Absolute motion

roosh

sbsquarepants wrote: »

Might be going slightly off topic here, but then the question arises of how thin the slices are. By that i mean how divisible is time, we know that matter is not infinitely divisible, you eventually get down to fundamental particles - we are almost certain we know what they are at this stage. It seems likely to me that if time is an actual physical thing, rather than a mere construct to help our minds make sense of our journey through the universe, then it would likely be constructed similarly, out of similar "lego" for want of a better word. If it can be infinitely divided, it's probably not a real physical "thing".

Also, definitely going off topic here, but if indeed, the future already exists, i assume that means it is set in stone, everything is already predetermined? I have already lived my life, died and so on, the "me" typing here just hasn't got to that particular stop on the cosmic bus route yet?

I can't decide if i find that comforting or depressing.:eek:

The block universe*, as described in the video below, does seem to imply predeterminism.

The issue of infinite divisibility arises, I think, when we try apply discrete units to something which is continuous. I don't think "moments" can have a duration, because every moment has to "flow" into the next one; there isn't any point at which one moment ends and the next one begins, it's just a continuous progression.

*The link in "block universe" jumps to the relevant part of the video on youtube; I don't know if it is possible to embed queued videos on here.

roosh

Morbert wrote: »

You're still chasing your own tail. You have also, again, strayed into a line of thinking that not even presentists would adopt. If it were an empirical issue, scientists would all be presentists. Scientists are not presentists.

<snip>

The same thing is happening that has happened before. You are ultimately repeating yourself. I am fine by that. If attrition is what is needed, then so be it. But new issues are popping up in parallel. So until we sort out the "empirical" issue above, I am putting aside the issue of interpreting the worldline. Once the above issue is sorted, we can return to it. Otherwise the thread will simply continue to branch into a fractal mess of issues.

The "empirical" issue is secondary, so it might be more prudent to proceed with the primary issue, that of how a block universe doesn't permit relative motion and should lead to a limited, frozen, experience of the 3D world. I will proffer a statement about it though.

Empiricism
All empirical evidence, all empirical experience, for every observer, occurs in the present moment; if no observer adopts the assumptions of an existent past and future, presentism is what is left.

If we start from this principle, that all evidence and experience occurs in the present moment of the observer, and we consider the evidence of constancy of light speed, without any assumptions, then the hidden dynamics is the conclusion we reach. Only when we adopt certain assumptions does the conclusion of hidden dynamics change, and the conclusion of co-existent past and future arise; conclusions which have to be assumed.

It might be worth noting that we don't need to assume presentism to begin with, the observer only needs to acknoweldge that all experience and evidence arises, for him, in his own present moment. If every observer does this, and doesn't adopt assumptions about the co-existence of past and future, presentism is what is left.


Frozen worldtubes
The issue still remains; as 3D manifestations on a, supposed, 4D worldtube, we only have "access" to a single "frame" or point on that worldtube; a point which corresponds to a certain reading on a clock; our experience of the 3D world should, therefore, not extend beyond that time; given the lack of moment to moment transition, or any other mechanism that could resolve the issue.

sbsquarepants

Morbert wrote: »

And a physical spacetime continuum would be no more difficult to divide than a number.

Sorry if i'm talking nonsense here, but i'm still trying to wrap my head around some of the concepts i've been reading about - i may well be mixing them up!
But, if space and time are not seperate entities, ie they are a conjoined entity - spacetime, and if as appears, space is not infinitely divisible, (the planck length seems to be some form of physical limit), surely then it wouldn't make sense for time to be.
If distances seperated by less than the planck length are effectively meaningless, ie they are at the same location in 3D space, times seperated by less than some equivalent measurement should be simultaeneous? No?

Ps - Roosh, thanks for the video. Will probably be the weekend before i get a chance to watch it though.

Morbert

roosh wrote: »

Empiricism
All empirical evidence, all empirical experience, for every observer, occurs in the present moment; if no observer adopts the assumptions of an existent past and future, presentism is what is left.

If we start from this principle, that all evidence and experience occurs in the present moment of the observer, and we consider the evidence of constancy of light speed, without any assumptions, then the hidden dynamics is the conclusion we reach. Only when we adopt certain assumptions does the conclusion of hidden dynamics change, and the conclusion of co-existent past and future arise; conclusions which have to be assumed.

It might be worth noting that we don't need to assume presentism to begin with, the observer only needs to acknoweldge that all experience and evidence arises, for him, in his own present moment. If every observer does this, and doesn't adopt assumptions about the co-existence of past and future, presentism is what is left.

