BTW, none of this directly relates to presentism, or A-theory as you call it. A preferred frame is not a preferred moment, even if a preferred moment seems to require a preferred foliation if not a frame. I know of no interpretation of QM or of relativity that asserts (or explicity denies) a preferred moment, although the presentist crowd does seem to congregate around absolute frame notational interpretations like Lorentz-ether-Theory, despite it not proposing a preferred moment in time.

Contrary to your claims, it would appear that preferred frames are the only the thing that saves nonlocal interpretations like Bohmian Mechanics from being refuted by the before-before experiment. This paper is very relevant to that. — Mr Bee

I got to the paper finally with the new link you provided. The term Leggett-like model is new to me. I don't see a description of before/before. I see it named, but not described. It interestingly defines a 'realism' as theories where 'results of observations are a consequence of pre-existing properties', i.e. cause before effect.

The article then goes on to describe relationships between measurements done by Alice and Bob respectively in space-like separated events, that only a preferred frame keeps the non-local influence time ordered.

Unfortunately, the before-before experiment (which I didn't see described) very much violates time-ordering since the effect measurement events by Alice and Bob are separated from the cause decision event by Victor in a time-like separation, not a space-like separation, and thus any proposed non-local influence is necessarily not going to be time ordered.

I'm not sure how Bohmian mechanics describes the before-before experiment. I thought it explained spooky-action through hidden variables, not through time ordered non-local influence, but I don't see how hidden variables can explain before-before.

It depends on what you mean by "support" then. If by the term you meant that you find that interpretation more useful as a practical tool for understanding QM, then that's one thing. — Mr Bee

QM is science, and not aided much at all with any interpretation. That is why a QM class will perhaps touch on the various interpretations, but not promote or dwell on one since none of them are QM. The "shut up and calculate" refers to this. Shut up about the interpretations, and calculate what QM theory actually says, because it made most amazingly accurate predictions right from the beginning. Interpretations are philosophy, and the QM class is not teaching philosophy.
I on the other hand am more interested in the philosophical implications of QM, so I don't shut up, and I have opinions, but recognize that my opinions are only that, and that different opinions are not wrong just because the differ with mine. Being an X-ist is not a denial of Y-ism.

However, if you mean that you believe in one interpretation being true, then if that interpretation is logically incompatible (as in mutually exclusive) with another interpretation, then you believe that other interpretation to be wrong.

Agree, so I think that when I say I'm an X-ist, it isn't a statement so strong as to say I assert it is true. Lacking any evidence, it would be a very poor thing to assert. So it remains a mere preference. If there was a way to actually know in the future, I would place my bets on certain views over others, and I suspect as probably many of us do that I would fare better than most in the horses I choose to back.
And I am also aware that there are horses that nobody has even suggested. Nobody would ever have suggested something as unintuitive as MWI before QM experiments forced the hand into a series of mutually unintuitive choices. The horses everybody chose back then were all proven wrong, but one of them still probably beat the others, even if they didn't win the race. So I'm more betting on my horses beating the other guy's horses, and not so much on them actually winning the race.
This is a pretty arrogant statement as I back some fairly unpopular horses.

MWI is effectively a special case of the Relational interpretation, as related only to the universe as a whole, or more specifically the big bang singularity event, so in a way, a subset of it. The only difference between the two would be that MWI would say the universal wave function is real, and Relational would say it is real in relation to the universe.

It should be viewable without download in the link provided. Just scroll down. — Mr Bee

Both chrome and IE show no page, just the download.

Just giving my own side thoughts about the relational interpretation since it was brought up and all.

OK, but your thoughts were only that it doesn't have collapse. It does.

I might say I support this interpretation, but you'd then say that means I find the other interpretations wrong, and I don't. So I am again agnostic by the way you explain above. To deny other interpretations is to deny that they are inconsistent with themselves. That they are inconsistent with my preferences is evidence of nothing if I have no empirical evidence that my preferences are correct.

I never said it was idealistic, just that it has a very idealistic tone to it since it makes everything observer dependent. I suppose the same problems I have with it are similar to that of the copenhagen interpretation. — Mr Bee

Neither of those interpretations require the observer to be a living thing. As I said, a rock will do.

You know that quote about the moon not being there where you're not looking at it? That's what first came to my mind.

It wouldn't be there if you had never looked at it, but it cannot be un-looked at. If you completely stop interacting with it (impossible), it would drop into a superposition of damn-likley existing, but possibly not. It's the moon. It isn't going anywhere. Both relational and copenhagen say this. Even if the moon by chance spontaneously decays into nonexistence, surely that would leave behind some energy wad that would still be the moon.

So it is. What I wanted to say was that I thought the copenhagen interpretation allowed for some observer independent states after collapse, unlike the relational interpretation, but that may not be correct.

Well, after collapse, no state is totally observer independent. Example would be nice I guess so I might comment on the different interpretations. We're getting kind of off-topic here.

And if you look at the paper I linked the author seems to suggest otherwise.

Cannot read it. It downloads a pdf with an unreadable font.

He brings up the problems with the preferred frame view (it's empirical unobservability, the free will problem), but he does not mention the lack of a time order which he considers to refute the other non-local views.

I'd have to look to see what you mean by that. Maybe you can find a more readable version.

Regardless, I still checked the citation list for the article to see what others thought of it (a habit of mine), and I found some objections (here is one of them) to the unpredictability argument that Tegmark promotes in his paper. Not sure what to make of it, but I'd thought I'd throw it out for people for those who do understand it to look at for themselves. — Mr Bee

A good habit to hunt down critique. Helps point out which parts on which focus should be placed. I do it myself for papers whether or not I agree with them. I'll try to look at that link closer, but a good deal of it is beyond me.

Tachyons, though weird, are not completely impossible from what I can tell but I have no idea how they work to say one way or the other.

I was actually more concerned with 1D life form, let alone one comprised of only stuff that can't go slow. But who am I to say that just because it is incomprehensibly different that coherent structures cannot form in it. 3D of time, whatever that means, is plenty of room for complexity. But I don't even follow the argument that only tachyons result.

If one is looking for a more practical definition of "life" then sure I am willing to grant that temporal persistence is necessary. But I wasn't trying to argue with those kinds of definitions.

I was thinking dynamics more than persistence. I cannot think of a single thing distinguishing life from non-life that doesn't involve dynamics (a reference to time).

My concern is with the possibility that we could, as conscious beings, be located on a single static moment of time.

That, if it were a being, would not be conscious. Yes, I had thought of Boltzmann brains when this was brought up, but even those have momentary dynamics. A Boltzmann brain is not a life form, even if it technically qualifies as conscious for a very brief duration.

Hmm, the relational interpretation sounds pretty idealistic to me. From what I've read it seems to suggest that there is nothing to the physical world other than our own observation of it.

Idealism has to do with relations to consciousness. The relational view, being non-anthropocentric, is relative to anything at all. A rock does fine, co-existing with the things with which it interacts. Hence no contradiction about how we came about before we gave existence to what was before us.

The only nearly anthropocentric QM interpretation I can find seems to be the Wigner one, which posits consciousness, but not necessarily human consciousness causing wave function collapse.

That is, there is no noumenon, no red ball in itself, since there is nothing to it if we are not looking at it.

