Wednesday, November 16, 2022

Not all astrophysicists understand General Relativity

This segment from the Science Channel's "How the Universe Works" reveals that astrophysicists do not tend to have a rigorous education in the mathematics of general relativity. Unfortunately, untrained creationists have an uncritical aceptance of such popular expositions and repeat them in their expositions.

Here is Grant Tremblay commenting on the image of a blackhole. He claims we are looking at an actual discontinuity in the fabric of spacetime!

There is no such thing as spacetime. A belief in spacetime as a real completed object is a belief in eternalism. Belief in spacetime is antitheistic and anti Biblical. Spacetime is an abstract mathematical model of relativistic physics. Spacetime is not a fabric. Also, mathematically egregious is the claim that the event horizon is a discontinuity (in the fabric of spacetime). The event horizon is not a discontinuity.

Creationists need to engage in critical mathematical and theological analysis and abandon such beliefs.

Sunday, February 6, 2022

Eternalism Visualized

In order to visualize the ontology of the eternalist I created this perhaps amusing model. In the photo the bamboo skewer is time and the orange paperdolls are someone's existence in the eternalist's block universe. All of the orange men at different internal temporal "locations" exist "simutaneously" in a timeless universe. One should imagine that there is an infinite number of paperdolls between the ones shown. View it as a continuum of dolls, a solid block comprising a spatial and temporal worm extended etenally in space and "time."

Since the paperdolls are a continuum in spacetime it is not proper to say that there is a spatial size or shape of the paperdolls. The size and shape are just a convention of what one defines as "simultaneous."

This model also illustrates the neccesity of eternalism for time travel. Suppose the photo shows the present in the foreground and the past recedes into the background. The photo shows that your "past" self exists eternally anxiously awaiting to be visited by your "future" self. All you have to do is hop off the skewer by some not yet discovered process and travel back to your "former" self!

My prior posts on eternalism can be found here and here.

Thursday, January 20, 2022

Time in Christian Perspective. The past is not a place. You can't get to 'then' from 'now.'

For us believing physicists, the distinction between past, present and future is only a stubbornly persistent illusion." - Albert Einstein (from The Expanded Quotable Einstein. Princeton University Press, 2000). p. 75).
What Einstein was referring to in the quote above, was the impossibility, according to his theory of relativity, of any objective determination of "now," and the lack of a unique objective distinction between past and future for some pairs of events, since these depend on the reference frame. In his words, "The four-dimensional continuum is now no longer resolvable objectively into sections, which contain all simultaneous events; “now” loses for the spatially extended world its objective meaning. It is because of this that space and time must be regarded as a four-dimensional continuum that is objectively unresolvable." -Einstein, Ideas and Opinions. (New York: Crown Publishers, 1954). p. 371.

I came upon this blog site while researching the topics of presentism and eternalism.

Is Time Travel Possible?

My answer is a resounding "No!" One's answer to that question depends from the start on whether one's philosophy of time is eternalism or presentism. What exactly are these philosophies?

Eternalism is the view that the past, present, and future all exist timelessly and eternally. The cosmos is an eternal four dimensional "block house." In philosophpical terms, spacetime is a completed ontological object -- an actual four dimensaional continuum rather than an abstract four dimensional concept. That notion has its roots in mistaken interpretations of Special Relativity, with an artificial construction and a conventionalist definition of “simultaneity.” Hillary Putnam in his essay "Time and Physical Geometry" rehearsed in detail an argument for eternalism that relied on that standard misrepresented implication of Special Relativity. His argument in brief rests upon the fact that the Lorentz transformation of SR does not preserve a "now" between observers in relative motion. If I am at rest then my time (i.e. t = 0) slice of spacetime (the set of all events "simultaneous" with me merely because it is assigned the same t coordinate, and what Putnam calls "me-now") does not correspond to your time' (i.e. t' = 0) slice of spacetime (what Putnam calls "you-now"). Putnam then asserts that if what exists in "my-now" is real; and if you and I are collocated at t = t ' = 0 (as you move past me), then me-now and you-now are simultaneously real. Finally, since this property of being real is transitive, it follows that every thing "simultaneous" with you-now is real and everything "simultaneous" with me-now is real, but you are real to me so all of the things real for you must also be real for me. Since some of the things real for you lie to the future of my-now and some to the past. It follows from this (specious) argument that all past, present and future events must be real. And that is eternalism. The attentive reader no doubt noticed the shifting meaning and properties assigned to Putnam's adopted conventional defintions of "simultaneous" and "real."

