"the eternalist owes us an account of why it should seem that there are such features [of change, temporal flow] in the world when there are not." — Luke

Eternalists have such accounts: Time is real. It is locally ordered. (I word it this way just to account for Special Relativity.) For every point in local time there is an immediately past point in local time and an immediately future point in local time. People, and other representationalist systems, such as fancy computers, can represent the past and the future relative to the point in time where the person or computer is located. They can understand the laws of nature well enough to make certain predictions about the future points in time from the past points in time. They can record information about the past in their memories, etc.

It's no big mystery. The only reason that Miller even says this is because she seems to be trying to write a balanced exposition of the two positions without forcing anyone's point of view. (I assume that this article is for a textbook for students who might then write papers where they argue for one of the two positions.) But if you read her article, you will have noticed that she has many more critiques about presentism. Would you like me to throw them all at you and force you to answer them?

|>ouglas

Another possible response from eternalists is the "spotlight theory". It's in Miller's article, so you can read more about it there.

Under the spotlight theory, such an eternalist will say that time is like a movie reel. It's all there all at once: past, future, and present. Only there's a spotlight that runs down the movie reel illuminating one frame at a time, in chronological order.

Most eternalists will say, "Exactly! Only there's no need for the stupid spotlight."

If you want a version of eternalism that works for you, start with the spotlight theory. And then convince yourself that you don't need a spotlight. Or remain committed to the spotlight if you wish. It's no skin off of my teeth either way.

|>ouglas

According to the Kristie Miller article cited in the OP, the difference between Presentism and Etetnalism is not only their differing views on existence, but also their staticity/dynamism. — Luke

Miller writes this:

Thus eternalists endorse the following pair of theses:

Eternalist Ontological Thesis (EOT): Past, present, and future times and events exist.

Static Thesis (ST): The present does not move: which moment is the present moment does
not change. — Miller

Now either Miller has no understanding of the position, or she's talking about something completely different. The view denies the existence of a preferred moment called 'the present' and hence the ST part is nonsense. I've actually heard of such a view, which is presentism without the movement, but Miller doesn't seem to be talking about that since she correctly states that all events at all times exist equally, which is not true of a model with a present that stays put like that.

Anyway, I'd never accept these points as worded. The first isn't totally wrong, but past/present/future are all relations like < = >, and not objective states like negative, zero, and positive, and the wording makes it sound like the latter.

Then I take it you agree with all of the following:

Eternalists, then, hold that the world as a whole is static in two senses: which events
exist does not change, and there is no sense in which the present moves. — Luke

I'd say there is no 'the present' to do any moving. 'The present' would be just any event's self reference, and that, by definition, cannot move.

Eternalists accept what is known as the B-theory of time. This is the view that the
world is a static block of events ordered by the earlier than, later than, and simultaneous
with, relations. [1]

Also known in physics as 4-dimensional spacetime. 3D Space and time are separate under presentism.

Presentists endorse the A-theory, since they hold that it is a genuine feature of a
presentist world which moment is present, and that this fact changes over time so that
different moments are present at different times. To say that a view accepts the A-theory
is really to say that it endorses the dynamical thesis, and to say that it endorses the
B-theory is to say that it rejects the dynamical thesis.

I haven't seen the dynamical thesis, but this seems right.

Eternalism, on the other hand, is a static view that rejects temporal flow. Since it certainly
seems to many that there is temporal flow and change, this is a cost to eternalism.
At the least, the eternalist owes us an account of why it s

The subjective flow of time is an illusion, illustrated empirically with the twins scenario in relativity. If people could detect the actual flow of time, then they'd be able to detect movement due to the subjective slowing of clocks when they're moving fast, wheras if it were an illusion, any traveler would notice no difference. This of course isn't easy to test given the cost of the experiment, but it is there.
No, it isn't a proof of one view or the other, just a demonstration that the flow of time is a subjective illusion.

Theoretical physics is just a branch of philosophy. How to interpret data is subjective. The sole thing Einstein noticed was the observation that external motion changes the size and some of the rate of change within the object. That's it. Since he didn't do the experiments, he probably didn't even come up with that. He was not a psychologist. He provided no data on how motion affects psychology. So he as kinda a fraud

Eternalists have such accounts: Time is real. It is locally ordered. (I word it this way just to account for Special Relativity.) For every point in local time there is an immediately past point in local time and an immediately future point in local time. — Douglas Alan

All you have stated here is that all points/moments in time exist. You have offered no account of why we apparently move in time from one moment to the next; of why we apparently age; of how change and/or temporal flow apparently occurs. I understand that these are very difficult to account for, but you said that eternalists had such accounts. It's one thing to tell me that Paris exists over there and another to explain how I can get there, especially if nothing really moves.

