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Is ours a world of timeless
being (the “block universe”) or of flowing time and true becoming? The current debate over the block universe,
represented in the essay by Chris Isham and John Polkinghorne, brings together
scientific, philosophical and theological arguments in a tightly-knit,
interwoven pattern.
Proponents of the block universe
appeal to special and general relativity to support a timeless view in which
all spacetime events have equal ontological status. The finite speed of light, the light cone structure, and the
downfall of universal simultaneity and with it the physical status of “flowing
time” in special relativity result in a heightened tendency to ontologize
spacetime. The additional arbitrariness
in the choice of time coordinates in general relativity makes flowing time
physically meaningless. Thus no
fundamental meaning can be ascribed to the “present” as the moving barrier with
the kind of unique and universal significance needed to unequivocally distinguish
“past” from “future.” Instead the
flowing present is a mental construct, and four-dimensional spacetime is an
“eternally existing” structure. God may
know the temporality of events as experienced subjectively by creatures, but
God cannot act temporally, since flowing time has no fundamental meaning in
nature. Theologians must accept the
Boethian and even gnostic implications of the block universe.
Opponents of the block universe begin
by distinguishing between kinematics and dynamics. Special relativity imposes only kinematic constraints on the
structure of spacetime. The dynamics of
quantum physics and chaos theory encourages a view of nature as open and
temporal, thus allowing for both human and divine agency. The problem of the lack of universal
simultaneity is lessened since simultaneity is an a posteriori construct.
Philosophically disposed to critical realism, opponents are wary of the
incipient reductionism of the block view.
They resist the Boethian implications of relativity, and argue instead
that divine omnipresence must be redefined in terms of a special frame of
reference, perhaps one provided by the cosmic background radiation. God’s knowledge of spacetime events in terms
of this frame of reference will be constrained by both the world’s causal
sequence and the distinction between past and future. Similarly God’s actions will be consistent with relativity
theory.
In the end, is the debate
merely philosophical or could it actually have scientific consequences? Proponents
of the block universe challenge their opponents to decide between a mere reinterpretation of the existing theories
of physics and the much stronger claim that these theories should be changed.
If forthcoming, such changes ought to be testable empirically and would
constitute a major achievement in the debate over time. Proponents also point to additional
complexities in the debate, such as the problem of giving a realist
interpretation of quantum physics.
These problems become even more acute when dealing with quantum
cosmology, making an atemporal interpretation almost inevitable. They do not object to positing that God
experiences the world through a special frame of reference or that God is aware
of the experience of temporality of living creatures. However they find it hard to understand how God’s action on the world can respect the causal
constraints on such action entailed by special relativity.
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