Except for the 'we' part, yes. Look up the principle of counterfactual definiteness. It says that the red ball exists even unmeasured. More formally worded, "counterfactual definiteness (CFD) is the ability to speak "meaningfully" of the definiteness of the results of measurements that have not been performed (i.e., the ability to assume the existence of objects, and properties of objects, even when they have not been measured)". That's straight off the wiki page, my bold.

This goes further than the copenhagen interpretation since at least that view allows for the collapse of the wave function.

Relation interpretation has collapse. Collapse is what makes the red ball real. MWI does not have collapse.

I don't know what to make of that (especially since I am qualified to look into it more deeply), but with regards to the topic in the thread, it doesn't seem to undermine the concept of time as we traditionally define it.

It relates to the state of the universe in the block, but also in the flowing view. You're right, it doesn't really come into play until you start bringing up determinism, which can be asserted one way or the other with either view of time.

No, I don't think this is correct. Contrary to your claims, it would appear that preferred frames are the only the thing that saves nonlocal interpretations like Bohmian Mechanics from being refuted by the before-before experiment. This paper is very relevant to that.

Bohmian mechanics is not refuted by any experiment. I never claimed that. It just denies locality, and so allows effect before cause, as does any interpretation that denies locality. That makes the interpretaion invalid only if you assert otherwise.

Try this, which was the first item on my little google of it:
https://www.quora.com/If-there-are-3-physical-space-dimensions-why-arent-there-3-time-dimensions

That isn't what I'm asking for, but it does address the other concern that I had about why we should prefer a 3+1 Universe on anthropic reasons. I am assuming you're referring me to the first answer in the post, which references Tegmark, but if not then please direct me to the appropriate answer. — Mr Bee

I didn't even see that there were other answers. Yes, the first one.
I got that myself from Tegmarks book The Mathematical Universe which spends about 80% of its content explaining physics to the layman, and about 20% on the subject in the title. Part of that 80% uses that diagram and has the whole list of things that vary when selecting a tuning, and another list of things that don't.

You can also look at Tegmark's paper referenced at the top of that answer. It is 400 pages and I think only deals with the dimensionality aspect.

I don't think he actually demonstrates that life cannot work in a universe that does not contain one time dimension. In fact, the author seems to indicate that a world that contains 3 time dimensions and 1 space dimensions is possible, albeit very strange, for life.

The 'tachyons only' choice? You can publish that if you can think of a way for tachyons to interact coherently to be structure, let alone one that is a life form. The author Mauro seems to think so, but he omits Tegmarks commentary on that. I think Mauro is mistaking the condition for 3 space and 1 time, but everything moves faster than light, not slower.

Not a photo of a dog, but a state of a universe containing a real dog while it's alive. Perhaps one can debate whether or not a single instant is sufficient for life, but I see no reason why it doesn't.

I think it violates every attempt at a definition of life that I've seen. Perhaps you'd like to give one that would include this timeless configuration of state.

At least with respect to the Many-Worlds interpretation of Everett it would appear that the number of states that exist would be multiplied, since they would all be realized together.

So yes, can be thought of as one collective determined state. I call that soft determinism since the future measurement of some trivial experiment still cannot be predicted even given perfect knowledge of the system and infinite computing capability. It's determinism only because every possible result happens, and that list of results can be (and already is) computable. The relational interpretation is similar, but says the results that were not measured are not real (they didn't happen 'elsewhere'), and is therefore not a deterministic interpretation.

As for the Bohmian interpretation, I don't think that adopting non-locality would require rejecting causality, provided one introduce a preferred frame to preserve it.

No, there are quantum experiments that seemingly effect past measurements by decisions made in the future of those measurements. The before-before experiment is one of them. Only interpretations with locality explain that without reverse causation. A preferred frame helps not at all. The issue is not ambiguous ordering such as spooky action between two events outside each other's light cones. The issue here is blatant cause after effect between events that are within each other's light cones.

If you're an Eternalist then you think Presentism is wrong. That's what it means to be an Eternalist.

Fine. I'm an agnostic then, by the way you use the terms.

Note that first, I am not claiming to provide a proof of the A-theory, just an argument in it's favour.

Second, ...

Finally, third, your argument for the B-theory — Mr Bee

I said I wasn't arguing for it. Just comparing mostly.

How so? I'm curious to see you try.

I interpreted the comment wrong. I see what you're saying now.

It isn't a dimension at all if time flows. — noAxioms

Why? The Presentist (nor the A-theorist) again does not disagree with the representation of time as a linear series of events, so whether they all exist together or occur one by one is irrelevant. It wouldn't be a dimension like space of course but that is not to say that it cannot be described as a dimension at all.

The representation as a dimension would not reflect reality. Yes, it still can be useful to describe it that way.

Really? It seems very obvious that time is a series of events.

If there were no space, then yes, there would be just this linear series of events. But most pairs of events are ambiguously ordered (at least in the eternal model), so time would then not be a series of events. Time seems to be relevant only to causally related events, so time seem more to be a a product of a structure with causal relationships. That's how I tend to view it at least. YMMV.

The former has no slices, just a changing 3D state. The latter has a block with no slices other than abstracted considerations that can be oriented any way one chooses, similar to the way the 3D universe has no mandatory choice for the X axis. — noAxioms

As stated before, the Presentist would still agree that time can be described with the features mentioned above.

I would think not. If there is a present, it is an absolute state, however undetectable, and other abstract slices of the block are simply misrepresentations of reality. There is no arbitrary choice about it. An arbitrary guess if something preferred suggests itself, and yes, it does.
Maybe the present is some wrinkled wiggly thing. So long as it foliates a map of all events, it works.

As for Eternalism, the fact that, under relativity, we can slice spacetime up in practically an inifnite number of ways does not change the fact that no matter how we look at it (under any given slicing), that time is a series of 3D slices of space.

Well, you could slice across one of the other dimensions and get 2D space and 1D time.

Not sure about this. I've heard inflation being used as a way of solving the cosmological constant problem, but varying constants is not the same as varying dimensions of time.

There's a list of stuff that can vary, and a list that cannot. Yes, the cosmological constant is one, and the hardest one to get to a workable value if you're just pulling random values out of your arse. I guess that implies a lot of bubbles.

People have also spoken about the "dimensionality" varying between universes, but as far as I can tell, this "dimensionality" that people speak about as varying refers strictly to space, not time, which is what I am concerned about. Do you have a reference that says that the time dimension can vary across bubble universes?

Try this, which was the first item on my little google of it:
https://www.quora.com/If-there-are-3-physical-space-dimensions-why-arent-there-3-time-dimensions

The idea of a multiverse is still debatable (at least of the stronger forms involved here), but if there can be other universes that exist along our own that contain more than one time dimension (or none at all), then that would undermine the linearity feature of my argument.

Technically the bubbles relate, being part of one QM structure, so different worlds in one universe. But other bubbles have completely different physical laws (especially the classic laws), so most qualify them as other universes.

This just sounds plainly wrong to me. I don't see why life would require 3+1 dimensions in order to exist.

The article I linked gets into this.

For one, such an idea would falsify string theory on the basis that the latter requires alot more than 3 dimensions of space to even work,

Yes, but most of them not macroscopic. We're counting the macroscopic ones here.