You have assumed mysterious dynamics, as opposed to a hyperbolic spacetime, to explain the observations of the speed of light. That is no more philosophically compelling than assuming a hyperbolic spacetime, as opposed to mysterious dynamics, to explain observations. Both would generate the same predictions. Both postulate an explanation that is not directly observable.

roosh

Morbert wrote: »

You have assumed mysterious dynamics, as opposed to a hyperbolic spacetime, to explain the observations of the speed of light. That is no more philosophically compelling than assuming a hyperbolic spacetime, as opposed to mysterious dynamics, to explain observations. Both would generate the same predictions. Both postulate an explanation that is not directly observable.

We don't assume mysterious dynamics, again, mysterious dynamics is the conclusion we reach when we drop all other assumptions.

It might be helpful to start off by considering a universe where you are the only observer; all your experience occurs in the present moment, all empirical evidence gathered exists for you in the present moment. You measure the speed of light to be constant regardless of your motion relative to the source. The conclusion you reach is that there must be mysterious dynamics at play.

You meet another observer, who you experience in the present moment; the two of you share that present moment; even when the other observer starts moving relative to you, he is still manifest in your present moment.

If all you experience is the present moment, and you don't assume that your past and future co-exist, then you don't arrive at the conclusion of hyperbolic geometry. Only if you assume that your past and future co-exist can you arrive at the conclusion of hyperbolic geometry.


That is assuming hyperbolic geometry is incompatible with presentism.

Morbert

roosh wrote: »

We don't assume mysterious dynamics, again, mysterious dynamics is the conclusion we reach when we drop all other assumptions.

Once, twice, three times again:

We observe the present moment.
We observe that the speed of light is the same for both observers.

We can either:
a) Assume a Newtonian space, where the present moment is the same for all observers, regardless of their velocity relative to each other, and conclude hidden dynamics that conspire to make all our measurements of the speed of light constant. The conclusion and assumption can be swapped.

b) Assume a spacetime with a local Minkowski structure.

It might be helpful to start off by considering a universe where you are the only observer; all your experience occurs in the present moment, all empirical evidence gathered exists for you in the present moment. You measure the speed of light to be constant regardless of your motion relative to the source. The conclusion you reach is that there must be mysterious dynamics at play.

You meet another observer, who you experience in the present moment; the two of you share that present moment; even when the other observer starts moving relative to you, he is still manifest in your present moment.

If all you experience is the present moment, and you don't assume that your past and future co-exist, then you don't arrive at the conclusion of hyperbolic geometry. Only if you assume that your past and future co-exist can you arrive at the conclusion of hyperbolic geometry.

The statement in blue is an assumption. The two of you will disagree over the ordering of events unless you suppose hidden dynamics.

That is assuming hyperbolic geometry is incompatible with presentism.

The hidden dynamics are specifically postulated to make observations consistent with Newtonian, non-hyperbolic, kinematics. I.e. They are invoked to preserve the spatial assumptions of Newtonian mechanics that would otherwise be inconsistent with observation.

Morbert

sbsquarepants wrote: »

Sorry if i'm talking nonsense here, but i'm still trying to wrap my head around some of the concepts i've been reading about - i may well be mixing them up!
But, if space and time are not seperate entities, ie they are a conjoined entity - spacetime, and if as appears, space is not infinitely divisible, (the planck length seems to be some form of physical limit), surely then it wouldn't make sense for time to be.
If distances seperated by less than the planck length are effectively meaningless, ie they are at the same location in 3D space, times seperated by less than some equivalent measurement should be simultaeneous? No?

The question of whether or not space is infinitely divisible is where the debate currently rests. Quantum mechanics implies it is not a smooth manifold at all scales, but as it stands, every measurement we make, no matter how small, shows no sign of a non-smooth space. But then again, we have not made relevant measurements within the true planck regime. One of the latest articles: shows that space is still smooth at the planck scale, but says nothing about below the planck scale.

So you answer your question: Yes, if space is quantised then so is time. (Though it wouldn't mean times separated by less than some measurement are simultaneous. Rather, it would mean times smaller than some interval would be undefined.). But the jury is still out as to whether or not space is quantised.

roosh

Morbert wrote: »

Once, twice, three times again:

We observe the present moment.
We observe that the speed of light is the same for both observers.

We can either:
a) Assume a Newtonian space, where the present moment is the same for all observers, regardless of their velocity relative to each other, and conclude hidden dynamics that conspire to make all our measurements of the speed of light constant. The conclusion and assumption can be swapped.

b) Assume a spacetime with a local Minkowski structure.

