Historical Background
Time and Eternity by Arthur C. Custance
Chapter 1
IT WILL BE convenient in this study to consider the matter under two
headings, one of which is strictly in the realm of physics and the other in the
realm of philosophy. The first is the relativity of time, and the second
is its coexistence with the created order. Or to put it a little more
elaborately, the first consideration is how fast time really goes and whether it
has a fixed speed independently of experience. And the second consideration is
what happens to experience in the total absence of time. The first question
involves us in a brief historical review which will prepare the way for a survey
of some important passages of Scripture that involve the second.
In spite of what has been said above about the dangers of using analogies,
even a historical sketch of this subject has to depend to a large extent upon
analogy. It used to be thought that light was, as it were, instantaneous. No
sooner did a man switch on his flashlight than the beam hit the wall. But in the
seventeenth century, an astronomer named Ole Roemer (1644-1710) found that
eclipses to the moons of Jupiter occurred sixteen minutes earlier when Jupiter
and the earth were on the same side of the sun than when on opposite sides. He
rightly concluded that light was not instantaneous. The difference in distance
between the earth and Jupiter in the two situations made the light late in
arriving, for it was actually taking time for it to travel over the intervening
gap. He calculated that the moons circling the planet took so many hours to
travel round once, thus establishing a regular time cycle for eclipses. These
eclipses could then be clocked, and by projecting the time interval, could
thenceforth be guaranteed to occur regularly over any number of years providing
it did not slow down.
However, it was found that when the planet Jupiter was on the other side of
the sun from the earth, the time sequence was thrown out and the eclipses were
sixteen minutes late. Sixteen minutes is 960 seconds. The orbit of the planet
gave the difference in the distance when on the same and on the opposite side of
the sun. This distance divided by 960 revealed that the speed of light must be
approximately 186,000 miles per second. His discoveries were published
posthumously in 1735. Subsequent experiments gave a more accurate figure of
186,319 miles per second
This discovery was very quickly seen to be the possible answer to another
question which had been troubling astronomers for some time. This question had
to do with the speed of the earth through the supposed ether. And this second
question took a form something like this: because light and heat reached the
earth from the sun, it was assumed that some kind of medium existed to convey
the waves. However, if this medium had any kind of "substance," it seemed
obvious that the earth would burn up as it raced through it in its circuit
around the sun. The problem was to find a medium real enough to convey waves,
but thin enough to offer no resistance to the passage of a body through it.
But this contingency led to a further question: Was this medium stationary
with respect to the universe, pervading it uniformly in every part of it, like a
sea in which the stars plowed their way? In which case the actual speed of the
earth relative to the universe and to all other moving bodies in it ought to be
discoverable. To determine this was very desirable. Our sun with all the other
stars appears to be rushing madly outward as the universe expands. This
assumption is based on certain observations which we do not need to enter into
here; it is sufficient to say that the distance between other galaxies and our
own seems to be increasing as the periphery of the universe is enlarged.
However, this increase in distance could mean that we might be chasing these
remote galaxies but losing in the race, like a dog chasing a car. Or they may
really be chasing us while we make our escape. All that we know about it is that
the distance between these systems appears to be growing gradually greater. But
if the ether is stationary, it would be possible to discover who was chasing
whom, and absolute motions could be calculated
A man who strolls the deck of a modern liner may be traveling relative to the
vessel at two miles per hour. If the boat is at rest on the St. Lawrence, this
is his absolute motion and direction with reference to the river. If the boat
begins to move at 15 knots, the whole problem changes. His speed relative to the
boat is still 2 m.p.h., but to the river may be 13 or 17 knots depending on the
direction of his walk. If he happens to be crossing the boat from side to side,
his motion relative to the river is 15 knots one way and 2 m.p.h. in a
perpendicular direction. When the current of the river is taken into account,
all these speeds are affected and altered relative to the shore and unless he is
in sight of some object on the shore which he knows to be stationary, he can
never determine his actual speed with respect to the earth itself. But when the
motion of the earth around the sun and the sun among the stars has also to be
considered, his absolute motion becomes exceedingly difficult to determine,
because there is no fixed point on the "shoreline" of space by which it can be
gauged. It had been hoped that the ether might provide this gauge.
If we know that a wind is passing us at 60 m.p.h. and we have a wind gauge in
our hands, we can from this knowledge discover our own speed. If the wind gauge
indicates a higher figure, it is because we are traveling toward it. If the
reverse, the opposite is the case. If there is no difference, we are probably
stationary. We need to know only that the wind is passing us at a uniform speed,
and the measurement of all subsequent movement is possible, given enough
instruments.
Every effort to demonstrate the reality of the ether had failed, and we
therefore had no "sea" through which the earth was passing with all the other
stars which could serve as a basis for establishing absolute movement. But
suddenly it appeared that a new yardstick had been provided by Roemer's
discovery. Without going into too many details, it seemed obvious that light
passing through a current of ether would be either accelerated or slowed up if
such a fluid medium did in fact exist to create a current, depending on which
way the light was traveling.
The history of the experiments which were at once undertaken to test this
hypothesis is now probably quite familiar. The most famous investigation has
since been known as the Michelson-Morley Experiment, and it was the findings of
these two scientists which led Einstein in 1905 to formulate the first two
principles of his Special Theory of Relativity. The historical background has
been given clearly and accurately by R. S. Shankland in the British Journal
Nature. (3)
A. A. Michelson was born December 19, 1852, in Strelno, Germany. When he was
two years old, the family moved to California. In 1869 he entered the U.S. Naval
Academy at Annapolis. Here, in 1877, he made his first measurements of the speed
of light and subsequently in 1880, while at the College de France, invented the
Michelson Interferometer as a means for measuring the earth's motion through the
ether. His interest in this problem had been aroused by a letter from James
Clark Maxwell, who emphasized that all experiments to observe the earth's motion
through the ether, which depended on measuring the first power of the ratio of
the earth's speed to that of light, were doomed to failure. He said, in effect,
that no terrestrial experiment for measuring the velocity of light could ever
detect the earth's motion in space. This was a challenge to Michelson. His first
experiment was made in Helmholtz's laboratory in the University of Berlin. Both
this and a second trial in 1881 gave a null result, although Michelson himself
never considered it conclusive.