I also fail to see why life would require a single dimension of time in order to operate. Although it isn't clear to me what it would exactly mean to say that there is more than one dimension to time I do not see what about it's nature would preclude conscious beings like us from existing in it.

I tried creating a simulation of that, and could only manage it with 1 space dimension.

With respect to a world that contains no time at all, the same reasoning applies. It could be that that some form of temporal solipsism is true, where one 3D slice of time exists and only that time, but that time can in theory describe a world where living animals and conscious beings such as us exist.

Makes no sense to me. You seem to describe a photo of a dog, which is not a living thing. It isn't life if there are no dynamics.

Don't see how quantum indeterminacy undermines or accounts for any of the features of time. A block universe with quantum indeterminacy (assuming that an indeterministic interpretation of QM is true) is still just as problematic as one that doesn't have it. Can you explain how it is relevant here?

Well, take the relational interpretation then, which has no meaningful state except as measured, and nothing measures the universe (the big bang is a point of view that sees nothing), so the universe has no state, just relations. Everett would say it has solutions to Schrodinger equations. Neither of those has meaningful state. The Bohmian interpretation has it (hard, single-outcome determinism), but it does so at the cost of cause before effect (locality). I personally find the latter more offensive, but that's just my taste.

I prefer the eternal model, but I don't assert that the presentist model is wrong. — noAxioms

Then you are a presentist then?

No, a presentist would not prefer the opposing model.

My assumption is that you're a firm eternalist, but in that case, you would believe that presentism is wrong.

I am a squishy eternalist. I only take firm stances against positions which don't seem self consistent.

In the philosophy of time, there are two major positions, the A-theory and the B-theory. The A-theory is often considered to be in line with the traditional view on time, where things change in accord with the passage of time and reality is dynamic. The B-theory on the other hand does not take the passage of time to be real at all and considers all events often taken to be past, present, and future, to be real in a static block universe. — Mr Bee

A terminology note. The A/B this is more correctly known as A-series and B-series, and they're not a philosophical stance, just a relative vs. more absolute way to speak of time.

The philosophical positions you are describing is presentism and eternalism, with the former asserting a flowing preferred moment in time separating all events into 3 distinct ontological states of happened, happening, and yet to happen. The latter gives equal ontological status to all events and disallows references to the nonexistent preferred moment.

Essentially I want to argue that the A-theory is better at accommodating certain features of time, those which seem to depict it time as flowing series of events, that would give reason to support it. — Mr Bee

It is certainly more practical, which is why A-series is used in everyday language and intuition. I can similarly argue that B-series gives a more practical framework in which physics can be discussed. But lacking an empirical distinction between the two, I don't see a proof being likely. Everyday life can be awkwardly described in B-series, and physics can be awkwardly described in A-series.

- History: The most defining feature of time is the fact that it describes the different states of the universe. If you were to take one slice of time and another, you would find that they contain the same matter and objects, just organized differently.

I can say the same with slices of space. The word 'history' carries an implication of a past, which is a presentist interpretation.

- Connectivity: There is a relation between adjacent times that we capture through the laws of nature. The slices of time and states of the universe are not just ordered arbitrarily, where each time is completely independent of the other, but they are connected together in specific ways (for instance, the state of the universe in 2018 would not be adjacent to a state very early in the universe's history in time).

Spacetime has connectivity yes. Calling them slices is from the eternalist interpretation. The presentist would only have the one current state of space, with no other 'slices' to connect with it.

- Linearity: We often talk about time as a line going from one end to the other. Unlike space, which contains three dimensions, time is one dimensional.

It isn't a dimension at all if time flows. 4D spacetime can have all four axes oriented arbitrarily, so yes, there's one time axis, but its orientation is arbitrary within the confines of the speed of light. Rotate beyond that, and a different axis assumes the role of the time axis. Fun factoid: This switching of roles of axes actually happens in black holes, which I think don't exist yet under presentism.

- Order: Under time there is also a preferred direction, which some refer to as the "arrow of time". We talk of events going from 2000 to 2001 but never the other way around.

Entropy defining the direction of the arrow. If entropy stabilizes, there would be no arrow.

It is these four features of time that I take to be better accounted for in the A-theory than in the B-theory. As far as I am aware of there is no explanation of why time is structured the way that it is in the latter.

Both account for it all just fine.

Why is time a series of slices depicting the history of the same 3D universe?

??? It isn't in either view. The former has no slices, just a changing 3D state. The latter has a block with no slices other than abstracted considerations that can be oriented any way one chooses, similar to the way the 3D universe has no mandatory choice for the X axis.

Why is there only one dimension of time and three (or more if we take string theory into account) of space?

From what I've read on inflation theory, this is chance. There are a lot of dimensions and some inflation bubbles have different numbers of macroscopic spatial and time dimensions. So maybe one bubble has 2 spatial and 3 time dimensions. Only the 3/1 configuration seems to allow the sort of physical mechanics that permits complex structures like atoms to form. Most of those strangely configured bubbles collapse immediately or explode into featureless fog. That 3/1 bit is part of a much longer list of tunings required to allow us to exist.

None of that answer really applies to presentism, which puts time outside the universe. There is no inflation theory under presentism that I know of, so the problems solved by it remain unsolved in the presentist view. The tuning problem is one of them.

Under the B-theory, all of the features seem to only be taken as a given in the block universe. It seems as though all events are simply laid out the way that they are with the relations between them, as a brute fact.

There is still quantum indeterminacy, so no brute fact implied by the block. A lot here depends on your quantum interpretation of choice. Hard determinism seems to be what you're describing here, and both time interpretations allow it but don't assert it.

If you're a B-theorist or at the least are actually familiar with the views, then I am interested in hearing from you.

I prefer the eternal model, but I don't assert that the presentist model is wrong.

I didn't mean it that literally, but rather like this: "Something which didn't come from anything has existed." I can't imagine what "coming from nothing" means if taken more literally, but I'd like to be helped by a description. — HuggetZukker

Much better. I came to the same conclusion, but then after a while even that seemed presumptuous to me, but that's just me.

I find an excellent model of the universe to be the set of all possible legal chess positions, which has 2D space, time, multi-world, deterministic, and entropy. Every state seems to be an effect of a prior cause (one move before), but to conclude that the initial state must have been caused would be an error. It didn't come from nothing, and it doesn't necessarily require platonic existence for it to be the set of all legal chess states.

Unlike our universe, it is very finite (8x8 discreet locations), finite discreet time (the longest possible chess game is about 10000 moves (counting each move, not each pair of moves as is normally recorded), but it is nicely illustrative of the sort of thing that we might be.

The argumentation goes:

If every effect has a preceding cause, as classical inquiry implies, there could have been no first cause, since it would constitute an uncaused effect, which contradicts the premise that every effect has a preceding cause. — HuggetZukker

Technically this doesn't follow. You would have to additionally posit that all causes are an effect of something else. It probably isn't unreasonable to do so, but it needs to be stated.

That said, there are known uncaused events like photon emission or radioactive decay. There are metaphysical interpretations that say there are hidden variables that make such events actually caused, if not predictable, but that is just one possible interpretation, sort of matching your option B below.

