Let us consider the concepts of space and time. Physics and Ra agree in positing a world of many “dimensions” (or densities) of space and time. Physics has not decided how many such dimensions there are, but nonetheless maintains that there is some number of such dimensions. Ra has fixed the number at seven.
What are space and time? To answer this question it is important to keep in mind that the distinction being expressed is illusory. It is usual in physics to think of space and time as being fundamentally non-distinct. All dimensions of space and time are simply dimensions in which objects are extended, and no real difference exists between the space dimensions and the time dimension(s). This is a popular perspective in Western academic philosophy as well. Ra again takes the same perspective.
First understand how reality is according to this perspective. There is a vast expanse of existence, spanning across the many-dimensional space-time. In this existence all events occur simultaneously in a single, eternal present moment.
This is how reality really is according to this perspective. And reality appears to us such that only one portion of space-time is ever visible, and in particular only one point in time is ever visible.
The distinction that Ra draws between space/time and time/space is the distinction between what is visible and what is hidden from our illusory perspective. Space/time is what is visible, and time/space is what is hidden. The line drawn between space/time and time/space does not describe a property of reality, but a property of our perceptions.
This line is not drawn in any clear and simple way; it is a complex thing, like the border to a country. It might be simple to hypothesize that the first three dimensions are space/time, and the remaining four dimensions time/space. But this is not the case. There is, for instance, such a thing as third density time/space, and such a thing as fifth density space/time.
The polarity between space/time and time/space is a feature of third density, and to a progressively lesser extent in the higher densities, until in seventh density this polarity is nonexistent.