The first edition of *New Foundations for Classical Mechanics* (1986) by David Hestenes included “Foundations of Mechanics” as Chapter 9. This was removed for lack of space in the second edition, but is available online as a pdf *here*. This space-time foundation may serve as a guide for the foundation of mechanics for time-space. To do so requires terms and correspondences in addition to switching space and time:

position space (spatiocosm) → tempocosm, (scalar) time → scalar space, particle → moticle, (space) position → time position, body → movement, instant → waypoint, clock → odologe, reference frame → reference timeframe.

Let’s focus on section 2 “The Zeroth Law of Physics” and start with the second paragraph on page 8, revising it for time-space:

To begin with, we recognize two kinds of entities, *moticles *and *movements *which are composed of moticles. Given a movement, *R*, called a *reference timeframe*, each moticle has a geometrical property called *its time position with respect to **R*. We characterize this property indirectly by introducing the concept of a *Tempocosm*. **For each reference timeframe ***R*, **a tempocosm ***T ***is defined by the following postulates:**

*T***is a 3-dimensional Euclidean space**.**The time position (with respect to***R***) of any moticle can be represented as a point in***T*.

The first postulate specifies the mathematical structure of a tempocosm while the second postulate supplies it with a physical interpretation. Thus, the postulates define a physical law, for the mathematical structure implies geometrical relations among the time positions of distinct moticles. Let us call it the **Law of Temporal Order**.

Notice that this law asserts that every moticle has a property called time position and it specifies properties of this property. But it does not tell us how to measure time position. Measurement is a separate matter, since it entails correspondence rules as well as laws. In actual practice the reference timeframe is often fictitious, though it is related indirectly to a physical movement. Our discussion is simplified by feigning that the reference timeframe is always a real movement.

We turn now to the problem of formulating the scientific concept of a scalar space. We begin with the idea that a scalar space is a measure of motion, and *motion is a change of time position with respect to a given reference timeframe*. The concept of a scalar space embraces two distinct relations: spatial order and temporally remote colocation. To keep this clear we introduce each relation with a separate postulate.

First we formulate the **Law of Spatial Order:**

**The motion of any moticle with respect to a given reference timeframe can be represented as an orbit in a tempocosm.**

This postulate has a semantic component as well as a mathematical one. It presumes that each moticle has a property called motion and attributes a mathematical structure to that property by associating it with an *orbit *in a tempocosm. Recall that an orbit is a continuous, oriented curve. Thus, a moticle’s orbit in a tempocosm represents an ordered sequence of time positions. We call this order a *spatial order*, so we have attributed a distinct spatial order to the motion of each moticle.

To define a physical, scalar space scale as a measure of motion, we select a *moving *moticle which we call a *moticle odologe*. We refer to each successive time position of this moticle as a waypoint. We define the *scalar space interval *Δ*s between two waypoints *by

Δ*s *= *c*Δ*t,*

where *c *is a positive numerical constant and Δ*t *is the scalar time interval of the odologe’s orbit between the two waypoints. Our measure of scalar space is thus related to the measure of duration in a tempocosm.

To use this scalar space scale as a measure for the motions of other moticles, we need to relate the motions of moticles at different time positions. The necessary relation can be introduced by postulating the

**Law of Coincidence:**

**At every waypoint, each moticle has a unique time position.**

This postulate determines a correspondence between the points on the orbit of any moticle and points on the orbit of a moticle odologe. Therefore, every moticle orbit can be parametrized by a scalar space parameter defined on the orbit of a moticle odologe.

Note that this postulate does not tell us how to determine the time position of a given moticle at any waypoint. That is a problem for the theory of measurement.

So far our laws permit orbits which are nondifferentiable at isolated points or even at every point. These possibilities will be eliminated by Newton’s laws which require differentiable orbits. We include in the class of allowable orbits, orbits which consist of a single time point across some scalar space interval. A moticle with such an orbit is said to be *fixed *with respect to the given reference timeframe through that scalar space interval. Of course, we require that the moticles composing the reference timeframe itself be fixed with respect to each other, so the reference timeframe can be regarded as a rigid movement.

Note that the pace of a moticle is just a comparison of the moticle’s distimement to the distimement of a moticle odologe. The pace of a moticle odologe has the constant value 1/*c *= Δ*t/*Δ*s*, so the odologe moves uniformly by definition. In principle, we can use any moving moticle as an odologe, but the dynamical laws we introduce later suggest a preferred choice. Any moving moticle defines a periodic process, because it moves successively over time intervals of equal length. It should be evident that any real odologe can be accurately modeled as a moticle odologe. By regarding the moticle odologe as the fundamental kind of odologe, we make clear in the foundations of physics that the scientific concept of scalar space is based on an objective comparison of motions.

We now have definite formulations of tempocosm and scalar space, so we can define a *reference system *as a representation x for the possible time position of any moticle at each *scalar space r* in some scalar space interval. Each reference system presumes the selection of a particular origin for scalar space and tempocosm and particular choices for the units of distance and duration, so each time position and scalar space is assigned a definite numerical value. The term “reference system” is sometimes construed as a system of procedures for constructing a numerical representation of tempocosm and scalar space.

After we have formulated our dynamical laws, it will be clear that certain reference systems called *facilial systems *have a special status. Then it will be necessary to supplement our *Law of Coincidence *with a postulate that relates coincident points in different facilial systems. That is the critical postulate that distinguishes classical mechanics from special relativity, but we defer discussion of it until we are prepared to handle it completely. It is mentioned now, because our formulation of tempocosm and scalar space will not be complete until such a postulate is made.

It is convenient to summarize and generalize our postulates with a single law statement, the **Zeroth **(or *Temporospatial*) **Law of Physics:**

**Every real movement has a continuous history in a tempocosm with scalar space.**