Is Time a Series or a Theory: What Do Philosophers Think?

[lmoh]

I just want to know what the consensus is by people here in general on PF, although the only place where I felt this question appropiate is at the philosophy subforum.

http://plato.stanford.edu/entries/time/#TheBThe

Anyway, in a nutshell, the A-series, or A-theory states that the passage of time is real and that reality is really changing while the B-series or B-theory states that there is no flow of time at all and that all past, present and future are fixed in a static state.

 

[Ryan_m_b]

The arrow of time would seem to make B is flawed proposal.

 

[ThomasT]

I just want to know what the consensus is by people here in general on PF, although the only place where I felt this question appropiate is at the philosophy subforum.

http://plato.stanford.edu/entries/time/#TheBThe

Anyway, in a nutshell, the A-series, or A-theory states that the passage of time is real and that reality is really changing while the B-series or B-theory states that there is no flow of time at all and that all past, present and future are fixed in a static state.

Via the conventional usage of the word reality, and the observationally supported fact that reality is changing, then the most reasonable conclusion is that reality is transitory.

The present refers to our experience. The past refers to our indexes of our experience. And the future refers to our projections based on those indexes.

So, it would be incorrect to say that "all past, present and future are fixed in a static state", because, clearly, there's ample evidence to the contrary.

 

[petm1]

I see outgoing signals as the past with incoming signals the future, the present is the interaction of these signals with matter. I see nothing that is static in my view of time other than those bits of matter moving in time relative to myself.

 

[wuliheron]

The entire question implies a false dichotomy as far as I'm concerned. The latest evidence supports contextual theories of quantum mechanics and I see no reason time can't also be framed contextually. If so such archaic metaphysical arguments of dubious value might finally be relegated back to the theologians and others for debate.

 

[madness]

Ryan - I don't agree with your reasoning. I think the arrow of time implies an asymmetry in time, but not necessarily a flow or privileged "present moment". Things can perfectly well be static and asymmetric. In fact, I think the laws of relativity are entirely at odds with the idea of a present moment or flow of time and rather support a "block universe". I am therefore inclined to think that the feeling of time flowing is a subjective trick, related to memory and other functions of our brains.

However, I am also careful to see physical theories as only models of the world, and would therefore be hesitant to take this view given by relativity too literally here.

 

[petm1]

I am therefore inclined to think that the feeling of time flowing is a subjective trick, related to memory and other functions of our brains

I would think the subjective trick of time is all the motion we do not see, from this constant acceleration I feel on earth, to the duration of a photon which I see as space, but just like Thomas said it does take a functioning brain to interpret the signals.

 

[B.E.M]

Going from you 'nutshell' definition, I definitely go with 'B'. Actually I am surprised to find it currently lagging behind A on a physics forum, though only a handful of votes are in I suppose.

I don't see the need of a present to explain anything within physics. Also, physicists tend not to like privileged coordinates or frames of reference. Show me a reason to introduce the special case of a present into my beautiful symmetrical physical laws!(the rest that follows is really just my feelings)

We all have this strong sense of time passing at a (outside moments of stress) constant rate, but does that even make sense? What units would the passage of time even have? It seems to me this rate is at most the ratio between your observations and your internal model. perhaps seconds per thought.

Personally I favor the notion that the direction of time is simply the direction of increasing entropy. Given that you exist in a part of the universe that is not totally uniform you could expect to be on a gradient between more and less ordered states. Even if non-uniformity is incredibly rare, all other points are probably to boring to support intelligence. We call the past the past because we can remember it. For example if the universe started as a big cube of ice, and the ice was smashed into smaller ice cubes, you could point to one of these cubes and say 'this is a memory of the original state', but the original ice cube is too simple to hold a model of higher entropy states.

As an aside: If our past is always in whatever direction order increases from our current coordinates then, regardless of the shape of the universe, all consciousness will perceive themselves to be in a present with a past that was slightly more ordered, and looking back further a past even more ordered than that, and so on perhaps until some sort of singularity is encountered.

(edit)

Just wanted to add that disbelieving the present is a necessary concept for physics does not necessarily mean believing the future is predetermined. For example perhaps not just one but every future is played out somewhere. Each future self would feel that just one future happened and could assume they were marching down a single linear predetermined path.

 

[rolerbe]

Depends on your frame of reference.

If you are traveling at less than the speed of light, then Series A is true - events are dynamic and unfold as a series of interactions in time.

If you are traveling at the speed of light, e.g. a photon, then everything happens at once and Series B is true.

They're both true. The cat is alive AND dead.

 

[Ryan_m_b]

If you are traveling at the speed of light, e.g. a photon, then everything happens at once and Series B is true.

No this is not the case, there is no frame of reference for an object traveling at c
https://www.physicsforums.com/showthread.php?t=511170

 

[B.E.M]

Depends on your frame of reference.

If you are traveling at less than the speed of light, then Series A is true - events are dynamic and unfold as a series of interactions in time.

As far as I know, there is no need for this concept within physics. I understand there are rules ordering cause and effect etc, but these are true of all points in history, not just true at one point that we call the present for example. I don't think the B theory excludes such notions as one point being near another in time, or defined as before or after with respect to some coordinate system.

Also my understanding that the laws of physics are all reversible with the qualified exception of entropy, mentioned above. Anything that physics models going forwards could also describe another possible system with time reversed. It seems to me that all we need to explain entropy is the notion that the universe is not entirely homogeneous and then the common experiences of past and future, such as the inability to remember the future, can be deduced.

 

[PhaseVelocity]

Time does not exist.
There is entropy and cause and effect. They result in a sequence of events that we perceive as time. But time is really just a concept so A and B theory are both equal as they are both nothing but sometimes useful concepts. For physicists B theory is obviously more useful but that does not change that it is nothing but a conceptual tools to create models of reality.

 

[mangaroosh]

I just want to know what the consensus is by people here in general on PF, although the only place where I felt this question appropiate is at the philosophy subforum.

http://plato.stanford.edu/entries/time/#TheBThe

Anyway, in a nutshell, the A-series, or A-theory states that the passage of time is real and that reality is really changing while the B-series or B-theory states that there is no flow of time at all and that all past, present and future are fixed in a static state.

I voted A because of the reference to "presentism", namely the idea that the present moment is all that exists. I wouldn't however agree with the notion that the passage of time is real, insofar as I would see time as being a manmade concept, not something that is real. I think the idea of time arises form our ability to remember the past and project the future; it is essentially a mental construct.

Obviously these ideas aren't original, but I think they are reasonable.

Just read the following, which I would agree with (to a certain extent)

Time does not exist.
There is entropy and cause and effect. They result in a sequence of events that we perceive as time. But time is really just a concept so A and B theory are both equal as they are both nothing but sometimes useful concepts. For physicists B theory is obviously more useful but that does not change that it is nothing but a conceptual tools to create models of reality.