A) MOST effects have a cause, which always precedes the effect
B) Every effect has a cause, which USUALLY precedes the effect

Cause preceding effect requires the principle of locality, which is a different set of metaphysical interpretations than those that assert that all events are caused.

A) If there was uncaused cause then
...
4. Something has come from nothing.

This doesn't follow. It assumes that 'nothing' is the first uncaused cause.

C) If infinite things have happened then

Infinite things having happened doesn't imply infinite time. There are infinite events (no end to space), so only finite time is necessary for infinite things to happen. I'm suggesting that C be worded as just infinite (non-cyclic) past time.

3. The cosmos was infinitely sustainable in the past, since otherwise it would have collapsed by now.
4. The future cosmos should also be infinitely sustainable (and never-ending), unless the laws of nature, which sustained the infinite past, will some day go on a fatal strike for no obvious reason.

Any model of this needs to account for entropy. It defines the arrow of time, and something needs to reset it, or it doesn't describe the reality we see.

One has to wonder what a brain operation inside the Matrix entailed from the patient, since there is only a plug into the back of the neck, and not the machines opening up pods and doing actual brain surgery. — Marchesk

Well, the simulated brain could be kept in sync with the vatted one, which works most of the time. An aneurysm in the vat could be reflected in the body, but there are certain scenarios like the effects of high G forces that would make an accelerating brain behave (black out) very differently that the one in the vat. Concussion comes to mind. That is not just fake experience that can be fed to the organ in the vat.

Matrix movie, like all entertainment, is not science. It is founded upon unrealistic premises and works only because the writers make it so. For instance, one purpose of envatting people was to harvest their heat and electrical energy. Guess what... People consume energy, they don't generate it. Far more efficient to just burn whatever they're using to keep the bodies alive.

On a Denettian position, it's difficult to see how being envatted and experiencing a fake physical world is possible. And in fact, Dennett has denied this is actually possible, because he doesn't think a computer program can handle the combinatorial explosion of interacting with a fake physical world. — Marchesk

It is pretty easy to disprove a literal brain (a pink biological thing like in the pictures) in a vat scenario. Everybody would have two brains, one in the vat (in charge) and one in the body (epiphenomenal). Somebody would notice the difference that signals from the body one are severed abruptly at some point in the brain stem to be replaced with uncaused signals controlling the motor functions.
Defects would be a distinguishing point. Bob has an aneurysm in the vat and displays the physical symptoms of that, but doctors find a brain with nothing wrong with it. Sue on the other hand has an aneurysm in the body brain, and yet continues to function normally, even after doctors notice the event (for whatever reason).

I think the BIV idea is not meant to be taken literally like this. It means an experiencer of complete unknown properties being fed experience of this world and this physics, but not being envatted in a similar world. Dennett is correct that our physics is not up to the task of running such a fake experience stream, but we know nothing of the limitations of the reality with the vat, so Dennett's denial is baseless.

BIV is a model of dualism, and all the evidence for or against it is evidence for or against the other.

The problem for the BIV is that their perceptions are not of a physical world, but a mental one constructed by the false sensory and bodily impressions the vat is feeding the brain. So epistemologically, the BIV has no grounds for their position. — Marchesk

They do have grounds. They have their empirical evidence. Problem is, you not given any clue as to the nature of the false reality being fed to this actual brain in a physical vat. If it is a story about a physical world, then the brain has grounds for their position. If on the other hand it is fed experience of a non-physical world, then it would have no empirical grounds.

However, it's also true that the vat and the brain are made up of physical stuff. So our BIV physicalist, while admitting they could be envatted, could argue that mental states are still physical.

Assuming you are a BIV is not a physicalist position. You seem to say this yourself:

It can if one is a direct realist, because then you're perceiving the actual physical objects, instead of being aware of some mental intermediary. — Marchesk

OK, you call it a direct realist here, but that is more or less the physicalist position: that what one perceives is the stuff that we're made of. The physics of the empirical reality being fed to the BIV would need to be capable of producing a conscious observer for physicalism to be a defensible position.

Global warming is a nice example of the prisoner's dilemma, where cooperation gives the best outcome, but with a better personal outcome for ratting out your fellow humans.

Is there any valid interpretation of QM that asserts that the nature of the photon as it is emitted from the source is affected by the measurement that will eventually be taken of it? There might be. Experiments like before-before definitely show retrocausality under certain nonlocal interpretations.

Surely we can conclude time is real with 90% certainty? — Devans99

Proof of retrocausality would prove that time (an ontological distinction between past, present, and future) is not real, not the other way around. The experiment is no proof of retrocausality, just a demonstration of the nonlocality of some quantum interpretations.

OK, I think I understand what you are arguing now. You are saying that some metaphysicians such as presentists, claim that human beings experience the passing of time. Others. like eternalists claim that what human beings experience and call "the passing of time" , is not really the passing of time, it's something different. — Metaphysician Undercover

I wouldn't call all of them metaphysicians since most people have no idea that some of their assumptions fall under the category of metaphysics. I like to confine that word to those that have given the matter explicit thought, such as those on these forums.

Further, you have already claimed that there is something called "the passing of time", which physicists measure with clocks.

That was your claim. Mine was that clocks measure physical time (duration), and they do so accurately. Furthermore, I assume (cannot prove) that human experience is a physical (natural) process that measures time similar to clocks, so what we experience is physical time, not metaphysical time.

My opinion, is that this distinction you make is unwarranted. I think that what a metaphysician refers to as "the passing of time" is the exact same thing as what the physicist refers to as "the passing of time".

Yes, I've noticed this.

The two, the metaphysician, and the physicist, just utilize different measurement techniques, one the human experience, the other a physical clock. This is very clear from the fact that human beings synchronize their experience with the clock, in our day to day life. That the physicist employs a more accurate measurement technique than the metaphysician is irrelevant to the fact that the two are measuring the very same thing.

Agree that they're measuring the very same thing, but none of it is metaphysical. The interpretational difference (flow or not flow, 4D spacetime or 3D state that changes at some unitless rate) is undetectable, and the rate of that flow (if it exists) is undetectable since experience would be the same if the rate was halved, tripled, or there was no rate.

I think we are talking past each other. Sure, metaphysical time is an interpretation of empirical physical time. In that sense, they are the same thing. But experience and empirical tests are all the same thing, and none of that makes any difference to the various valid interpretations. If you think the 4D model would result in a different experience, then you don't understand it or the interpretation is invalid. If the universe changes in time, the rate of that change is inexpressible, let alone measurable. If the rate changed, no device or experience would detect that. That flow or the rate of it is nonexistent in eternalism, but is the thing that I refer to as metaphysical time.

That means there is no metaphysical time in eternalism. The phrase is simply a reference to an ontological addition made by a different view. Time is pure physical under eternalism, and is essentially a 4th dimension of a single structure that has no present state.
An eternalist would say time is real if the structure is real. Time has the same ontology as space.
A presentist would say time is real because there is a real current state of space.
Asking both if time is real results in them talking past each other, and I think we're doing that.