And again, we don't have to assume that the present moment is the same for all observers, we only have to acknowledge that all our experience occurs in our present moment, that all empirical evidence we encounter occurs in our present moment. That is self-evidently true and requires zero assumptions.

Operating from this fact we then consider the constancy of the speed of light, without any assumptions, and the conclusion we arrive at is that there are dynamics at play that we don't yet understand.

Only if every observer adopts the assumption that their past and future co-exist with their present, can they arrive at the assumption of Minkowski spacetime. More accurately, the conclusion of Minkowski spacetime and co-existent past and future can only be supported if those conclusions are assumed.

If no observer makes those assumptions, then presentism is what is left.

Morbert wrote: »

The statement in blue is an assumption. The two of you will disagree over the ordering of events unless you suppose hidden dynamics.

If you and I are standing side by side, we are sharing the present moment; if we start moving relative to each other you will still be in my present moment, and I will still be in yours. We both still measure the speed of light to be constant; we both still only experience our own present moment. If we disagree over the ordering of events but don't assume that our past and future co-exist, we arrive at the conclusion of dynamics that we don't yet understand.

Morbert wrote: »

The hidden dynamics are specifically postulated to make observations consistent with Newtonian, non-hyperbolic, kinematics. I.e. They are invoked to preserve the spatial assumptions of Newtonian mechanics that would otherwise be inconsistent with observation.

So, if we have presentism does that mean we necessarily must have Newtownian mechanics + dynamics we don't yet understand?

If so, then it's simply the same issue; without the assumptions of a co-existent past and future we arrive at the conclusion of a set of dynamics we don't yet understand.

Masteroid

Morbert wrote: »

And the thermodynamic structure of the universe gives us awareness of events in one direction but not the other.

Thermodynamic?

But 'Thermodynamics' can explain both 'Time' and 'Entropy' in terms of a process of change, a change of order. Hot becomes cold simply because energy is dissipated, energy is the thing that moves at the speed of light, energy is the thing that gives rise to causality and determinism can explain 'now' without having a cubiverse that represents nothing more than the thermal arrangement at any given point in its process of change.

I understand that you are not even trying to make any ontological argument for your position but how can you use the term 'themodynamic structure of the universe' in an argument that is meant to rebut 'absolute motion'?

If absolute motion doesn't exist then why should the thermodynamic configuration of any time-slice vary from any other? Something must be communicated between the slices, things like momentum and inertia have to emerge from this model.

It does seem to me that your model can be reduced to one time-slice and determinism though and I think that's why I'm finding it difficult to understand the argument. Why can't there be a form of presentism that can be expanded and modeled as time-slices and vice-versa. Nothing ontological about that but a good model should be based on as few assumptions as possible.

And thermodynamics never seems to be violated except in either an illusory way or in a way that can be explained in terms of statistical small-scale phenomena.

The inverse square law seems pretty safe too.

So why not start with one thing, a perfect void say which contains all of space and assign it one property that produces a univers as we observe it and satisfies thermodynamics at the same time.

All we have to do is define 'perfect void' and make it conform to to a law through which physics (and meta-physics) will emerge.

And can't we keep infinity out of it whilst at the same time allowing eternal in? The big bang cannot be the first beginning of existence. The possibility of this universe existing must have existed when the universe did not.

And if absolute motion comes up then why not entertain it? Maybe the big bang was the origin of the known universe but if that was due to a collision, I'd want to know.

Morbert

roosh wrote: »

And again, we don't have to assume that the present moment is the same for all observers, we only have to acknowledge that all our experience occurs in our present moment, that all empirical evidence we encounter occurs in our present moment. That is self-evidently true and requires zero assumptions.

Operating from this fact we then consider the constancy of the speed of light, without any assumptions, and the conclusion we arrive at is that there are dynamics at play that we don't yet understand.

Only if every observer adopts the assumption that their past and future co-exist with their present, can they arrive at the assumption of Minkowski spacetime. More accurately, the conclusion of Minkowski spacetime and co-existent past and future can only be supported if those conclusions are assumed.

If no observer makes those assumptions, then presentism is what is left.

If you and I are standing side by side, we are sharing the present moment; if we start moving relative to each other you will still be in my present moment, and I will still be in yours. We both still measure the speed of light to be constant; we both still only experience our own present moment. If we disagree over the ordering of events but don't assume that our past and future co-exist, we arrive at the conclusion of dynamics that we don't yet understand.