 

[mangaroosh]

I think the main arguments against B-series, which only slightly favour A-series - insofar as A-series postulates that the present moment is all that exists - are:

- A clock doesn't measure a physcial property called time; a clock provides a regularly occurring, repetitive process which is used as a standard unit, which facilitates the comparison of other physical processes, and the expression of those processes in standardised units. At no point in the process is there a physical property called "time" actually measured.

- There is no experiment that can, or ever will, be conducted that isn't in the present moment. All that can ever be experienced by anyone is the present moment.

- Following on from that; there is no direct evidence that "the past" or "the future" exist; what we have are the mental constructs of "past" and "future". Without such direct evidenece, both have to be assumed to exist, and "time" along with them.

 

[lmoh]

A bit late to add my own take on the issue, but in my opinion, the philosophical case against the A-series is quite weak to say the least. However, physics apparently points in the other direction on this issue (though I am not certain just how relevant the science is to philosophical issues such as this one), which sort of leaves me in the middle.

 

[GeorgeDishman]

I voted "B Series" though elsewhere I have seen "A versus B" explained in terms of relative versus absolute time which is slightly different.

IMHO, the Twins Paradox of special relativity argues strongly against most forms of presenntism. If as enduratism says, an object is "wholely present at each instant", then the traveling twin will be in the future of the stay-at-home twin after the trip even if they agree to meet at the same location. This means that a "future" stay-at-home can only meet a "past" traveller. On that basis, I am a perdurantist. Until a quantum substratum can be developed from which spacetime becomes emergent, I would have to adopt the postulate that time and distance are continuous hence I would further suggest that worm theory is the scientifically favoured model.

http://plato.stanford.edu/entries/temporal-parts/#7

The question about whether time is "real" is that of substantivalism. In that area, I think the observations by Hulse and Taylor for which they won the Nobel Prize are crucial. They showed by careful timing that a pair of stars including a pulsar was losing orbital energy at the rate expected to result from gravitational radiation. That means that ripples in the metric of spacetime carry off energy. Recent advanced simulations of the merger of two black holes can, if their spins are aligned correctly, impart a thrust to the merged product. The effect is known as gravitational wave recoil. If ripples of time can transport energy and momentum, it is hard to see them as anything but real. For that reason, I support Metric Substantivalism. However, I would argue against Manifold Substantivalism on the basis of Leibniz Equivalence and the Hole Argument (on the latter, note that the SEP does not differentiate between the two forms and really only addresses Manifold Substantivalism).

http://plato.stanford.edu/entries/spacetime-holearg/

 

[Luigi Acerbi]

there is no direct evidence that "the past" or "the future" exist; what we have are the mental constructs of "past" and "future". Without such direct evidenece, both have to be assumed to exist, and "time" along with them.

Some years ago I thought that this was a proof of the nonexistence of time, but then I realized that it is not necessarily the case, or at least there are some caveats.

It is quite important, as you mention, that the past and the future are inferred from the present, and we do that through patterns and regularities (e.g. the laws of nature and other hacks). We never 'directly' observe them, true.
However, the special status of direct observation applies to truly a small fraction of events/things (someone would say to none), especially in modern physics. We observe lots of things indirectly - we infer the existence of quarks or other subatomic particles starting from very indirect observations, through a certain set of patterns and regularities (e.g. QCD). We have reason to believe their existence because there is overwhelming, consistent evidence.
So if we do accept 'existence by inference', I am not sure why we should treat the ontological status given by inference differently when dealing with the time direction rather than any other 'direction' (e.g. scale).

Given this, my current feeling is towards an "extended presentism". That is, I think that the present carries some structure about some of the future and some - possibly a lot (but it might depend on the scale) - about the past, for this point see the 'time capsules' theory of Julian Barbour (even if he is arguing for the non-existence of time).

 

[mangaroosh]

Some years ago I thought that this was a proof of the nonexistence of time, but then I realized that it is not necessarily the case, or at least there are some caveats.

It is quite important, as you mention, that the past and the future are inferred from the present, and we do that through patterns and regularities (e.g. the laws of nature and other hacks). We never 'directly' observe them, true.
However, the special status of direct observation applies to truly a small fraction of events/things (someone would say to none), especially in modern physics. We observe lots of things indirectly - we infer the existence of quarks or other subatomic particles starting from very indirect observations, through a certain set of patterns and regularities (e.g. QCD). We have reason to believe their existence because there is overwhelming, consistent evidence.
So if we do accept 'existence by inference', I am not sure why we should treat the ontological status given by inference differently when dealing with the time direction rather than any other 'direction' (e.g. scale).

Given this, my current feeling is towards an "extended presentism". That is, I think that the present carries some structure about some of the future and some - possibly a lot (but it might depend on the scale) - about the past, for this point see the 'time capsules' theory of Julian Barbour (even if he is arguing for the non-existence of time).

The point may have been misunderstood; we don't infer "past" and "future" from the present; we can't even infer them from the present; it is always the present, and all we ever have are mental constructs of "past" and "future"; even a photograph of a "past" event exists only in the present, and isn't the event that was photographed.

All we can infer, from the present, is that "past" and "future" are mental constructs.

 

[Luigi Acerbi]

The point may have been misunderstood; we don't infer "past" and "future" from the present; we can't even infer them from the present; it is always the present, and all we ever have are mental constructs of "past" and "future"; even a photograph of a "past" event exists only in the present, and isn't the event that was photographed.

All we can infer, from the present, is that "past" and "future" are mental constructs.

I suppose my point has been misunderstood.
It is always the Present, yep, we agreed on that from the start.

However we do infer - i.e. compute/construct through an inference process given some evidence and a set of rules - the 'Past' from the present. 'Past' is a useful label/index/category that we use to refer to some specific structure/ordering in the information in the present (e.g. the time capsules Julian Barbour talks about). A photography is a good example. A slightly different argument but similar in flavour applies to the Future.
Anyhow, we never see the Past nor the Future.

So yes, they are mental constructs, useful descriptions - as are 'electrons' and 'quarks'. Subatomic particles are inferred too (i.e. computed/constructed through an inference process given some evidence and a set of rules). They are too a useful label/index that we use to refer to some specific structure in the information in the present. You do not see an electron, you see a trace on a plate. Even less we can see of a quark.

Subatomic particles are just an example. The point I was making is that we are typically happy to grant 'existence by (sound) inference', so I am not sure why we should deny it to the Past and Future on the basis that we never see them directly.
OK, it can be argued that 'Past/Future' and 'particles' belong to completely different ontological categories, and so different rules apply, still I do not see why.

 

[mangaroosh]

I suppose my point has been misunderstood.
It is always the Present, yep, we agreed on that from the start.