The train and diesel fuel example above, was not about sensing motion or acceleration. Rather it was about viewing two study state references after all the acceleration is done. Both parties go into the final references, blind to any energy balance. This allows both references can apply the relative reference assumption in good conscience. — wellwisher

Fine. The total energy and momentum is conserved in the frames of each of the observers, but they're not the same to each other.
A rock (as a sole existent) in a frame where it is stationary has zero total momentum, where in a different frame where it is moving, the same rock has nonzero momentum. Conservation of momentum is within one frame and does not mean that energy or momentum is the same in different frames. You seem to think otherwise. All this is Newtonian mechanics.

However, since a third party knows the energy conservation answer before the two references tell us what their reference appears to say, we have a way to prove if their assumptions are true or an illusion.[/quote]Wrong. The total energy was always different in the different frames. It changed in neither, since it is conserved.

If we did not know how much fuel was used such that the energy balance was left open ended, then the illusion would work.

Fuel consumption does not change total energy. It just changes form from chemical energy to kinetic energy and heat. Total energy is conserved in both frames, but was never the same in either frame.

The train and landscape may not be a good example, since rational common sense would say the landscape can't move, unless the entire earth was moved, which is unlikely due to the energy needed.

It doesn't take energy to move or even accelerate. It takes force. The Earth happens to move quite a bit with significant acceleration, all without expenditure of energy. The velocity of Earth is entirely dependent on the frame in which it is considered. Its acceleration is not frame dependent, and is about .06% of the acceleration of a dropped rock here on Earth.

When we look at the universe , we do not have an accurate energy balance. The idea of no preferred reference or center of the universe tells us that. We know the Conservation of energy applies, but we don't have a hard starting number.

We actually have a starting number for energy, which is zero. Gravitaional potential energy is negative, and it seems to exactly cancel out the positive energy. Total momentum also seems to be zero from any viewpoint or frame, which is unintuitive, but it follows from the universe being infinite, to which any finite adjustment for frame is meaningless.

Eternalism does not deny that the human subject experiences the passing of time. — Metaphysician Undercover

Since there is no passing of time, the eternalist denies that it is what is experienced. So closer to say that humans interpret their experience as the passage of time.

It just does not provide an explanation for this experience.

Natural physics explains this, not metaphysics. Biological creatures naturally interpret their experience as the passage of time, else they'd not be fit. The rational part might realize otherwise (as Einstein did).

So yes, I am serious. The interpretation is a metaphysical difference only, and has no implications for empirical experience. The experience in both views must be the same.

It is the capacity to understand and to describe time which matters, not the name.

Yes, and the above post makes me question that capacity. I'm not telling you that your interpretation is wrong, but you seem to think the alternate interpretation (if it were the case) would result in a different experience, and that points to a lack of capacity to understand, and to distinguish physics from metaphysics.

Let me expand on this to make my point. We start with these two references; train and landscape. I place a person in each reference. Before the experiment begins, I place each person in a seal container so they can't see or feel what I am about to do. — wellwisher

Newton's laws are enough for the acceleration concepts you are describing. Relativity doesn't seem to come into play at all. You are about to accelerate the train observer. He'll notice that from inside a box. It is a local effect.

I use 1000 gallons of diesel fuel to propel the train. This fuel defines our two reference system energy balance. Lastly, I let each person out of their sealed container and tell each to do an energy balance from the POV of their relative reference.

As I said, the kinetic energy observed (of everything except the train) was always the same from that post-acceleration inertial reference frame (IRF). An accelerated person is the thing that changed, and the thing that gained or lost kinetic energy in one IRF or another. The fuel represents entropy. It could be done with a hill without change of entropy.

The person who thinks the landscape is in relative motion will assume more energy was added than was in reality.

No. He detects the acceleration and knows it is himself that is now in a different IRF, one where the landscape was always moving. You can make him not know that (by sleeping say), but that just forces him to forget a knowable objective fact: that he is the thing that accelerated. There is no symmetry going on here.

It will take more than 1000 gallons of diesel fuel to move that mountain. He will add imaginary energy due to assuming reference is relative and no reference is preferred. The experiment was designed on an absolute hierarchy, since only the train gets the energy. The other is an illusion.

Well, momentum was transferred to the landscape per Newton's third law, in proportion to their relative masses. Momentum is conserved whether fuel or a hill is used to get things up to speed.

The part below is relevant to relativity, unlike the part above:

In the twin experiment, only the twin who was given motion, based on rocket fuel, shows permanent time dilation.

Due to acceleration, not due to motion (which is frame dependent, not absolute), and not due to fuel consumption, which can be avoided if different means are used like springs and trampolines and such. A frictionless clock pendulum ages slower than a stationary one, all without fuel consumption, and does so because it accelerates more than the non-swinging pendulum. To be precise, it is the moment of acceleration (acceleration times leverage distance) that determines the magnitude of the dilation. Two things can both accelerate equally but age differently if the moment is different.

I'm a metaphysician, and that's my business, to analyze metaphysical theories looking for strengths and weaknesses. — Metaphysician Undercover

So your username suggests.

You are saying that if time wasn't passing, we would still experience time in the exact same way that we do. Are you serious?

To be unaware of this view (or for that matter, the name of the view that you do hold) seems pretty inexcusable for someone who makes metaphysical interpretations (they're not theories) their business. Look up Eternalism. Spacetime is an eternalist model if you take it as metaphysical, which you seem to.

I was operating from SR at that point. In GR we don't have inertial frames, but there can be a preferred foliation, which serves the same function with respect to this conversation as an absolute frame that describes the correct order of events in the universe's history. — Mr Bee

Yes, agree.

The differences you describe appear to be purely conceptual. Under the 3D view, time dilation and length contraction is a real effect on moving objects whereas in the 4D view it arises from moving through space-time.

Yes, the differences are metaphysical, and the equations are not, so there is no need to perform them the difficult way like that unless you are computing metaphysical values for things like which point on Pluto is the center of the side that is objectively facing us right now, and even this is not computable without an unverifiable assumption that comoving foliation is the same foliation as 'the present'. The only evidence of that is that there seems to be only two choices available: That one or anything else.

Hmm, you have a reference for this? The best example that comes to mind is Galileo's proposed experiment which involved lanterns but not clocks.

That lantern thing was an early attempt, but yielded no results. They might have measured sound speed with such a setup, but the distances were too small for the limited precision of the timing methods.

The clock was the moons of Jupiter or Saturn, and the distance to that varied mostly from Earth moving back and forth every half year. You could see the eclipses down to almost the second, so it made a pretty good clock. Observations on the increased delay of those eclipses vs. distance yielded the first reasonably accurate light speed measurements. The difference could be over 15 minutes, well within the precision of the clocks of the day.

If we open the envelope and see £10 then we know that the other envelope contains either £5 or £20. By switching there's a 50% chance of losing £5 and a 50% chance of gaining £10. Switching seems like the better option. — Michael

Might as well just not even bother looking in the first envelope then, and pick the second one from the start. Looking at the contents seems not to affect this decision. This tells me it doesn't matter if you switch.

My solution is to switch only if the amount in the envelope is an odd number.

With the exception of the absolute frame measurements. — Mr Bee

Keep in mind that the absolute frame is not an inertial one, nor accelerated or anything else. All the things you can do with a frame are not valid even in this absolute non-frame.

Other than that, the rest will be distorted due to a certain degree and will have to be adjusted, but they will all find the speed of light to be constant.