Under the spotlight theory, such an eternalist will say that time is like a movie reel. It's all there all at once: past, future, and present. Only there's a spotlight that runs down the movie reel illuminating one frame at a time, in chronological order.

Most eternalists will say, "Exactly! Only there's no need for the stupid spotlight." — Douglas Alan

I consider the moving spotlight view to be a hybrid of Presentism and Eternalism, since it contains all times/events (Eternalism) plus motion (Presentism). If you remove the spotlight, you remove the motion, and then you need to account for the appearance of motion. This is exactly the problem for eternalists.

If you want a version of eternalism that works for you, start with the spotlight theory. And then convince yourself that you don't need a spotlight. Or remain committed to the spotlight if you wish. It's no skin off of my teeth either way. — Douglas Alan

I find the lack of a compelling account for the appearance of motion/temporal flow/ageing to be too problematic for Eternalism. You can pretend as though it's unproblematic if you wish.

The subjective flow of time is an illusion, illustrated empirically with the twins scenario in relativity. If people could detect the actual flow of time, then they'd be able to detect movement due to the subjective slowing of clocks when they're moving fast, wheras if it were an illusion, any traveler would notice no difference. — noAxioms

It's unclear to me what the illusion is that you are referring to. What 'movement' is going undetected? What 'movement' would be detectable if "people could detect the actual flow of time"?

Do you not detect any motion, notice yourself ageing, or find yourself now at one moment and now at another? If all of that is an illusion, then what is illusory about it? And how do you account for it?

The argument is simply that relativity of simultaneity isn't sufficient by itself to imply a block universe. An additional premise is required, which is that all events to the past of any observer's surface of simultaneity are fixed and certain. — Andrew M

But that would not be sufficient for a block universe either. Unless observers are spread throughout the entire spacetime, their past light cones sweep only part of it, resulting in a moving block. Which is why he adds the stipulation of all observers - meaning, apparently, the entire spacetime block. Which, of course, assumes the conclusion.

And in any case, whether the argument is for a moving block or for the full block, nowhere does relativity do any work here. All you need, according to this argument, is the assumption that there are some observers for whom the past is fixed.

I don't understand what your hangup is. "Static" is an unfortunate choice of a word in Miller's article, because it normally means that either there is no change over time or that time is not in the consideration, and neither of these common meanings are relevant here. But Miller says exactly what she means by the Static Thesis: it refers to the B-theory of time, according to which there is no objective partition of time into present, past and future; present, past and future are relational terms. But there is still time in the eternalist's account, just as in the presentist's!

Here is a simple space-time diagram:



Both the presentist and the eternalist agree that the diagram depicts movement of a body through space. But the presentist adds that there is a fact of the matter about where on the diagram the body is right now, while the eternalist says that there is no such fact of the matter (not without reference to a specific observer). Nevertheless, the eternalist will agree with the presentist that the body is located at 10 m from the coordinate center at time 1 s and at 20 m at time 2 s, and that the difference constitutes a change in the body's position.

"Static" is an unfortunate choice of a word in Miller's article — SophistiCat

Then it must also be an "unfortunate" choice of words when Miller describes the B-theory of time as "the view that the world is a static block of events", or that a view which endorses the B-theory "rejects the dynamical thesis", or that "Eternalism...is a static view that rejects temporal flow."

But there is still time in the eternalist's account, just as in the presentist's! — SophistiCat

Of course there is time in both the presentist and eternalist accounts; they are theories of time. I have never disputed this. If you wish to equate time with motion, then perhaps Eternalism isn't for you.

Nevertheless, I get the message, and I won't interrupt the discussion any further.

