More on Eternalism. The Conventionalism of "Simultaneity." The loss of the "Present." The Banishment of Spatial shapes.
In the prior post (
link), I touched briefly on the implications of eternalism and how it is an antiChristian philosophy.
In this post I discuss how eternalism is the basis of the convetionality thesis of Jason Lisle.
All of the traits listed in the title are consequences of the eternalist philosophy. Before outlining the proof of those last two, I'll give another description of the two philosophic positions on time: eternalism and presentism. Here follows two brief descriptions of how each philosophy views the properties of existing objects.
Presentism
In presentism what exists are objects with extensions in the 3 spatial
dimensions that
persist through time. This view is perfectly compatible with relativistic physics. In scientific parlance it is called the 3+1 formulation of relativistic physics. The "3+1" formulation is the one used everyday in numerical relativity calculations, such as computing the time evolution of orbiting black holes and gravitational waves. It is referred to as the ADM formalism (follow this
link for more details). Opposed to presentism is the philosophy called...
Eternalism“Gentlemen! The views of space and time which I wish to lay before you … They are radical. Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.”
Herman Minkowski (1908)
As described before, eternalism espouses an eternal blockhouse spacetime, in which past, present and future events exist eternally in a timeless spacetime.Minkowski was the father of eternalism,as the quote above reveals.
The Difference in a "nutshell"
To summarize the difference of the two philosophies:
In Eternalism there is no "now." There is no "present" moment. There is just an eternal set of "events." For some pairs of events there is no absolute "simultaneity" so there is no "simultaneity" except by convention and hence there is no "now." The past, present and future all coexist eternally. The past is "still there"; the future is "already there"; and the present is just a "subjective illusion."
In Presentism there is a passing moment, called the present. throughout the universe, though we cannot determine it or experimentally detect it.
The Conventionality of "Simultaneity"
Much confusion has been interjected into the discussion of the actual physics of relativity (whether special or general) by use of the empty term "simultaneity." As used in the eternalist vocabulary, "simultaneous" does not mean in the same metaphysical "now" of presentism (except we will see that the "now" of the eternalist now(!) means all of the history of the eternal universe). In eternalist parlance "simultaneous" merely means two events that have been assigned the same time label. Assignment of time labels can be dones by various procedures -- some are: Einstein synchrony (which yields a Euclidean "now", clock transport, and a complete conventional assignment by way of the Reichenbach "epsilon" convention. The last is advoated by YEC scientist Jason Lisle which he calls the "Anisotropic Synchrony Convention" (ASC). From the relativity of time due to time dilation of clocks in motion, the issue of clock "synchronization" becomes an issue. I agree that clock synchronizations are important for measuring time intervals, and physical speeds, etc. Any physical quantities which depend on chronometry. However, where the eternalist train jumps the tracks is allowing any synchronization procedure (subject to certain mathematical and phsyical restrictions) of clocks by
convention.
It logically follows from the conventionality of synchrony, that we deduce the conventionality of simultaneity. This occurs because by a mere non-operational, arbitrary change in the Reichenbach "simultaneity" parameter (denoted by the Greek letter "epsilon" in the literature) events that had the same time label now do not, and the former "simultaneity" of the two events vanishes. Note that this bizarre "physics" occurs by the mere wave of the mathematical pen to change epsilon from the value one, to say, zero.
It should be plain that once one admits the above, that one must agree there is no absolute simultaneity. In fact, it means the word "simultaneity" has been emptied of all objective metaphysical meaning. It is a mere noise word. The end result of this train of thought is back to eternalism. All of the history of the universe exists in the eternal "now." That "now" includes "past, present and future" in the eternalist object known as "spacetime."
So much for the conventionalist stance. There is a milder stance, called "the relativity of simultaneity" espoused by Einstein; but we won't discuss that at the moment. Suffice it to say that the "relativity of simultaneity" leads to the same conclusion of an eternalist universe when the Einsteinian notion of "simultaneity" (equality of time labels) is conflated to be in the same metaphysical "present." I trust the reader can see the argument holds in the relativity case. However, I will briefly give a diagramtic illustration and summary of the argument of Hilary Putnam
1 that everything is "real" including past, present and future, for all denizens of the Minkowski spacetime. Conclusion: There is no time, and the universe exists eternally in a single timeless moment.
In the figure we show "You" and "Me" via the now common place Minkwoski diagram. You are traveling to the left and I am at rest. By the Lorentz transform we find that events located at your time zero is different than the events located at my time zero. Your space of simultaneity, denoted "Your now" is "tilted" relative to mine.