I thought about it, and light speed is constant only in an absolute sense. Of course light speed is constant, just as is sound in a stationary medium. But if you are moving at 1/2c, delta real light speed in one direction is .5c, and it is 1.5c in the other. The subjective moving observer will not notice that since he's perhaps measuring round trip, not one direction.. So he puts a mirror 300000 km away (they have these), and it takes 0.666 real seconds one way and 2 seconds the other way, which is 2.66 seconds round trip. But his clock runs slow and the mirror appears to be 346000 km away, so it says 2.3 seconds have elapsed and hides the fact that light in one direction moved slower than the other way.
I probably screwed up the maths somewhere, but it was my shot at it. This is what I mean by more complicated to do it in 3D. In 4D, it is just 2.3 seconds for a 692000 round-trip with everything being stationary in its frame.

Interestingly, the first light speed measurements were done in one direction by putting a clock very far away and then syncing a local clock to our image of it as its light arrives here at (unknown at the time) lightspeed. Now you move that distant clock even further away and notice the amount that it gets out of sync. You move it closer again and it appears to catch back up. In this way, light speed was measured by dividing the increase in separation distance by the amount of time the two clocks appeared to get out of sync. No compensation for relativistic implications (all unknown at the time) of accelerating clocks, but good enough for the precision they were after.

I bring this up because it would again be an interesting exercise to express that one-way measurement in absolute terms.

Of course, if one assumes a preferred order of events, then every other order that people find in other reference frames will be considered false. — Mr Bee

And all measurements of time and distance are false as well only if you consider them to describe the 3D metaphysical interpretation.

But to my mind there is no difference in the scientific approach for someone who has different interpretations of relativity, which is what you seemed to have stated earlier. Like with QM, the equations remain the same regardless of your metaphysical views and the maths aren't any different.

That's right. The equations are scientific ones that describe what will be observed. The reality of the universe as 4D or 3D is a metaphysical difference with no empirical implications, so the equations describing empirical expectations need not change depending on your metaphysical view. The equations are not metaphysical.

The train thought experiments are a demonstration of the relativity of simultaneity, describing a situation where two or more observers have differing views on the ordering of events. The presentist version of this situation would certainly describe it differently, as it will take one or more of these observers as being incorrect in their assessments.

It is an interesting exercise to do just that. Assume that the train is the thing stationary, which helps one see past the bias that the platform is always the stationary thing. The platform observer detects the two events at once and is equidistant from the marks left by the events. Why is he wrong in concluding simultaneity?

To be clear, both the 3D and 4D interpretation use the same mathematical equations, so one approach mathematically isn't any more or less complex than the other. — Mr Bee

Well, those equations describe a 4D model, even if a 3D interpretation is assumed. To do it in 3D, each experiment must adjust for inaccuracies of measured mass, length and time since all these are dilated if one is moving. The train thought experiments assume a non-absolute definition of space, which is incorrect in the 3D model. Incorrect conclusions of event simultaneity are drawn.

Relativistic mass is rarely discussed in the same breath as space-time, even though it is 1/3 of Special Relativity. The result is a 2-D illusion called relative reference and/or no preferred reference. — wellwisher

I think I replied to most of this in my post 4 days ago.

The twin paradox tries to disguise this by using twins. Twins have the same mass, therefore kinetic energy and momentum will be the same for both references. This is how the system was gamed. If you use different masses, the energy conservation problem appears when you assume relative references and no preferred reference.

There is no suggested energy conservation in the hypothetical experiment. We have a rocket blasting energy and momentum all over the place. Are you attempting to deny the twin experiment? It is hard to tell, but you say 'how the system was gamed' like the description is faulty in some way.

However, we can't measure mass or relativistic mass, directly.
We have to infer rest mass from changes in energy; GR, with energy a relationship in distance and time, but not in mass.

Relativistic mass is a relational concept, not a property. Rest-mass is a property and can be directly measured. Not sure what you consider 'mass' to be if different from both rest mass and relativistic mass.

If the mass of the train and the mass of the train station are not the same, and we know how much energy; diesel fuel, was used to achieve this system motion, then you can infer who has to be moving and who has to be stationary.

No. This is just wrong. Mass comes not into play with the concepts being illustrated with this example. "Bigger-thing is the stationary one". Relativity does not support that.

A person on a train, looking out the window will appear to see the landscape moving at velocity V, If they assume they are stationary; train is stopped. It looks this way to the eyes but they just added energy to the universe, since the landscape what more mass.

They did not add kinetic energy to the universe. It was always there. The landscape/universe was always moving at V in that frame.

It is exactly this "constant local speed measurement" which makes SR a ,metaphysical assumption rather than empirically proven. It has only been empirically proven In "local speed" which is a very small portion of all possible speeds, yet it is claimed as a constant for all speeds. — Metaphysician Undercover

There is no 'local speed'. Local means 'inside a limited size box', like one drawn around the galaxy. They've tested small clocks moving at .98c and higher, just so you know.

Your post seems to attempt to throw doubt on SR, like it does indeed threaten your position. Interesting that you feel the need to attack it when you say it is a metaphysical theory.

The human capacity for observations of this is very limited. A large percentage of the various existing situations are not directly observable by a human being, and that light speed remains constant in these situations, is an assumption which is not empirically proven.

Again an attack, and dragging 'human' into it. You think light speed is different for humans than for other things?

Metaphysical time is the passing of time as we experience it, and this is what clocks measure.

Thing is, if time did not flow at all, we'd experience it exactly the same way. So what we are experiencing is not the metaphysical flow rate. You experience physical time, the same thing clocks measure. Your interpretation of that as flow is indeed a metaphysical interpretation, but relativity theory renders no opinion on which interpretation is correct. You seem to think otherwise as you seem to feel the need to cast it into doubt in your above posts, like there is empirical evidence against your view.

If clocks in relative motion do not measure time in the same way, then I suggest that people in relative motion do not experience time in the same way.

They both measure/experience physical time, and in the same way. Principle of relativity says you can't notice the dilation, but you would if you were experiencing a century of flow in only 10 years of high absolute speed travel. Indeed, nobody has tested this. It assumes that experience is a physical process, and you suggest it is a metaphysical process, that humans are metaphysically different than the rest of matter. Even your presentism doesn't assert this, but you seem to feel the need to add this to it. Yes, SR then would be a threat to your position.

So there is no difference between metaphysical time and physical time. The claimed "actual age of the universe" is calculated from principles and models. If the models are wrong, then so is the "actual age of the universe".

I'm not talking about the age of the universe from a point of view. I'm talking about the objective age of it, which doesn't exist except in some metaphysical views, my own not included.

Your problem is that you understand only one metaphysical interpretation and process all my comments with only that interpretation in mind, so you can't separate the parts that are different between the various metaphysical views. Einstein's work is compatible with both of them, and is thus not disproving one view or the other, but you don't see that because you don't see which parts are metaphysical differences. This would be easy if you understood the alternate view like Minkowski spacetime, the very concept that is the subject of this forum topic. That is a metaphysical view, and one that renders the relativity equations so much simpler, but relativity also works in a 3D model (at a massive expense of complexity) so doesn't assert those metaphyiscs. If it did, then yes, you are correct to attack relativity because it would indeed disprove your position. This is why I said that you have been empirically falsified when you said physical time is the same as metaphysical time.

