FREE ESSAY ON NEWTONIAN ABSOLUTE SPACE

NEWTONIAN ABSOLUTE SPACE

Newton's Absolute Space1
When Newton proposed his axioms describing fundamental laws of physics, he insisted on
the necessity of absolute space to a completed theory of mechanics. Absolute space can be
best described as not-relationally-dependent space. Newton purports that there is
something more to space than just being a vessel to conceptualize positional differences
between specific bodies; he claims that there is some objective truth to space -- that
spatial differences are not dependent upon the matter contained within space. In his
Principia, he states that the difference of relational and absolute space becomes
manifest in the consideration of place, velocity, and acceleration. These considerations
serve to metaphysically establish absolute space in themselves. However, Newton attempts
to support the existence experimentally in his famous 'bucket experiment'. Through an
explication of his reasoning and an analysis of his motivation, I intend to show that
Newton's notion of space is, at best, incomplete.
Newton describes the difference between absolute and relative space in the scholium to
definition eight in the Principia: Absolute space...without relation to anything
external, remains similar and immovable. Relative space is some movable dimension or
measure of the absolute spaces (152). His first relevant explication in the scholium is
of place. Place is that which a body occupies in space. Absolute place differs from
relative place in that it requires no relationship to any other body to be determined; it
is determined by the construct of absolute space itself. Absolute motion, then, is the
translation of a body from one absolute position to another. In the same trend, absolute
velocity is constant absolute motion in time, and absolute acceleration is a change in
absolute velocity in time. 
With that clearly laid out, Newton has explicitly shown how absolute space is
conceptually applied to mechanics. The validity of absolute space in itself still remains
in question. These definitions of absolute mechanics are, in fact, used retroactively to
validate the existence of absolute space. In using discussions of absolute place,
velocity, and acceleration, Newton's proponents hope to show that there is a difference
between these and their relational counterparts. There is an inherent flaw, though, in
arguing for an independent, self-evident difference between absolute and relational in
considering place or velocity. However, acceleration, as considered in the bucket
experiment, shows promise.
The difference in absolute versus relational place is mere semantics; instead of being
defined by making reference to another body, absolute place is determined by making
reference to the unsubstantiated concept of absolute space. The question can be asked:
What if the universe were to be moved four inches that way? Such a shift would be
entirely undetectable, because there would be no shift from any point of reference, save
a place in a presupposed absolute space. Only after accepting absolute space does
absolute position make sense. Claiming theoretical superiority would be entirely based
upon preconceived bias.
Absolute velocity is equally indiscernible from relational velocity. Velocity of a body
can only be determined in reference to something. In common perception, I determine the
velocity of a body by reference to another. In absolute space though, that velocity,
considered in the absolute sense, might have a different magnitude. Newton's example of a
passenger on a ship roughly runs: A man standing still on a ship moving at a constant
velocity can be said to be in absolute motion, though he is in relative rest to the ship.
An observer not on the ship is able to see that the man is in motion. Theoretically, it
would be an observer, aware of absolute space in itself, that would be able to determine
the man's true motion (as it is known by Newton). However, there is no such observer,
save maybe God, with such an awareness, and thus absolute velocity is indiscernible. It
requires a pre-established absolute point of reference to be determined.
True motion is a technical term that Newton employs. The existence of true motion, he
thinks, directly lends to the existence of absolute space. Newton distinguishes absolute
and relative motions by the forces impressed upon bodies to generate motion (156). True
motion of a body is motion that occurs as a result of a force imparted directly on that
body; relative motion can occur as a result of peripheral forces causing motion in the
referential bodies. This means that true motion of a body can only be determined in the
right inertial frame. An inertial frame describes the total spacio-temporal system that a
surveyor considers when assessing the mechanics of a body. By considering all relevant
effectors on a body, an accurate portrayal of the active forces can be determined, rather
than just relative accelerations to surrounding bodies. Newton assumes that the 'right'
inertial frame to consider all 'relevant' forces is universal for every body, because
there must be an underlying absolute truth to the motion of bodies that is objectively