Alas, I'm not sure where the confusion is arising. If you believe that GR entails eternalism, the forward direction of time is given straight-forwardly by the direction of increasing entropy. (Modulo situations in which there is no such clear direction, such as post-heat death of the universe. But since there won't be philosophers existing then to worry about the problem or to experience what it is like to live in this time, this would seem to be moot to an eternalist.) — Douglas Alan

GR doesn't know anything about entropy - it's not part of the theory. For those who base their theory of time exclusively on GR - call them "relativity fundamentalists" - entropy is a stolen concept. They have to limit themselves to GR's coordinate time, which increases monotonically (in simply connected topologies), but in an arbitrarily chosen direction. Therefore, if it is possible for the entropy gradient to reverse itself along the length of one worldline, then a relativity fundamentalist faces a problem, because her theory of time is not sensitive to this change. Either she has to add something extra to the theory (which, incidentally, is what presentists do as well and for which they are criticized by fundamentalists), or she has to bite the bullet and say that the direction of time given by the entropy gradient can sometimes be wrong. (And then when is it right - and why?)

In the less contentious heat death scenario physical time effectively disappears, since there are no physical clocks to mark its passage, but the coordinate time continues - another contradiction that can be solved by acknowledging that mathematical time is not identical with physical time.

GR doesn't know anything about entropy - it's not part of the theory. — SophistiCat

I understand this. The second law of thermodynamics is not even fundamental law. It is stochastic.

They have to limit themselves to GR's coordinate time, which increases monotonically (in simply connected topologies), but in an arbitrarily chosen direction. — SophistiCat

For an eternalist, I should not think that this is a problem. Time is symmetric with respect to fundamental law. (Modulo Cronin and Fitch. It's a bit hard to know what to make of this at my level of understanding, but I'm going to put it down as "annoying detail" until someone informs me otherwise.)

Since time in fundamental law is symmetric, it has no forwards or backwards. It just has two different directions that are equivalent, except for the fact that they point in opposite directions. Only thermodynamic tells us which direction is foward and which is backwards. Were one to travel through a strange region of space in which the entropy gradient changed directions, this would no doubt be problematic in terms of how we normally conceive of causality, etc., but fundamental law, including GR, should have no problem at all with it. In GR, time still has two directions, and there is no difference between the two directions, other than which one is heading toward increased entropy. GR and the rest of fundamental law doesn't care about this, however.

Or at least that's how I understand things.

Therefore, if it is possible for the entropy gradient to reverse itself along the length of one worldline, then a relativity fundamentalist faces a problem, because her theory of time is not sensitive to this change. — SophistiCat

I don't see the problem. There are two directions of time. Neither of these directions of time ever changes. The only thing that might change is which direction of time is pointing towards greater entropy could change. But the direction is not changing. Only what is in that direction might change.

Now I certainly agree that having the entropy gradient reverse directions on you has all sorts of potentially unsavory and weird consequences, which, I suppose is one reason that some people think that this will go away when GR and QM are unified.

Others just think that universes where things get too weird in this regard, are just very improbable universes, so we're not likely to find ourselves in one. E.g., typical time travel paradoxes that are not logically impossible. E.g., a being from the future brings you back via a wormhole the solution to clean fusion energy production. In the future, the only reason that clean fusion energy exists is because you published a paper on how to achieve it. The invention of clean nuclear energy production came into existence without any inventor. (Well, I'm sure I'm now belaboring a point that you already fully understand.)

There's nothing in GR that precludes this. But amongst the solutions to the equations of GR, the solutions that include such strange occurrences are much less prevalent than the number of solutions that don't include such strange occurrences. (Yes, I know blah, blah measures on such infinities don't exist, blah, blah. Understanding any of that or how to resolve these objections is beyond my pay grade, but I assume that there is some answer that is something along these lines. I.e., my friend who is a UPenn professor with a PhD in number theory doesn't seem worried about this kind worry, despite the fact that I don't think he can answer the worry about measures in infinite spaces. In fact, he's fully signed onto Tegmark's MUH.)

|>ouglas

I consider the moving spotlight view to be a hybrid of Presentism and Eternalism, since it contains all times/events (Eternalism) plus motion (Presentism). If you remove the spotlight, you remove the motion, and then you need to account for the appearance of motion. This is exactly the problem for eternalists. — Luke

The appearance of motion is something that is represented in your brain. Where else would there be an appearance of motion? Since physics is the same under presentism and eternalism, your brain is going to represent the same things under either presentism and eternalism. Consequently, if your brain represents the appearance of motion under presentism, it will do so under eternalism, and vice versa.