If observers don't assume all observers share the same present moment, and they measure the speed of light to be the same, then they are in no way compelled to assume some hidden dynamics. They can conclude that the disagreement over the ordering is simply the case.

So, if we have presentism does that mean we necessarily must have Newtownian mechanics + dynamics we don't yet understand?

No. It would mean you have non-Newtonian dynamics + Newtonian spatial geometry. It is an inelegant mess of ideas to preserve the assumption that space is Newtonian, and that our intuition is accurate. Like the horrible mess of orbitals to preserve the idea that the Earth was the centre of the universe.

roosh

Morbert wrote: »

If observers don't assume all observers share the same present moment, and they measure the speed of light to be the same, then they are in no way compelled to assume some hidden dynamics. They can conclude that the disagreement over the ordering is simply the case.

As mentioned, you don't need to assume that all observers share the same present moment; every observer only needs to acknowledge that they, themselves, only ever experience the universe in the present moment, and that all empirical evidence is observed in the present moment. As long as no observer adopts the assumption that their past and/or future co-exists with their present, what you have is presentism. It's an absence of assumptions in a similar sense that Atheism is said to be the absense of a particular belief.

We know that all observers share our present moment; that is, all observers are present, with us, in our Now; when you and I are moving relative to each other, you are still in my present moment and I am still in yours. We might disagree over the timing of two events, but as long as we don't assume that our past and/or future are co-existent with our present, we conclude that hidden dynamics are at play.

Morbert wrote: »

No. It would mean you have non-Newtonian dynamics + Newtonian spatial geometry. It is an inelegant mess of ideas to preserve the assumption that space is Newtonian, and that our intuition is accurate. Like the horrible mess of orbitals to preserve the idea that the Earth was the centre of the universe.

As opposed to the elegance of circular reasoning that would force us to assume something exists, which we can't even investigate in theory, or a philosophical model which arguably doesn't allow for what we experience of the 3D world?

Morbert

roosh wrote: »

We know that all observers share our present moment.

No we don't.

As opposed to the elegance of circular reasoning that would force us to assume something exists, which we can't even investigate in theory, or a philosophical model which arguably doesn't allow for what we experience of the 3D world?

There is no circular reasoning. The spacetime interpretation predicts the same observations and experiences the dynamical interpretation predicts.

roosh

Morbert wrote: »

No we don't.

That statement was further qualified. It might be easier to consider just two observers in the universe; let's say myself and yourself; let's say we're moving relative to each other at 0.5c; you are in my present moment; that is, you are one of the things that makes up my present moment; I share that present moment with you; even if we assume spacetime, the 3D manifestation of you inhabits my Now slice, such that we share that moment. The same is true for you.

Nevertheless, the rest of the point stands; presentism simply requires observers to acknowledge that their experience is always in the present moment, and that other people occupy that present moment with them. As long as no observer assumes a co-existent past and future, then presentism is what is left. It is essentially, the absence of assumptions about co-existent past and future.

Morbert wrote: »

There is no circular reasoning. The spacetime interpretation predicts the same observations and experiences the dynamical interpretation predicts.

Except it requires the conclusion that past and future co-exist with the present; a conclusion which has to be assumed.

Morbert

roosh wrote: »

That statement was further qualified. It might be easier to consider just two observers in the universe; let's say myself and yourself; let's say we're moving relative to each other at 0.5c; you are in my present moment; that is, you are one of the things that makes up my present moment; I share that present moment with you; even if we assume spacetime, the 3D manifestation of you inhabits my Now slice, such that we share that moment. The same is true for you.

This is not what I mean by share present moment. The qualification you have tendered is irrelevant and (I would argue) misleading. By share the present moment, I mean all observers agree with what set of events are occurring simultaneously. I.e. They assume absolute simultaneity.

Nevertheless, the rest of the point stands; presentism simply requires observers to acknowledge that their experience is always in the present moment, and that other people occupy that present moment with them. As long as no observer assumes a co-existent past and future, then presentism is what is left. It is essentially, the absence of assumptions about co-existent past and future.

Except it requires the conclusion that past and future co-exist with the present; a conclusion which has to be assumed.

It requires observers to assume simultaneity is absolute.

roosh

Morbert wrote: »

This is not what I mean by share present moment. The qualification you have tendered is irrelevant and (I would argue) misleading.