As you don't seem to understand, let me explain why the special theory of relativity is metaphysical. Einstein took the existing theory of relativity, which was a metaphysical theory concerning motions, and adapted it to be applicable to the motion of light. The classical theory of relativity stated that all motions are relative, and this is a metaphysical principle which denies the possibility of absolute rest. — Metaphysician Undercover

A principle yes, more than a theory, and a local one at that. You putting a label of 'metaphysical' on everything doesn't make it thus.

In Einstein's day, there was a problem in applying this principle to the motion of light. Classical relativity theory did not appear to hold in relation to the motion of light. According to classical relativity theory, the speed of light relative to various objects moving in relation to each other would have to be variable according to the various different motions of the objects. So, Einstein proposed that the classical theory of relativity be adapted such that the speed of light be understood as constant relative to the various moving objects. This is "the special theory of relativity".

I think I object to 'be understood as'. SR was born of empirical evidence of constant local speed measurement, not an adjustment of understanding about it. The theory was a reaction to that evidence that did not fit current models. All of SR follows from constant light speed.

So, the classical theory of relativity, which was a metaphysical theory excluding the possibility of absolute rest, was seen to be incompatible with the motion of light.

The principle says the laws are the same in any frame, and thus no test can be devised to determine absolute rest. It never asserted the impossibility of it. There are always exceptions. Speed of sound in a particular medium is relativistic, but only locally. I can talk to the person ahead of me in a supersonic jet, but I cannot hear the aircraft behind us. Sound has a medium, and light was initially supposed to have one. SR threw that out, and GR sort of brought it back.

Instead of rejecting relativity as wrong, which is what the observations of the relations between the motions of light, and physical bodies did, it proved classical relativity to be wrong, Einstein proposed adapting relativity theory to allow that the speed of light remains constant relative to moving bodies.

Well, relative to stationary bodies. Light does not travel at c relative to a body that is moving in a given frame.

Prior to classical relativity, absolute rest, was the metaphysical principle employed. Classical relativity was proven wrong by the motion of light. Instead of returning to absolute rest as the metaphysical principle, it was replaced with the speed of light, as the assumed constant. Since these are each different fundamental ontological assumptions, absolute rest, and the constancy of the speed of light, which are taken for granted, depending on which one assumes, each is a metaphysical principle.

I disagree that there is any ontology asserted one way or another by any theories. Constant light speed is an observation, not an assumption, and GR shows that speed of something is undefined if not local, so light has speed different than c when not local, and depending on how speed is defined. Those definitions might indeed be metaphysics, but GR doesn't depend on them.

You asserted that metaphysical time is the same as physical time. The latter is that which is measured by clocks, but since clocks in relative motion do not measure the same value, they are not measuring metaphysical time (the actual age of the universe, a concept denied by spacetime metaphysical model). There is no device that can measure that. Best one can do is assume an objective foliation as perhaps suggested by GR and use that, but one still cannot express the unitless rate of it. If the universe suddenly aged at half the pace it did before, nothing physical could detect that change. That's why metaphysical time and physical time are not the same.

Very well then. Your metaphysical view of time is in direct conflict with TOR then. Your theory makes empirical predictions that have been falsified.

I didn't think it did, but you seem to insist.

Right, and that's clearly a metaphysical statement, just like the opposing claim that there is an absolute ordering of events is a metaphysical statement. Whether the ordering of events is frame dependent or not, is an issue concerning the nature of being, existence, and is therefore an ontological question, thus metaphysical — Metaphysician Undercover

You seem to be confusing physical time (the thing measured in seconds or years in any physics equation) with metaphysical time (the assertion of a present time (or alternatively, a lack of it), and the unitless rate at which it moves if it exists).

If these two (physical and metaphysical time) are the same thing and the theory of relativity is really a metaphysical statement as you say, then the theory of relativity (a century old empirical theory that is empirically put to the test every second of every day) is in conflict with your presentist metaphysical stance (a model that I claim makes no empirical predictions). One of them is wrong.
Fortunately, the theory of relativity makes no metaphysical claims, and your presentism is safe.

But what is spacetime absent any perspectives? Is spacetime a mental construction of a perspective? — Harry Hindu

Well that does seem to be a metaphysical question, and possibly doesn't have a correct answer even if it is unknowable. To me, spacetime seems not to be itself a thing that relates to other things, but is part of the relation itself between things that relate to each other in this universe. GR might have a good counter to this. If space is expanding and light has a speed relative to that space, then it is indeed a thing, despite it not being a thing under SR.
Fixed light speed is a local thing, and SR is a local theory and doesn't really apply to reality. Light very much does move at greater or less than c if not local, and that would not be true if spacetime was only a relation. So my feel for what it is needs an update.

One thing I noticed is space and time is always discussed when discussing SR. However, relativistic mass is rarely included in the discussion, even though it is part of the 3 part SR package. One may notice, SR is reduced to 2-D; space and time and not taught as 3-D; space, time and mass. This is the 2-D and 3-D clock problem in another guise. — wellwisher

SR is taught as 4D spacetime (one thing, not two separate things), but most of the examples (e.g. the train platform or barn-pole or twins 'paradoxs')are done in 2D spacetime (one each of space and time) to reduce the trigonometric overhead that is irrelevant to the points being made. Mass and length dilation are very much part of the teachings of SR. Gravity, acceleration, and non-locality are not part of the special case that is SR, and these topics are covered in GR teachings.

Relativistic mass is connected to an energy balance; relativistic kinetic energy, which tells us that all references are not relative, but rather they are absolute at some level. Unlike space and time, Mass is an invariant.

Kinetic energy is definitely not absolute. An object has none in the frame in which it is at rest. Mass is completely frame dependent. Rest-mass is not, but you didn't say that. Spacetime on the other hand is invariant. Any event is the same event in any frame.

As an example, say I had two rocket ships in the dead of space with a relative velocity V.
...
The same velocity is seen from either ship. — wellwisher

This cannot be. If rocket R1 has a velocity V relative to R2, then R2 has velocity -V (not V) relative to R1. Each ship does not observe the same velocity when measuring the other.

If we add mass, such as one ship has mass M and the other side has mass 2M, the energy balance is not the same in both references, even with the same relative velocity. Reference preference will double or half the total energy. The references are made distinct by their relativistic mass and energy balance due to the impact of a common 2-D relative variable, on two different 1-D invariants.

All this is ambiguous. Are you saying that one ship has twice the rest-mass of the other? No speed has been specified. For all I know, these ships are moving apart at a walking pace. So I cannot parse your example.

This can be proven by collisions and how the system responds to the recoil. The 2M ship will always punt the 1M ship if it has the velocity. There will always be an absolute hierarchy in the recoil response. Relative reference is an illusion due to using 2-D SR, instead of 3-D SR.

Seems to be some asymmetrical claim concerning momentum and such, but again I cannot parse what exactly you imagine going on. I imagine two billiard balls (with masses 1 and 2) in a collision, doing Newtonian sort of inertial momentum exchange without loss from friction, but perhaps at (unspecified) relativistic speeds. Yes, SR would be wrong if total energy or momentum was different before than after the collision.