In 1882 Michelson returned to Cleveland and made further measurements on the
speed of light, obtaining a value of 299,853 plus or minus 60 kilometers per
second, the most reliable measure until 1927. He subsequently met Edward W.
Morley while attending a series of lectures by Lord Kelvin, and the two men
collaborated in further experiments, using more refined methods
In 1886 Michelson and Morley together undertook the investigation which has
since been known as the Michelson-Morley Experiment. All kinds of precautions
were taken to render any results obtained absolutely conclusive. As Shankland
put it: (4)
The work with this apparatus continued from 1886 until July 1887 and was
conducted in buildings on the adjacent Case and Western campuses. The
definitive null result obtained in these experiments led to profound changes
in the development of Physics...It is needless to say that the most direct and
now universally accepted explanation for the Michelson- Morley Experiment...is
provided by the Special Theory of Relativity given by Albert Einstein in
1905.
J. N. W. Sullivan has summarized the significance of these events. (5)
Since then the Michelson-Morley Experiment has been repeated many times. In
principle it is very simple, and consists in comparing the velocity of light
in different directions. If the earth is moving through a stationary ether, it
can be shown that two rays of light, the one moving in the direction of the
earth's motion, and the other at right angles to it, should take unequal times
to cover the same distance. But although the experiment has often been
repeated, no difference has ever been found, although in some of these
experiments the apparatus has been so delicate that a difference one hundred
times less than the difference expected could have been
measured...
The dilemma thus created is a very real one and the way out, which was shown
by Einstein in 1907, is an effort of genius of the highest order...Einstein
asserted that the velocity of light is always the same whether we measure this
velocity from a system which is in motion or a system which is at rest.
It often happens in the history of science that an effort to prove a theory
fails in its immediate objective but leads by accident to a much more important
truth. This was so in the case of the Michelson -Morley Experiment: it led
ultimately to the discovery that light impacts an object at a uniform velocity
regardless of whether the object is moving toward or away from the source of
light at any speed less than the speed of light. Einstein's principle of
constancy means that light rays if unobstructed have an observed constant
velocity irrespective of the relative velocity between the observer and the
source of light. Or to put it slightly more dramatically in the words of William
Hudgings: (6)
Einstein's declaration is that if two observers are on the opposite sides
of the rotating earth, one revolving away from the sun and the other toward
it, the instruments of each observer will indicate that the rays from the
flash are traveling past him at exactly the same speed of 186,000 miles per
second regardless of whether he is traveling towards or away from the
sun.
As it stands, this seems like an impossibility.
With profound insight, Einstein had pointed out in so many words that while
the speed of impact of the light must logically be different, it could not be
measured because the rate of flux of time was changing in such a way as to
conceal any difference in the two velocities being measured, and time is a basic
function of velocity. It is as though two watches keeping different time, one
faster than the other, were being employed in this one experiment, the one watch
for the speed of light in one direction and another watch for the speed of light
in the other direction, so that by taking into account the difference in the
time intervals shown by the two watches which were not synchronized together,
the logical contradiction could be explained. The question then arises which of
the two watches was keeping "correct" time. Einstein's answer is "both" and
"neither": there is no such thing as correct time in the sense of Absolute Time.
The passage of time is entirely relative, and its rate of flow is established by
each observer in each situation for himself--quite unconsciously. In some
way, Nature has contrived--sometimes the word conspired is used--to make
it impossible to discover any absolute passage of time.
However, in any given situation there is a measurable flow of time
which makes possible the measurement of distance or volume or speed for that
particular situation. Time therefore becomes the fourth dimension of all
measurements taken within the framework of the physical universe. Without time
no thing exists, and without things time has absolutely no meaning. This brings
us in a circle, back once again to the observation made by Einstein which we
have already quoted: (7)
If you don't take my words too seriously, I would say this. If we assume
that all matter would disappear from the world, then, before relativity, one
believed that space and time would continue existing in an empty world. But
according to the theory of relativity, if matter and its motion disappeared
there would no longer be any space or time.
One is reminded of the profound insight of Augustine, that time began with
Creation. Or, to use his own words, "Beyond doubt, the world was made not in
Time, but together with Time." (8)
As Sullivan says, Nature knows nothing of the distinction we make between
space and time. The distinction we make is due to a psychological peculiarity of
our own minds. This brings us to one consideration which is a little difficult
to deal with because it is very easy to confuse the physical aspects of the
Theory of Relativity with the psychological aspects. And these in turn have to
be distinguished from what, for want of a better term, we can only refer to as
the spiritual aspects. So we turn, first, to psychology and the realm of
experience.
References:
3. Shankland. R. S., "Michelson, A. A., 1852-1931," in Nature 171
(Jan. 17, 1953):101ff.
4. Ibid., p. 102.
5. Sullivan, J. W. N., Limitations of Science, Pelican, London, 1938,
p. 36.
6. Hudgings, W. F., An Introduction to Einstein's Theory of Relativity,
Haldiman-Julius, Girard, Jean., 1923, p. 23.
7. Einstein: quoted by Philipp Frank, ref. 2, p. 178.
8. Augustine, D, Civitate Dei, book 11. char. 6.
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