I understand that's not what you meant, but that is what I meant, and I don't think it is irrelevant becuase it represents the actual scenario people find themselves in, and would find themselves in, even if we were moving relative to one another at speeds where relativistic effects become noticeable; you share your present moment with other observers regardless of whether you disagree over the simultaneity of events, or the age of the person you are sharing it with. I don't think it was misleading either, because it was qualified to clarify what it was that I meant.

It might be clearer to say that every observer shares their own present moment with other observers, that is, other observers are present in their now.

Morbert wrote: »

By share the present moment, I mean all observers agree with what set of events are occurring simultaneously. I.e. They assume absolute simultaneity.
...
It requires observers to assume simultaneity is absolute.

I'll take these two together because they relate to the same issue.

Firstly, if Relativity of Simultaneity is a key feature of Einsteinian relativity and relativity is compatible with both presentism and Minkowski spacetime, then RoS will occur in a presentist universe. It will just have a different interpretation.

Secondly, observers aren't required to assume absolute simultaneity, absolute simultaneity would be a natural consequence of presentism and the absence of assumptions about past and future.

If RoS occurs in a presentist universe, then observers would be disagreeing over the readings on a clock attributed to each event - even if it lead them to believe that the ordering was different. To arrive at the conclusion of Minkowski spacetime they would first have to assume that the clocks measure physical time and then they would have to assume that their past and future co-exist.

If neither observer makes the assumption about past and future, then what they have is presentism and the hidden dynamics explains the phenomenon of RoS, without the need to assume that the clock measures something physical called time.



But the question of empiricism doesn't address the issue of the incompatability of our experience, of the 3D world, with 4D spacetime and worldtubes.

Morbert

roosh wrote: »

I understand that's not what you meant, but that is what I meant, and I don't think it is irrelevant becuase it represents the actual scenario people find themselves in, and would find themselves in, even if we were moving relative to one another at speeds where relativistic effects become noticeable; you share your present moment with other observers regardless of whether you disagree over the simultaneity of events, or the age of the person you are sharing it with. I don't think it was misleading either, because it was qualified to clarify what it was that I meant.

It might be clearer to say that every observer shares their own present moment with other observers, that is, other observers are present in their now.

It is irrelevant to the discussion at hand.

We observe the present moment.
We observe that the speed of light is the same for both observers.

We can either:
a) Assume a Newtonian space, where the present moment is the same for all observers, regardless of their velocity relative to each other, and conclude hidden dynamics that conspire to make all our measurements of the speed of light constant. The conclusion and assumption can be swapped.

b) Assume a spacetime with a local Minkowski structure.

Not once did I mention the sharing you are discussing.

I'll take these two together because they relate to the same issue.

Firstly, if Relativity of Simultaneity is a key feature of Einsteinian relativity and relativity is compatible with both presentism and Minkowski spacetime, then RoS will occur in a presentist universe. It will just have a different interpretation.

Secondly, observers aren't required to assume absolute simultaneity, absolute simultaneity would be a natural consequence of presentism and the absence of assumptions about past and future.

If RoS occurs in a presentist universe, then observers would be disagreeing over the readings on a clock attributed to each event - even if it lead them to believe that the ordering was different. To arrive at the conclusion of Minkowski spacetime they would first have to assume that the clocks measure physical time and then they would have to assume that their past and future co-exist.

If neither observer makes the assumption about past and future, then what they have is presentism and the hidden dynamics explains the phenomenon of RoS, without the need to assume that the clock measures something physical called time.

You are still juggling assumptions. Now you are simply assuming presentism to conclude absolute simultaneity.

If neither observer makes the assumption about hidden ad hoc dynamics, then what they have is Einsteinian relativity.

But the question of empiricism doesn't address the issue of the incompatability of our experience, of the 3D world, with 4D spacetime and worldtubes

It is an incompatibility that you have by no means established, but has been eclipsed by your increasingly fringe positions on empiricism. You are not only at odds with philosophers who advocate a block universe, you are now wholly at odds with all scientists. Even those who adopt instrumentalist viewpoints.

roosh

Morbert wrote: »

It is irrelevant to the discussion at hand.
...
Not once did I mention the sharing you are discussing.

It's pertinent to the question at hand because it is true for both a presentist universe and a Minkowskian one; other observers, relatively moving or not, make up part of your present moment, and you make up part of theirs; that is, you share your present moment with others, and they share it with you. The issue is whether you both share the same present moment with each other. But we can look at you in your present moment and the observer you share it with and look at what the deduction would be if neither makes any assumptions about presentism, absolute simultaneity, or past and future.

Morbert wrote: »

We observe the present moment.
We observe that the speed of light is the same for both observers.