Spacetime diagram used in Putnam’s argument for Eternalism.
You are traveling relative to me in the negative x direction. By the Lorentz
transformation and the Einstein definition of “simultaneity” we have
different sections of spacetime that we call “now.” Putnam asserts that
all events “simultaneous” with an observer are “real.” At time t = t′ = 0 we
are both at the origin and thus equally real to each other. By transitivity
Putnam then argues that (1) “My now” is real to me, (2) you are real to me,
(3) “Your now” is real to you, therefore (4) “My now” and “Your now” are
equally “real” in a timeless cosmos
2.
The Banishment of Spatial ShapesIn eternalism, no object is a merely 3
dimensional spatial object, every object in the block house is a 4 dimensional object with extensions in 3 spatial
dimensions and also a temporal extension. So you and I do not have a spatial volume measured in cubic meters, rather we have a spacetime volume measured in units of "cubic meter-seconds."
So then, due to this blending /unification
of space and time into spacetime, it cannot be said that objects have an actual 3 dimensional spatial shape. The reason is that the shape would depend on which clock synchronization one
chooses
by convention. The clock synchronization does not single out an actual present but rather a selecton of a particular cross section (from an infinitude of such) of an eternal four-dimensional object. The figure below shows that the "cross section" of a rigid eternal spacetime ruler "A" (at rest) of rest length L depends on the epsilon parameter. If epsilon has the Einstein value (one-half) then the ruler has length L. But for a general value of epsilon the length is:
Spacetime diagram Illustrating Epsilon dependent Length.
The figure shows the cross section of atoms (specified by the diagonal
x-axis) -- considered to be "at the same time" by the choice of epsilon -- and comprising the ruler for a general value of epsilon. We will call this the "Reichenbach-Lisle Ruler." By Lisle's reasoning the shape of objects are conventional and
thus not real. The Reichenbach-Lisle Ruler has no real length. One wonders then how photographs and movies (produced by incoming light rays) are objective and seem not to change when the conventionalists decide in their minds to change the value of epsilon (the Reichenbach simultaneity parameter). Of course, photgraphs do not change when the abstract epsilon changes value. The epsilon parameter does not represent anything real and changing it cannot change the one-way physical speed of light. Since photographic images of objects (especially those in motion) depend on the one-way speed of light,we conclude the one way-speed of light is a facet of reality and cannot be changed by "mere assertion." If one claims the one-way speed of light cannot be measured, that merely means its value is unkown, not that it has no value. However, I do not accept that weakened argument. Photographs depend on the one-way speed of light. Movies of moving objects can reveal the one-way speed of light.
The Loss of the Present
In Presentism, the "present" denominates the universal moment in which 3-dimensional objects exist in a realm of 3 three spatial dimensions. As time passes (contra eternalism) objects find themselves in a different moment - a new present moment. What was present is in the past as time passes. Some say this concept is antithetical to relativistic physics, but such is not the case. Presentism and relativistic physics are perfectly compatible. This has been pointed out by others, and is reflected in the ADM (or 3+1) formalism of general relativity mentioned above. The bottom line is that presentism maintains the causal order of events. Two points spatially separated in the actual present can not causally influence each other. Another point is that in general relativity the "big bang" solution of the Einstein field equations, reintroduced an absolute time for the cosmos. (A discovery that many found astounding at the time -- in light of special relativity.) That absolute time is the age of the universe.
This post is in progress and will be updated. Stay tuned.
1
Putnam, H. 1995. Time and physical geometry. In Mathematics, Matter
and Method, Philosophical Papers, vol. I., 2nd edition, pp. 198-205.
Cambridge: Cambridge University Press.
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2
For those knowledgable of the special theory of relativity, here is a quick argument. Two spatially separated events E1 and E2 with times assignment t2 > t1 (i.e. E2 is in the future of E1) according to one inertial observer (A), can have reversed time assignements for another inertial observer (B) moving with respect to observer A., i.e. T1 > T2. Here T1 and T2 are the times assigned to the events E1 and E2 by observer B. By this method of time label assignment observer B says E1 is in the future of E2. Since this results in a time reversal of events the eternalist claims this proves there is no past, present or future. Of course, the last assertion is not a proof. It is a mere claim based on a philosophy and ascribing metaphysical significance to the time labels. Spatially separated events can have no causal influence on each other, so the time labels are irrelevant to the causal physics. Conversely, all observers will agree on the temporal order of events that are causally connected -- which is an absolute ordering of events in that case. That ordering is the mathematical foundation of the ADM (3+1) formalism and the philosophic basis of presentism.
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