As for aging, this is yet again a physical process that works exactly the same under presentism and under eternalism. Under eternalism, you can think of your life as a film roll, and at one end of the film roll you are a newborn baby, and at the other end of the film roll you have hopefully died happily at the age of 107 of natural causes in your sleep. In each frame between your birth and death, there will be evident an incremental bit of aging.

|>ouglas

The subjective flow of time is an illusion, illustrated empirically with the twins scenario in relativity. If people could detect the actual flow of time, then they'd be able to detect movement due to the subjective slowing of clocks when they're moving fast, whereas if it were an illusion, any traveler would notice no difference.
— noAxioms

It's unclear to me what the illusion is that you are referring to. What 'movement' is going undetected? What 'movement' would be detectable if "people could detect the actual flow of time"? — Luke

Not movement. I refer to the rate at which the present moment progresses into say a moment one second hence. No device measures this, and the subjective experience of a human is no exception to this. If there was, one could design an objective clock that would stay in sync with any other objective clock regardless of where it was or how much it has been accelerated around.

How to interpret data is subjective. The sole thing Einstein noticed was the observation that external motion changes the size and some of the rate of change within the object. That's it. — Gregory

This is totally wrong. The sole observation from which Einstein did his SR work was the apparent constant speed of light. From that, all the things above were predicted, not measured ahead of time.

Since he didn't do the experiments, he probably didn't even come up with that.

Indeed, he didn't do them himself.

The appearance of motion is something that is represented in your brain. Where else would there be an appearance of motion? Since physics is the same under presentism and eternalism, your brain is going to represent the same things under either presentism and eternalism. Consequently, if your brain represents the appearance of motion under presentism, it will do so under eternalism, and vice versa. — Douglas Alan

Except that there is actually no motion according to Eternalism. I would imagine that it's much easier to explain why we perceive motion if there actually is motion than if there actually isn't. My point, again, is better expressed by Kristie Miller:

For the eternalist, the key challenge lies in explaining temporal phenomenology and in explaining the apparent directionality of time. There has been significant work in this area, but questions still remain: why do we have such a different relationship with the future than with the past: why is it that effects typically precede their causes when the laws of nature are symmetric: why do we remember the past, but not the future: why does the present seem to us to have a particularly salient quality that other moments lack; what are the cognitive apparatuses that underlie our experience of temporality and how do they function to create temporal phenomenology; what is the evolutionary significance of the phenomenology of temporal flow and to what extent is the phenomenology of temporal flow essential for agency. — Kristie Miller

Except that there is actually no motion according to Eternalism. I would imagine that it's much easier to explain why we perceive motion if there actually is motion than if there actually isn't. My point, again, is better expressed by Kristie Miller:

For the eternalist, the key challenge lies in explaining temporal phenomenology and in explaining the apparent directionality of time. There has been significant work in this area, but questions still remain: why do we have such a different relationship with the future than with the past: why is it that effects typically precede their causes when the laws of nature are symmetric: why do we remember the past, but not the future: why does the present seem to us to have a particularly salient quality that other moments lack; what are the cognitive apparatuses that underlie our experience of
temporality and how do they function to create temporal phenomenology; what is the evolutionary significance of the phenomenology of temporal flow and to what extent is the phenomenology of temporal flow essential for agency.
— Kristie Miller — Luke

I think I'm up to that explanation, which, from a physicalist point of view, can be explained through entropy and evolution, but almost nobody actually accepts physical monism deep down. I think I have but it was a multi-year struggle to shake off the biases put there by a very proficient liar.

So the story from the dualist POV (there is an (physical or spiritual, doesn't matter) identity 'I' that consistently experiences the life of physical body X. The analogy here is that physics is like a first person Harry Potter movie and the experiencer is the guy in the cinema. Eternalism is the same thing, except no cinema, no entity watching the show, and especially no projector.

Under presentism, the present is whatever frame is currently being projected. Normally the film runs front to back, but if it were run back to front, the experiencer in the cinema would notice the difference but Harry would not. The movie would end with the guy in the cinema knowing Harry's life story (the future) but Harry wouldn't even know that he's a wizard at the end. Harry obviously has different memories than the guy in the cinema. So the movie always runs forward because we'd be able to tell if it didn't.

Hence it being totally unintuitive to such a dualist to conceive of eternalism, which requires the lack of the experiencer (the definer of the present), and he interprets the description (the word 'static') as the experience of a stuck projector. The view is anything but that.