We can either:
a) Assume a Newtonian space, where the present moment is the same for all observers, regardless of their velocity relative to each other, and conclude hidden dynamics that conspire to make all our measurements of the speed of light constant. The conclusion and assumption can be swapped.

b) Assume a spacetime with a local Minkowski structure (assume that past and future co-exist with the present, even though we only ever experience the present, and assume that clocks measure physical time).
...
You are still juggling assumptions. Now you are simply assuming presentism to conclude absolute simultaneity.

Firstly, are a) and b) the only options? Would Julian Barbour's Platonia also be an option?

But, let's start with zero assumptions. Let's start with yourself and the fact that your experience of the universe is always in the present; let's say that there is an observer moving relative to you; that observer is present in your Now, he makes up part of your present moment. Now, don't assume that your present moment is the same as his, and don't assume that your past and future co-exist with your present. What you are left with is presentism, simply by virtue of not adopting the assumption of co-existent past and future. You haven't assumed presentism from the outset, that is, you haven't assumed that the present moment is the same for all observers, however, when you also don't assume that your past and future are co-existent with your present what you are left with is presentism, by default.

If you're left with presentism by default, then hidden dynamics is the conclusion.

Morbert wrote: »

If neither observer makes the assumption about hidden ad hoc dynamics, then what they have is Einsteinian relativity.

Is that strictly speaking true? Are there other theories, like Barbour's, which are also an option?

Hidden dynamics, however, isn't the assumption; the conclusion we arrive at, when we don't adopt assumptions is that there is a set of dynamics at play, that we don't yet understand.

Morbert wrote: »

It is an incompatibility that you have by no means established, but has been eclipsed by your increasingly fringe positions on empiricism. You are not only at odds with philosophers who advocate a block universe, you are now wholly at odds with all scientists. Even those who adopt instrumentalist viewpoints.

I think your initial expectation about my position on empiricism has coloured your interpretation, because I'm not sure how my position could be described as "fringe". My position is simply that all empirical observation and experience occurs in an observers present moment. If there are any philosophers or scientists who disagree with that position, then I would suggest they revisit their line of reasoning.


With regard to the issue of incompatability, some might say that the term "eclipse" and "avoid" could be used here, interchangably. While the contention might be that it is a position which has not been established, it is a position still awaiting refutation.

Morbert

You keep doing this. You keep arguing over tiny points that are entirely uncontroversial to everyone but you. So again, I must suspend the sub-issue we were discussing and focus once more on this tiny issue you have decided to blow up. I simply do not have the time to simultaneously address every contention you bring up that could be solved if you would simply slow down and think about what you are saying in your responses. Not only does this stifle the discussion, but it also removes any didactic qualities the thread might have for both you and any masochist that happens to still be reading.

roosh wrote: »

It's pertinent to the question at hand because it is true for both a presentist universe and a Minkowskian one; other observers, relatively moving or not, make up part of your present moment, and you make up part of theirs; that is, you share your present moment with others, and they share it with you. The issue is whether you both share the same present moment with each other. But we can look at you in your present moment and the observer you share it with and look at what the deduction would be if neither makes any assumptions about presentism, absolute simultaneity, or past and future.

<snip>

This issue is not whether we both "share the present moment" under the definition you supplied. It is not in any way pertinent to the question at hand. It is completely and utterly irrelevant. What is relevant is I explicitly said the issue is whether or not "the present moment is the same for all observers". I.e. Is the set of events that I call the present, the same as the set of events that you call the present. No experiment or observation suggests that they are necessarily the same. All we can say is that, for observers moving slowly, relative to each other (where "slowly" is defined as much less than the speed of light), absolute simultaneity is a sufficient approximation for most purposes.

Masteroid

Morbert wrote: »

This issue is not whether we both "share the present moment" under the definition you supplied. It is not in any way pertinent to the question at hand. It is completely and utterly irrelevant. What is relevant is I explicitly said the issue is whether or not "the present moment is the same for all observers". I.e. Is the set of events that I call the present, the same as the set of events that you call the present. No experiment or observation suggests that they are necessarily the same. All we can say is that, for observers moving slowly, relative to each other (where "slowly" is defined as much less than the speed of light), absolute simultaneity is a sufficient approximation for most purposes.

I think you are at cross-purposes here.

If we consider that every change in the configuration of the universe has an associated 'time-slice' then the entire history, and future, of the universe could (theoretically) be mapped out discretely.