Not a lot of people in more 'popular' media keep the science (only predictive value) and possible metaphysical implications seperate... — ChatteringMonkey

For example:

Simultaneous is a statement about what "is". — Metaphysician Undercover

No, it is just a way of relating two events. SR only says that the ordering of two non-causally related events is frame dependent. That is not a statement of what is. A statement that '7 is greater than 5' is not a metaphysical assertion despite the presence of the word 'is' in there.

Special relativity is a metaphysical theory. It renders an opinion on the reality of simultaneity. — Metaphysician Undercover

Nope. SR works whether simultaneity is real or not, or if actual simultaneity is objective or relative. SR is an empirical theory, which makes it non-metaphysics in my book.

If i'd have to put a label on my views, it would be materialism (what exists is the physical). I do try to refrain from metaphysics as much as possible. My goal in this thread was figuring out what kind of view of time physicist are assuming in special relativity, and if the theory is compatible with a non-metaphysical view on time. — ChatteringMonkey

Relativity theory IS a non metaphysical theory, so it doesn't render an opinion on say what is real. Like any scientific theory, it makes predictions about what to expect when observing the world, and that is not really metaphysics.
It is far easier to understand the mathematics behind it using the B-series (block universe) of time, but that is just an objective reference framework for spacetime, not a metaphysical assertion of what is real, or a scientific view that makes different predictions than does the A-series which has a present to reference.
I say all this because you ask how the physicists use it. Physicists may also each have a metaphysical opinion on the matter, but this opinion is not grounded on empirical falsifiability.

And additionally, figure out if we still need a notion like spacetime then... That's why i named the thread "SpaceTime?" (questionmark).

Yes, Minkowski spacetime is a 4-dimensional structure best described by B-series descriptions, and it is really hard to work with relativity if you have to convert to a different model. Everything is confusing and unintuitive in A-series, but is clean and symmetrical in B-series.

What is real to me is what can be percieved. I can see 'space', or rather i can see distances and objects in three dimensions. — ChatteringMonkey

I thought about this some more, and technically this is incorrect.

For any two points (events) in spacetime, there exists one or more inertial reference frames in which the separation between the two events is either pure spatial (simultaneous) or pure temporal (in the same place). From a given point of view reference event ('you', 'here', 'now'), the events that are perceivable are all of the kind that are pure temporal sort, meaning there exists a reference frame in which the perceived thing is at the same spatial location as the observation point. None of the pure spatially separated events are perceivable.

That means you can only see time, not space. The moon (spatially separated, but now) cannot be seen, only some past state of it when it was right here in that reference frame described above. If what is real is what is perceived, then the spatially distant moon (now, but not here) is not real, but the temporally separated moon (here, but not now) is the thing that is real.

Anyway, I don't buy into the idealistic definition of reality when discussing spacetime. It isn't an idealistic model.

noAxioms, there's a lot to consider in your posts, so let's start at the beginning.

What is real to me is what can be percieved. I can see 'space', or rather i can see distances and objects in three dimensions. I suppose space is real in that sense. — ChatteringMonkey

Well, you interpret it that way. You (here at a moment in time) can't see objects that are not here, only the light that reaches you from past objects, and only when that light gets 'here', just like you (now) don't experience times other than 'now'. Spacetime is more of a view-independent model that does not have a privileged here or now, so isn't particularly compatible with an idealistic definition of existence being dependent on perception.

What I've been discussing is the title of the thread (spacetime), not just space and yes also time, whatever it is, which is a different model.

The units we use to measure that, or x,y,z axis in geometry are abractions, these are not real. We invented those.

Yes The units to measure time are similarly abstractions.

So then why is time real? I have never seen time.

You can measure it, so isn't that perception of it? By your definition, it is real then. I cannot make a physical measurement of an abstract circle, so abstract circles are not real in that sense.

Also is defining the measurement of time as the measurement of temporal separation not merely a tautaulogy? I don't get it.

Yes, if you define time as temporal separation. That's what it means to be a definition. Different words for the same thing. You don't have to accept the definition. The flowing time model (with 3D space, no spacetime) would probably word the definition differently, but perhaps now.

In Minkowski Spacetime, space and time are the same thing, so seconds can be measured in meters if you choose. Two points in spacetime have a frame-independent separation, meaning the 'interval' between them is not subject to dilation when considered in different reference frames. This is mostly because a point in spacetime has no velocity since it does not move.

The idea of timetravel for instance is nonsensical if time is not real. We maybe don't believe it can be done practically, but we sure theorise about the possibility — ChatteringMonkey

Space is real, so time is real, but things don't 'travel' in spacetime. Take just space: A boat is 100 meters long, so does the boat travel for 100 meters? No, the whole thing just exists for 100 meters, and the point at the bow and the point at the stern are considered different points of the same boat. Likewise, I do not travel through time despite the fact that I exist in 2008. That younger-me is considered to be the same 'me' as the 2018 me, any only because of that designation is it said that I travel through time. Nothing actually 'moved' through spacetime to do that. The 2008 version of me cannot be elsewhere than 2008 any more than the bow of the boat can be at the stern (except the Titanic which attempted that feat).

Under spacetime, time is just another dimension and does not flow. It is exactly as real as space, so it is real if you consider space to be real.
As for the arrow of time, it is just like the arrow of space: There is indeed a local test that can be made to determine which direction is 'future' from a given point, so an arrow is defined. On any planet, there is an arrow of space for all three dimensions, with a clear direction for 'down' which can be determined with a plumb line, 'north' which can be determined by looking at the way the stuff in the sky rotates, and 'east' which is the remaining dimension. Out in deep space, these methods don't work, so there is no objective direction that is 'up' for instance. Perhaps away from the most influential gravitational force, which might be something like the great attractor if you're not particularly near any specific galaxy. Time would still have an arrow so long as there is work being done where your point of measurement takes place.

If time is just the measurement of change, and not some kind of 'thing' that literally exists, or that 'flows' or has an arrow or what have you.... would it still make sense in Einsteins special relativity? — ChatteringMonkey

Your title mentions spacetime, not time. Time is the same sort of thing as space, so if space is a measurement of separation, then so it time. It does not measure change since a slower process needs more time to produce the same change, but it would be the same time if it was a measurement of change.
So the spacetime concept (Minkowski spacetime) says that the measurement of time (not time itself) is a measurement of temporal separation just like the measurement of space is a measurement of spatial separation. Under spacetime, time and space are the same thing and can even share units.

And would there still be a need to fuse it together with space into spacetime to make the theory fit?

The above description is effectively fusing them together. The two are the same thing.

In special relativity high speed and mass influences time.

They do not influence time, but mass is a function of speed, and time is a component of a specification of a speed.

If time is a measurement of change, in special relativity this then would mean that high speed and mass influence the rate of change.

Yes, it influences the rate of change, but per what I said above, time is not a rate of change. An object does not have speed or velocity as a property, but only as a relation to an inertial frame. So the same object in its own inertial frame has normal mass and rate of change of any process. The rate of change is not a real property, and so isn't objectively different than the rate of change for an object of different velocity. SR says that given two objects moving at vastly different velocities, there is no local test that would determine that change is taking place faster or slower for one than for the other. This is a consequence of the principle of relativity which goes back to even before Galileo.