The eternalist view has no experiencer. It doesn't even have Harry (as an identity). It only has the individual frames in the film and one can talk about the experience of that frame, and yes, the experience of any given frame is one of motion of the passing car. One is forced to use B-series language to express what each frame experiences because there is no preferred frame defined by a projector, and A-series requires that preferred reference. By 'frame' here, I'm talking a frame of film (the local state of things at a particular time), and not relativity's reference frame.

I don't see the problem. There are two directions of time. Neither of these directions of time ever changes. The only thing that might change is which direction of time is pointing towards greater entropy could change. But the direction is not changing. Only what is in that direction might change. — Douglas Alan

The problem that I see here is that there is no inherent connection between the direction of time given by the time coordinate of the relativistic spacetime and the direction of time from the entropy gradient (which in turn is a proxy for physical time). Even if it so happens that in our universe these two never diverge, when you make a commitment to relativistic time, you are opening yourself to this contingency where your theory may diverge from reality.

And in case of heat death, which is currently taken to be the most likely future of our universe, this is more than just a contingency. If the prognosis is right, then eventually relativistic time will diverge from physical time.

So as a proxy for physical time, relativistic time is fine, most of the time, but it should not be taken to be identical with physical time, on pain of paradoxes.

GR is a philosophical interpretation. Data can never show that colors don't exist, can never show that time doesn't exist, nor can it even show that the data wasn't time dependent and that say the speed of light will change someday. Einstein's work was primarily about philosophy, although he didn't read enough about it do realize Hume was correct. A person who changes speed will change size andthe speed will affect how fast his body moves. But there is no proof that time exists. That's a subjective opinion. Saying "someone traveling very fast will experience so and so" is psychology. Maybe speed affects all our perceptions.

The problem that I see here is that there is no inherent connection between the direction of time given by the time coordinate of the relativistic spacetime — SophistiCat

It's been a long time since I studied special relativity (we spent several weeks on it in Physics 101), but IIRC, relativity doesn't provide a forward and reverse direction of time. It just provides two directions of time, and they are symmetric.

Sure, there's talk about the "future" direction and the "past" direction, but it seems to me that that is just so that you can do thought experiments and the like about causality. Those two directions, for the purpose of thought experiments, are specifically chosen to match with thermodynamics. But other than for the purposes of thought experiments involving causality, which presupposes well-behaved thermodynamics, special relativity IIRC is completely agnostic on which direction is the future and which is the past.

|>ouglas

Except that there is actually no motion according to Eternalism. I would imagine that it's much easier to explain why we perceive motion if there actually is motion than if there actually isn't. My point, again, is better expressed by Kristie Miller: — Luke

I don't think you understand how philosophy works. You pointed me at something that putatively needs to be explained, and I provided my putative explanation. It is now your job, should you chose to accept it, to provide your putative explanation for why what I argued is wrong.

Instead of doing this, you just repeat the same thing, as if I have said nothing.

Also, you seem to be arguing from authority that Miller is right and consequently I am wrong. This is bad philosophy for several reasons. I'm not going to get into all of the reasons for that, but I will point out that you seem to think that Miller is on your side. At least from this article, she is not. The book from which this chapter was selected seems to be a textbook that a Philosophy professor would assign their students to read. Such treatises are often specifically designed leave certain questions unanswered, in order to allow for debate in the classroom and for students to write papers where they have the leeway to chose which position they want to argue for.

I will point out that Miller also describes plenty of problems for presentists, and you are cherry-picking your argument from authority by ignoring the fact that Miller has more objections against presentism than she has against eternalism. This probably just follows from the fact that the orthodoxy these days is that eternalism is the true account. (I don't know this for sure, but that's the impression that I got from attending some Philosophy conferences at MIT where everybody but me was actually a professional philosopher.)

|>ouglas

P.S. It's likely the case that your actual worry is about phenomenal consciousness. If that's the case, I am quite sympathetic. I am not a physicalist with respect to phenomenal consciousness myself, and I'm sure that feelings similar to mine are one of the reasons for the spotlight theory being prevalent to whatever degree it is, but despite many years pondering and studying the issue of phenomenal consciousness, I feel no closer to an answer today than when I started.

I don't think you understand how philosophy works. You pointed me at something that putatively needs to be explained, and I provided my putative explanation. It is now your job, should you chose to accept it, to provide your putative explanation for why what I argued is wrong.