Suppose we take the time-slice where roosh is observing the clock turn to and display 12:08 and you are observing roosh and the clock from a distance of one light-minute away. And suppose we were able to locate and analyse the set of events that correspond to you and roosh encoded by that time-slice.

Let's say that we can extrapolate the view of any observer. And let's say that you begin to observe roosh a few seconds before he observes the clock strike 12:08.

What I think roosh is getting at is, in that time-slice, as roosh sees the clock turn to 12:08, would you be observing 12:07 on the same clock?

So, in this particular time-slice we have a record of roosh saying, "Oh Sh...!" and a record of you saying, "Hey, it's roosh a minute ago!"

And for roosh as he says 'Oh Sh..!' it is 'now' and for you as you say 'Hey...' it is now. A shared now.

I think that what roosh is asking is, is this time-slice the same for all observers?

Are there any frames of reference where the time-slice that contains roosh saying 'Oh sh..' contains you not saying 'Hey, it's roosh...'?

Then take a time-slice from a minute later when you observe roosh's clock turn to 12:08. In that time-slice you say 'Oh Sh..!'; is there any frame of reference that can produce a time-slice where you say 'Oh sh..!' and where roosh has not been vaporised?

Morbert

Masteroid wrote: »

I think you are at cross-purposes here.

If we consider that every change in the configuration of the universe has an associated 'time-slice' then the entire history, and future, of the universe could (theoretically) be mapped out discretely.

Suppose we take the time-slice where roosh is observing the clock turn to and display 12:08 and you are observing roosh and the clock from a distance of one light-minute away. And suppose we were able to locate and analyse the set of events that correspond to you and roosh encoded by that time-slice.

Let's say that we can extrapolate the view of any observer. And let's say that you begin to observe roosh a few seconds before he observes the clock strike 12:08.

What I think roosh is getting at is, in that time-slice, as roosh sees the clock turn to 12:08, would you be observing 12:07 on the same clock?

So, in this particular time-slice we have a record of roosh saying, "Oh Sh...!" and a record of you saying, "Hey, it's roosh a minute ago!"

And for roosh as he says 'Oh Sh..!' it is 'now' and for you as you say 'Hey...' it is now. A shared now.

I think that what roosh is asking is, is this time-slice the same for all observers?

Are there any frames of reference where the time-slice that contains roosh saying 'Oh sh..' contains you not saying 'Hey, it's roosh...'?

Then take a time-slice from a minute later when you observe roosh's clock turn to 12:08. In that time-slice you say 'Oh Sh..!'; is there any frame of reference that can produce a time-slice where you say 'Oh sh..!' and where roosh has not been vaporised?

If I am stationary with respect to roosh, then we would agree with what is the present no matter how far away I was.

roosh

Morbert wrote: »

You keep doing this. You keep arguing over tiny points that are entirely uncontroversial to everyone but you. So again, I must suspend the sub-issue we were discussing and focus once more on this tiny issue you have decided to blow up. I simply do not have the time to simultaneously address every contention you bring up that could be solved if you would simply slow down and think about what you are saying in your responses. Not only does this stifle the discussion, but it also removes any didactic qualities the thread might have for both you and any masochist that happens to still be reading.



This issue is not whether we both "share the present moment" under the definition you supplied. It is not in any way pertinent to the question at hand. It is completely and utterly irrelevant. What is relevant is I explicitly said the issue is whether or not "the present moment is the same for all observers". I.e. Is the set of events that I call the present, the same as the set of events that you call the present. No experiment or observation suggests that they are necessarily the same. All we can say is that, for observers moving slowly, relative to each other (where "slowly" is defined as much less than the speed of light), absolute simultaneity is a sufficient approximation for most purposes.

Agreed, it is irrelevant.

It doesn't change the fact that presentism doesn't have to be assumed from the outset. An observer simply has to acknoweldge that their empirical experience and observations only ever occur in their present moment; they don't have to assume that their present moment is the same as everyone elses i.e. they don't have to assume presentism; when the assumptions about co-existent past and future are also not made, what is left is presentism.

Morbert

roosh wrote: »

Agreed, it is irrelevant.

It doesn't change the fact that presentism doesn't have to be assumed from the outset. An observer simply has to acknoweldge that their empirical experience and observations only ever occur in their present moment; they don't have to assume that their present moment is the same as everyone elses i.e. they don't have to assume presentism; when the assumptions about co-existent past and future are also not made, what is left is presentism.

