Albert Einstein’s book Relativity: The Special and General Theory was originally published in German and translated into English in 1920. In the second chapter he introduces “The System of Co-ordinates”. The following post gives Einstein’s text followed by a revision that exchanges length with duration and space with time. First, Einstein’s text, with alternative wordings in square brackets:

End of Chapter I – If, in pursuance of our habit of thought, we now supplement the propositions of Euclidean geometry by the single proposition that two points on a practically rigid body always correspond to the same distance (line-interval), independently of any changes in position to which we may subject the body, the propositions of Euclidean geometry then resolve themselves into propositions on the possible relative position of practically rigid bodies.

Chapter II – On the basis of the physical interpretation of distance which has been indicated, we are also in a position to establish the distance between two points on a rigid body by means of measurements. For this purpose we require a “distance” (rod S) which is to be used once and for all, and which we employ as a standard measure. If, now, A and B are two points on a rigid body, we can construct the line joining them according to the rules of geometry; then, starting from A, we can mark off the distance S time after time [again and again] until we reach B. The number of these operations required is the numerical measure of the distance AB. This is the basis of all measurement of length.

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An object is stable. A rock is an object. Water is an object if it is in a container. A rigid rod is an object.

A subject changes. A person is a subject. Air is a subject since it keeps moving. A clock is a subject.

The grammatical subject and object are distinguished in a sentence, though they both may be things. For example, “The rock rolled down the hill.” Both the rock and the hill are things, that is objects, but in the sentence the rock is the subject and the hill is the object.

Objects are acted upon. A predicate is required to go with an object. An object apart from a sentence is a thing, something passive.

Subjects are active. A verb is required to go with a subject. A subject apart from a sentence is still a potential change agent.

Space is like an object and time is like a subject. If we start with objects and then discuss their motions, we are beginning with the passive objects of space and then adding the active subjects of time. If we start with subjects, we get their motions, too, and may then bring in the objects of space. That is beginning with an active time and adding the passive objects of space.

A reference motion must be active and so include a subject. A comparative motion is passive in relation to the reference motion and so must include an object.

Bodies and things may be subjects or objects, though many are usually one or the other. The difference is in whether they change or move. An object need not move. A subject is usually moving.

Objects are in space. Subjects are in time. Space never moves. Time always moves.

In mathematical finance, a replicating portfolio for a given asset is a portfolio of assets with the same properties. Here we replicate time through motions that have the same properties as time.

Step 1. Consider the motion of a rigid body A with a translation and a rotation around the same axis, such that the translation and rotation begin and end together. Measure the displacement of the translation as a multiple of the rigid body length along the axis. Count the number of rotations and any fractional rotation of the rigid body. The assertion here is that the quantity of rotations is a measure of the distimement, that is, the duration of motion around the axis of rotation.

Step 2. Separate the motion of rigid body A into a translation of rigid body B and a rotation of rigid body C such that the displacement of B and the distimement of C are the same as the displacement and distimement of A in step 1. Then the displacement of B is a measure of the displacement of A, and the distimement of C is a measure of the distimement of A.

Step 3. Construct an independent clock as a rotating rigid body that matches the rotation of rigid bodies A and C but runs continuously. Note the marking on the clock when rigid bodies A and C start and stop moving. The quantity of rotations between the start and stop is equal to the duration of motion of rigid bodies A and C. The reading on the clock is a measure of scalar time.

Conclusion. In order to generalize this the clock needs to move at a constant rate that is standardized for all clocks. Then allow another rotation so that the motion of translation and rotation replicates any rigid body motion per Chasles [shahl] Theorem of kinematics.

Chasles [shahl] Theorem states: Every rigid body motion can be realized by a rotation about an axis combined with a translation parallel to that axis. (Reference)

The independent clock generates a scalar time because it is not associated with any axis or direction. If the clock is associated with an axis of motion, then it generates a vector time, just as a rigid rod along an axis generates a vector length.