Instead of doing this, you just repeat the same thing, as if I have said nothing. — Douglas Alan

I am only trying to get some acknowledgement from you and others in this discussion that Eternalism entails a static world devoid of any temporal flow, change or motion.

You appear to maintain that the world works the same way whether Presentism or Eternalism is true, but it remains to be explained how anything works if nothing moves. You and others appear to maintain it is unproblematic that we find ourselves now at one time and now at another, or that we find ourselves aging, when according to Eternalism nothing moves from point A to point B (or from time A to time B).

The book from which this chapter was selected seems to be a textbook that a Philosophy professor would assign their students to read. Such treatises are often specifically designed leave certain questions unanswered, in order to allow for debate in the classroom and for students to write papers where they have the leeway to chose which position they want to argue for. — Douglas Alan

I consider Miller's article to be an even-handed presentation of the issues, and you might recall that it was introduced in the OP, not by me. Call it "argument from authority" if you like, but I am simply attempting to have it recognised that Eternalism entails a motionless world. Many seem to find this either inconsequential or incorrect. This is why I keep returning to the associate professor's article. It can be difficult pushing back against the orthodoxy.

I will point out that Miller also describes plenty of problems for presentists, and you are cherry-picking your argument from authority by ignoring the fact that Miller has more objections against presentism than she has against eternalism. — Douglas Alan

I have never claimed to be arguing for Presentism. I even acknowledged that Presentism has many problems of its own in my first post to this discussion. But it's not all bad.

I consider Miller's article to be an even-handed presentation of the issues, and you might recall that it was introduced in the OP, not by me. Call it "argument from authority" if you like, but I am simply attempting to have it recognised that Eternalism entails a motionless world. — Luke

I think the issue here is that the terms like "motionless" and "static" are ambiguous and emotionally laden when talking about something like eternalism. Let's consider a film reel of the best car chase ever filmed. It's so perfect that no decent aficionado of films could disagree with this.

Now consider that in one sense, this film reel is static. It never changes. In another sense, it's full of change and motion. One can imagine that the film editor working on it, if they were really good, they might not even ever have to watch the scene to edit it. Their sense of film editing might be so refined, that they can just fathom all this motion in their heads from individual frames, while they cut and paste bits of film around.

Now imagine that there might be aliens who love human films. Imagine that they don't need to see the movie projected in real time in order to enjoy our films. They just ask for our films as mp4's and their brains are sophisticated enough to decode the mp4's and model what is going on in a film. And boy do they love this car chase! Even though they have never watched it frame by frame. They just absorbed it all at once. But their brains can model all the exciting motion that is going on the film without having to have actually viewed anything moving.

Or you might imagine the same thing about our greatest novels. All sorts of things might be happening in them, right? But no. Nothing happens in a novel. They are static. They don't change. Well, it depends on what sense of the word "happens" and "change" you are using when use these words to describe the novel.

Again we can imagine aliens, or some super-smart person, who doesn't have to read a novel in order in order to appreciate it. You can give them the pages in any order, and in their heads they can reconstruct the proper order for the pages, and appreciate the entire novel in an instant.

Is a great novel static? Or is it dynamic and full of exciting and interesting events?

You tell me!

Now consider that a human life has some similarities to a novel. If eternalism is true, one can view it as either static, or as very dynamic, depending on what sense of the words you are choosing to use when you describe it.

In any case, even if you just consider the above to be a bunch of incorrent blathering, my account has addressed all of Miller's stated worries about eternalism. I can't go over each sentence at the moment, but let's take just one:

why do we have such a different relationship with the future than with the past

One hugely important reason for this is that we can remember the past and not the future. This is true in eternalism just as much as it is true in presentism. It follows plainly from thermodynamics and information theory.

|>ouglas

It's been a long time since I studied special relativity (we spent several weeks on it in Physics 101), but IIRC, relativity doesn't provide a forward and reverse direction of time. It just provides two directions of time, and they are symmetric. — Douglas Alan

You remember right, but that wasn't at issue - we've both acknowledged that this is the case. My point is that relativistic time is not identical to physical time (the time that physical clocks measure). There are at least two reasons to think so: First, it is an idealization that wasn't designed to perfectly track physical time. Second, we have specific examples - probable or at least possible - where relativistic time diverges from physical time.

