I would like to clarify a few points:

In sections I and II of the paper, I discuss time from a "point-endurantist"
perspective. I do not consider four-dimensionalism until sections III and IV.
The purpose of the brick example in section I is to introduce the reader to the
notion of a "persisting present" -- i.e., a persisting mind. (The mind is an
entity that persists.(1) However, it is difficult to visualize a "persisting
mind." It is somewhat easier to visualize a persisting *physical* entity,
such as a brick.)

Persistence is a *dynamic* process (i.e., a dynamic activity);
spacetime, however, is a *static*, geometric structure. Since the
persisting mind is dynamic, it cannot exist within spacetime.

Although spacetime is static, the mind perceives this 4-dimensional structure as unfolding. In section IV, I suggest that the relationship between dynamic (subjective) time and static (objective) time gives rise to our impression of an unfolding universe.

In my view, the fourth dimension of spacetime--the so-called "time"
dimension--is a type of spatial entity. We should not confuse this fourth
dimension with duration. Duration (i.e., temporal passage) is not a dimension of
spacetime. It seems to me that the phenomenon of time flow has to take place
*outside* the framework of Minkowski's static, 4-dimensional structure.

When quantum theory is applied to spacetime, the notion of "superspace"
arises. Paul Davies discusses the concept of superspace in his book *Other
Worlds*.(2) On page 103 of his book, he writes:

"If we now picture all the possible worlds ... as a sort of gigantic, multi-dimensional superworld, in which all the alternatives are placed in parallel on an equal footing, then we can regard the world which is found to be 'real' on observation to be a three-dimensional projection from, or section through, this superworld."

He describes the superspace concept again a little later in his book. On page 106, he writes:

"Quantum mechanics implies that we must consider not one spacetime, but an infinity of them, with different shapes and topologies. These spacetimes all fit together after the fashion of waves, each interfering with the other. The strength of the wave is a measure of how probable it is that a space of that particular shape is found to represent the actual universe when an observation is made."

In the Everett (i.e., the many-universes) interpretation of quantum theory, superspace is described as having a concrete physical existence. However, I prefer an interpretation of superspace that is more in keeping with the philosophical views of Bohr and Heisenberg. The three-dimensional projections that a mind observes are, of course, real. However, neither four-dimensional spacetime nor superspace is physically real.

We do not have to adopt the view that parallel worlds exist concretely. We can regard the worlds that inhabit superspace as mathematical possibilities rather than as actualities.

The theories of Isaac Newton and Charles Darwin presume that there is an objective flow of time in the world. The theory of evolution makes good sense as long as it is discussed within the context of Newton's universe (i.e., within the framework of Newton's objective/universal time flow). However, Darwin's theory does not seem to "fit-in" very well or "belong" in Einstein's universe. Einstein's theory of relativity suggests that there is no objective flow of time in the world; relativity suggests that time flow is entirely subjective and mind-dependent!

Can Darwin's objective evolutionary process take place in a universe in which there is no objective flow of time?

1. The subjective "present" of consciousness persists for a finite period of time and then ceases to persist (i.e., ceases to exist). In my paper "Temporal Passage," I represent the present's persistence visually as rightward motion along a timeline. When the present (i.e., Point-P) ceases to persist, it comes to a halt at a point on the timeline.

2. Paul Davies, *Other Worlds* (New York: Simon & Schuster, 1980).

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