I'm not sure we could make sense of our current scientific paradigms without special relativity. And as you've indicated, there have been experimental confirmations of it. However, the question of time isn't a closed one as scientific paradigms change over time. With new data come new hypotheses, eventually leading to new insights, new experiments, and new theories. I think that the nature of time has an appeal because it seems so intuitive. I mean, time is a measure of change, like you say, but if what it's measuring changes as well, it seems that time itself could change.

Are you looking for something more stable to measure with? Or, are you asking whether or not time is a valid measurement of change because time itself changes? If the latter, I think that's a good question. What is ultimately doing the measuring if time is changing, too? What is the standard? It seems there would need to be another reference point.

Hi Preston, Thank you for your response.

I want to figure out if the hypothesis that time is just the measurement of change is compatible with current science, and special relativity in particular.

What i mean with 'time is just the measurement of change', is that time does not literally exist. We do not see time, we see things changing, and at some point invented units to keep track of that change for our convenience. Just like we invented units (or a standard) for measuring distances. A mile for instance also doesn't literally exists, it's an abstraction, or a convention if you will, that allowed us to keep track of distances and communicate them better.

Time (a second, an hour, a day etc...) is the standard. It's not that time 'the units' (in this hypothesis) itself changes really, it's that the normally fixed intervals of jumping particles change under different circumstances (high speed and mass). We measure change by fixed (or so we thought) change essentially.

But that's not really a practical problem (it is for satellites apparantly), because we do not normally live in these circumstances. So i'm not looking for a more stable standard. I also don't think there would be one if einstein was right. I'm looking to do away with what might be a mistaken metaphysical notion of time, as a thing... and am wondering if that notion isn't the cause of some of the weird implication drawn from the theories of physics. Like Spacetime, and the block universe etc...

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

I am not sure I understand what tension you see here. So there are "things" that "literally exist" - what are those things? Tangible things that you see, touch, smell? And then anything that does not "literally exist" - it does not make sense at all? So relations, for example, do not make sense? But how do we make sense of the world without relations?

I'm looking to do away with what might be a mistaken metaphysical notion of time, as a thing... — ChatteringMonkey

What would "time as a thing" or conversely "time as not a thing" imply metaphysically or otherwise? What difference would drawing such a distinction make to anything?

We all understand that time is not a thing in the same way that cat or a mat are things, for example. But... what of it?

To be clear, I have no problem with abstractions or relations etc... they are usefull to be sure, as long as we don't forget they are abstractions.

What is the difference you ask? 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... Or the block-universe is another one, i just don't see how you get to the belief that all 'points in time' exist simultanuously without a notion of time as something real.

Anyway, i'm not a physicist, and it may very well be that i'm mistaken about how they view time, in fact I think it's very unlikely that I somehow have a better idea than all these smart people, that's why i'm asking.

To be clear, I have no problem with abstractions or relations etc... they are usefull to be sure, as long as we don't forget they are abstractions. — ChatteringMonkey

Well, anything we contemplate becomes an abstraction in our mind. This goes for "things" as well as not-"things".

What is the difference you ask? The idea of timetravel for instance is nonsensical if time is not real. — ChatteringMonkey

Why not? We travel forward in time, obviously, and that makes perfect sense. We also can orient and move in space in any directions, and space is just as "abstract" as time, isn't it? The question of why we cannot (easily) travel backwards in time both makes sense to ask and not trivial to answer.

Time is not changing. Time is the way change happens. That is, it is the geometry according to which change happens.

There is a conceptual disconnect between the way we measure time and the way we observe time, that nobody seems to notice. Time moves in one direction; to the future. Relativity may slow down or speed up time, but time is a vector that always moves forward. Time does not flow in a way that allow us to go back to the past, in any spontaneous way. That would require tools which are manmade.

With that being said, we measure time using clocks that are based on cycles, which is not how time moves. Clocks behave more like the nature of energy, instead of the observed nature of time. Energy is a wave that moves in cycles. Time is mono-directional, which is not how the clock behaves.