However we do infer - i.e. compute/construct through an inference process given some evidence and a set of rules - the 'Past' from the present. 'Past' is a useful label/index/category that we use to refer to some specific structure/ordering in the information in the present (e.g. the time capsules Julian Barbour talks about). A photography is a good example. A slightly different argument but similar in flavour applies to the Future.
Anyhow, we never see the Past nor the Future.

So yes, they are mental constructs, useful descriptions - as are 'electrons' and 'quarks'. Subatomic particles are inferred too (i.e. computed/constructed through an inference process given some evidence and a set of rules). They are too a useful label/index that we use to refer to some specific structure in the information in the present. You do not see an electron, you see a trace on a plate. Even less we can see of a quark.

Subatomic particles are just an example. The point I was making is that we are typically happy to grant 'existence by (sound) inference', so I am not sure why we should deny it to the Past and Future on the basis that we never see them directly.
OK, it can be argued that 'Past/Future' and 'particles' belong to completely different ontological categories, and so different rules apply, still I do not see why.

The point is that there isn't even a trace of "the past" or "the future"; there is nothing from which to infer it. We construct models of the future and have records of the past, but all that can be inferred is that the present moment is ever changing.

"Past" and "future" are useful concepts, but that is all that can be said of them, they are merely concepts. If we take the photograph example, how do we infer that "the past" continues to physically exist?

The photo was taken in the present; the scene that the photograph pictured has since changed and can no longer be observed, so there is no evidence of its continued existence. The photograph only ever exists in the present. How can we infer that the past is anything more than a mental contstruct; or the same for the future?

 

[Luigi Acerbi]

The point is that there isn't even a trace of "the past" or "the future"; there is nothing from which to infer it. We construct models of the future and have records of the past, but all that can be inferred is that the present moment is ever changing.

"Past" and "future" are useful concepts, but that is all that can be said of them, they are merely concepts. If we take the photograph example, how do we infer that "the past" continues to physically exist?

The photo was taken in the present; the scene that the photograph pictured has since changed and can no longer be observed, so there is no evidence of its continued existence. The photograph only ever exists in the present. How can we infer that the past is anything more than a mental contstruct; or the same for the future?

I'll try to unpack a bit my thoughts, since you're stating things I agree on as if I was saying the opposite, not sure I am expressing properly.

For me the Past/Future have no independent existence from the Present. They are 'derived quantities', not fundamental. As I already said, I am a Presentist at the moment. (Of course I couldn't be at any other moment.) I'll make a couple of examples to explain myself:

1) If a demon changed all the present evidence regarding a 'past event', I mean all the information regarding the event which has decohered in the universe, people would typically think that our available information regarding the Past has been changed, but not the Past itself. My opinion would be that after the demon's intervention the Past has been changed, since the Past sits 'on top' of the Present (or in other words, it from bit, if you change the information regarding the thing, you change the thing).
There is no thing as an 'independent Past', lying somewhere behind us (or in front of us, according to the http://www.nytimes.com/2006/06/27/science/27side.html/partner/rssnyt?_r=1).

2) If the structure of the Present does not support the existence of records of any type, or inference systems, Past and Future lose meaning. Past and Future are labels we give in the presence of specific patterns of structure. I want to mention though that these are not arbitrary labels, they do depend on objective features of the patterns (independent observers would agree on the ordering of causally related events).

So if by existence you mean 'independent existence', I think we more or less agree from the start on that, Past and Future are not 'out there', they are (re)constructed from the Present. What I wanted to point out with my first post were only a couple of remarks:

a) Existence does not mean only independent existence. We typically do grant existence to things which depend on other things to exist.
But I agree that it is good to keep the distinction in mind, and since most people do believe in an independent existence of Past/Future from the Present, I see why it is easy to overreact and take the opposite side, that they do not exist at all (I did that).

b) I do not think that the 'mental construct' position is a particularly useful one; if you dig deep enough (almost) everything is a mental construct. So it's not false, I appreciate that, but I don't see the specifics that make it non-vacuously true.

 

[GeorgeDishman]

Anyhow, we never see the Past nor the Future.

On the contrary, all we ever observe is the past. If I stand 3m from someone, it takes light 10ns to travel from them to me so I see them as they were 10ns into the past. From that and our experience that objects persist in some manner (conservation laws), we infer that they still exist. In fact QM permits the possibility that they ceased to exist 5ns ago (at a very low but non-zero probability).

What you need to consider though is what the labels "past" and "future" really mean. Suppose one person, "Alice", walks east past someone else, "Bob", who is standing still. They momentarily brush arms as they pass which defines a reference event 'P'. There is another person "Charlie" standing 300m ahead of us who claps his hands defining event 'Q'. If the image of event Q arrives 1us after event P then Bob will conclude that P and Q were simultaneous, that is he considers Q occurred what he called the present at event P. Alice on the other hand finds the image arrives less than 1us after P hence she classifies it as having already happened before P, it was already in her past. Similarly, someone walking west who also brushed arms with Bob at P would consider Q happened later than P, it was in their future. The concepts of past, present and future are labels which can be arbitrarily assigned to events which are space-like separated. This is one reason why many people think that it is very hard to reconcile presentism with relativity.

 

[lmoh]

On the contrary, all we ever observe is the past. If I stand 3m from someone, it takes light 10ns to travel from them to me so I see them as they were 10ns into the past. From that and our experience that objects persist in some manner (conservation laws), we infer that they still exist. In fact QM permits the possibility that they ceased to exist 5ns ago (at a very low but non-zero probability).

What you need to consider though is what the labels "past" and "future" really mean. Suppose one person, "Alice", walks east past someone else, "Bob", who is standing still. They momentarily brush arms as they pass which defines a reference event 'P'. There is another person "Charlie" standing 300m ahead of us who claps his hands defining event 'Q'. If the image of event Q arrives 1us after event P then Bob will conclude that P and Q were simultaneous, that is he considers Q occurred what he called the present at event P. Alice on the other hand finds the image arrives less than 1us after P hence she classifies it as having already happened before P, it was already in her past. Similarly, someone walking west who also brushed arms with Bob at P would consider Q happened later than P, it was in their future. The concepts of past, present and future are labels which can be arbitrarily assigned to events which are space-like separated. This is one reason why many people think that it is very hard to reconcile presentism with relativity.

I understand that there can be delays in our perceptions to what is happening "out there", but I think it is a little misleading when people say that "we perceive the past" as though the past is still eixsting as we perceive it in the present. It is no more different than sending a letter across the world in my opinion.

But I imagine that the situation in SR is more deeper than that, but that is just my impression from what I am learning about it currently.