Nobody is saying presentism has to be assumed from the outset. I explicitly said as much many times. I am instead saying that, if you want to conclude presentism, you have to make other assumptions. You have to suppose the disagreement between different observers over what events are occuring presently is down to undetectable dynamics.

roosh

Morbert wrote: »

Nobody is saying presentism has to be assumed from the outset. I explicitly said as much many times. I am instead saying that, if you want to conclude presentism, you have to make other assumptions. You have to suppose the disagreement between different observers over what events are occuring presently is down to undetectable dynamics.

Presentism doesn't have to be assumed, and neither do the hidden dynamics. As you were saying, if you have presentism then a set of dynamics that we don't yet understand goes hand in hand with it; equally, if we don't assume past and future then the conclusion we arrive at is a set of dynamics that we don't yet understand.

Again, all we need is for every observer to acknowledge that all of their empirical experiences and observations occur in the present moment; they also acknoweldge that their present moment is populated with other observers; as long as none of the observsers assumes a co-existent past and future, then the conclusion each of them reaches is a set of dynamics that they don't yet understand.

Morbert

roosh wrote: »

Presentism doesn't have to be assumed, and neither do the hidden dynamics. As you were saying, if you have presentism then a set of dynamics that we don't yet understand goes hand in hand with it; equally, if we don't assume past and future then the conclusion we arrive at is a set of dynamics that we don't yet understand.

Again, all we need is for every observer to acknowledge that all of their empirical experiences and observations occur in the present moment; they also acknoweldge that their present moment is populated with other observers; as long as none of the observsers assumes a co-existent past and future, then the conclusion each of them reaches is a set of dynamics that they don't yet understand.

No, that is categorically not all that is needed, because different observers will disagree over what constitutes the present moments. I.e. They will disagree over the simultaneity of events. They will disagree over the simultaneity of events because the speed of light is the same for all observers. They can either assume this is the case, or they can assume there are hidden dynamics which render their measurements illusory.

roosh

Morbert wrote: »

No, that is categorically not all that is needed, because different observers will disagree over what constitutes the present moments. I.e. They will disagree over the simultaneity of events. They will disagree over the simultaneity of events because the speed of light is the same for all observers. They can either assume this is the case, or they can assume there are hidden dynamics which render their measurements illusory.

The observers will disagree over the measurements, which will cause them to disagree over the order of events; each will say that the others clock is incorrect; but, if neither of them assumes a co-existent past and future then they can't conclude that Minkowski spacetime is the explanation.

If they don't assume a co-existent past and future, they are left with presentism and the conclusion that there are dynamics at play, which they don't yet understand.


Is the speed of light being the same for all observers an observation or an assumption?

Morbert

roosh wrote: »

The observers will disagree over the measurements, which will cause them to disagree over the order of events; each will say that the others clock is incorrect; but, if neither of them assumes a co-existent past and future then they can't conclude that Minkowski spacetime is the explanation.

If they don't assume a co-existent past and future, they are left with presentism and the conclusion that there are dynamics at play, which they don't yet understand.

And if neither of them assume there are dynamics working to make all their measurements of the speed of light the same, then they are left with the conclusion that past and future exist.

Is the speed of light being the same for all observers an observation or an assumption?

No.

roosh

Morbert wrote: »

And if neither of them assume there are dynamics working to make all their measurements of the speed of light the same, then they are left with the conclusion that past and future exist.

Again, this doesn't have to be assumed; it is the conclusion arrived at by, simply, not adopting any assumptions.

You start with the self-evident fact that all experiences and empirical observations occur in the present moment, for every observer. You take the observation of the constancy of c and you're left with the question of "how?", for which an explanation is required. Now, if the observers don't assume that the present moment is the same for everyone, they simply acknowledge their own experience occurs in the present, and if they don't assume that hidden dynamics are the cause, then they are still left with the question of how. If they don't adopt the assumption of past and future, then what is left is presentism and, by default, hidden dynamics.

Morbert wrote: »

No.

not an assumption I presume.

Morbert

roosh wrote: »

Again, this doesn't have to be assumed; it is the conclusion arrived at by, simply, not adopting any assumptions.

You start with the self-evident fact that all experiences and empirical observations occur in the present moment, for every observer. <snip>

That's not a self-evident fact.

roosh

Morbert wrote: »

That's not a self-evident fact.

All your experiences and observations occur in your present; all mine occur in my present; all X's occur in X's present; the same is true for all observers.

That is all that is required.

Morbert

roosh wrote: »

All your experiences and observations occur in your present; all mine occur in my present; all X's occur in X's present; the same is true for all observers.

That is all that is required.

That is not all that is required. Absolute simultaneity must also be assumed.