level of detail.
The human "default frame of reference" that is usually assumed when
speaking of time is all objects at all levels of the entire universe.
This occurs with such frequency that most people do not understand that
there are other frames of reference that may and should be used.
Measuring Change
Change is a byproduct of existence. There are things that do
not change, of course, such as empty space or atoms at absolute zero
temperature, and for these things (in their own frame of reference)
we can safely say that time is non-existent ("time stands still", if you will).
Most things change, however, and therefore the measurements offered by
time are applicable to them.
Let's once again direct our attention to the cardboard box in the example
presented above, and assume that it is empty save for the air within.
If we speak of time, and our spatial frame of reference is
the space within the confines of the box (but not including the box itself),
and specify that the level of detail for our frame of reference is above
the molecular level, then we can quite properly state that time is
standing still. That is, that between two successive measurements of
the state of the objects within the frame of reference (regardless of the
amount of time that has passed external to the frame of reference), no changes
were detected. To put it in the vernacular, we looked in the box twice and
it looked the same inside both times. Therefore, nothing changed, and
time within the box stood still between the two observations.
Placing an object into the box may or may not affect the passage of time,
depending once again on our frame of reference. For example, if we place
a pair of dice inside the box, and the dice do not move between observations,
then the determination that time was suspended is still valid. Even if we
place a cat inside the box, we can still say that time stood still, if we
change the level of detail in our frame of reference to a sufficiently
high value, e.g., "presence of all contents regardless of their relative
positions".
Conversely, if we specify in our frame of reference that the level of
detail is molecular or atomic, then (assuming that the box is maintained
at a temperature above absolute zero) it would be very difficult to truthfully
say that time in the box was suspended between observations.
Units of Measure
The units of measure that we are accustomed to when dealing with time are
hours, minutes, seconds, and so on. These can be as large as light years,
or as small as picoseconds, but can all be normalized to the basic unit of
time, the second. The second, which the fundamental unit of measure for time,
is related to the concept of change by its
official 1967 definition:
"...the duration of a certain number (9,192,631,770) cycles of microwave light
absorbed or emitted by the hyperfine transition of cesium-133 atoms in their ground
state undisturbed by external fields." Thus, the official definition of
time shows that it is indeed a measurement of change, with the frame of reference
being the cesium-133 atoms and an atomic level of detail.
The official definition above clearly shows that the second, being a unit of time,
is indeed an entirely man-made construct.
Manipulating Time
Direction
By taking advantage of our new definition, we can now manipulate
the passage of time. For example, suppose that our box contained the pair
of dice mentioned above, and our frame of reference is spatially within
the box, with a level of detail specified to be "the relative location of
solid objects within". We could make three observations of the location
of the dice: the first (noting the location and position of the dice),
the second after moving the dice to the other side of the box,
and the third after restoring the dice to their original location and position.
Based on these observations and frame of reference, we could accurately state
that time went "forwards" between the first and second observations, and it
went "backwards" between the second and third. This simple experiment becomes
much more dramatic as more and more dice are placed within the box.
Of course, if we change the level of detail in our frame of reference for
the above example to a fine enough resolution, time ceases to run backwards
and immediately runs forward again.
Speed
The speed in which time passes can only be specified as a value relative to
the change of an object. When we speak of "time", we normally reference it,
by default, directly to the change in position of the hands (or digits) of a clock.
This value is also referenced, albeit indirectly, to the vibrations of the
cesium atoms at the United
States Naval Observatory.
To change the rate of the passage of time, we merely have to specify the
object of comparison in our frame of reference.
to be continued...