FRANK HÄTTICH, *Quantum Processes: A Whiteheadian Interpretation of
Quantum Field Theory*, Münster: Agenda Verlag, 2004: 280 pages.
\[Reviewed by Henry P. Stapp, Lawrence Berkeley Laboratory, University
of California, Berkeley\]

This book is a "must-read" for philosophers and physicists interested in
the problem of constructing an ontology that is compatible with
contemporary physics. The apparent suitability of Whitehead's ideas as a
foundation for the development of a *theory of reality* has been noted
by many quantum physicists, including Abner Shimony (1993), Rudolf Haag
(1996), and myself (Stapp, 1979).

The main reasons are, firstly, that Whitehead's "actual occasions" (or
"actual events") are functionally similar to the "reductions of the wave
packet" (or "collapses of wave function") that play a key role in
orthodox contemporary physics; and, secondly, that both Whitehead's
ontology and orthodox quantum theory give these events a *mental*
aspect, and make these aspects causally efficacious in the physical
world. In orthodox quantum theory this causal efficacy of experiential
realities arises from von Neumann's "Process 1", which injects effects
of conscious choices crucially into the dynamics. Also, Heisenberg
(1958), when considering what is *really happening*, speaks of these
reduction events as transitions from "possible" to "actual", in accord
with Whitehead's idea of the function of actual occasions..

Whitehead mentions quantum theory several times in *Process and
Reality*, and was clearly aware of, and influenced by, the early phases
of the development of quantum theory (PR, p. 239). But Hättich correctly
emphasizes that contemporary basic quantum theory, namely quantum field
theory, was developed later and is conceptually much more sophisticated
than what is suggested by those early models, particularly as regards
the incorporation of the constraints imposed by the Theory of
Relativity. The difference, in this regard, between Whitehead's approach
and that of Quantum field theory is major, and Hättich claims that the
*former* encounters inconsistencies that the latter avoids.

Whitehead introduces the impact of Relativity with the words: "Curiously
enough, even at this early stage of metaphysical discussion the
influence of the 'relativity theory' of modern physics is important."
(PR, p. 65). Whitehead was certainly very familiar with Einstein's
theory of relativity. But that theory is a *classical* theory, and is
deterministic: the entire history of the universe is laid out. The idea
of an "open future", which is not yet fixed, but remains to be
determined by "decisions", in accordance with some process, while
compatible with both Whitehead and quantum theory, is incompatible with
the determinism of classical physics. Hence certain key features of the
classical-physics implementation of relativity theory need to be altered
in the passage to an open-future theory.

In the deterministic world of classical relativity theory one can label
the actual space-time points in a variety of ways. In different labeling
schemes the surfaces of "constant time" cut through the four-dimensional
space-time continuum at different angles. Thus two space-time points
that are "at the same time" according to one labeling convention will
usually be at different times according to another convention. All of
these labeling schemes are ontologically on a par. But in classical
physics there is no objective idea of "becoming" associated with these
surfaces: the whole history of the universe is fixed, and hence the idea
of a "coming into being", or a "becoming", is fundamentally illusory.
Different observers who use different labeling conventions would have
different *illusions* about which events are in "unison of becoming",
but because the whole idea of "becoming" is itself an illusion, there is
no rational reason to transcribe *all* of these conflicting illusions
about "unison in becoming" into realities in the passage to an
open-future theory. Indeed, from the perspective of Relativistic Quantum
Field Theory, Whitehead makes an actual mistake when he tries to elevate
*all* of the conflicting classical-physics illusions about which
occasions are in "unison in becoming" into ontological realities.

The natural ontology associated with relativistic quantum field theory
was not really clarified until the works of Tomonaga and Schwinger in
the 1940's. In non-relativistic quantum theory, ontologically
interpreted, there is an advancing constant-time surface that separates
the fixed (already determined) past from the open (yet-to-be determined)
future. By an "advancing" surface is meant a linear sequence of surfaces
such that the region lying behind any surface lies also behind all
subsequent surfaces. Tomonaga and Schwinger showed that the
non-relativistic idea could be carried over to relativistic quantum
field theory, with the constant-time surfaces of the non-relativistic
theory generalized to "space-like surfaces", which are surfaces that can
be formed by continuous transformations of a constant-time surface that
maintain the condition that every pair of different points on the
surface are separated by a *space-like* displacement. The
Tomonaga-Schwinger construction shows how the proper generalization of
the idea of "unison of becoming" is tied to a *single advancing
space-like surface* along which potentialities are converted into
actualities. This construction allows a coherent meaning to be given to
Whitehead's idea of "the expansion of the universe with respect to
actual things." (PR, p. 214).

Pauli once remarked to me that this Tomonaga-Schwinger idea of an
advancing spacelike surface was not basically different from the
nonrelativistic idea of an advancing constant-time surface. The
Tomonaga-Schwinger idea of a single preferred advancing spacelike
surface might appear to go against the intuitive flavor of relativity
theory. But according to quantum thinking it is the *predictions of the
theory* that must conform to the precepts of the theory, not the
mathematical structure of a reality that lies *behind* the predictions.
Tomonaga and Schwinger show that the predictions of quantum field theory
will conform to the demands of the theory of relativity, even though all
of the classically allowed surfaces of "unison in becoming" are not
treated on an ontological par. Thus Whitehead's attempt satisfy the
requirements of the theory of relativity within an open future context
by imposing *classically motivated* conditions tries to do something
that seems ill-conceived, first, because it tries to apply in an
essentially indeterministic setting conditions that owe their validity
to determinism, and, second, tries to impose, by virtue of relativity,
conditions that ontologically conceived relativistic quantum field
theory does not satisfy..