Presentism, on the contrary, which is the view that only the present exists, future is not yet, and the past is gone. In other words, the past, present and future do not persist in an unchanging four dimensonal "spacetime." There is just space that persists through time. Yesterday's gone. You can’t get to there from now – the past is not a place.

It was through the illegitmate wedding of space and time into a single entity known as spacetime that is the core presupposition of eternalism. It was this philosophical view that lead Einstein to declare time as an illusion -- and indeed it would be in eternal spacetime. I call this philosophical presupposition the myth of spacetime

Presentism is the Christian view, but I won’t argue from that at the moment.

Rather, I will critique eternalism and the mistaken idea that time travel is possible.

Clearly, on presentism, time travel is not possible. The past is not a place one can visit in a temporal analog of a spatial trip in an automobile. This brings me to the specific blog entry by physicalists arguing time travel is possible. Spatialization of time implies same constraints as a loop of string. A loop of string cannot be a spatial loop and fail to connect to its other end as one traces the loop. The loop is physically constrained to be such. The blog referenced above makes that incisive observation. Physicalists’ glib declaration that one can’t travel into the past and kill ones grandfather because you didn’t is true but that doesn’t explore the reason and the implications. In the same way that the loop is physically constrained, so is the purported time traveler, as he is a physical system and must obey the dictates of a constrained physical solution. The conclusion is clear. There is no human autonomy from physical causation. Physical systems have to act according to the physical laws. Time travel paradoxes only arise because their creators conveniently fail to examine the entire set of implications of their physicalist presuppositions. Specifically, they simultaneously embrace human autonomy and also physical determinism of the unchangning block universe. Those two are contradictory. Hence, no autonomy and no paradox.

Such belief in eternalism and possibility of time travel are rather prevalent among non-Christians. However it may come as a surprise that some Christians have uncritically adopted the eternalist view of Einstein. In particular is Jason Lisle and his ill conceived Anisotropic Synchrony Convention (ASC) for accounting for a young earth in an old(?) universe. That Lisle has embraced eternalism is not a mere conjecture since he ascribes to the possibility of time travel as "implied" by Special Relativity (SR). Actually the view of Special Relativity that Lisle holds is more than the mathematical structure of the theory. He has also adopted the assumption of the eternalist. A belief in the myth of spacetime.

That Jason Lisle has succumbed to the eternalist view of special relativity is evident from his book “The Physics of Einstein.” Examples from chapter 10 “How to Build a Time Machine” of that book are:
(1) that he gives lip service to time travel which is impossible in presentism;
(2) his claim that time travel is provable using the Lorentz transformation.
The second claim is a false conclusion that is based on an unstated and uncritically examined presupposition of eternalism – i.e. the presupposition that the past still exists and is a place that can be visited. Rejecting that unproven presupposition and adopting presentism (as Christian theism requires) shows that time travel is not provable from the Lorentz transformation. The mathematics of Special Relativity do not prove the possibility of time travel. The possibility of time travel is based on a commitment to a philosophical presupposition.

Here is an extended quote of Lisle:
“As we saw in the previous chapter the theory of relativity allows for the possibility of traveling backward in time if it is also possible to travel faster than the speed of light. That's the good news. The bad news is that there are some compelling reasons to think that faster than light travel is not possible, at least not for information bearing systems. We have seen hints of that in previous chapters, and we will go into greater depth in later chapters. Nonetheless, hypothetically if faster than light travel were possible, then time travel into the past would also be possible. This is provable from the Lorentz transformation, and gives us a much more profound understanding of the nature of space and time. " (emph. added)
The Lorentz transform alone does not prove time travel. It requires the extra commitment to an eternalist Minkowski spacetime as it requires the past to exist in order to be “revisited.” That is the notion that “time is a place,” which is part-and-parcel of Minkowski’s eternal block universe as espoused by Einstein ("time is an illusion"). Lisle's "profound understanding of the nature of space and time" is infected by eternalism as his inference requires that the past is a place, sitting there waiting to be revisited, if only, we could travel faster than the speed of light. This idea is what has infected and influenced the views of “conventionality” of simultaneity, synchronization and Lisle's “Anisotropic Synchrony Convention” model.

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 Putnam1 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 cosmos2.

The Banishment of Spatial Shapes
In 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.
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.