 

[GeorgeDishman]

I understand that there can be delays in our perceptions to what is happening "out there", but I think it is a little misleading when people say that "we perceive the past" as though the past is still existing as we perceive it in the present. It is no more different than sending a letter across the world in my opinion.

Absolutely, the acts of posting and receiving are "timelike" separated, in all inertial frames they will occur in that order, you can only read what was written in your past. That doesn't imply that it still exists though, as you say.

But I imagine that the situation in SR is more deeper than that, but that is just my impression from what I am learning about it currently.

Yes, in the example I gave, the events P and Q are defined as happening at the same time in Bob's frame. Those events each exist at some instant. What you have to think about is when they exist as viewed by the two people passing Bob. At the moment when they agree P is "now", one thinks Q is yet to happen while the other thinks it has already happened but they all agree the event actually happened. It is just one event but one considers it part of the past while for the other it is part of their future.

 

[apeiron]

On the contrary, all we ever observe is the past. If I stand 3m from someone, it takes light 10ns to travel from them to me so I see them as they were 10ns into the past.

The point is that there isn't even a trace of "the past" or "the future"; there is nothing from which to infer it. We construct models of the future and have records of the past, but all that can be inferred is that the present moment is ever changing.

If we take time as some general attempt to measure change, then the problem seems to be that change has two contrasting sources. So the "present" becomes a mixed state.

One source of change is global constraint. That is the sum of everything that has gone before to create a history. And because it takes time - in a sub-relativistic world at least - for distant events to impinge on some particular locale, this history is always "just arriving". For a locale, some constraint - like perhaps the ripple of a gravity wave as mentioned - was not there a moment ago, but is changing things for that locale right now.

This is the kind of deterministic change modeled by Newtonian mechanics. The past is already coming at you, like a piano dropped off a high building above your head, but you just don't know it yet.

But there is also a second source of change, and that is local degrees of freedom. Whatever is not past-constrained is a source of future-oriented spontaneity. It is a potential waiting to be realized in some locally independent fashion.

Now mostly our large~cold universe seems to have very little spontaneity about it. It has so much past-history that the state of every locale is highly constrained, almost completely determined. The trajectory of particles is inertial, apparently tied to the track of its history and with no freedom to swerve or in any other way show accelerative change.

But QM shows that there still is some kind of actual local freedom, some indeterminacy that complicates any simple measure of change.

And for actually complex systems like humans, there is a lot of local freedom. We can look up and see the falling piano. Or for some other reason, just happen to step out of its path. The psychological notion of time thus emphasises the local freedom, the creative spontaneity, that comes with being able to anticipate - "look into the future" - and so respond according to imagined constraints rather than being just determined by past ones.

So time is our attempt to model/measure change. And the model we have constructed actually reflects a rather particular "time" in the universe's development - it is the view when things have become generally so expanded and cold that almost all the local spontaneity has been squeezed out of the picture, nearly everything is narrowly determined by a history of past constraint. A deterministic Newtonian model works because it covers 99.99...% of what is "happening". Back nearer the big bang of course, the spontaneity of fluctuations ruled.

Now a further feature of our modelling of time is that almost without comment, we take the sub-relativistic view as our natural baseline, as if a lack of change - being at rest - is the default state of things. But of course, it is the relativistic realm of the photon which is the real baseline state for the universe. When mass condensed out as the universe expanded~cooled, suddenly a new local freedom was created - the possibility to go slower, to lag behind. If we are talking about dimensions, this phase change added another general temporal dimension that had not existed previously.

So we have a general story that the notion of time is our attempt to create some general or universal measure of change. It would be conveniently simple if it were just a Newtonian dimension - a metric without any complex structure. If every locale marched in lockstep with no local degrees of freedom, just a single universal history in which not just past-constraint completely rules, but also all action is being measured from the most extreme case of "locales at rest", the farthest possible end of the non-relativistic case.

However, time does have this more complex structure. The balance between local freedom and global constraint changes simply because the universe cools and expands. The hot quantum possibilities get decohered, the universe becomes more classically past-determined. On top of this, there is the condensing out of mass that sets up a new dimension of change, the sub-light realm where it takes time for locales to learn about events (and so creates new local inertial degrees of freedom). On top of this again develops the kind of psychological degrees of freedom we have that come from being able to imagine our futures, and act on the resulting beliefs.

Presentism recognises that there is this intersection between global constraints and local freedoms. It divides them into a map of the past vs a map of the future. But then it also wants to universalise this story - to apply it everwhere to create a universal moment.

I think this can be done in reasonable fashion if anchored to a thermal notion of time (as being suggested by Carlo Rovelli, for instance). The temperature of the universe at some common "moment" does create an average benchmark of change (the relative remaining potential for change, as well as its direction).

But still, a lot of the nagging ontological questions being asked here appear to arise from wanting to have some overly simple model of time - collapsing its complex and processual structure to a single universal dimension.

Now it is quite possible that a more complex model of time is of no real practical use - physics could do without it. Yet I think as we come to understand the universe and the big bang in terms of entropy dissipation, and the fact that sub-relativistic mass is an emergent extra to the story, not a fundamental fact, then the modelling/measuring of time may indeed be in for a shake-up.

As well as Rovell's thermal time, there are other interesting stabs at the problem, like Stu Kauffman's notion of the adjacent possible - an edge of chaos type balancing act story where, as I argue, the present moment for any locale is a dynamic balance of past constraints and future freedoms.

The retrocausality implied by QM nonlocality also has to be fitted into the picture. The future seems to create its own past in some admittedly very slight degree.

Debates around the nature of time usually stick to Newtonianism vs relativity. But QM and thermodynamics are also ingredients in the story. Boil it all up and what is our overall model of change then?

 

[Luigi Acerbi]

I cannot agree more...

But then it also wants to universalise this story - to apply it everwhere to create a universal moment. [...]

But still, a lot of the nagging ontological questions being asked here appear to arise from wanting to have some overly simple model of time - collapsing its complex and processual structure to a single universal dimension.

Definitely. By the way, I think that the same mistake occurs with 'existence' - here we were talking about the existence or non-existence of something, but probably people were using different definitions, most of them were probably categorical and global.

On the opposite, my feeling is that 'existence' is relational and graded, not a on-off property. I suppose I follow a modern, Bayesian version of the Berkeleyan esse est percipi motto, that can be reformulated as to be is to be inferred. Maybe one day I'll open another post on this, now I am off topic.

 

[B.E.M]

On the opposite, my feeling is that 'existence' is relational and graded, not a on-off property. I suppose I follow a modern, Bayesian version of the Berkeleyan esse est percipi motto, that can be reformulated as to be is to be inferred. Maybe one day I'll open another post on this, now I am off topic.