If we used a standard clock to measure time, the clock repeats 12 o'clock noon, each day. Time on the other hand, never returns to any original point, as do clocks. Measuring time with cyclic clocks is like measuring magnetic north with a thermometer. It requires an elaborate conceptual schema that does not always make sense due to the conceptual disconnect.

A known physical parameter that parallels the nature of time, better than energy, is entropy. The entropy of the universe has to increase. Entropy moves in the same way as time; one direction. A much better way to measure time would be an entropy clock. This is analogous to using a compass to measure magnetic north. It is straight forward.

An example of an entropy clock would be a dead fish clock. We place a fresh dead fish on the counter and when it starts to stink, that will be one unit of time. This is not a reversible clock, since we can't un-stink the dead fish and reuse it the next day in a cycle. Like an interval of universal time, it can only happen once and is done.

What is interesting about this dead fish entropy clock is we can speed up our unit of time; stink interval, by increasing the room temperature. Or we can slow down the uint of time, by cooling the room. With the entropy clock, temperature, which is connected to energy, works like relativity.

Since everyone knows time is mono directional, why did humans decide to measure time using tools that cycle and repeat like energy? It had to do with human productivity and money. If you were a caveman working in the stone wheel factory, the factory owner needs you to replicate your efforts each day; quality control. He does not want you to constantly reinvent and evolve the wheel each day, even if this is how time behaves. Using the cyclic clock to express time is not done for time, but for human needs; artificial and not natural.

Before civilization the caveman took each day as a new happening like the nature of time. Civilization require more budgeting of time so humans begins to notice cyclic patterns in day and night and time of the year, and position of the planets and stars, needed to be more productive. Science inherited this artificial time tradition.

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.

To be clear, I have no problem with abstractions or relations etc... they are usefull to be sure, as long as we don't forget they are abstractions. — ChatteringMonkey
Well, anything we contemplate becomes an abstraction in our mind. This goes for "things" as well as not-"things". — SophistiCat

Yeah, but things refer to something that exists (that we can percieve), and not-'things' do not. If you don't make a difference between the two, you are probably lost for this world.

What is the difference you ask? The idea of timetravel for instance is nonsensical if time is not real. — ChatteringMonkey
Why not? We travel forward in time, obviously, and that makes perfect sense. We also can orient and move in space in any directions, and space is just as "abstract" as time, isn't it? The question of why we cannot (easily) travel backwards in time both makes sense to ask and not trivial to answer. — SophistiCat

We do not travel forward in time, in the sense that is meant in timetravel, that is to some arbitrary point in the future.

We see distances in three dimensions, but we do not see time, we see change. It's not just as "abstract".

If we stick to what we see, and see time (an hour, a second,...) only as a measurement of change, travelling through time doesn't make a whole lot of sense because for travelling backwards in time that would entail that the whole universe changing back to some previous state. Travelling forward in time maybe would be somewhat easier to phantom, in that we could theoretical propel a human being to the speed of light or throw him into a black whole, and he would stop changing while the rest keeps changing at the same rate. But that's not really 'timetravel', but rather something like cryogenic sleep.

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.

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).

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

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

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

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.

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, I'm not an idealist, maybe i shouldn't have formulated it like that (eg what exist is what can be percieved). I do assume that there exist something out there regardless of me percieving it. It's just that the only access we have to that outside world is via the senses. 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. And additionally, figure out if we still need a notion like spacetime then... That's why i named the thread "SpaceTime?" (questionmark).

Not an expert here. My understanding is that time does not have to be a "thing" for matter to confirm to the second law of thermodynamics. Time is simply how we frame these changes in entropy. The 2nd law provides the reason a dropped egg will never reform, which is why backwards time travel is sketchy theory. Rate of speed may slow down the entropy of the moving objects, in relation to the slower moving objects, but entropy is always increasing?

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.

Relativity theory IS a non metaphysical theory, so it doesn't render an opinion on say what is real. — noAxioms

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

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.

noAxioms, thank you very much, that was exactly the kind of info i was looking for. It helped me a lot to clarify my position on this. Not a lot of people in more 'popular' media keep the science (only predictive value) and possible metaphysical implications seperate...