determinable. This ultimate inertial frame is implicit in absolute space. 
The concept of inertial frame is important, because it is integral to an attempt at
rationalizing the existence of absolute acceleration, Newton's final hope in proving the
existence of absolute space. A proper inertial frame allows an observer to view the
action of real forces, and real forces produce real and not merely relative accelerations
(xxxvii). From this, it follows that absolute acceleration is discernible. However,
depending upon the understanding of force to describe acceleration is circular, because
force is defined to be equal to the product of a body's mass and acceleration. Therefore,
the observable effects of an acting force are otherwise undetectable except for it's
effects on acceleration. Then, by viewing a body's real acceleration, we can determine
it's real acceleration. This is fruitless. Because of the theoretical impossible of
separating force from acceleration, we can no longer determine the force's magnitude. We
lose the notion of 'real', and we are forced to resign ourselves to the language of
relations.
Rotational motion saves the consideration of acceleration from the circularity of purely
linear considerations. This is shown in the bucket experiment. The experiment consists of
a bucket, filled with water, hanging from a rope. The bucket is rotated manually,
building tension in the rope. The bucket is then released and allowed to spin. The focus
of this experiment is on the action of the water:
The water begins initially at rest. As the bucket spins, there is a transfer of momentum
from the bucket to the water, causing the water the swirl in the bucket. The water
continues to angularly accelerate until its angular velocity equals that of the bucket.
An interesting phenomenon occurs in the water: as it accelerates, it ascends up the sides
of the bucket; it's surface becoming vaguely funnel-shaped. This ascension is due to
centripetal acceleration. There is a force that occurs orthogonal to the path of any body
in rotational motion, which is equal to the product of the body's mass and the square of
its tangential velocity divided by the radius of its path. 
The importance of this lies in the fact that the water is in relative rest to the bucket,
because their velocities are equal. An observer on the surface of the water would assume
that he is at rest, because his reference body is the bucket. However, the ascension of
the water is indicative of motion, so the same observer could be lead to believe, with
knowledge of physics, that he is not at rest. Since there is a logical inconsistency in
considering merely relational references, Newton concludes that he has found proof for
absolute space in the need of physics for absolute reference points.
His experiment falls short of his lofty hopes, because all Newton has really accomplished
is proving the existence of true motion. More specifically, he has shown that every
inertial frame will not necessarily capture all imposing factors on a system. The
inertial frame has to be carefully chosen, so all relevant action is considered. If the
observer is immersed in the observed system as an element being acted upon, then the
inertial frame is 'too small'. An observer on the surface of the water might not be able
to tell that he is in motion, but an observer looking down at the bucket can see the
water and bucket moving together. The second observer has a 'wide' enough inertial frame
so that the questioned action is put into perspective. 
Newton wants True perspective though. He believes that the only truly correct inertial
frame is the one that encompasses everything. He suggests that no relational perspective
can completely account for the relevant forces affecting a body. Though to figure out
that the water in the bucket experiment was moving, I don't need to take the seat of God.
It simply requires me walking up to the bucket, as a man, and then looking down.
Newton knows that the distinction of absolute space isn't of practical importance in
physics. In our everydayness instead of absolute places and motions, we use relative
ones. It is only in philosophical disquisitions we ought to abstract from our senses, and
consider things themselves, distinct from what are only sensible measures of them (155).

The reason why Newton insists on universal truth is to buttress his Faith in God. In
fact, the idea of absolute space is completely manufactured around the presupposition
that there is an observer who has ultimate knowledge of the truth of space. God has
ultimate knowledge of everything, including spatial relations, thus what he knows is
absolute space. The idea of absolute space is reactionary, rather than empirical. I don't
think that it was necessarily intentional. However, it is easy to see how religion
motivated an otherwise unfounded claim. He simply declares true motion requires absolute
space, because there isn't adequate empirical rationale. Perhaps, he never looked for
such a connection, because he just assumed it was there the entire time.
Bibliography
All references made in this paper came from: Alexander, H.G. The Leibniz-Clarke
Correspondence. Manchester University Press; New York: 1998.