Why is this important? To bring this back to the original topic, a common argument for the B-theory and against the A-theory is that the theory of relativity, though it may not rule out the A-theory, does not offer any support for it either. The A-theory requires additional assumptions that are not part of SR or GR. The implicit thesis here is that we ought to base our theory of time on the theory of relativity and nothing else. But this thesis is weakened if the identity between relativistic time and physical time is weakened.

The eternalist view has no experiencer. — noAxioms

Is a great novel static? Or is it dynamic and full of exciting and interesting events?

You tell me! — Douglas Alan

Whether a novel or a book or the world is static or dynamic is not the right question. Let's assume that the world is static, as per Eternalism. Then the question becomes: how are we able to perceive it? That is, why do we perceive the world the way we do (dynamically) if it really is static? Furthermore, how do our perceptions and/or our bodies work in those conditions? It would seem to require a complete overhaul of our understanding of human physiology to discard dynamism. This includes if we were to consider our perceptions of motion to be an illusion.

In order to perceive/understand a book or a movie, we must read it or watch it, or have someone describe it, or read a summary of the plot; all of which require dynamism as far as I know. Fanciful examples of aliens outside of time, or in a motionless world, who can perceive books, movies and/or the world simply pushes the problem back a step. It then needs to be explained how the perceptions of those aliens works in a static world.

why do we have such a different relationship with the future than with the past

One hugely important reason for this is that we can remember the past and not the future. This is true in eternalism just as much as it is true in presentism. It follows plainly from thermodynamics and information theory. — Douglas Alan

This begs the question. Why assume that 'time flows' from ordered to disordered states? Because that accords with our perceptions? It remains unexplained why there should be a preferred directionality to our perceptions of temporal flow if nothing really moves.

This begs the question. Why assume that 'time flows' from ordered to disordered states? Because that accords with our perceptions? It remains unexplained why there should be a preferred directionality to our perceptions of temporal flow if nothing really moves. — Luke

I don't assume that time flows from ordered to disordered states. In fact, since I have stated that eternalism is true, I have stated that time doesn't flow at all. This doesn't mean that our brains can't represent time as flowing.

You seem to constantly willfully ignore a fact that I have repeatedly stated: SInce physical law is the same under both eternalism and presentism, our brains are going to be in the same states either way for any given point in time. And because they are going to be in the same states either way, our minds are going to represent things the same way regardless of whether it is eternalism that is true or presentism that is true.

The question that needs to be answered it not why does time flow in a certain direction. The question that needs to be answered is why does time seem to flow in a certain direction. The answer to that question is because our brains represent time as flowing in a certain direction whether or not there is actually any flow.

All I have to do is explain why our brains represent things in a certain manner, and then I have answered why things seem to be a certain way. The only way that things can seem to be, is the way in which our minds represent them.

Why does the world seem to be three dimensional, rather than nine dimensional, for instance? The world may be nine dimensional. That is what is predicted by string theory. The short answer is because our minds represent the world as three dimensional. Because our minds represent the world as three dimensional, the world seems to be three dimensional.

Is it your assertion that our brains can represent things as being one way, and yet it could seem to us that things are different from how our brains are representing things? If that's your assertion, I'd certainly like an account of how this is possible and how it would work!

|>ouglas

I don't assume that time flows from ordered to disordered states. In fact, since I have stated that eternalism is true, I have stated that time doesn't flow at all. — Douglas Alan

You implied that time has a naturally preferred directionality when you stated that we remember the past and not the future, which "follows plainly from thermodynamics and information theory." I don't see how you can consistently argue both that time doesn't flow and that time has a preferred directionality.

SInce physical law is the same under both eternalism and presentism, our brains are going to be in the same states either way for any given point in time. And because they are going to be in the same states either way, our minds are going to represent things the same way regardless of whether it is eternalism that is true or presentism that is true. — Douglas Alan

If nothing moves or flows, then how do we get from one brain state to the next? Are there any theories of how our brains work (e.g. to produce our minds and represent things) which do not require motion?

You implied that time has a naturally preferred directionality when you stated that we remember the past and not the future, which "follows plainly from thermodynamics and information theory." I don't see how you can consistently argue both that time doesn't flow and that time has a preferred directionality. — Luke

I have not said that time has a "preferred directionality". I have said that you can remember the past and not the future. Which direction is "preferred"? The directions just have different properties due to the laws of thermodynamics. Laws which are not affected in the slightest by eternalism or presentism.

