The parallel concept of time–space divergence
provides for the tangible measurement of increases
in separation between places that result from
traffic congestion and failure to maintain infrastructure.
Implicit in the convergence}divergence viewpoint
is the recognition that physical points (places on the
earth) are in relative motion with respect to one
another whenever functional measures (such as travel
time and cost) are used as the distance metric. Because
levels of investment in transportation and communication
technologies are not uniform, some places
converge much more rapidly with the remainder of the
settlement system than others. Some places, bypassed
by modern space-adjusting technologies, will diverge,
and others will converge and diverge selectively relative
to various parts of the urban system. Variations in
the set of rates that define convergence among all
possible pairs of places create a nonhomogeneous
time–space that is relative and dependent on the
inferred movement of places with respect to one
another. In this time–space, places are seen to compete
in their quest to gain relative accessibility over other
places, thereby gaining advantages for attracting
economic and other opportunities.
Time–space convergenceis analogous to the physical
concept of velocity and purports to assess the earthshrinking
impact of technological investments to
overcoming distance. As a time-rate changes over time,
it fits in the domain of metaconcepts. It is not a
velocity of sensation; rather it is a process identifiable
and abstracted only through measurement. The structure
of the resulting space, the frame of reference for
human activities, is constantly in flux and is not
describable in terms of Euclidean geometry. Even
though this abstraction of reality may not be recognized
intuitively, the time–space convergence}divergence
process embraces explicit recognition of its
social origins as the result of deliberative innovation
through investment decisions. It is this human behavioral
response to time–space convergence that reshapes
the space of human geography. Yet, Forer
(1974) demonstrates reciprocity in this process,
whereby the existing spatial structure of society also
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influences emergent patterns of investment to encourage
time–space convergence.
As a complement to time–space convergence, Janelle
(1973) advanced a reciprocal concept of human
extensibility. Developed more fully by Adams (1995),
this refers to the ability of an individual or agency to
extend their influence and presence over space and
through time to distant locations via media and other
means of influence over human resources. Human
extensibility parallels the construct of time–space
distanciation as advanced in Giddens’s (1984) structuration
theory. Together, these concepts pose questions
regarding the closure or spatial boundedness of
human societies and systems. They also bring forward
issues concerning the differential abilities of individuals,
firms, nations, and other forms of human
agency to reach beyond their physical locations to
shape possibilities for human livelihood elsewhere.
Such discrepancies lead Harvey (1990) to advance yet
another conception of time–space, one rooted in the
historical materialism of the political economy