I also came up with a similar idea. suppose as a thought experiment you define a virtual universe by a small computer algorithm which uses pi as random seed to place the atoms, then anyone with a sufficiently powerful machine could run this simulation forwards and see what happens in this universe. In a way this whole universe exists somewhere, and has always existed. but it doesn't exist relative to us.

If however a frame of this simulation produced our present moment (including our present memories of our past) then the simulated universe becomes real, or at least a better theory of what is real, what actually happened to produce this present moment, than any other we currently have.

 

[GeorgeDishman]

I also came up with a similar idea. suppose as a thought experiment you define a virtual universe by a small computer algorithm which uses pi as random seed to place the atoms, then anyone with a sufficiently powerful machine could run this simulation forwards and see what happens in this universe. In a way this whole universe exists somewhere, and has always existed. but it doesn't exist relative to us.

If however a frame of this simulation produced our present moment (including our present memories of our past) then the simulated universe becomes real, or at least a better theory of what is real, what actually happened to produce this present moment, than any other we currently have.

The trouble with that approach to considering the problem is that each simulation frame is a unique snapshot thus it intrinsically assumes endurantism.

Suppose three gods had a creation contest. The first god creates a perfect block universe, it is the most beautiful paperweight ever made, with a big bang at one end and a big crunch at the other. The second god goes one better, he makes a similar paperweight except that he includes dark energy so that it is no longer finite, it opens out into an infinite bell so that an infinite number of copies of all possible finite paperweights are included in it. The third god has to find a way to make his even better so he decides to include randomness at every event. His infinite block universe shimmers and sparkles because the closer you look, the less well defined each part becomes.

I don't believe in deities but I think science suggests we cannot think of spacetime and quantum indeterminacy independently and what is needed is a block universe model that doesn't include hard determinism.

 

[Dale]

The latest evidence supports contextual theories of quantum mechanics and I see no reason time can't also be framed contextually.

What are you referring to here?

 

[lmoh]

Yes, in the example I gave, the events P and Q are defined as happening at the same time in Bob's frame. Those events each exist at some instant. What you have to think about is when they exist as viewed by the two people passing Bob. At the moment when they agree P is "now", one thinks Q is yet to happen while the other thinks it has already happened but they all agree the event actually happened. It is just one event but one considers it part of the past while for the other it is part of their future.

After some thought, even if theories such as SR may suggest that there is a block universe, I think it is a mistake to go as far to say that there exists no change whatsoever in the world, especially in the face of our own changing conscious experience. Personally, I see this experience in itself as being enough to support the A-series as I defined it, though some B-theorists may just accept it as an "illusion" to be explained. So even if I accept those theories, I believe that there has to be some way to reconcile this experience with reality, either by defining some "present moment" to the physical universe somehow, or maybe even going beyond that and distinguishing between the time of our experience and the time of the physical world.

 

[GeorgeDishman]

After some thought, even if theories such as SR may suggest that there is a block universe, I think it is a mistake to go as far to say that there exists no change whatsoever in the world,

The block universe model doesn't say there is no change, change will still happen but, to some people in my present, those changes have already happened therefore must already have a fixed value. Viewed that way, it suggests that the future is not open to alteration by our decisions, it is predetermined and therefore the outcome of our decisions must also be predetermined. Thus it argues against free will.

However, that ignores Heisenberg Uncertainty which says that at the quantum level, outcomes are random and can only be constrained statistically. That reflects as true randomness in Brownian motion and thermal noise in electrical signals, both of which affect the connections between neurons in the brain. Hence I contend that sufficiently finely balanced decisions must have a random component and the future cannot be fully predetermined.

especially in the face of our own changing conscious experience. Personally, I see this experience in itself as being enough to support the A-series as I defined it, though some B-theorists may just accept it as an "illusion" to be explained. So even if I accept those theories, I believe that there has to be some way to reconcile this experience with reality, either by defining some "present moment" to the physical universe somehow, or maybe even going beyond that and distinguishing between the time of our experience and the time of the physical world.

Many would say that assigning a physical "present" to the universe conflicts with the observations that support relativity but that is still subject to some debate. Perceived time is another matter. The present is our "now" and after some thought, the only definition I can suggest for "now" is this:

Now is the moment that separates that part of my life which, in principle, I can remember from that which I can only anticipate.​

Looking back over your life, you never experienced anything that didn't happen "now" at the time when it happened and the same is true of future events, the time will be "now" when they happen too. It also means that your now and my now are independent, it does not require a universal now for all. Interaction is still constrained to be within our future and past light cones by causality of course.

It is tempting to think of "now" as a surface between a quantum entangled "many worlds" future versus the single-valued past described by history books, but that surface then identifies a form of presentism which again is questionable according to relativity. Instead, I think physics has symmetry in local time and Feynman's "sum over histories" suggests our past may also be entangled and multi-valued in some sense. The way my views are heading is that our preceived "now" is like a pinch-point in a quantum-entagled universe created by the past and future light cones which limit our experience and influence respectively.

 

[lmoh]

The block universe model doesn't say there is no change, change will still happen but, to some people in my present, those changes have already happened therefore must already have a fixed value.

Depends upon what you mean by "change". I was following my definition of change from the OP, which was referring to something like the flow of time (I apologize if I didn't make that explicit earlier). I agree that the block universe model in itself does not entail no change as I have defined it, as I said before, but that it is also compatible with the "Moving Spotlight" view of time which is part of the A-series.

Viewed that way, it suggests that the future is not open to alteration by our decisions, it is predetermined and therefore the outcome of our decisions must also be predetermined. Thus it argues against free will.

However, that ignores Heisenberg Uncertainty which says that at the quantum level, outcomes are random and can only be constrained statistically. That reflects as true randomness in Brownian motion and thermal noise in electrical signals, both of which affect the connections between neurons in the brain. Hence I contend that sufficiently finely balanced decisions must have a random component and the future cannot be fully predetermined.

The block universe model does not necessarily require determinism and it is compatible with indeterminism as far as I am concerned. There is no problem in imagining events on the block universe that have no strict connection to other events.

As for free will, for the most part, I am a pretty open compatibilist on the issue, so determinism (and even indeterminism) does not pose a problem for me. But that's a topic for another discussion.

Many would say that assigning a physical "present" to the universe conflicts with the observations that support relativity but that is still subject to some debate.

Yeah, I understand. That is why I am just holding out for either some hidden "present" that is compatible with relativity, or some way to define a "present moment" in later physics if that is possible. But if push comes to shove, there can be a block universe, but it would be like the Moving Spotlight view above.

As far as I am concerned, we experience the world in sequence, and that is enough to vindicate the A-series. Note that I am not talking about what we perceive, but how we perceive it. I am not going to say that the physical universe changes (indeed, it may be like a block universe), but at the very least, there is change when it comes to consciousness.