Repeat after me: FOR EVERY POINT IN TIME, THE PHYSICAL STATE OF THE UNIVERSE AT THAT POINT IN TIME IS IDENTICAL UNDER ETERNALISM AND PRESENTISM.

Until you can acknowledge and comprehend this irrefutable fact, you will be forever lost.

If nothing moves or flows, then how do we get from one brain state to the next? — Luke

Who says that we "get" from one brain state to the next? At time T1, you are in brain state A. At time T2, you are in brain state B. For any given time Tn, physical law tells us what brain state you will be in. And that brain state will be the same brain state whether eternalism is true or presentism is true.

Are there any theories of how our brains work (e.g. to produce our minds and represent things) which do not require motion? — Luke

Repeat after me: FOR EVERY POINT IN TIME, THE PHYSICAL STATE OF THE UNIVERSE (INCLUDING YOUR BRAIN) AT THAT POINT IN TIME IS IDENTICAL UNDER ETERNALISM AND PRESENTISM.

|>ouglas

@Luke didn't you go over this with noAxioms and others for ages and ages on the old forum? That did you no good: you are still stuck on this idea that there is no motion under eternalism. Do we need to flog this dead horse for 20 more pages? Why don't you give it a rest and find something else to argue about?

I have not said that time has a "preferred directionality". I have said that you can remember the past and not the future. Which direction is "preferred"? The directions just have different properties due to the laws of thermodynamics. Laws which are not affected in the slightest by eternalism or presentism. — Douglas Alan

Let's just say you implied that time has a direction, or that there is an arrow of time, if you will. How is this consistent with your agreement that "time doesn't flow at all"? No flow should entail no direction.

Why don't you give it a rest and find something else to argue about? — SophistiCat

Okay, sorry.

Let's just say you implied that time has a direction, or that there is an arrow of time, if you will. How is this consistent with your agreement that "time doesn't flow at all"? No flow should entail no direction. — Luke

Does space flow towards the north pole? And yet there is a spacial "arrow" that points towards the north pole.

And the state of things that are "here" is different for every point in space that lies between me and the north pole.

In eternalism, "now" is like "here", only for time, rather than for space, and the "past" (the direction towards the Big Bang) is like "south" and the "future" (the direction away from the Big Bang) is like "north".

Now why would any of this commit me to whatever your concept of "flow" is? I have my own notion of "flow", but it only entails that for adjacent points in time, we have some power of calculation about how the physical state of the universe will differ between those two points in time. These powers of calculation come from our understandimg of physical law. And what we will calculate, and what the actual states will be, is unaffected by eternalism vs presentism.

|>ouglas

You remember right, but that wasn't at issue - we've both acknowledged that this is the case. My point is that relativistic time is not identical to physical time (the time that physical clocks measure). — SophistiCat

Personally, I would not refer to time as measured by a clock as "physical time". I would call it "clock time" or some such. Time as measured by a clock is stochastic. It only follows from the second law of thermodynamics, which is not fundamental law. It doesn't even make an assertion that is true in all possible worlds that have the same fundamental law as ours. And that have a Bug Bang.

There is a possible world where my fair coin has always come up heads, even though I have tossed it a quadrillion times. Likewise, there is a possible world in which my pocket watch has always run backwards, without being broken in any way.

In my eyes, "physical time" must not be stochastic. (Unless it turns out that the universe is stochastic all the way down.) Consequently, Relativity provides for two directions of time. This is the only "physical time". There are two directions of physical time that point in opposite directions, and we label one the future and one the past for our convenience. But in perverse situations, and after the heat death of the universe, these labels may not be perfectly appropriate.

Why is this important? To bring this back to the original topic, a common argument for the B-theory and against the A-theory is that the theory of relativity, though it may not rule out the A-theory, does not offer any support for it either. The A-theory requires additional assumptions that are not part of SR or GR. The implicit thesis here is that we ought to base our theory of time on the theory of relativity and nothing else. But this thesis is weakened if the identity between relativistic time and physical time is weakened.

The fact that clocks are not reliable in all possible worlds, or after the heat death of the universe leads me to exactly the opposite conclusion: We should not be making any profound metaphysical conclusions at all based on clock time. We should stick to relativistic time. Labeling one direction of time the future and one the past is just a convenience for discussion, in that we are usually talking about situations that have a readily fathomable entropy gradient.

|>ouglas