Hättich examines this question of "the unison in becoming" in great
detail. On the basis of Whitehead's words themselves, he concludes that
the demands of rational coherence requires abandoning Whitehead's effort
to ascribe "unison in becoming" to all of the different frames
associated with different observers. Dropping that unachievable demand,
but retaining the rest, Hättich arrives at "a unique layer-cake
structure" (p. 84), in which the successive "durations" sit on top of
each other like the layers of a cake in four-dimensional space-time.
Each layer is associated with a concrescence. The "Actual World" of each
layer (i.e., the complete source of the input data for that layer)
consists of *all* of the lower layers. But each whole new layer
eventually separates into a discrete *set* of concrescing actual
occasions that are "located in" disjoint spacetime regions.

It is probably significant that Whitehead seemed less than certain in
his discussion of this idea of "unison in becoming" and "duration" (PR,
p.125). He stressed that the complex idea about duration that he was
proposing "is based upon scientific examination of our cosmic epoch, and
not on any more general metaphysical principle". (PR. P. 125). But it
now turns out that *his idea* of what scientific examination reveals is
not concordant with what contemporary basic physics reveals: his idea
was based too heavily on the illusions about becoming associated with
*deterministic* classical physics.

Hättich notes (p.75) that similar conclusions about the causal structure
were obtained by Stapp (1975, 1979) and by Nobo (1986). The approach of
Stapp

Is based on the need to accommodate certain faster-than-light
information transfers entailed by *certain generalizations* of the
arguments of Einstein, Podolsky, and Rosen (1935), and of John Bell
(1964). Hättich confirms that the hidden-variable approach of Bell and
his followers are too weak to establish the needed faster-than-light
conclusion: one needs to go to the non-hidden-variable approach used by
Stapp (1975, 1979, 2004, 2005)

Hättich's main conclusion (p. 249) is that Whitehead's doctrine of
actual worlds is ruled out. But that conclusion does not follow from his
arguments. The simplest way to rescue Whitehead's theory from the impact
of Hättich's analysis is to postulate that: (1) The actual occasions
form *an ordered sequence* \-\-- i.e., that each of Hättich's layers
consists of one single occasion\-\--with the regions associated with the
sequence of events/occasions separated by an advancing sequence of
spacelike surfaces; (2) The actual world of any occasion consists of the
already determined occasions that lie in its backward light cone; and
(3) Whitehead's principle of the Objective Immortality of the actualized
occasion be understood in the way suggested by his example (PR p. 43) of
the Castle Rock at Edinburgh": when it shatters, the various the
fragments are its *parts*, so that which parts are used in the
construction of some later occasion influences which parts *remain
available* for use in the construction of other later occasions. Thus
the nonlocal (faster-than-the speed-light) features of quantum theory
are explained by the fact that the choice in one region of which
potentialities emanating from a prior occasion are chosen to be used in
this region influences the content of the set of potentialities *that
remain*, and hence are available for use in another region. This is the
way the subtle faster-than-light effects are generated in (relativistic)
quantum field theory\-\--in a way concordant with Whitehead's doctrine
of actual worlds.

Hättich's book is valuable because it presents Whitehead's ideas, or at
least one view of Whitehead's ideas, in a *detailed* *linear way* that
meshes with the ideas of contemporary relativistic physics. From the
perspective of quantum theory it provides a possible foundation for
passing from the established pragmatic framework to a broader
non-anthropocentric cosmological theory. From the perspective of Process
Philosophy it gives a different slant on what conditions are really
imposed by compatibility with Einstein's theory of relativity..

**References.**

Bell, J. S. (1964): "On the Einstein Podolsky Rosen Paradox". *Physics*
**1**, 195-200. Reprinted in (Bell, 1987, pp. 14-21).

Bell, J. S. (1987): *Speakable and Unspeakable in Quantum Mechanics.*
Cambridge: Cambridge University Press.

Einstein, A, B. Podolsky, and N. Rosen (1935): "Can Quantum Mechanical
Description of Physical Reality be Considered Complete?". *Phys.
Rev.***47,** 777-780.

Haag, R. (1996): *Local Quantum Physics.* 2^nd^ Edition. Berlin:
Springer.

Nobo, J (1986): *Whitehead's Metaphysics of Extension and Solidarity.*
Albany: SUNY Press.

Shimony, A. (1993): *Natural Science* *and Metaphysics.* Volume 2 of
*Search for a Naturalistic World View.* Cambridge: Cambridge University
Press.

Stapp, H. P. (1975): "Bell's Theorem and World Process". *Nuovo Cimento*
**29,** 270-276.

Stapp, H. P. (1979): "Whiteheadian Approach to Quantum Theory and
Generalized Bell's Theorem". *Found. Phys.* **9,** 1-25.

Stapp, H. P. (2004): "Bell's Theorem Without Hidden Variables". *Amer.
J. Phys.*

**72,** 30-33. (Also at
http://www-physics.lbl.gov/\~stapp/stappfiles.html)

Stapp, H. P. (2005): "Comments on Shimony's Analysis" To be published in
Found. Phys., In the Asher Peres Festschrift.