Perhaps this is related to the issue between mind and matter, at least this is how this paper I read years ago defines it: http://fqxi.org/data/essay-contest-files/Nikolic_FQXi_time.pdf. I highly recommend you read it, because some of it speaks to my own views on the matter, and probably describes it in a better way than mind.

 

[GeorgeDishman]

Depends upon what you mean by "change". I was following my definition of change from the OP, which was referring to something like the flow of time (I apologize if I didn't make that explicit earlier). I agree that the block universe model in itself does not entail no change as I have defined it, as I said before, but that it is also compatible with the "Moving Spotlight" view of time which is part of the A-series.

I was keeping it more general and simple meaning different states at different times without implying flow or any other model for time.

The block universe model does not necessarily require determinism and it is compatible with indeterminism as far as I am concerned. There is no problem in imagining events on the block universe that have no strict connection to other events.

Agreed but an indeterminate future together with a single-valued past implies a point between where the many possibilities become the one selected, perhaps like the Copenhagen Interpretation of QM. A surface joining those points looks like the present of a Moving Spotlight model (of which more later).

As for free will, for the most part, I am a pretty open compatibilist on the issue, so determinism (and even indeterminism) does not pose a problem for me. But that's a topic for another discussion.

As am I so it isn't a threat to my world view, but philosophically there is a fundamental difference which warrants consideration, perhaps even a dichotomy.

Yeah, I understand. That is why I am just holding out for either some hidden "present" that is compatible with relativity, or some way to define a "present moment" in later physics if that is possible. But if push comes to shove, there can be a block universe, but it would be like the Moving Spotlight view above.

A "present" is required by QM but incompatible with relativity, that's the problem with unified theories. I found a paper on this by Skow but haven't had time to read it yet:

http://web.mit.edu/bskow/www/research/timeinrelativity.pdf

As far as I am concerned, we experience the world in sequence, and that is enough to vindicate the A-series. Note that I am not talking about what we perceive, but how we perceive it. I am not going to say that the physical universe changes (indeed, it may be like a block universe), but at the very least, there is change when it comes to consciousness.

If you read my definition of "now", I think we are of like mind on this.

Perhaps this is related to the issue between mind and matter, at least this is how this paper I read years ago defines it: http://fqxi.org/data/essay-contest-files/Nikolic_FQXi_time.pdf. I highly recommend you read it, because some of it speaks to my own views on the matter, and probably describes it in a better way than mind.

OK, it's on a fairly long list though ;-)

 

[lmoh]

I was keeping it more general and simple meaning different states at different times without implying flow or any other model for time.

Yeah, that was the sort of definition I was expecting, and I don't think anybody would disagree with it. I should probably use a different word next time.

Agreed but an indeterminate future together with a single-valued past implies a point between where the many possibilities become the one selected, perhaps like the Copenhagen Interpretation of QM. A surface joining those points looks like the present of a Moving Spotlight model (of which more later).

Something doesn't sound right here, but I cannot pinpoint it exactly. If this conception has any relation to the Moving Spotlight model, then I am not sure what you are referring to by the terms "future" and "past" here.

Usually, I imagine an MS model would consist of two times, one of the Block universe, and one in which time lapses (this is what I would attribute to consciousness). The relation between these two times is pretty much as the name describes it: the latter time "moves" along the former time so to speak, shining upon each and every moment of it successively (like a moving spotlight). With that in mind, I cannot make out what you are saying here.

A "present" is required by QM but incompatible with relativity, that's the problem with unified theories. I found a paper on this by Skow but haven't had time to read it yet:

http://web.mit.edu/bskow/www/research/timeinrelativity.pdf

Even if I am holding out for some A-theory in physics, I am not so sure about that. I have heard that QM does not necessarily require a present moment, especially since we agree that indeterminism poses no threat here.

On another note, people have already combined QM and SR to form Quantum Field Theory, so they are not totally incompatible. It is QM and GR that are incompatible, according to my knowledge. Whether a combination of the two would open up a path for a "present moment" is still to be seen though.

As for the paper, I am not sure if I've read it before (I looked into the philosophy of time a while back, but barely have a recollection of it), but I will get back to it later if I can.

If you read my definition of "now", I think we are of like mind on this.

Yeah, I've read over it, but I felt as though the definition dealt more with the contents of experience rather than how we experience it, a distinction in which I referred to in my last post. But I am guessing if you were aware of this, then we would agree for the most part here.

OK, it's on a fairly long list though ;-)

No worries. Take your time . But if it takes some of the load off, the paper is fairly short.

 

[GeorgeDishman]

Yeah, that was the sort of definition I was expecting, and I don't think anybody would disagree with it. I should probably use a different word next time.

It's difficult to avoid implying a temporal model just because the concept is ingrained in our language.

Agreed but an indeterminate future together with a single-valued past implies a point between where the many possibilities become the one selected, perhaps like the Copenhagen Interpretation of QM. A surface joining those points looks like the present of a Moving Spotlight model (of which more later).

Something doesn't sound right here, but I cannot pinpoint it exactly. If this conception has any relation to the Moving Spotlight model, then I am not sure what you are referring to by the terms "future" and "past" here.

Usually, I imagine an MS model would consist of two times, one of the Block universe, and one in which time lapses (this is what I would attribute to consciousness). The relation between these two times is pretty much as the name describes it: the latter time "moves" along the former time so to speak, shining upon each and every moment of it successively (like a moving spotlight). With that in mind, I cannot make out what you are saying here.

That's how I view it too. You've probably seen sci-fi films where something is "scanned" by having a laser swept to form a plane of light which then moves across it. If the block universe is a glass paperweight with the big bang at one end and the heat death of the universe at the other, the "Moving Spotlight" is like that laser plane moving through it. Our present (the location of consciousness) is the point where the plane intersects our individual worldline and the time of cosmology is a measure of how far through the glass the plane has moved (13.7 billion years so far). In that model, the past is the section that has already been scanned and the future lies ahead of the spotlight plane.

Our perception of a "flow of time" in this model is like looking out of a train window and seeing the countryside flow past, but in fact the landscape ahead is already set in stone and the flow is an illusion. "Change" is the sequential variation of the intersection of the plane with the worms of our lifelines.

Yeah, I've read over it, but I felt as though the definition dealt more with the contents of experience rather than how we experience it, a distinction in which I referred to in my last post. But I am guessing if you were aware of this, then we would agree for the most part here.

Your distinction is rather subtle, I see our awareness of the passage of time as emergent, an interpretation of the accumulation of seemingly ordered memories. However, that gets us into the complexities of neuroscience and I'm far from up on that topic!

 

[lmoh]

Your distinction is rather subtle, I see our awareness of the passage of time as emergent, an interpretation of the accumulation of seemingly ordered memories. However, that gets us into the complexities of neuroscience and I'm far from up on that topic!

