Polar plot in space and time

This post builds on others such as this.

It’s not unusual to see a map of travel time from a central location, for example, this map of Washington, DC, USA (click to enlarge):

Two-dimensions of travel time are represented as in space but could be represented as in time. Here is an example, first of a time contour on a 2D space map, in which a circle represents a constant distance:

The next illustration is a space contour on a 2D time map:

This illustrates the complementary relation of space and time.