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. — noAxioms

Your "book" contains a very odd definition of metaphysics. Ontology is metaphysics, and ontology concerns what "is". Simultaneous is a statement about what "is". The special theory of relativity makes statements about the nature of simultaneity, therefore it makes statements about what is, and is clearly a metaphysical theory. Whether it "works", or has in your opinion been empirically proven, (as "empirical theory" is self-contradictory, by the way), is irrelevant.

Space-time has the same dimensions as energy; distance and time. Science convention uses an energy and wave analogy to measure time; cyclic waves, round clocks, vibrating atoms. However, time does not behave like energy wave, since time does not cycle, but moves in one direction, never to repeat itself like a wave. This is a big problem.

Time does not behave like a wave or anything that cycles. Although ancient religious conventions discusses rebirth after death, which is conceptually similar to an energy/wave clock. After midnight it is morning again. Religion may have started this time convention.

Time behaves more like entropy, which explains the association of time wth change. The entropy of the universe has to increase, it does not have to cycle. We should be measuring time with an entropy clock. I explain one such clock in my previous post. Time creates a series of unique states in the universe that is not a wave. The way you bridge the gap between an energy clock and entropy clock is to add a third axis to the energy clock to make it 3-D.

Picture a helix. In some respects a helix acts as a wave, but since it exists in 3-D, it never repeats itself exactly in 3-D, because it also moves along a z-axis that is not cyclic like x and y. Energy clocks look down the z-axis, so the z-axis is not seen. Instead we appear to see a circle that repeats itself. Time needs both the x,y and Z axis so even things that cycle in the short terms are part of larger term change that does not exactly repeat; unique set of variables for each instant in time.

In the dead fish clock; entropy clock, of my former post, each time interval uses a new dead fish, that starts fresh and ends when it stinks. The series of of such fish is the z-axis, with each fish, part of a common cyclic process, that is unique on the z-axis.

Rebirth symbolism in religions, shows the old man being born again as a new baby. However, the future path of this new baby is not the same as the previous cycle. Instead there is a new path, such as in reincarnation, Karma, heaven or Hell. This is 2-D energy/wave moving along a z-axis, with the z-axis conscious to the ancients. They were correct.

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.

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.

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.

As an example, say I had two rocket ships in the dead of space with a relative velocity V. If we only take into account space-time; distance and time, there is no preferred reference. The same velocity is seen from either ship. 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.

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.

Time has its own illusion in 2-D, compared to 3-D entropy clocks for time. Statistics tries to address the z-axis, as the changes that occur in real or future time, that did not occur on the last cycle of the 2-D clock. Statistics reflects time moving in the 3-D helix, when z is not seen by the clock.

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. — noAxioms

Exactly. There is a "local" test that can be made to determine which direction the arrow of space-time takes. In other words, it's all relative. I could actually be off-planet and still have the directions of space that you speak of. The directions would be relative to me, instead of the planet, with things above my head being up and below my feet being down. In other words, when talking about perspectives, there seems to be directions flowing away from the present perspective in both space and time. But what is spacetime absent any perspectives? Is spacetime a mental construction of a perspective? Does it really exist outside of our perspectives?

You can only measure space and time by comparing it to other shapes that occupy their own space (a ruler) and change (the rotation of the Earth) respectively. It's all relative and non-existent absent some perspective.

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.

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.

Is time an actual fabric, and not the human abstraction of events and change? I have not found a certain clarity in my studies of physics, but entropy is undoubtedly present. Heat, molecules, atoms, and objects typically become dispersed with forward time. Heat will rarely conglomerate within a body of water by random dispersion; it will be transferred throughout into equilibrium. To reverse time would be to observe teacups reassemble, foodstuff scents retract into their origin, and fallen objects travel upwards. There are definite laws of progression for our cosmos, but how should we define the temporal?

Abstractions are obstreperous to delineate. They are products of information assigned by human schematics, but what do they actually entail beyond our phanerons?

I have often been preoccupied by the fanciful notion of a plane or volume of time. While I think it impossible to comprehend such an abstraction, it provides an abundant fecundity for fiction.

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. — noAxioms

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

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.