I just want to hammer in your last point here. Memories are necessary for a perceived change, are not necessarily required for changes in perception. I can be an animal with virtually no memory of my life, yet I can still experience t1, then t2, then t3, even if at t2, I have no perception that time has passed from t1 to t2 (because I barely have an ordered memory of it).You can say that neuroscience can deal with the former well, but as for the latter, it is a bit more complicated. In fact, if we are going to have a block universe scenario, then as I said before, the emergence of this kind of "passage of mind" may be entirely unrelated to the issue of matter. But with that said, it is possible to view our changing experiences as the byproduct of having brain states in different parts of the block universe, especially if you take in entropy as a description for why our experience moves from t1 to t2.

 

[mangaroosh]

Just a question about the A-theory of time, and presentism in particular: I thought the concept was fairly well understood, but in a discussion on this site, it appears that it might not be that well understood.

I'm just looking for a fairly concise explanation of presentism. I would say that it is the idea that there is a single, universal present moment, common to all observers. I would see this as being incompatible with the relativity of simultaneity, which I think leads to the B-theory of time, and the idea that there is no single, universal present moment, but that the present moment is relative to each individual (although it can be shared).

I was also under the impression that Lorentz Ether Theory incorporates presentism, I'm just wondering if anyone knows if this is true or not?

p.s. I don't want to get into a philosophical discussion about the accuracy, or otherwise of LET, I'm just wondering if it incorporates the concept of presentism [as I outlined above]

 

[GeorgeDishman]

Just a question about the A-theory of time, and presentism in particular: I thought the concept was fairly well understood, but in a discussion on this site, it appears that it might not be that well understood.

I'm just looking for a fairly concise explanation of presentism. I would say that it is the idea that there is a single, universal present moment, common to all observers.

Presentism is the belief that only the present moment exists. This is a basic article on it:

http://en.wikipedia.org/wiki/Presentism_(philosophy_of_time )

This is more comprehensive and introduces relativity too:

http://plato.stanford.edu/entries/temporal-parts/

I would see this as being incompatible with the relativity of simultaneity,

From the SEP page:

"If STR thereby rules out presentism, and if endurantism requires presentism in order to explain change (see section 3), then STR rules out endurantism: things have temporal parts. But not all endurantists agree that they must be presentists, and not all presentists agree that their view is undermined by STR."​

which I think leads to the B-theory of time, and the idea that there is no single, universal present moment, but that the present moment is relative to each individual (although it can be shared).

This article should give you a clearer idea of the A and B theories:

http://www.iep.utm.edu/time/#H1

This is a paper on B-theory by Pruss which might also give you some background:

http://www9.georgetown.edu/faculty/ap85/papers/BTheory.html

I was also under the impression that Lorentz Ether Theory incorporates presentism, I'm just wondering if anyone knows if this is true or not?

What I suggested in the other forum was that it is difficult to start from a presentist philosphical approach and not be driven to an aether-style theory but the converse need not be true. It is possible for example to assume clock effects caused by an aether within the philosophy of a block universe, but much of the motivation for the block view is then removed.

p.s. I don't want to get into a philosophical discussion about the accuracy, or otherwise of LET, I'm just wondering if it incorporates the concept of presentism [as I outlined above]

The accuracy or otherwise of theories is not a philosophical topic anyway and would probably be inappropriate here.

 

[lmoh]

I'm just looking for a fairly concise explanation of presentism.

Presentism is basically the idea that only the present exists. However, what is meant by "present" can vary. The present moment may consist of a single moment in time or consist of multiple moments or an "extended present" (Luigi Acerbi advocated this earlier in the thread) for example, and if you want, you can even extend presentism to include something like the moving spotlight view (which George Dishman mentioned in the other thread).

I would see this as being incompatible with the relativity of simultaneity, which I think leads to the B-theory of time, and the idea that there is no single, universal present moment, but that the present moment is relative to each individual (although it can be shared).

I would not necessarily say that the B-theory would follow, and there are some people would follow me on that point as George . As for myself, I would at best say that it may suggest a block time, but that does not necessarily vindicate the B-theory, and I would still hold on to an A-theory for my own reasons mentioned earlier.

I was also under the impression that Lorentz Ether Theory incorporates presentism, I'm just wondering if anyone knows if this is true or not?

I would not necessarily say that LET incorporates presentism, but is compatible with it, just as SR does not necessarily rule out presentism (assuming that you can assume an undetectable present that is not the same as an ether theory). Scientific theories are indfferent on philosophical issues such as this.

The only person that I can recall that uses LET to support presentism is William Lane Craig, who opts for a "neo-lorentzian" interpretation (and he is the only person to do so apparently according to a paper I've read a while ago). I am not a fan of his work though, but you can look him up if you want.

 

[mangaroosh]

Presentism is basically the idea that only the present exists. However, what is meant by "present" can vary. The present moment may consist of a single moment in time or consist of multiple moments or an "extended present" (Luigi Acerbi advocated this earlier in the thread) for example, and if you want, you can even extend presentism to include something like the moving spotlight view (which George Dishman mentioned in the other thread).

Thanks for the reply lmoh.

That would be my own general understanding also, but with the added qualification that there is only one present, common to all observers.

I would not necessarily say that the B-theory would follow, and there are some people would follow me on that point as George . As for myself, I would at best say that it may suggest a block time, but that does not necessarily vindicate the B-theory, and I would still hold on to an A-theory for my own reasons mentioned earlier.

I suppose it depends on what is meant by RoS; if it refers to the mutual simultaneity and non-simultaneity of events, then I think it would have to lead to a B-theory, because it would mean that there is no universal present.

I would not necessarily say that LET incorporates presentism, but is compatible with it, just as SR does not necessarily rule out presentism (assuming that you can assume an undetectable present that is not the same as an ether theory). Scientific theories are indfferent on philosophical issues such as this.

I think it is a nice notion that scientific theories are indifferent on philosophical issues, but insofar as they are based on certain assumptions, they tacitly assume a philosophical position on certain specific issues.

LET appears to be founded on Newtonian assumptions about space and time, which was inherently presentism-friendly; while Einsteinian relativity doesn't appear to be presentism-friendly.

I don't mean to be facetious, but saying that SR doesn't necessarily rule out presentism, assuming that you can assume an undetectable present that is not the same as an ether theory, sounds a bit like saying, it doesn't rule out presentism as long as you can find an undetectable present that is compatible with SR.

If the above description of RoS is accurate, and SR incorporates it, then it is incompatible with the definition of presentism above.

The only person that I can recall that uses LET to support presentism is William Lane Craig, who opts for a "neo-lorentzian" interpretation (and he is the only person to do so apparently according to a paper I've read a while ago). I am not a fan of his work though, but you can look him up if you want.

I discovered as much, myself, after learning about LET on here, when trying to find out more about it. It is an unfortunate fact that it's WLC who happens to be trying to resurrect it, given his expressed motivation for doing so, but it might provide for healthy debate of the issue, to a certain extent that is.

 

[GeorgeDishman]

I would not necessarily say that the B-theory would follow, and there are some people would follow me on that point as George . As for myself, I would at best say that it may suggest a block time, but that does not necessarily vindicate the B-theory, and I would still hold on to an A-theory for my own reasons mentioned earlier.

I suppose it depends on what is meant by RoS; if it refers to the mutual simultaneity and non-simultaneity of events, then I think it would have to lead to a B-theory, because it would mean that there is no universal present.

As has been said many, many times, the term "relativity of simultaneity" comes from SR and in SR it refers to the consequences of clock synchronisation. Since clocks in reality behave in one particular fashion RoS must apply to any theory that accurately describes that behaviour regardless of any philosophy.

However, SR also has a geometric interpretation (often attributed to Minkowski rather than Einstein) which is also carried forward to GR. That interpretation describes a 4-dimensional hypervolume we call spacetime. Within that, there is nothing intrinsic which uniquely distinguishes the basis vector of time. Since a surface of uniform time (isotemporal?) would be perpendicular the time vector, it too cannot be physically meaningful, thus the geometric interpretation of SR which is fundamental to GR supports the B-theory (and 4-dimensionalism in particular).

The effect known as "relativity of simultaneity" is irrelevant from the philosophical perspective.

 

[petm1]

Since a surface of uniform time (isotemporal?) would be perpendicular the time vector,it too cannot be physically meaningful,

Isn't the surface of matter a surface of uniform time, with every point of its surface perpendicular to its center of mass? If the act of being re/emitted only happens in the present then it only happens at what I see as the surface of matter, when coupled with the sun as the spotlight looks more like A=series.

 

[GeorgeDishman]

Isn't the surface of matter a surface of uniform time,

No, I wasn't talking about matter at all. Are you perhaps thinking of the geoid defining the surface of the Earth being a surface of uniform gravitational potential?

with every point of its surface perpendicular to its center of mass?

The rotation of the planet makes it slightly oblate so, other than at the poles and equator, a perpendicular to the surface doesn't pass through the centre.

If the act of being re/emitted only happens in the present then it only happens at what I see as the surface of matter, when coupled with the sun as the spotlight looks more like A=series.

I have no idea what that is supposed to mean, sorry.

None of your comment appears to relate to foliation of spacetime.

 

[mangaroosh]

Are the A- and B-theories of time linked to any scientific theories?

The impression that I get is that B-theory is linked to Einsteinian relativity, or that it is compatible with it, while A-theory is not compatible with Einsteinian relativity.

 

[mangaroosh]

EDIT: I don't want to derail this thread into a discussion about RoS, so I will just reply to this one post and leave it at that.

As has been said many, many times, the term "relativity of simultaneity" comes from SR and in SR it refers to the consequences of clock synchronisation. Since clocks in reality behave in one particular fashion RoS must apply to any theory that accurately describes that behaviour regardless of any philosophy.

One of the consequences of that clock synchronisation appears to be that events that are simultaneous in one reference frame can be non-simultaneous in another; at least that is the definition that was supplied by some of the other posters on here. If that is the case, then it is incompatible with presentism, or the idea that there is a universal present, common to all observers, and therefore incompatible with the A-theory.

However, SR also has a geometric interpretation (often attributed to Minkowski rather than Einstein) which is also carried forward to GR. That interpretation describes a 4-dimensional hypervolume we call spacetime. Within that, there is nothing intrinsic which uniquely distinguishes the basis vector of time. Since a surface of uniform time (isotemporal?) would be perpendicular the time vector, it too cannot be physically meaningful, thus the geometric interpretation of SR which is fundamental to GR supports the B-theory (and 4-dimensionalism in particular).

The effect known as "relativity of simultaneity" is irrelevant from the philosophical perspective.

Again, if one of the consequences of the effect known as RoS is that events which are simultaneous in one reference frame are non-simultaneous in another - as mentioned by DaleSpam and Harrylin - then it preculedes the philosophical perspective of A-theory and favours B-theory.

 

[harrylin]

[..] One of the consequences of that clock synchronisation appears to be that [..] it is incompatible with presentism, or the idea that there is a universal present, common to all observers, and therefore incompatible with the A-theory.[..]

Quite to the contrary - the cited reference of the OP explains as one variant of the A-model:
"it can be plausibly argued that the theory [of relativity ] [..] has no bearing on whether there is such a phenomenon as absolute simultaneity."

Consistent with that (and despite the fact that I don't believe in a literal "flow of time"), I will now vote A.
A very hasty reading gives me the impression that I largely agree with Taggert, as I define time as being a measure of progress of physical processes - which implies change.

PS however, I now see that Taggert claimed that A is wrong, despite the fact that he largely agreed with my thinking; and like him I also hold that time doesn't really exist. And I definitely disagree with B. Thus perhaps I should change my vote to "other"?

 

[harrylin]

I now see that it's impossible to correct a vote; thus it's not a very good poll, regretfully. While I certainly disagree with B, I'm not sure that I fully agree with A.

 

[lmoh]

Consistent with that (and despite the fact that I don't believe in a literal "flow of time"), I will now vote A.

A very hasty reading gives me the impression that I largely agree with Taggert, as I define time as being a measure of progress of physical processes - which implies change.

If by "literal flow of time" you are referring to some substance called time that flows from past to future, then I essentially agree with what you are saying. For me, what you are saying sounds more like the issue of whether or not time or change is fundamental (you can refer to Section 2 of my orignal link for more info). Many (including myself) would argue the same that time cannot exist without change, that it is simply a measure of change, but I don't see how that matches up with McTaggert's thinking.

I now see that it's impossible to correct a vote; thus it's not a very good poll, regretfully. While I certainly disagree with B, I'm not sure that I fully agree with A.

Same here. I actually felt like changing my position to "A" from "I don't know" after some recent thought, but apparently I can't change my vote either.

 

[harrylin]

[..] Same here. I actually felt like changing my position to "A" from "I don't know" after some recent thought, but apparently I can't change my vote either.

Did you not create this poll? I guess that it depends on how the poll is set up...
Still it gives a very rough indication about how participants think about time; it appears that there is no clear majority view!

 

[GeorgeDishman]

Many (including myself) would argue the same that time cannot exist without change, that it is simply a measure of change, but I don't see how that matches up with McTaggert's thinking.

Do you think there is an aether which interacts with physical systems moving through it so that clocks (including radioactive decay) tick more slowly rather than the geometric explanation given by SR? If not, I may be able to give an example that sheds some light on the question.

It might be tomorrow, I have to go out soon.